Search

Factors contributing to variations in the quality and microbiota of ensiled forages and in bulk tank microbiota in milk from cows fed different forages were investigated. Nutritional quality, fermentation parameters and hygiene quality of forage samples and corresponding bulk tank milk samples collected in 3 periods from 18 commercial farms located in northern Sweden were compared. Principal coordinates analysis revealed that the microbiota in forage and bulk milk, analyzed using 16S rRNA gene-based amplicon sequencing, were significantly different. The genera Lactobacillus , Weissella , and Leuconostoc dominated in forage samples, whereas Pseudomonas , Staphylococcus , and Streptococcus dominated in bulk milk samples. Forage quality and forage-associated microbiota were affected by ensiling method and by use of silage additive. Forages stored in bunker and tower silos (confounded with use of additive) were associated with higher levels of acetic and lactic acid and Lactobacillus. Forage ensiled as bales (confounded with no use of additive) was associated with higher DM content, water-soluble carbohydrate content, pH, yeast count, and the genera Weissella , Leuconostoc , and Enterococcus. For bulk tank milk samples, milking system was identified as the major factor affecting the microbiota and type of forage preservation had little effect. Analysis of common amplicon sequence variants (ASV) suggested that forage was not the major source of Lactobacillus found in bulk tank milk. The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. [ABSTRACT FROM AUTHOR]

Bacterial infections result in 7,700,000 deaths per year globally, with intracellular bacteria causing repeated and resistant infection. No drug is currently licenced for the treatment of intracellular bacteria. A new screening platform mimicking the host milieu has been established to explore phytochemical antibiotic adjuvants. Previously neglected isoprenylated flavonoids were found to be effective against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Specifically, the synergistic effect between glabrol and streptomycin against intracellular bacteria was observed for the first time. The glabrol-streptomycin combination targets bacterial inner membrane phospholipids, disrupts arginine biosynthesis, inhibits cell wall proteins and biofilm formation genes (agrA/B/C/D), and promotes ROS production, causing subsequent membrane and wall damage. To enhance the selective uptake of combination drug into infected cells, hyaluronic acid-streptomycin-lipoic acid-glabrol nanoparticles (HSLGS-S) were designed and synthesized to trigger the intracellular delivery of the glabrol-streptomycin combination. Thus, the treatment can be transported into the infected intracellular region and selectively release the glabrol-streptomycin combination to the bacterial at site. The bioactivity of HSLGS-S in clearing intracellular bacteria was 20-fold higher than that of the glabrol-streptomycin combination alone in vitro and 2- to 10-fold higher in vivo. [Display omitted] • A new screening platform to explore antibiotic adjuvants with the previously neglected phytochemicals. • Glabrol-streptomycin destroyed bacterial inner membrane, arginine biosynthesis, the cell wall proteins and biofilm formation. • HSLGS-S against intracellular MDR bacteria in vivo and in vitro. [ABSTRACT FROM AUTHOR]

To evaluate the effect of disposable cystoscopes on the rate of symptomatic urinary tract infections (UTI) following post-renal transplant cystoscopic stent removal. We performed a retrospective study of post-renal transplant cystoscopic stent removals in our outpatient clinic from March 2019 to March 2022. Our clinic converted to disposable cystoscopes in October 2021. All outpatient, phone, and portal encounters were reviewed for 30 days following the procedure. The primary outcome was the number of post-procedural symptomatic UTI within 30 days of the procedure. Symptomatic UTI was defined as fever, dysuria, or hematuria accompanied by a positive urine culture. A total of 323 patients had post-transplant stent removals including 123 with reusable scopes and 200 with disposable scopes. Around 1.6% (2/123) of patients with a reusable cystoscope experienced symptomatic UTI's. They had positive urine cultures for Escherichia coli and Klebsiella. 2.0% (4/200) of patients with a disposable cystoscopy had a symptomatic UTI. The 3 types of positive urine cultures they experienced were E Coli , Klebsiella, and Enterococcus. The conversion from reusable to disposable cystoscopes did not decrease symptomatic UTI following renal transplant stent removal. [ABSTRACT FROM AUTHOR]

Nocardioform placentitis is a poorly understood disease of equine late gestation. The presence of nocardioform, filamentous branching gram-positive bacteria, has been linked to the disease, with Crossiella equi , Amycolatopsis spp., and Streptomyces spp. being the most frequently identified bacteria. However, these bacteria are not found in all clinical cases in addition to being isolated from healthy, normal postpartum placentas. To better understand this form of placentitis, we analyzed the microbial composition in the equine placenta (chorioallantois) of both healthy postpartum (control; n = 11) and nocardioform-affected samples (n = 22) using 16S rDNA sequencing. We found a lower Shannon index in nocardioform samples, a higher Chao1 index in nocardioform samples, and a difference in beta diversity between control and nocardioform samples (p < 0.05), suggesting the presence of dysbiosis during the disease. In the majority of the NP samples (77 %), one of the following genera— Amycolatopsis , Crossiella , Lentzea , an unidentified member of the Pseudonocardiaceae family, Mycobacterium, or Enterococcus —represented over 70 % of the relative abundance. Overall, the data suggest that a broader spectrum of potential opportunistic pathogens could be involved in nocardioform placentitis, extending beyond the traditionally recognized bacteria, resulting in a similar histomorphological profile. • Non-nocardioform opportunistic pathogens may be associated with placentitis. • Nocardioform placentitis is associated with dysbiotic changes. • Nocardioform placentitis exhibits a unique microbial diversity distinct from control samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Culturable enterococci decreased at the thermophilic phase of sludge compost. • The proportion of VBNC enterococci increased at the thermophilic phase. • Extending the cooling phase of sludge compost reduced VBNC enterococci ratio. • Antibiotic-resistant enterococci were residual in the compost product. • Sludge compost products should be considered as a significant reservoir for ARGs. Sludge composting is a sludge resource utilization method that can reduce pollutants, such as pathogens. Enterococci are regarded as more reliable and conservative indicators of pathogen inactivation than fecal coliforms, which are typically used as indicators of fecal pollution. Non-spore pathogenic bacteria may enter a viable but non-culturable (VBNC) state during composting, leading to residual risk. The VBNC status of bacteria is related to their survival during composting. However, the survival mechanisms of enterococci during sludge composting remain unclear. Therefore, this study aimed to investigate the VBNC state of enterococci in different phases of simulated sludge composting and the fate of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) during the composting process. This study is expected to provide a basis for subsequent exploration of possible methods to completely inactivate enterococci and reduce ARGs during sludge composting. Culturable enterococci were reduced in the thermophilic phase of sludge composting, but the proportion of VBNC subpopulation increased. It was reported for the first time that most VBNC enterococci were killed by extending the cooling phase of sludge compost, and by prolonging the cooling phase the types of ARG were reduced. However, there was a certain quantity (approximately 104/g dry weight) of culturable and VBNC enterococci in the compost products. In addition, MGEs and ARGs exist in both bacteria and compost products, leading to the risk of spreading antibiotic-resistant bacteria and antibiotic resistance when sludge compost products are used. [ABSTRACT FROM AUTHOR]

Enterococcal Infective Endocarditis (EIE) is usually treated with the combination of penicillin/ampicillin with gentamicin or ampicillin with ceftriaxone. To enable prolonged outpatient treatment, a combination of benzylpenicillin and ceftriaxone has been suggested. This study aimed to describe the incidence and characteristics of EIE and to determine the outcome of EIE cases treated with benzylpenicillin and ceftriaxone. This was a retrospective single-center study including all patients diagnosed with infective endocarditis (IE) during 2016–2021, comparing EIE with IE caused by other pathogens. We described the outpatient treatment of patients with EIE, comparing those treated of benzylpenicillin - ceftriaxone with other regimes. Among 222 patients with IE, 44 (20%) were diagnosed with EIE. Those were older, had a male predominance (p = 0.035), and were more disabled (p = 0.004). The incidence of EIE reached 30% towards the last year, becoming the leading etiology. Twenty-six patients received outpatient treatment, five of whom were discharged with benzylpenicillin and ceftriaxone. Adding patients from this cohort to the scarce data available, revealed similar recurrence and mortality rates compared to other treatment regimes. EIE is becoming a more frequent cause of IE, involving older, more disabled patients with male predominance. Our experience and existing literature suggest that the combination of benzylpenicillin and ceftriaxone is as safe as more conventional regimes, although further research is needed. [ABSTRACT FROM AUTHOR]

To determine which bacteria are associated with an increased risk of 90-day complications after urethroplasty. Preoperative bacteriuria is associated with an increased risk of complications after urethroplasty. However, it remains unclear which specific micro-organisms are the primary drivers of this morbidity. A single-institution, 2-surgeon retrospective review was performed on patients undergoing urethroplasty from 08/2003 to 06/2021. Preoperative bacteriuria was considered significant when the patient had a mixed culture with ≥108 CFU/L or an identifiable micro-organism with ≥106 CFU/L. Descriptive statistics were used to summarize the results and chi-square was used to determine the association between 90-day complications (Clavien ≥2) and clinical characteristics/bacteria. Out of 1611 patients, 23.2% (373) had significant preoperative bacteriuria. The most common pathogens included coagulase-negative staphylococcus 18.5% (69), mixed growth 15.8% (59), Escherichia coli 10.7% (40), and Enterococcus 14.2% (53). 7.9% (128/1611) experienced a significant 90-day complication (Clavien-Dindo ≥2). Gram-negative bacilli including E coli, Pseudomonas sp, Klebsiella sp, Serratia sp, Citrobacter sp, Achromobacter sp, Stenotrophomonas sp, and Morganella sp were associated with higher rates of postoperative complications (14.2%; P =.01) as well as Enterococcus sp (15.1%; P =.03). However, gram-positive cocci (7.9%; P =.97), gram-positive bacilli (11.8%; P =.47), mixed growth (5.1%; P =.54) and Candida (16.7%; P =.27) were not. Neither escalating concentrations of bacteria (P =.44) or number of strains (P =.08) were associated with increased risk of complications. The main driver of bacteriuria-related complications after urethroplasty are gram-negative bacilli and Enterococcus sp. Patients with bacteriuria related to other micro-organisms can likely proceed with urethroplasty without increased risk of postoperative complications. [ABSTRACT FROM AUTHOR]

