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Terminalia ferdinandiana Exell, Terminalia grandiflora Benth., Terminalia microcarpa Decne., and Terminalia muelleri Benth. (family: Combretaceae) belong to the genus Terminalia. Plants of this genus have been extensively used as traditional medicines to treat a variety of illnesses, including pathogen infections. However, we were unable to find any studies that have investigated the antibacterial activity of T. microcarpa. Similarly, whilst some preliminary studies have examined the antimicrobial properties of T. muelleri and T. grandiflora, they did not test the extracts against antibiotic-resistant pathogens. This study screens the antimicrobial activity of T. grandiflora, T. microcarpa, and T. muelleri and compares it to that of T. ferdinandiana extracts prepared from both the fruit and leaves against a range of pathogens, including multi-antibiotic-resistant strains. Solvents with varying polarities were used to extract different phytochemical constituents from the leaves of T. grandiflora, T. microcarpa, and T. muelleri and from the fruit and leaves of T. ferdinandiana. The aqueous and methanolic extracts each displayed significant antimicrobial activity when tested against the bacterial pathogens, including against the multidrug-resistant strains. When these extracts were tested in combination with selected antibiotics, some extracts potentiated the antimicrobial activity. This study identifies twelve synergistic, fifty-eight additive, and sixty non-interactive combinations, as well as thirty antagonistic effects. The extracts were evaluated for toxicity using the Artemia franciscana nauplii lethality assay (ALA) and were each classified as non-toxic, with the exception of the methanolic and aqueous T. ferdinandiana fruit extracts and the aqueous and ethyl acetate T. ferdinandiana leaf extracts. Metabolomic analysis using liquid chromatography–mass spectrometry (LC-MS) highlighted several flavonoids and tannins that may contribute to the antimicrobial activities reported herein. The potential antibacterial mechanism(s) of the T. ferdinandiana extracts are discussed in this study. [ABSTRACT FROM AUTHOR]

Abstract The current comprehensive review covers four main parts, of which some are presented in the form of a personal account. 1. Anodic oxidation of a) N‐alkyl and N,N‐diallyl carbonyl moieties, b) Azacycloalkyl amides and the effect of ring‐size on the outcome, c) Lactams, d) Sulfonamides, and e) The effect of a substituent R attached to carbonyl (N−CO−R) or sulfonamides (N−SO2R) on their oxidation potentials. 2. Anodic oxidation of aromatic amides, in particular of type Ph2CHCONHAr, lacking hydrogen(s) at the α‐position to nitrogen. They undergo three types of bond‐cleavage, yielding a variety of fragmentation products. 3. a) Anodic oxidation of symmetrical bisamides of type ZCONH(CH2)nNHCOZ (Z=Me, Ph, Ar; n=2–4) under constant current electrolysis, in methanol. For n=3, 4 they afford mostly mono‐ and dimethoxylation products. For n=2 they undergo ′CH2−CH2′ bond cleavage to yield fragmentation products. b) Anodic oxidation of symmetrical bisamides of type ArCONH(CH2)2NHCOAr under controlled potential electrolysis, in acetonitrile, leads to gem‐unsymmetrical bisamides of type ArCONHCH2NHCOMe as the major product, in fair yields. 4. Utilization of the anodic process in organic synthesis to form C−C bonds by both intra‐ and inetrmolecular processes; as well as C−O and C−N bonds for generating heterocycles.

Herein, we leverage the Ni-catalyzed enantioselective reductive dicarbofunctionalization of internal alkenes with alkyl iodides to enable the synthesis of chiral pyrrolidinones bearing vicinal stereogenic centers. The application of newly developed 1-Nap Quinim is critical for formation of two contiguous stereocenters in high yield, enantioselectivity, and diastereoselectivity. This catalytic system also improves both the yield and enantioselectivity in the synthesis of α,α-dialkylated γ-lactams. Computational studies reveal that the enantiodetermining step proceeds with a carbamoyl-NiI intermediate that is reduced by the Mn reductant prior to intramolecular migratory insertion. The presence of the t-butyl group of the Quinim ligand leads to an unfavorable distortion of the substrate in the TS that leads to the minor enantiomer. Calculations also support an improvement in enantioselectivity with 1-Nap Quinim compared to p-tol Quinim.