To prioritize healthcare investments, ranking of infections caused by antibiotic-resistant bacteria should be based on accurate incidence data. We performed a systematic review to estimate frequency measures of antimicrobial resistance for six key bacteria causing bloodstream infections (BSI) in European countries. We searched PubMed, Web of Science, Embase databases, and the ECRAID-Base Epidemiological-Network platform. We included studies and surveillance systems assessing resistance-percentage, prevalence, or incidence-density of BSI because of carbapenem-resistant Pseudomonas aeruginosa , Acinetobacter baumannii , Klebsiella pneumoniae , and Escherichia coli , third-generation cephalosporins-resistant E. coli and K. pneumoniae , vancomycin-resistant Enterococcus faecium , and methicillin-resistant Staphylococcus aureus. Reviewers independently assessed published data and evaluated study quality with the modified Joanna Briggs Institute critical appraisal tool. Pooled estimates were determined using random effects meta-analysis. Consistency of data was assessed using random effects meta-regression (Wald test, p > 0.05). We identified 271 studies and 52 surveillance systems from 32 European countries. Forty-five studies (16%) reported on BSI, including 180 frequency measures most commonly as resistance-percentage (88, 48.9%). Among 309 frequency measures extracted from 24 (46%) surveillance systems, 278 (89%) were resistance-percentages. Frequency measures of methicillin-resistant S. aureus and vancomycin-resistant E. faecium BSI were more frequently reported from Southern Europe and Western Europe (80%), whereas carbapenem-resistant P. aeruginosa BSI from Northern Europe and Western Europe (88%). Highest resistance-percentages were detected for carbapenem-resistant A. baumannii (66% in Central Eastern Europe) and carbapenem-resistant K. pneumoniae (62.8% in Southern Europe). Pooled estimates showed lower resistance-percentages in community versus healthcare-associated infections and in children versus adults. Estimates from studies and surveillance systems were mostly consistent among European regions. The included data was of medium quality. Pathogen-specific frequency measures of antimicrobial resistance in BSI are insufficient to inform antibiotic stewardship and research and development strategies. Improving data collection and standardization of frequency measures is urgently needed. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance in the laying hen production industry has become a serious public health problem. The antimicrobial resistance and phylogenetic relationships of the common conditional pathogen Enterococcus along the laying hen production chain have not been systematically clarified. 105 Enterococcus isolates were obtained from 115 environmental samples (air, dust, feces, flies, sewage, and soil) collected along the laying hen production chain (breeding chicken, chick, young chicken, and commercial laying hen). These Enterococcus isolates exhibited resistance to some clinically relevant antibiotics, such as tetracycline (92.4%), streptomycin (92.4%), and erythromycin (91.4%), and all strains had multidrug resistance phenotypes. Whole genome sequencing characterized 29 acquired antibiotic resistance genes (ARGs) that conferred resistance to 11 classes of antibiotics in 51 pleuromutilin-resistant Enterococcus isolates, and lsa(E) , which mediates resistance to pleuromutilins, always co-occurred with lnu(B). Alignments with the Mobile Genetic Elements database identified four transposons (Tn554, Tn558, Tn6261, and Tn6674) with several ARGs (erm(A), ant(9)-la, fex(A) , and optrA) that mediated resistance to many clinically important antibiotics. Moreover, we identified two new transposons that carried ARGs in the Tn554 family designated as Tn7508 and Tn7492. A complementary approach based on conventional multi-locus sequence typing and whole genome single nucleotide polymorphism analysis showed that phylogenetically related pleuromutilin-resistant Enterococcus isolates were widely distributed in various environments on different production farms. Our results indicate that environmental contamination by antimicrobial-resistant Enterococcus requires greater attention, and they highlight the risk of pleuromutilin-resistant Enterococcus and ARGs disseminating along the laying hen production chain, thereby warranting effective disinfection. [Display omitted] [ABSTRACT FROM AUTHOR]

Bacterial infections are common after liver transplantation (LT) and cause serious morbidity and mortality. In our center, prolonged selective digestive decontamination (SDD) is the standard of care, which may lead to a reduced number and severity of bacterial infections. The aim of the current study was to investigate bacterial infection rates, the causative pathogens, localization, and the possible influence of SDD within the first year after LT. A retrospective single-center cohort study was performed. Patients within their first year after LT between 2012 and 2017 were included. Patients received SDD for 3 weeks immediately after LT. The type of infection, bacterial subtype, CSI classification, severity, and potential interventions were recorded. One hundred eighty-six patients were included in the study. Seventy-eight patients (41.9%) had a bacterial infection within the first year after LT. The most common types of infection were cholangitis (25.8%) and secondary infected abdominal fluid collections (25.3%). The most common bacteria were Gram-positive enterococcal- (36.5%) and Gram-negative enterobacterial species (34.2%). 35.5% of the infections occurred within the first month after LT, mainly caused by Gram-positive bacteria (76.7%). Cholangitis and infected abdominal fluid are the most common types of infection within one year after LT, mainly caused by enterococcal- and enterobacterial species. Within the first month after LT, infections were mostly caused by Gram-positive bacteria, which could be a consequence of protocol use of SDD. The results can be used for the choice of empirical antibiotic therapy based on the most common types of bacteria and the time frame after LT. [ABSTRACT FROM AUTHOR]

Enterococcus faecalis is the most common enterococcal species associated with infective endocarditis and 1 of the most commonly detected bacteria in cases of secondary/persistent endodontic infection (SPEI). Antimicrobial resistance is a global public health concern. This review aimed to answer the following research question: "Is there a change in the antibiotic resistance profile in clinical strains of E. faecalis over the years?". P (population) - patients with SPEI, I (intervention) –endodontic retreatment, C (comparison) -not included, O (outcome) - profile of Enterococci resistance and susceptibility to systemic antibiotics used. Two authors independently performed study selection, data extraction, and risk of bias assessment. The literature search was conducted using the following electronic databases: PubMed, Scopus, EMBASE, Web of Science, and Medline. Clinical studies in which Enterococci strains were isolated to assess their antimicrobial resistance were included. Eleven clinical trials were included. Overall, E. faecalis isolated from teeth with SPEI presented an intermediate resistance to 16 antibiotics. In recent years, E. faecalis showed a little resistance to amoxicillin (without clavulanate) and benzylpenicillin. Erythromycin and rifampicin presented an increase in the intermediate-resistance status between the first and the last studies. E. faecium presented intermediate-resistance results. The most effective drugs remain the combination of amoxicillin and clavulanate, followed by amoxicillin and benzylpenicillin. In patients allergic to penicillin derivatives, moxifloxacin and azithromycin may be indicated with caution. The antibiotics with the highest pattern of resistance against E. faecalis are clindamycin, gentamicin, metronidazole, and rifampicin and are therefore, contraindicated in cases of SPEI. Very few clinical studies using a microbiological approach in teeth with endodontic failure have been carried out to improve the efficacy of prophylactic regimens. However, as bacteria periodically develop resistance to the main drugs used, regular studies should be carried out on the action of these drugs in infection control. [ABSTRACT FROM AUTHOR]