Klebsiella aerogenes is an important opportunistic pathogen with the potential to develop resistance against last-line antibiotics, such as carbapenems, limiting the treatment options. Here, we investigated the antibiotic resistance profiles of 10 K. aerogenes strains isolated from patient samples in the intensive-care unit of a Brazilian tertiary hospital using conventional PCR and a comprehensive genomic characterization of a specific K. aerogenes strain (CRK317) carrying both the blaKPC-2 and blaNDM-1 genes simultaneously. All isolates were completely resistant to β-lactam antibiotics, including ertapenem, imipenem, and meropenem with differencing levels of resistance to aminoglycosides, quinolones, and tigecycline also observed. Half of the strains studied were classified as multidrug-resistant. The carbapenemase-producing isolates carried many genes of interest including: β-lactams (blaNDM-1, blaKPC-2, blaTEM-1, blaCTX-M-1 group, blaOXA-1 group and blaSHVvariants in 20-80% of the strains), aminoglycoside resistance genes [aac(6')-Ib and aph(3')-VI, 70 and 80%], a fluoroquinolone resistance gene (qnrS, 80%), a sulfonamide resistance gene (sul-2, 80%) and a multidrug efflux system transporter (mdtK, 70%) while all strains carried the efflux pumps Acr (subunit A) and tolC. Moreover, we performed a comprehensive genomic characterization of a specific K. aerogenes strain (CRK317) carrying both the blaKPC-2 and blaNDM-1 genes simultaneously. The draft genome assembly of the CRK317 had a total length of 5,462,831 bp and a GC content of 54.8%. The chromosome was found to contain many essential genes. In silico analysis identified many genes associated with resistance phenotypes, including β-lactamases (blaOXA-9, blaTEM-1, blaNDM-1, blaCTX-M-15, blaAmpC-1, blaAmpC-2), the bleomycin resistance gene (bleMBL), an erythromycin resistance methylase (ermC), aminoglycoside-modifying enzymes [aac(6')-Ib, aadA/ant(3")-Ia, aph(3')-VI], a sulfonamide resistance enzyme (sul-2), a chloramphenicol acetyltransferase (catA-like), a plasmidmediated quinolone resistance protein (qnrS1), a glutathione transferase (fosA), PEtN transferases (eptA, eptB) and a glycosyltransferase (arnT). We also detected 22 genomic islands, eight families of insertion sequences, two putative integrative and conjugative elements with a type IV secretion system, and eight prophage regions. This suggests the significant involvement of these genetic structures in the dissemination of antibiotic resistance. The results of our study show that the emergence of carbapenemase-producing K. aerogenes, coharboring blaKPC-2 and blaNDM-1, is a worrying phenomenon which highlights the importance of developing strategies to detect, prevent, and control the spread of these microorganisms. [ABSTRACT FROM AUTHOR]

A dynamic kinetic asymmetric transformation, involving the generation of four stereogenic centers with a well‐defined configuration, occurs in the cyclocondensation of diastereomeric mixtures of 2‐oxocyclohexanepropionic acid racemates 6 with (1S,2R)‐cis‐aminoindanol: two major tetracyclic lactams, 7 a and 7 b, that differ in the configuration of the four stereocenters on the decahydroquinoline moiety were obtained. From the above lactams, the removal of the chiral auxiliary, the introduction of a 2‐piperidone ring, and the closure of the diazine ring complete the first enantioselective total synthesis of the Myrioneuron alkaloid (−)‐schoberine B and its enantiomer (+)‐schoberine B. [ABSTRACT FROM AUTHOR]