Enterococci facilitate polymicrobial infections, leading to more complicated pathogenesis and poorer prognoses, and compromise the efficacy of antimicrobial agents by promoting the colonization, proliferation, and persistence of diverse pathogenic bacteria. The elucidation of synergistic interactions between enterococci and pathogens is expected to accelerate the discovery and development of novel therapies against polymicrobial infections. Multitargeted or combinatorial therapies provide promising alternative strategies to treat polymicrobial infections by simultaneously targeting pathogens and enterococci, thereby mitigating or eliminating both the causative agents and pathobionts. Enterococci are ubiquitous members of the gut microbiota in human beings and animals and are among the most important nosocomial organisms. Due to their opportunistic pathogenicity, enterococci are referred to as pathobionts and play decisive roles in a diverse array of polymicrobial infections. Enterococci can promote the colonization, pathogenesis, and persistence of various pathogens, compromise the efficacy of drugs, and pose a severe threat to public health. Most current treatments tend to focus on the sole pathogenic bacteria, with insufficient attention to the driving role of enterococci. In this review, we summarize the characteristics of enterococci in infections, the factors facilitating their outgrowth, as well as the sites and types of enterococci-associated polymicrobial infections. We present an overview of the underlying mechanisms of enterococci-mediated pathogenesis in polymicrobial infections. Furthermore, we discuss alternative strategies and potential intervention approaches to restrict such infections, shedding light on the discovery and development of new therapies against polymicrobial infections. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a growing worldwide public health issue due to the overuse and inappropriate use of antibiotics. AMR has been more prevalent during the coronavirus pandemic of 2019 (COVID-19) compared to previous periods. Therefore, this study was conducted to evaluate the AMR profile of common bacteria that were isolated for routine analysis during the pandemic of COVID-19 in Central Taiwan. The main goal of this study was to examine and analyze the AMR patterns both before and after the start of the COVID-19 pandemic. We conducted a retrospective analysis of clinical samples collected from two different time periods: the 1-year period before the onset of the COVID-19 pandemic (January 2019 to December 2019) and the 2-year period following the start of the pandemic (September 2020 to September 2022). The data for this study were obtained from clinical records, and both bacterial identification and antibiotic susceptibility testing were performed using the Phoenix identification system. Among the 8152 bacterial isolates obtained during the study period from September 2020 to September 2022, 4022 (49.3%) were Escherichia coli , 1346 (16.5%) were Klebsiella pneumoniae , 1156 (14.2%) were Staphylococcus aureus , 887 (10.9%) were Pseudomonas aeruginosa , 376 (4.6%) were Enterococcus faecium , and 365 (4.5%) were Acinetobacter baumannii. The overall prevalence of resistant bacteria during the COVID-19 pandemic was as follows: vancomycin-resistant Enterococcus, 69%; carbapenem-resistant A. baumannii, 65%; methicillin-resistant S. aureus, 49%; carbapenem-resistant K. pneumoniae, 29%; carbapenem-resistant P. aeruginosa, 17%; and carbapenem-resistant E. coli, 2%. Carbapenem-resistant A. baumannii , vancomycin-resistant Enterococcus , carbapenem-resistant K. pneumoniae , and carbapenem-resistant E. coli increased by 19%, 10%, 2%, and 1%, respectively. On the other hand, carbapenem-resistant P. aeruginosa and methicillin-resistant S. aureus decreased by 6%, respectively. This study provides a comprehensive assessment of AMR during the COVID-19 pandemic in Central Taiwan. Understanding the prevalence of AMR is crucial for preventing infection and formulating disease prevention policies. Further research is warranted to elucidate the correlation between AMR and the severity of infection in COVID-19 patients. [ABSTRACT FROM AUTHOR]

Bovine mastitis is the most common and costly disease affecting dairy cattle throughout the world. Enterococcus faecalis is one of the environmental origin mastitis-causing pathogens. The treatment of bovine mastitis is primarily based on antibiotics. Due to the negative impact of developing antibiotic resistance and adverse effects on soil and water environments, the trend toward use of nonantibiotic treatments is increasing. Phages may represent a promising alternative treatment strategy. However, it is unknown whether phages have therapeutic effects on E. faecalis -induced mastitis. Thus, the objective of this study was to investigate the degree of protection conferred by a phage during murine mastitis caused by multidrug-resistant E. faecalis. Enterococcus faecalis was isolated from the milk of dairy cows with mastitis, and a phage was isolated using the E. faecalis isolates as hosts. The bactericidal ability of the phage against E. faecalis and the ability to prevent biofilm formation were determined in vitro. The therapeutic potential of the phage on murine mastitis was evaluated in vivo. We isolated 14 strains of E. faecalis from the milk of cows with mastitis, all of which exhibited multidrug resistance, and most (10/14) could form strong biofilms. Subsequently, a new phage (EF-N13) was isolated using the multidrug-resistant E. faecalis N13 (isolated from mastitic milk) as the host. The phage EF-N13 belongs to the family Myoviridae , which has short latent periods (5 min) and high bursts (284 pfu/cell). The genome of EF-N13 lacked bacterial virulence-, antibiotic resistance-, and lysogenesis-related genes. Furthermore, bacterial loading in the raw milk medium was significantly reduced by EF-N13 and was unaffected by potential IgG antibodies. In fact, EF-N13 could effectively prevent the formation of biofilm by multidrug-resistant E. faecalis. All of these characteristics suggest that EF-N13 has potential as mastitis therapy. In vivo, 1 × 105 cfu/gland of multidrug-resistant E. faecalis N13 resulted in mastitis development within 24 h. A single dose of phage EF-N13 (1 × 104, 1 × 105, or 1 × 106 pfu/gland) could significantly decrease bacterial counts in the mammary gland at 24 h postinfection. Histopathological observations demonstrated that treatment with phage EF-N13 effectively alleviated mammary gland inflammation and damage. This effect was confirmed by the lower levels of proinflammatory cytokines IL-6, IL-1β, and tumor necrosis factor-α in the mammary gland treated with phage EF-N13 compared with those treated with phosphate-buffered saline. Overall, the data underscored the potential of phage EF-N13 as an alternative therapy for bovine mastitis caused by multidrug-resistant E. faecalis. [ABSTRACT FROM AUTHOR]

We report a case of an 80-year-old woman with botulism from 2020 in Osaka, Japan. The patient complained of dysarthria and dizziness. On the same day, the patient developed respiratory failure, and was intubated and placed on mechanical ventilation. Subsequently, ophthalmoparesis and quadriparesis progressed rapidly. Ten days after onset, the patient failed to respond to any external stimulation. Blood tests showed anemia, and computed tomography revealed undiagnosed cervical cancer. Initially, diagnosis of neuromuscular junction disorder and acute motor neuropathy, including paraneoplastic syndrome, were considered. However, intravenous immunoglobulin therapy and plasma exchange were ineffective. A fecal sample on day 30 showed a large number of C. botulinum spores. On day 34, a mouse bioassay revealed botulinum toxin type A in the patient's serum; therefore, a botulinum antitoxin was administered. Later, the patient's muscle strength was gradually improved. However, severe muscle paralysis persisted, and the patient died of cachexia owing to cervical cancer on day 196. The etiology of this case was unknown because no contaminated food was identified during an inspection of the patient's home. Fecal 16S rRNA gene sequencing revealed dysbiosis of the intestinal microbiota with abundant Enterococcus species. Long-lasting excretion of substantial botulinum spores even on day 30 indicated colonization of C. botulinum in the intestinal tract. This case suggests that C. botulinum colonization with co-existing intestinal dysbiosis may be associated with severe and prolonged symptoms of botulism. [ABSTRACT FROM AUTHOR]

Bacteriocins generated by lactic acid bacteria have increased in popularity due to their safety and versatility of application. Dairy products are rich sources of lactic acid bacteria. This work screened 31 Egyptian dairy product isolates for antimicrobial activity. Two bacteriocinogenic isolates, Enterococcus faecium CH019 and Enterococcus faecium CM019, were identified using molecular techniques. The production conditions of Bacteriocin-like inhibitory substances (BLIS) were optimized. The physical and chemical properties of the Enterococcus faecium CM019 bacteriocin-like compound were analyzed. Cytotoxic and antiviral properties against SARS-CoV-2 were evaluated. Enterococcus faecium CM019 produces bacteriocin-like substances most effectively in MRS broth with a pH of 6.5 and incubation temperature of 35 °C for 24 h. In the presence of surfactant, solvent, and high temperature, the bacteriocin-like substance activity was persistent, but it was eliminated by proteinase K, trypsin, and lipase. The BLIS proved effective against Listeria monocytogenes and Staphylococcus aureus. The CC50 of the bacteriocin-like compound was 108.3 µg/ml, while the IC50 against SARS-CoV-2 was 22.9 µg/ml. With an acceptable toxicity limit, BLIS generated by Enterococcus faecium CM019 isolated from Egyptian dairy products has a broad antimicrobial spectrum and can be employed as an antibacterial agent against Gram-positive bacteria and anti-SARS-CoV-2. [Display omitted] • Lactic acid bacteria bacteriocins have gained popularity due to their ease of use. • Egyptian dairy product isolates were screened for antimicrobial activity. • Two isolates of Enterococcus faecium (CH019, CM019) were molecularly identified. • Bacteriocin- like inhibitory substance anti SARS-CoV-2 activity was evaluated. • Antibacterial potency of bacteriocin-like inhibitory substance was demonstrated. [ABSTRACT FROM AUTHOR]

To describe the prevalence of potentially clinically relevant gut pathogens and associations with the carriage of resistant organisms in UK care home residents. Stool samples were collected pre-randomisation from care home residents participating in a randomised placebo-controlled trial. Cultivable clinically relevant bacteria were analysed. Antimicrobial susceptibility testing was performed by agar dilution (amoxicillin, co-amoxiclav, gentamicin, trimethoprim, nitrofurantoin, and ciprofloxacin). We also aimed to detect resistance to third-generation cephalosporins, carbapenems, and vancomycin. Stool samples were available for 159/310 residents participating in the trial (51%) from 23 care homes between 2016 and 2018. In total, 402 bacterial isolates were cultured from 158 stool samples and 29 different species were cultured. The five most common species were Escherichia coli (155/158, 98%), Pseudomonas aeruginosa (40/158, 25%), Enterococcus faecalis (35/158, 22%), Enterococcus faecium (30/158, 19%), and Proteus mirabilis (25/158, 16%). Enterobacterales isolates were cultured from 157 samples (99%), and resistance to at least one of the tested antimicrobials was found in 119 of these (76%). There were high levels of variation in outcomes by care home. We demonstrated that care home residents harbour significant levels of antimicrobial-resistant organisms in their stool. This work emphasises the importance of both enhanced infection control practices and antimicrobial stewardship programmes to support the appropriate use of antimicrobials in this setting. [ABSTRACT FROM AUTHOR]