This work describes the palladium(II)‐catalyzed regioselective C8‐H olefination of 1‐naphthamides. Interestingly, naphthamide fused lactam 2,3‐dihydro‐1H‐benzo[de]isoquinolin‐1‐one derivatives were also synthesized in the case of a particular class of napthamides. This protocol was found well compatible with a diverse range of acrylates and styrenes leading to product formation in good yields along with a wide functional group tolerance. The developed strategy was further applied to the synthesis of different drug derivatives. [ABSTRACT FROM AUTHOR]

A reductive (3+2) annulation of lactams through iridium‐catalyzed hydrosilylation and photoredox coupling with α‐bromoacetic acid was developed. The iridium‐catalyzed hydrosilylation of the lactam carbonyl group and subsequent elimination provide a transient cyclic enamine, which undergoes iridium‐catalyzed photoredox coupling with α‐bromoacetic acid in a one‐pot process. The developed conditions show high functional‐group tolerance and provide cyclic N,O‐acetals containing a quaternary carbon center. The resulting N,O‐acetals undergo a variety of acid‐mediated nucleophilic addition reactions via iminium ions to give substituted cyclic amines. The developed sequence including reductive (3+2) annulation and acid‐mediated nucleophilic addition was successfully applied to the four‐step total synthesis of (±)‐eburnamonine. [ABSTRACT FROM AUTHOR]

OBJECTIVE To assess the ability to de-label pediatric patients of their beta-lactam allergy by using a newly implemented institutional protocol and to identify potential barriers to the de-labeling process. METHODS All patients with reported allergies to prespecified beta-lactam antibiotics were eligible for a beta-lactam allergy interview. Following the interview, patients were grouped into 4 risk categories--no risk, low risk, moderate risk, and high risk--and assessed for intervention eligibility. Potential interventions included de-labeling based on the interview alone or proceeding to an oral amoxicillin challenge with or without penicillin allergy skin testing. RESULTS Of the 62 patients eligible for beta-lactam allergy interviews, 40% (n = 25) were de-labeled. Among de-labeled patients, 60% (n = 15) were de-labeled on the basis of the interview alone. Additionally, no failures were documented in patients who underwent an oral amoxicillin challenge or penicillin skin testing. Barriers to performing oral amoxicillin challenges or penicillin skin testing included concomitant systemic steroid or antihistamine use, refusal of intervention, and insufficient resources to perform penicillin skin testing. CONCLUSIONS There was a high frequency of patients de-labeled of their beta-lactam allergies in this study. Increased education to patients, parents, and providers on the de-labeling process, as well as increased personnel available to coordinate and perform de-labeling interventions, may result in more beta-lactam allergy de-labeling. [ABSTRACT FROM AUTHOR]

Background: An increasing number of drugs are used each year in the treatment of small pets (cats and dogs), including medicines (cephalosporins and fluoroquinolones) used in human therapy. Aim: The purpose of this study was to isolate and explore the antibiotic resistance of opportunistic Enterobacteriaceae (Escherichia coli, Klebsiella, Proteus, Ci trobacter, Enterobacter) from cats and dogs, and to isolate resistance genes in the microorganisms. Methods: In 2021, 808 samples of biological material from small domestic animals were collected in veterinary clinics in Kostanay. From these, 210 microorganisms were isolated and identified. Results: A large majority of the strains sampled belonged to E. coli-149 (70.9%), Enterobacter-11 (5.2%), Klebsiella-28 (13.3%), Proteus-12 (5.7%) and 10 Citrobacter isolates (4.8%). In all isolates identified, antibiotic resistance/sensitivity was determined by disc-diffusion method to ampicillin, cefoxitin, gentamicin, levomycetin, tetracycline, ciprofloxacin, norfloxacin, ofloxacin, cefoperazone, cefpodoxime, streptomycin, kanamycin, doxycycline, gemifloxacin, nalidixic acid, furazolidone, furadonine, amoxicillin, and enrofloxacin. Conclusion: The study has demonstrated that the greatest number of Enterobacteriaceae were sensitive to the action of meropenem, which belongs to the group of beta-lactam antibiotics; resistance was demonstrated against tetracycline, doxycycline, ampicillin, amoxicillin, ofloxacin, and cefpodoxime. The most common genes encoding antimicrobial resistance were as follows: BlaTEM and OXA in 41 and 28 isolates, respectively, encoding resistance to beta-lactams; StrA and StrB in 45 and 48 isolates encoding aminoglycosides; and tetA and tetB in 43 and 28 isolates encoding tetracyclines. Obtained data demonstrate that uncontrolled and frequent use of beta-lactam and tetracycline antibacterials, in cats and dogs, results in the spread of genotypic resistance among micro-organisms of the family Enterobacteriaceae. [ABSTRACT FROM AUTHOR]