In this investigation, Blue Cherry fruit was used to isolate potential probiotic isolate and characterized for their beneficial attributes. The main objective of the study was to evaluate the antagonistic activity of the isolated bacteria against plant pathogenic bacteria such as Ralstonia solanacearum , Pectobacterium carotovorum sub sp. carotovorum and Xanthomonas oryzae pv oryzae and also to evaluate the isolate for potential probiotic, plant growth promoting and biocontrol activity. A total of nine isolates were isolated from Blue Cherry fruit and initially screened for microscopic and biochemical characters. The agar-well diffusion method, paper disc, spot inoculation and microplate method were used to test the antibacterial activity from the cultured supernatants against plant pathogenic bacteria and zone of inhibition ranged from 0.6 to 2.1 cm and per cent inhibition of plant pathogenic bacteria ranged from 64.81 to 71.70 %. Effective isolate MYSBC14 was genotyped based on 16S rDNA and identified as Enterobacter faecium OL454757. Effective isolate E. faecium MYSBC14 was further characterized for probiotic properties, PGPR and bio-control attributes. MYSBC14 survived under pH 2 and pH 4 after 2 and 4 h after incubation (38.08 and 23.16 %, 87.90 to 82.02 % respectively) and was susceptible to majority of antibiotics evaluated. A survival rate of 52.67 and 43.01 % was recorded at 0.3 % oxgall salt concentration after 2 and 4 h after incubation. The cell surface hydrophobicity of 90.24 % and auto aggregation of 8.10 to 22.02 % represented the adhesion properties of the isolate. MYSBC14 showed indole acetic acid production (11.56 µg/mL), gibberellic acid production (10.18 µg/mL) and gave positive results for solubilization of phosphate, potash, protease and siderophore production and was found negative for zinc and silicon solubilization, cellulose degradation activity, HCN production activity and amylase activity. The findings of the present investigation showed that isolated probiotic organism possesses promising antibacterial, probiotic attributes, plant growth promoting characteristics and bio-control traits. [ABSTRACT FROM AUTHOR]

ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and enteric bacteria Shigella dysenteriae, Salmonella typhimurium and Escherichia Coli have been causing increasing nosocomial infections worldwide, contributing to high mortality and morbidity in surgical wards. This study attempts to investigate the feasibility of dieletrophoresis (DEP) electrode in detecting both ESKAPE and enteric bacteria in water samples. The detection is based on the bacteria's response to the non-uniform electric field in micro tapered DEP electrode and microfluidic chamber. Responses of each bacterium were recorded by varying the frequency of sinusoidal 6 voltage (peak to peak) from 10 to 13,000 kHz. Utilising the unique electrokinetic responses of each bacterium, the performance of DEP application is assessed in detecting the ESKAPE and enteric bacteria from samples within the urban water cycle, i.e., wastewater, river, runoff, and treated water from an urbanised developed area. The positive (P DEP) , negative (N DEP) and transitional, (denote as the crossover frequency f x 0) responses for each bacterium were consistently determined, spanning between 52.3 and 12,000 kHz. DEP technique was successfully able to detect ESKAPE and enteric bacteria from water samples, where water from the river proved to be the most microbially contaminated in urban water cycle. [ABSTRACT FROM AUTHOR]

The objective of this scoping review was to identify, describe, and characterize the literature on probiotic supplementation in dairy calves. Eligible studies were nonrandomized, quasi-randomized and randomized controlled trials in English, Spanish, or Portuguese that evaluated the effect of probiotic supplementation on growth and health of dairy calves. The search strategies were based on a modification of the PICO (Population, Intervention, Comparator, Outcome) framework and used synonyms and words related to "dairy calves" (population), "probiotics" (intervention), and "growth and health measurements" (outcomes). No restrictions for publication year or language were applied. Searches were conducted in Biosis, CAB Abstracts, Medline, Scopus, and the Dissertations and Theses Database. In total, the search identified 4,467 records, of which 103 studies (110 controlled trials) met the inclusion criteria. The studies were published between 1980 and 2021 and originated from 28 countries. Trials were randomized (80.0%), nonrandomized (16.4%), and quasi-randomized (3.6%), ranging in sample size from 5 to 1,801 dairy calves (mode = 24; average = 64). Enrolled calves were frequently Holstein (74.5%), males (43.6%), and younger than 15 d at the beginning of probiotic supplementation (71.8%). Often, trials were conducted in research facilities (47.3%). Trials evaluated probiotics with single or multiple species of the same genus: Lactobacillus (26.4%), Saccharomyces (15.4%), Bacillus (10.0%), Enterococcus (3.6%), or multiple species of various genera (31.8%). Eight trials did not report the probiotic species used. Lactobacillus acidophilus and Enterococcus faecium were the species most supplemented to calves. The duration of probiotic supplementation ranged from 1 to 462 d (mode = 56; average = 50). In trials with a constant dose, it ranged from 4.0 × 106 to 3.7 × 1011 cfu/calf per day. Most probiotics were administered mixed solely into feed (88.5%; whole milk, milk replacer, starter, or total mixed ration) and less frequently orally as a drench or oral paste (7.9%). Most trials evaluated weight gain (88.2%) as a growth indicator and fecal consistency score (64.5%) as a health indicator. Our scoping review summarizes the breadth of controlled trials evaluating probiotic supplementation in dairy calves. Differences in intervention design (mode of probiotic administration, dose, and duration of probiotic supplementation) and outcomes evaluation (type and methods) justify future efforts toward standardized guidelines in clinical trials. [ABSTRACT FROM AUTHOR]

The high incidence of endodontic failure is associated with the remnants of Enterococcus faecalis present within the intricate anatomies of the root canal system (RCS), often inaccessible by the current endodontic practices. This study was aimed at evaluating the effect of high-intensity focused ultrasound (HIFU) and photodynamic therapy (PDT) on E. faecalis biofilms in artificially infected root canals for the potential application in current endodontic practices. Forty-five single-rooted extracted teeth were instrumented using hand files, sterilized in an autoclave, infected with E. faecalis and incubated for 4 wk. The specimens were treated and identified as follows: Control, 4% sodium hypochlorite (NaOCl); riboflavin (1 mg/mL); light only; HIFU (250 kHz, 20 W, 60s); PDT; riboflavin/HIFU; light/HIFU; and riboflavin/HIFU/light. Bactericidal efficacy was determined by colony-forming units (CFU), (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) (MTT) assay, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Enterococcus faecalis biofilm exhibited significantly lower metabolic activity when treated with HIFU (250 kHz, 20 W, 60 s) compared with the control (4% NaOCl) and PDT groups. A similar phenomenon was observed with the CFU assay. HIFU remained the most effective treatment modality, with consistent results in CLSM and SEM. This study highlighted the potential application of HIFU as an adjunct drug-free, non-destructive root canal disinfection method for endodontic treatment, suggesting an alternative to the current gold standard of 4% NaOCl and PDT. [ABSTRACT FROM AUTHOR]

Infectious disease consultation (IDC) has been associated with improved outcomes in several infections, but the benefit of IDC among patients with enterococcal bacteraemia has not been fully evaluated. We performed a 1:1 propensity score–matched retrospective cohort study evaluating all patients with enterococcal bacteraemia at 121 Veterans Health Administration acute-care hospitals from 2011 to 2020. The primary outcome was 30-day mortality. We performed conditional logistic regression to calculate the OR to determine the independent association of IDC and 30-day mortality adjusted for vancomycin susceptibility and the primary source of bacteraemia. A total of 12,666 patients with enterococcal bacteraemia were included; 8400 (63.3%) had IDC, and 4266 (36.7%) did not have IDC. Two thousand nine hundred seventy-two patients in each group were included after propensity score matching. Conditional logistic regression revealed that IDC was associated with a significantly lower 30-day mortality rate compared with patients without IDC (OR = 0.56; 95% CI, 0.50–0.64). The association of IDC was observed irrespective of vancomycin susceptibility, and when the primary source of bacteraemia was a urinary tract infection, or from an unknown primary source. IDC was also associated with higher appropriate antibiotic use, blood culture clearance documentation, and the use of echocardiography. Our study suggests that IDC was associated with improved care processes and 30-day mortality rates among patients with enterococcal bacteraemia. IDC should be considered for patients with enterococcal bacteraemia. [ABSTRACT FROM AUTHOR]

To investigate the distribution and antimicrobial susceptibility of causative microorganisms recovered from patients with intra-abdominal infections (IAIs). A total of 2,926 bacterial and fungal strains were identified in samples collected from 1,679 patients with IAIs at the Peking Union Medical College Hospital between 2011 and 2021. Pathogenic bacteria and fungi were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Antimicrobial susceptibility testing (AST) was performed using the VITEK 2 compact system and the Kirby–Bauer method. AST results were interpreted based on the M100-Ed31 clinical breakpoints of the Clinical and Laboratory Standards Institute. Of the 2,926 strains identified, 49.2%, 40.8%, and 9.5% were gram-negative bacteria, gram-positive bacteria, and fungi, respectively. Escherichia coli was the most prevalent pathogen in intensive care unit (ICU) and non-ICU patients; however, a significant decrease was observed in the isolation of E. coli between 2011 and 2021. Specifically, significant decreases were observed between 2011 and 2021 in the levels of extended-spectrum β-lactamase (ESBL)-producing E. coli (from 76.9% to 14.3%) and Klebsiella pneumoniae (from 45.8% to 4.8%). Polymicrobial infections, particularly those involving coinfection with gram-positive and gram-negative bacteria, were commonly observed in IAI patients. Moreover, Candida albicans was more commonly isolated from hospital-associated IAI samples, while Staphylococcus epidermidis had a higher ratio in community-associated IAIs. Additionally, AST results revealed that most antimicrobial agents performed better in non-ESBL-producers than in ESBL-producers, while the overall resistance rates (56.9%–76.8%) of Acinetobacter baumanmii were higher against all antimicrobial agents than those of other common gram-negative bacteria. Indeed, Enterococcus faecium , Enterococcus faecalis , S. epidermidis , and S. aureus were consistently found to be susceptible to vancomycin, teicoplanin, and linezolid. Similarly, C. albicans exhibited high susceptibility to all the tested antifungal drugs. The distribution and antimicrobial susceptibility of the causative microorganisms from patients with IAIs were altered between 2011 and 2021. This finding is valuable for the implementation of evidence-based antimicrobial therapy and provides guidance for the control of hospital infections. [ABSTRACT FROM AUTHOR]