Background and Aim: Antimicrobials are extensively used in poultry production for growth promotion as well as for the treatment and control of diseases, including avian pathogenic Escherichia coli (APEC). Poor selection, overuse, and misuse of antimicrobial agents may promote the emergence and dissemination of antimicrobial resistance (AMR) in APEC. This study aimed to assess antimicrobial susceptibility patterns and detect antibiotic resistance genes (ARGs) in APEC isolated from clinical cases of colibacillosis in commercial broiler, layer, and breeder chickens. Materials and Methods: A total of 487 APEC were isolated from 539 across 300 poultry farms in various regions of Nepal. Antimicrobial susceptibility patterns was determined using the Kirby-Bauer disk diffusion and broth microdilution methods. The index of AMR, such as multiple antibiotic resistance (MAR) index, resistance score (R-score), and multidrug resistance (MDR) profile, were determined. Polymerase chain reaction was employed to detect multiple ARGs and correlations between phenotypic and genotypic resistance were analyzed. Results: The prevalence of APEC was 91% (487/539). All of these isolates were found resistant to at least one antimicrobial agent, and 41.7% of the isolates were resistant against 8-9 different antimicrobials. The antibiogram of APEC isolates overall showed the highest resistance against ampicillin (99.4%), whereas the highest intermediate resistance was observed in enrofloxacin (92%). The MAR index and R-score showed significant differences between broiler and layers, as well as between broiler breeder and layers. The number of isolates that were resistant to at least one agent in three or more antimicrobial categories tested was 446 (91.6%) and were classified as MDR-positive isolates. The ARGs were identified in 439 (90.1%) APEC isolates, including the most detected mobilized colistin resistance (mcr1) which was detected in the highest (52.6%) isolates. Overall, resistance gene of beta-lactam (blaTEM), mcr1, resistance gene of sulphonamide (sul1) and resistance gene of tetracycline (tetB) (in broiler), were detected in significantly higher than other tested genes (p < 0.001). When examining the pair-wise correlations, a significant phenotype-phenotype correlation (p < 0.001) was observed between levofloxacin and ciprofloxacin, chloramphenicol and tetracycline with doxycycline. Similarly, a significant phenotype-genotype correlation (p < 0.001) was observed between chloramphenicol and the tetB, and colistin with blaTEM and resistance gene of quinolone (qnrA). Conclusion: In this study, the current state of APEC AMR in commercial chickens is revealed for the first time in Nepal. We deciphered the complex nature of AMR in APEC populations. This information of molecular surveillance is useful to combat AMR in APEC and to contribute to manage APEC associated diseases and develop policies and guidelines to enhance the commercial chicken production. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance is a global health issue that affects humans, animals, and agriculture. This study assessed the prevalence and antimicrobial susceptibility of extended-spectrum betalactamase-producing Escherichia coli (ESBL-EC) in poultry and hand swabs of meat handlers working in a dressing plant in the Philippines. Fourteen (14) hand swabs from poultry handlers and 89 poultry cecal samples were collected and screened for ESBL production using MacConkey agar supplemented with cefotaxime and eosin methylene blue agar. Identification of E. coli through biochemical testing and antimicrobial susceptibility testing was then performed using the VITEK 2 System. Results showed that 7.14% (1/14) of the hand swabs and 23.60% (21/89) of the poultry cecal samples were positive for ESBL-EC. Identified isolates were further evaluated for their antimicrobial susceptibility using 33 antibiotics from various groups. Results showed 