Seaweed biomass has been proposed as a promising alternative carbon source for fermentation processes using microbial factories. However, the high salinity content of seaweed biomass is a limiting factor in large scale fermentation processes. To address this shortcoming, three bacterial species (Pediococcus pentosaceus, Lactobacillus plantarum, and Enterococcus faecium) were isolated from seaweed biomass and evolved to increasing concentrations of NaCl. Following the evolution period, P. pentosaceus reached a plateau at the initial NaCl concentration, whereas L. plantarum , and E. faecium showed a 1.29 and 1.75-fold increase in their salt tolerance, respectively. The impact that salt evolution had on lactic acid production using hypersaline seaweed hydrolysate was investigated. Salinity evolved L. plantarum produced 1.18-fold more lactic acid than the wild type, and salinity evolved E. faecium was able to produce lactic acid, while the wild type could not. No differences in lactic acid production were observed between the P. pentosaceus salinity evolved and wild type strains. Evolved lineages were analyzed for the molecular mechanisms underlying the observed phenotypes. Mutations were observed in genes affecting the ion balance in the cell, the composition of the cell membrane and proteins acting as regulators. This study demonstrates that bacterial isolates from saline niches are promising microbial factories for the fermentation of saline substrates, without the requirement of previous desalination steps, while preserving high final product yields. • Seaweed isolated lactic acid bacteria resisted 71 g/L NaCl. • Equal lactic acid concentration in natural seaweed- and hypersaline media. • Increased salt affected cell metabolism, cell membrane and strain-specific proteins. [ABSTRACT FROM AUTHOR]

[Display omitted] • Enterococci with optrA increased in mesophilic and thermophilic anaerobic digestion. • IS 1216E in plasmid plays key role in horizontal transfer of optrA. • Chromosomal optrA linked to Tn 554 spread vertically in dominate E. faecalis ST631. • Hyper-thermophilic anaerobic pretreatment reduced plasmid-borne optrA in enterococci. The extensive use of florfenicol in poultry industry results in the emergence of optrA gene, which also confers resistance to clinically important antibiotic linezolid. This study investigated the occurrence, genetic environments, and removal of optrA in enterococci in mesophilic (37 °C) and thermophilic (55 °C) anaerobic digestion systems, and a hyper-thermophilic (70 °C) anaerobic pretreatment system for chicken waste. A total of 331 enterococci were isolated and analyzed for antibiotic resistance against linezolid and florfenicol. The optrA gene was frequently detected in enterococci from chicken waste (42.7%) and effluents from mesophilic (72%) and thermophilic (56.8%) reactors, but rarely detected in the hyper-thermophilic (5.8%) effluent. Whole-genome sequencing revealed that optrA -carrying Enterococcus faecalis sequence type (ST) 368 and ST631 were the dominant clones in chicken waste, and they remained dominant in mesophilic and thermophilic effluents, respectively. The plasmid-borne IS 1216E - fexA - optrA - erm (A)-IS 1216E was the core genetic element for optrA in ST368, whereas chromosomal Tn 554 - fexA - optrA was the key one in ST631. IS 1216E might play a key role in horizontal transfer of optrA due to its presence in different clones. Hyper-thermophilic pretreatment removed enterococci with plasmid-borne IS 1216E - fexA - optrA - erm (A)-IS 1216E. A hyper-thermophilic pretreatment is recommended for chicken waste to mitigate dissemination of optrA from animal waste to the environment. [ABSTRACT FROM AUTHOR]

Carriers of multidrug-resistant bacteria are at risk of infections with these bacteria; the precise size of this risk is unclear. We aimed to quantify the effect of gut colonisation on subsequent risk of infection with multidrug-resistant bacteria. We performed a systematic review and meta-regression analysis. We searched PubMed, Embase, Web of Science Core Collection, and Google Scholar for follow-up studies published from Jan 1, 1995, to March 17, 2022, that measured the incidence of infections with multidrug-resistant Gram-negative bacteria (MDR-GNB) and from Jan 1, 1995, to March 15, 2022, that measured the incidence of infections with vancomycin-resistant enterococci (VRE). We included original cohort studies and case-control studies that used incidence-density sampling, included 50 or more patients with enteric colonisation or positive urinary samples as a surrogate marker of colonisation, or both, and analysed infections clearly preceded by colonisation. We did not use any language restrictions. We excluded studies not reporting length of follow-up. Summary data were extracted and independently cross-verified by two authors. Carriage was defined as MDR-GNB or VRE, detected in faecal or urinary cultures. Our primary outcomes were cumulative incidence and incidence density of infection in patients colonised by multidrug-resistant bacteria. To estimate pooled incidences, general linearised mixed-effects meta-regressions were used, adjusting for varying follow-up durations. This study is registered with PROSPERO, CRD42020222415. Of the 301 studies identified, 44 studies (26 on MDR-GNB, 14 on VRE, and four on both MDR-GNB and VRE) from 14 countries were retained for qualitative synthesis, 40 of which were analysed with meta-regression, comprising data for 14 049 patients colonised with multidrug-resistant bacteria. The pooled cumulative incidence of infection was 14% (95% CI 10–18; p<0·0001) at a median follow-up time of 30 days for MDR-GNB (845 cases of infection in 9034 patients colonised) and 8% (5–13; p<0·0001) at 30 days for VRE (229 cases of infection in 4747 patients colonised). Infection incidence density (4·26 infections per 1000 patient-days; 95% CI 1·69–6·82) and cumulative incidence of infection (19%, 95% CI 15–25; p<0·0001; 602 cases of infection in 4547 patients colonised) were highest for carbapenem-resistant Gram-negative bacteria at 30 days. Risk of bias was rated low to moderate. The risk of infection was substantial, with the highest risk for patients colonised with carbapenem-resistant Gram-negative bacteria and the lowest in patients with VRE. These data might help to guide prophylactic and treatment decisions and form a valuable resource for planning clinical trials on targeted prevention. The Netherlands Organization for Health Research and Development [ABSTRACT FROM AUTHOR]

Vancomycin-resistant enterococci (VRE) are prevalent infectious agents that particularly affect critically-ill patients, and they are on the rise in Lebanon. We aim at determining the potential risk factors and complications for VRE and vancomycin-susceptible enterococci (VSE) infections in a hospital setting and identify risk factors for in-hospital mortality. A case-case-control study design was used where patients with VRE and VSE were included as two separate groups and each group was compared to uninfected controls. We also constructed binary regression models to detect risk factors that were associated with the acquisition of a VRE or a VSE infection. We also identified independent mortality predictors for all patients with enterococcal infection as well as patients with only a VRE infection. A total of 142 patients with enterococcal infections (VRE and VSE) were compared to 142 in-patients not infected with Enterococcus spp. independent risk factors for a VRE infection were steroid therapy within 30 days and the presence of another infection preceding the VRE infection (aOR 15.4, 95 % CI 2.4–99.3 and 23.9, 95 % CI 3.9–1482, respectively). An independent risk factor for VSE was diabetes mellitus (aOR 5.4, 95 % CI 1.1–26.6). Based on these risk factors, we developed a risk score to be used in quantifying the risk of VRE in a patient with an enterococcal infection. Male sex and low albumin were significant risk factors for mortality in our patient cohort. VRE and VSE infections have distinct risk factors that can be used to guide empiric antimicrobial therapy. [ABSTRACT FROM AUTHOR]

The VanRS two-component system regulates the resistance phenotype of vancomycin-resistant enterococci. VanS is a sensor histidine kinase that responds to the presence of van-comycin by autophosphorylating and subsequently transferring the phosphoryl group to the response regulator, VanR. The phosphotransfer activates VanR as a transcription factor, which initiates the expression of resistance genes. Structural information about VanS proteins has remained elusive, hindering the molecular-level understanding of their function. Here, we present X-ray crystal structures for the catalytic and ATP-binding (CA) domains of two VanS proteins, derived from vancomycin-resistant enterococci types A and C. Both proteins adopt the canonical Bergerat fold that has been observed for CA domains of other prokaryotic histidine kinases. We attempted to determine structures for the nucleotide-bound forms of both proteins; however, despite repeated efforts, these forms could not be crystallized, prompting us to measure the proteins' binding affinities for ATP. Unexpectedly, both CA domains displayed low affinities for the nucleotide, with KD values in the low millimolar range. Since these KD values are comparable to intracellular ATP concentrations, this weak substrate binding could reflect a way of regulating expression of the resistance phenotype. [ABSTRACT FROM AUTHOR]

Daptomycin (DAP) is an antibiotic frequently used as a drug of last resort against vancomycin-resistant enterococci. One of the major challenges when using DAP against vancomycinresistant enterococci is the emergence of resistance, which is mediated by the cell-envelope stress system LiaFSR. Indeed, inhibition of LiaFSR signaling has been suggested as a strategy to "resensitize" enterococci to DAP. In the absence of LiaFSR, alternative pathways mediating DAP resistance have been identified, including adaptive mutations in the enolpyruvate transferase MurAA (MurAAA149E), which catalyzes the first committed step in peptidoglycan biosynthesis; however, how these mutations confer resistance is unclear. Here, we investigated the biochemical basis for MurAAA149E-mediated adaptation to DAP to determine whether such an alternative pathway would undermine the potential efficacy of therapies that target the LiaFSR pathway. We found cells expressing MurAAA149E had increased susceptibility to glycoside hydrolases, consistent with decreased cell wall integrity. Furthermore, structure-function studies of MurAA and MurAAA149E using X-ray crystallography and biochemical analyses indicated only a modest decrease in MurAAA149E activity, but a 16-fold increase in affinity for MurG, which performs the last intracellular step of peptidoglycan synthesis. Exposure to DAP leads to mislocalization of cell division proteins including MurG. In Bacillus subtilis, MurAA and MurG colocalize at division septa and, thus, we propose MurAAA149E may contribute to DAP nonsusceptibility by increasing the stability of MurAA-MurG interactions to reduce DAP-induced mislocalization of these essential protein complexes. [ABSTRACT FROM AUTHOR]

This study explored the effects of H 2 O 2 on Cyanobacteria and non-target microbes using fluorometry, microscopy, flow cytometry, and high throughput DNA sequencing of the 16S rRNA gene during a series of mesocosm and whole-ecosystem experiments in a eutrophic pond in NY, USA. The addition of H 2 O 2 (8 mg/L) significantly reduced Cyanobacteria concentrations during a majority of experiments (66%; 6 of 9) and significantly increased eukaryotic green and unicellular brown algae in 78% and 45% of experiments, respectively. While heterotrophic bacteria declined significantly following H 2 O 2 addition in all experiments, bacteria indicative of potential fecal contamination (Escherichia coli, Enterococcus , fecal coliform bacteria) consistently and significantly increased in response to H 2 O 2 , evidencing a form of 'pollution swapping'. H 2 O 2 more effectively reduced Cyanobacteria in enclosed mesocosms compared to whole-ecosystem applications. Ten whole-pond H 2 O 2 applications over a two-year period temporarily reduced cyanobacterial levels but never reduced concentrations below bloom thresholds and populations always rebounded in two weeks or less. The bacterial phyla of Cyanobacteria, Actinobacteria, and Planctomycetes were the most negatively impacted by H 2 O 2. Microcystis was always reduced by H 2 O 2 , as was the toxin microcystin, but Microcystis remained dominant even after repeated H 2 O 2 treatments. Although H 2 O 2 favored the growth of eukaryotic algae over potentially harmful Cyanobacteria, the inability of H 2 O 2 to end cyanobacterial blooms in this eutrophic waterbody suggests it is a non-ideal mitigation approach in high biomass ecosystems and should be used judiciously due to potential negative impacts on non-target organisms and promotion of bacteria indicative of fecal contamination. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, the inactivation of Escherichia coli and Enterococcus faecalis by sulfate radical (SO4•-) and hydroxyl radical (•OH) using Fe2+/peroxydisulfate (PDS) and Fe2+/H2O2 systems under neutral pH condition were investigated. 6 log of E. coli and 2.71 log of E. faecalis were inactivated in Fe2+/PDS system, respectively, compared to 0.98 log and 0.51 log in Fe2+/H2O2 system. E. coli was much easier to be inactivated than E. faecalis. And the inactivation rate of E. coli within the first 30 min was higher than that in 30-120 min, while the E. faecalis was the opposite. This suggests that the different inactivation patterns of bacteria by advanced oxidation treatments were due to the variation of microbial structures. In addition, the inactivation ability of Fe2+/PDS on E. coli and E. faecalis in the wastewater effluent decreased by 23.5% and 23.6%, respectively, while the inactivation ability of Fe2+/H2O2 decreased by 88.8% and 78.2%, respectively. Higher inactivation efficiencies by SO4•-were obtained than that by •OH. Therefore, inactivation efficiency by SO4 •-based advancedoxidation treatment was less affected by the actual reclaimed water matrix for disinfection. [ABSTRACT FROM AUTHOR]

Exopolysaccharide (EPS) biomolecules produced by lactic acid bacteria (LAB) are of prodigious interest due to their unique structural, physico-chemical, and functional characteristics. Several genera of LAB including Enterococcus spp. have been studied for EPS production by various research groups worldwide. EPS produced by various strains from Enterococcus spp. have shown a wide range of functional and technological properties with potential commercial applications. Numerous techniques are used in the characterization of Enterococcus EPS to reveal their structure, linkage, monosaccharide units, functional groups, morphology, and thermal properties. Bioactive potentials of Enterococcus EPS include antioxidant, antibacterial, antibiofilm, anticancer, immunological, prebiotic, and antidiabetic potentials which have been widely reported. These functional and biological properties make Enterococcus EPS a candidate of great importance for multiple applications in the area of food, pharmaceuticals, biomedical and environmental. This review is focused on EPS produced by various strains of the Enterococcus genus isolated from different sources. Several procedures and parameters involved in the production and purification of Enterococcus EPS are also deliberated along with the functional aspects and potential applications. [Display omitted] • Structurally diverse Enterococcus EPS produced from various sources. • Thorough outline of Enterococcus EPS production, purification and characterization. • Physico-functional and biological properties of Enterococcus EPS deliberated. • Conferred applications and further recommendations of Enterococcus EPS. [ABSTRACT FROM AUTHOR]

Composting is a common practice used for treating animal manures before they are used as organic fertilizers for crop production. Whether composting can effectively reduce microbial pathogens and antibiotic resistance genes remain poorly understood. In this study, we compared 3 different dairy manure composting methods—anaerobic fermentation (AF), static compost (SC), and organic fertilizer production (OFP)—for their effects on antibiotic-resistant bacteria, antibiotic resistance genes, and microbial community diversity in the treated manures. The 3 composting methods produced variable and distinct effects on antibiotic-resistant bacteria, zoonotic bacteria, and resistance genes, some of which were decreased and others of which showed no significant changes during composting. Particularly, SC and OFP reduced chloramphenicol resistance gene fexA and opportunistic pathogen Vibrio fluvialis , whereas AF significantly reduced tetracycline resistance gene tetB and opportunistic pathogens Enterococcus faecium and Escherichia fergusonii. The compositions of microbial communities varied significantly during the composting processes, and there were significant differences between the 3 composting methods. In all 3 composts, the dominant phyla were Firmicutes , Proteobacteria , Bacteroidetes , and Actinobacteria. Interestingly, Firmicutes , Proteobacteria , and Bacteroidetes remained stable in the entire AF process, whereas they were dominated at the beginning, decreased at the early stage of composting, and rebounded at the later stage during SC and OFP. In general, SC and OFP produced a more profound effect than AF on microbial community diversities, pathogens, and dominant species. Additionally, Enterococcus aquimarinus was isolated from AF for the first time. Phylogenetic Investigation of Communities by Reconstruction of Unobserved States function prediction analysis indicated that the genes related to membrane transport and amino acid metabolism were abundant in the 3 composts. The metabolism of amino acids, lipids, and carbohydrates increased as composting progressed. The biosynthesis of antibiotics was enhanced after fermentation in the 3 composting methods, and the increase in the SC was the most obvious. These results reveal dynamic changes in antibiotic-resistant bacteria, antibiotic resistance genes, microbial community composition, and function succession in different dairy manure composts and provide useful information for further optimization of composting practices. [ABSTRACT FROM AUTHOR]

Infective endocarditis is a result of infection of the endocardium, particularly of the heart valves (native or prosthetic valves). The most common causative organisms in the paediatric population are: Streptococci, Staphylococci and Enterococci. The classical signs of infective endocarditis like Roth spots, Janeway lesions, splinter haemorrhages and Osler's nodes are relatively rare in children. A high index of suspicion in a febrile child with a new murmur, detailed history, meticulous examination, repeated blood cultures, and echocardiography are essential in establishing the diagnosis. Management of infective endocarditis involves a prolonged course of antibiotics, at least for 4–6 weeks depending upon the causative organism and underlying heart condition. Complications of infective endocarditis include congestive heart failure resulting from valvular damage/regurgitation, infective emboli leading to abscesses in other organs and abnormal host immunological responses. Prophylactic antibiotics for dental and other medical procedures like genitourinary tract procedures are no longer recommended in the UK. The emphasis should be on educating children and their parents in early recognition of infective endocarditis. Children at high risk of developing endocarditis should be assessed urgently after clinical suspicion. [ABSTRACT FROM AUTHOR]

Fermented milk and palm wine are regularly used by several ethnic groups in Cameroon in traditional treatment rituals for infections, inflammatory, cardiovascular disorders, and even metabolic diseases such as diabetes, hypercholesterolemia etc. Reports from many studies have demonstrated that fermented milk and palm wine are potential sources of probiotic bacteria. However, the capacity of probiotics isolated from these natural sources to alleviate neuropathic pain has not been experimentally tested. This study aimed at investigating the ameliorative potential of lactic acid bacteria isolated from palm wine and traditional fermented cow milk on the chronic constriction injury (CCI) induced neuropathic pain in mice. Pour plating technique on De Man Rogasa (MRS) agar was utilised for isolation of lactic acid bacteria from fermented cow milk and palm wine, and identified using the 16S r RNA gene sequencing. Neuropathic pain was induced by chronic constriction injury of the sciatic nerve. These bacteria were orally administered at different concentrations to Balb/c mice by gavage for 14 consecutive days. Cold allodynia, mechanical hyperalgesia and exploratory behaviour were evaluated on day 0, 7th and 14th respectively. The total level of calcium, oxidative stress markers and myeloperoxidase were also quantified in the sciatic nerve homogenate. Cyclooxygenase-2(COX-2) and cytokine profile were determined from serum. Lactic acid bacteria were isolated from fermented cow milk and palm wine and two isolates were chosen according to their probiotic potentials and identified as strain of Limolactobacillus fermentum and Enterococcus lactis. Their 16 S rRNA gene sequences were deposited in NCBI genbank with accession number of OP896078 and OR619545, respectively. Pretreatment with Limosilactobacillus fermentum and Enterococcus lactis significantly alleviated mechanical hyperalgesia and cold allodynia with similar effect to the reference drug, morphine. These two isolates ameliorated CCI induced neuropathic pain by increasing antioxida776nts (GSH, CAT and SOD, P < 0.01) and decreasing pro-oxidants (MDA and NO, P < 0.01). Also, they inhibited the release of proinflammatory cytokines (IL-1β, TNF-α, IFN-γ, and IL-6; P < 0.01) and IL-10 level was significantly (P < 0.01) increased when compared to the negative control. Treatment with these bacteria significantly dropped the level of total calcium (P < 0.01), COX-2 (P < 0.01) and MPO (P < 0.01) when compared with the negative control. The neuroprotective potentials of these selected lactic acid bacteria against CCI induced neuropathic pain may be attributed to their anti-oxidant, anti-inflammatory properties and reduced calcium deposition in sciatic nerve. [Display omitted] • Fermented milk and palm wine are sources of lactic acid bacteria with probiotic potential. • Pretreatment with probiotic Limosilactobacillus fermentum and Enterococcus lactis significantly attenuated mechanical hyperalgesia and cold allodynia. • The neuroprotective potentials of Limosilactobacillus fermentum and Enterococcus lactis is associated to their anti-oxidant, anti-inflammatory properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • E. faecium B6 has lipogenic properties and promotes hepatic steatosis symptoms. • Whole genome analysis systematically reveals the underlying genes of E. faecium B6. • Pan-genome study showing the unique functions of E. faecium B6 in ABC transporters. • The underlying metabolic traits of E. faecium B6 are uncovered for the first time. Evidence has indicated that Enterococcus plays a vital role in non-alcoholic fatty liver disease (NAFLD) development. However, the microbial genetic basis and metabolic potential in the disease are yet unknown. We previously isolated a bacteria Enterococcus faecium B6 (E. faecium B6) from children with NAFLD for the first time. Here, we aim to systematically investigate the potential of strain B6 in lipogenic effects. The lipogenic effects of strain B6 were explored in vitro and in vivo. The genomic and functional characterizations were investigated by whole-genome sequencing and comparative genomic analysis. Moreover, the metabolite profiles were unraveled by an untargeted metabolomic analysis. We demonstrated that strain B6 could effectively induce lipogenic effects in the liver of mice. Strain B6 contained a circular chromosome and two circular plasmids and posed various functions. Compared to the other two probiotic strains of E. faecium , strain B6 exhibited unique functions in pathways of ABC transporters, phosphotransferase system, and amino sugar and nucleotide sugar metabolism. Moreover, strain B6 produced several metabolites, mainly enriched in the protein digestion and absorption pathway. The unique potential of strain B6 in lipogenic effects was probably associated with glycolysis, fatty acid synthesis, and glutamine and choline transport. This study pioneeringly revealed the metabolic characteristics and specific detrimental traits of strain B6. The findings provided new insights into the underlying mechanisms of E. faecium in lipogenic effects, and laid essential foundations for further understanding of E. faecium -related disease. [ABSTRACT FROM AUTHOR]

This study explores the efficacy of plasma-processed air (PPA) as a non-thermal treatment for decontamination of dry food surfaces, such as wheat grains, black peppercorns, and onion flakes. We compared the effect of various inoculum types of Enterococcus faecium , revealing a higher resistance of the powder form compared with liquid and slurry inocula on black peppercorns. Furthermore, Enterococcus faecium NRRL B-2354 appeared to be a suitable control indicator for Salmonella. The PPA efficacy varied across matrices, being higher on medium agar (7.0 ± 0.5 log 10), followed by wheat grains (2.1 ± 0.2 log 10), black peppercorns (1.5 ± 0.1 log 10), and no reduction on onion flakes. Variation was also found across microorganisms, as the natural microbiota was reduced on wheat grains (1.6 ± 0.6 log 10 for mesophilic count and 0.8 ± 0.3 log 10 for spores), while on black peppercorns this was only achieved after upscaling (1.3 ± 0.2 log 10 for mesophilic and 1.5 ± 0.1 log 10 for spores). The findings of this study give guidance to further optimize the application of PPA treatment by changing the technical parameter settings of the plasma setup to increase the microbial efficacy and/or combining the PPA treatment with other methods to enhance microbial control. • Enterococcus faecium NRRL-B2354 can serve as a control indicator for Salmonella in PPA applications. • Powder inoculum can show a higher resistance compared with liquid and slurry inocula. • Reduction on smooth agar medium surfaces was more effective than on food matrices. • Reduction was highest on wheat grains, followed by black pepper and no reduction on onion flakes. [ABSTRACT FROM AUTHOR]

Currently, there is a high demand for fresh, minimally processed foods. Therefore, the search for natural compounds that can be used to increase the quality and shelf life of food, as well as to control or eliminate the development of pathogens has been increasing. The general objective was to determine the simultaneous production, at a controlled pH 6, of bacteriocin and bioemulsifier by the Enterococcus mundtii Tw278 strain and evaluate the conservation capacity in a food model. The pH control did not affect the production of the compounds when the optimal production media were used (LAPTg for bacteriocin and LAP LW for bioemulsifier), respectively. The values obtained for bacteriocin were 819,200 AU/mL at 9 h in the batch, while this value was obtained at 12 h in the reactor. The highest emulsification index (E24) was 60.97 at 24 h in the batch, while in the reactor, it was 54.3 at 12 h. The bioemulsifier produced would be a glyprotein, according to FTIR analysis, with the capacity to form polydisperse oil-in-water emulsions with particles with an average diameter of 50 μm. Finally, it was found that E. mundtii Tw278 strain, as well as its antilisteria extract, were able to control and reduce the initial population of 3.4 log CFU/mL of Listeria monocytogenes Scott A to undetectable values in a yogurt model, with production at 42 °C for 8 h and storage at 4 °C for 15 days and bacteriocinogenic strain and its extract did not alter the physicochemical properties inherent to yogurt. [ABSTRACT FROM AUTHOR]

Microbiota exposed to pollution provide insights into host physiology and ecosystem disruption. This study evaluated Enterococcus spp. tolerant to arsenic (As), copper (Cu), and mercury (Hg) from red-billed tropicbirds (Phaethon aethereus) and brown boobies (Sula leucogaster), which previously showed these metals in their blood and feathers, and their potential use as bioindicators of metal contamination. Enterococcus casseliflavus (47.9 %), E. faecalis (34.1 %), E. hirae (11.7 %), and E. faecium (5.3 %) were identified. Both seabird species had a high incidence of As-tolerant bacteria (84.0 %), with 40.4 % of these strains containing As efflux system genes (arsA_I and arsA_II). Cu efflux pump gene (tcrB) was detected in 30.9 % of strains, while Hg reductase genes (mer) were not found. As- and Cu-tolerance in enterococci observed in this study underlines their potential as bioindicators in metal-polluted marine environments. Further research may elucidate the role of these metal-tolerant enterococci in seabird gut and their adaptability to polluted environments. • Bacteria are useful bioindicators of metal contamination in marine environments. • Enterococci isolated from seabirds exhibit arsenic and copper tolerance. • Genes linked to arsenic and copper tolerance were detected in enterococci strains. • The potential of enterococci as metal bioindicators is demonstrated. [ABSTRACT FROM AUTHOR]

This study investigated the safety characteristics and potential probiotic properties of Enterococcus faecium by using whole genome analysis, and then explored the effect of this strain on the virulence of Listeria monocytogenes in vitro and during the storage of fermented sausages. Results showed that E. faecium B1 presented enterocin A, B, and P, enterolysin A, and UviB, and the exotoxin related genes and exoenzyme related genes were not detected in the genome of E. faecium B1. However, the adherence genes including acm and scm were present in this strain, which also positively correlated with characteristics related to probiotic potential. In addition, E. faecium could adapt to the condition of fermented sausages, and decrease the survival of L. monocytogenes in vitro and in vivo. The expression of the virulence genes (prfA , hly , inlA , and inlB) and sigB -related genes (prli42 , rsbT , rsbU , rsbV , rsbW , and sigB) were all inhibited by E. faecium B1 to different extents during the storage of fermented sausages at 4 °C. Moreover, compared with the E. faecium B1 group, the expression level of entA , entB , and entP genes of E. faecium B1 in the co-culture of fermented sausages was increased during the storage, which may be the inhibition mechanism of E. faecium B1 on L. monocytogenes. These results demonstrated that E. faecium B1 could potentially be used as bio-protection to control L. monocytogenes in meat products. • E. faecium B1 exhibited better safety characteristics by whole genome analysis. • E. faecium B1 inhibited the survival of L. monocytogenes in fermented sausages. • The expression of entA / B / P in E. faecium B1 was increased during co-culture. • E. faecium plays an important regulatory role in the virulence genes of pathogens. [ABSTRACT FROM AUTHOR]

• Five novel enterococcal phages were isolated and characterized with varied host range. • SHEF14 has a small genome (19.3 Kb) and effectively infects a VRE strain. • Enterococcal polysaccharide antigen (EPA) has a crucial role for SHEF phage infection. • A carbohydrate-targeting domain (CBM22) was found conserved within three phage genomes. Enterococci are robust Gram-positive bacteria that pose a significant threat in healthcare settings due to antibiotic resistance, with vancomycin-resistant enterococci (VRE) most prominent. To tackle this issue, bacteriophages (bacterial viruses) can be exploited as they specifically and efficiently target bacteria. Here, we successfully isolated and characterised a set of novel phages: SHEF10, SHEF11, SHEF13, SHEF14, and SHEF16 which target E. faecalis (SHEF10,11,13), or E. faecium (SHEF13, SHEF14 & SHEF16) strains including a range of clinical and VRE isolates. Genomic analysis shows that all phages are strictly lytic and diverse in terms of genome size and content, quickly and effectively lysing strains at different multiplicity of infections. Detailed analysis of the broad host-range SHEF13 phage revealed the crucial role of the enterococcal polysaccharide antigen (EPA) variable region in its infection of E. faecalis V583. In parallel, the discovery of a carbohydrate-targeting domain (CBM22) found conserved within the three phage genomes indicates a role in cell surface interactions that may be important in phage-bacterial interactons. These findings advance our comprehension of phage-host interactions and pave the way for targeted therapeutic strategies against antibiotic-resistant enterococcal infections. [ABSTRACT FROM AUTHOR]

Facing the rapid spread of antimicrobial resistance, methods based on single-cell Raman spectroscopy have proven their advances in reducing the turn-around time (TAT) of antimicrobial susceptibility tests (AST). However, the Raman-based methods are still hindered by the prolonged centrifugal cell washing procedure, which may require complex labor operation and induce high mechanical stress, resulting in a pretreatment time of over 1 h as well as a high cell-loss probability. In this study, we developed a micro-flow cell washing device and corresponding Raman-compatible washing chips, which were able to automatically remove the impurities in the samples, retain the bacterial cell and perform Raman spectra acquisition in situ. Results of washing the 5- and 10-μm polymethyl methacrylate (PMMA) microspheres showed that the novel technique achieved a successful removal of 99 % impurity and an 80 % particle retention rate after 6 to 10 cycles of washing. The micro-flow cell washing technique could complete the pretreatment for urine samples in a 96-well plate within 10 min, only taking 15 % of the handling time required by centrifugation. The AST profiles of urine sample spiked with E. coli 25922, E. faecalis 29212, and S. aureus 29213 obtained by the proposed Raman-based approach were found to be 100 % consistent with the results from broth micro-dilution while reducing the TAT to 3 h from several days which is required by the latter. Our study has demonstrated the micro-flow cell washing technique is a reliable, fast and compatible approach to replace centrifuge washing for sample pretreatment of Raman-AST and could be readily applied in clinical scenarios. [Display omitted] • Micro-flow cell washing enables automatic impurity removal, bacterial cell retention, and in-situ Raman spectra acquisition. • Micro-flow cell washing can be seamlessly integrated into the Fast Raman-assisted Antibiotic Susceptibility Test pipeline. • The sample handling time for the sample in a 96-well plate was reduced by 85 % compared to centrifuging. [ABSTRACT FROM AUTHOR]

• Lactic acid bacteria were isolated from fermented black cherry fruit, which had never been investigated before and they are afforded generally regarded as safe status and have positive influence on gastrointestinal tract of human and other consumer animals. • The LAB strains exhibited strong survival properties and antimicrobial activities, highly desirable features for probiotic application against foodborne pathogens. • Salmonella paratyphi a sessile cells were effectively reduced after treatment with the CFS of lactiplantibacillus plantarum MYSAS1 and enterococcus faecium MYSAS4 all the in-vitro assays. Salmonella spp is one of the leading causes of bacterial foodborne illnesses worldwide resulting in acute gastroenteritis. The current study aimed to explore the inhibitory activity of two newly isolated probiotic candidates Lactiplantibacillus plantarum MYSAS1 and Enterococcus faecium MYSAS4 from fermented black cherry fruit, against Salmonella enterica subsp. enterica serovar Paratyphi A. Results demonstrated effective inhibitory activity of selected Lactic acid bacteria (LAB) strains against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Salmonella Paratyphi A. In addition, the cell-free supernatant (CFS) of both strains showed potent antimicrobial activity on growth of S. Paratyphi A were demonstrated by agar well diffusion, broth microdilution assay, in vitro time-kill assay, and co-culture experiments. Besides, Salmonella sessile cells were effectively reduced by 70% after treatment with the CFS of L. plantarum MYSAS1 and E. faecium MYSAS4, as determined by crystal violet and 3-(4, 5-dimethylthiazol-2-y1)-2, 5-diphenyltetra bromide (MTT) biofilm assays. The antimicrobial substances of CFS were thermostable but sensitive to pH neutralization, suggesting that the observed antisalmonella activity is likely due to organic acids. Liquid Chromatography- Tandem Mass Spectrometry (LC-MS/MS) analysis of CFS revealed that the antimicrobial activity is likely due to the presence of 11 different organic acids. The isolated strains exhibited important probiotic characteristics, such as sensitivity to most of the antibiotics tested (except vancomycin and kanamycin), anti-hemolytic activity, tolerance to acidic pH and 0.3% bile, and survival ability at different temperatures. L. plantarum MYSAS1 and E. faecium MYSAS4 also exhibited auto-aggregation and cell surface hydrophobicity of 45 and 80%, respectively. Our findings demonstrated important probiotic features isolated from black cherry fruits while inhibiting multiple pathogens, suggesting possible applications of these potential probiotic strains as alternatives for antibiotics and chemical preservatives in the veterinary and food sectors. [ABSTRACT FROM AUTHOR]

• Propolis is a natural bee product with wide range of biological activities. • Nanoparticles in clinical endodontics improve the stability and effectiveness of drug treatment. • Propolis nanoparticle as an endodontic irrigant was effective in inhibiting biofilm formation. • Its, was able to inhibit E. faecalis biofilm adherence in concentration of sub-MIC. Propolis is a natural product that is collected by honey bees from parts of plants, buds, and exudates. The general composition of this substance varies in different geographical locations and climates. The biological characteristics of propolis are attributed to its chemical composition especially polyphenols and flavonoids. In recent years, the current trend has been towards the identification of natural products in disinfection. In addition, Nanoparticles are able to penetrate bacteria and bacterial biofilms, so they can be a potential agent for controlling the growth of bacterial infections. Therefore, this study aimed to investigate the antimicrobial efficacy of propolis and propolis nanoparticle (PN) as an endodontic irrigant against E. faecalis biofilm in vitro. PN was prepared by the ultrasonication method. Scanning electron microscopy and dynamic light scattering were used to measure the size and morphology of the produced nanoparticles. The antimicrobial and anti-biofilm activity of Iranian propolis (IP), PN and sodium hypochlorite (5.25% NaOCl) against E. faecalis (PTCC 1778) were assessed. Results indicated that PN, at a concentration 10 times lower, was more effective against E. faecalis (PTCC 1778) than IP (p <0.001). Also, PN was able to inhibit the adhesion of E. faecalis biofilm at lower concentrations than IP (p <0.001) which could be due to the reduced particle size, leading to better nanoparticle penetration. Further research is needed to investigate the synergistic effect of propolis and PN in combination with endodontic irrigants and to understand their mechanism of action. [ABSTRACT FROM AUTHOR]

Enterocin K1 (EntK1), a bacteriocin that is highly potent against vancomycin-resistant enterococci, depends on binding to an intramembrane protease of the site-2 protease family, RseP, for its antimicrobial activity. RseP is highly conserved in both EntK1-sensitive and EntK1-insensitive bacteria, and the molecular mechanisms underlying the interaction between RseP and EntK1 and bacteriocin sensitivity are unknown. Here, we describe a mutational study of RseP from EntK1-sensitive Enterococcus faecium to identify regions of RseP involved in bacteriocin binding and activity. Mutational effects were assessed by studying EntK1 sensitivity and binding with strains of naturally EntK1-insensitive Lactiplantibacillus plantarum-expressing various RseP variants. We determined that sitedirected mutations in conserved sequence motifs related to catalysis and substrate binding, and even deletion of two such motifs known to be involved in substrate binding, did not abolish bacteriocin sensitivity, with one exception. A mutation of a highly conserved asparagine, Asn359, in the extended so-called LDG motif abolished both binding of and killing by EntK1. By constructing various hybrids of the RseP proteins from sensitive E. faecium and insensitive L. plantarum, we showed that the extracellular PDZ domain is the key determinant of EntK1 sensitivity. Taken together, these data may provide valuable insight for guided construction of novel bacteriocins and may contribute to establishing RseP as an antibacterial target. [ABSTRACT FROM AUTHOR]