100% (22/22) resistance to the following antimicrobial drugs: ampicillin, ticarcillin, cefalotin, cefuroxime, cefuroxime axetil, cefixime, cefotaxime, nalidixic acid, ciprofloxacin, levofloxacin, moxifloxacin, ofloxacin, tetracycline, trimethoprim, and trimethoprim/sulfamethoxazole. Resistance of select ESBL-EC isolates against other drugs under the beta-lactam, tetracycline, chloramphenicol, and aminoglycoside groups were also observed. Antimicrobial-resistant bacteria may be found in both human and animal sources, which highlights the need for ensuring safety practices to prevent their spread in the community. Gene sequencing and phylogenetic analysis may be used to further evaluate this relationship. Continuous surveillance and review of standards and protocols are also needed to monitor antimicrobial resistance, as underlined by the strategies of the One Health approach. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the different present and future therapeutic β-lactam/β-lactamase inhibitor (BL/BLI) alternatives, namely aztreonam-avibactam, imipenem-relebactam, meropenem-vaborbactam, cefepime-zidebactam, cefepime-taniborbactam, meropenem-nacubactam, and sulbactam-durlobactam against clinical isolates showing reduced susceptibility or resistance to cefiderocol in Enterobacterales, Acinetobacter baumannii, and Pseudomonas aeruginosa. Methods: MIC values of aztreonam, aztreonam-avibactam, cefepime, cefepime-taniborbactam, cefepime-zidebactam, imipenem, imipenem-relebactam, meropenem, meropenem-vaborbactam, meropenem-nacubactam, sulbactam-durlobactam, and cefiderocol combined with a BLI were determined for 67, 9, and 11 clinical Enterobacterales, P. aeruginosa or A. baumannii isolates, respectively, showing MIC values of cefiderocol being ≥1 mg/L. If unavailable, the respective β-lactam breakpoints according to EUCAST were used for BL/BLI combinations. Results: For Enterobacterales, the susceptibility rates for aztreonam, cefepime, imipenem, and meropenem were 7.5%, 0%, 10.4%, and 10.4%, respectively, while they were much higher for cefepime-zidebactam (91%), cefiderocol-zidebactam (91%), meropenem-nacubactam (71.6%), cefiderocol-nacubactam (74.6%), and cefiderocol-taniborbactam (76.1%), as expected. For P. aeruginosa isolates, the higher susceptibility rates were observed for imipenem-relebactam, cefiderocol-zidebactam, and meropenem-vaborbactam (56% for all combinations). For A. baumannii isolates, lower susceptibility rates were observed with commercially or under development BL/BLI combos; however, a high susceptibility rate (70%) was found for sulbactam-durlobactam and when cefiderocol was associated to some BLIs. Conclusions: Zidebactam- and nacubactam-containing combinations showed a significant in vitro activity against multidrug-resistant Enterobacterales clinical isolates with reduced susceptibility to cefiderocol. On the other hand, imipenem-relebactam and meropenem-vaborbactam showed the highest susceptibility rates against P. aeruginosa isolates. Finally, sulbactam-durlobactam and cefiderocol combined with a BLI were the only effective options against A. baumannii tested isolates. [ABSTRACT FROM AUTHOR]

Introduction: The emergence and spread of drug-resistant pathogens due to the improper use of antibiotics have become increasingly apparent in recent years. Objective: This retrospective comparative analysis aimed to assess and compare antibiotic prescription trends in Italy across two different regions based on geographic area and healthcare structure. One region represents a large hospital institution, while the other represents a populous local Italian health agency. The study also examined the impact of documented antibiotic stewardship programs and efforts to promote responsible antibiotic use at all levels, in alignment with international goals. Antibiotic consumption data were collected from the Umberto I Polyclinic Hospital and the ASL Napoli 3 South Local Health Agency. Methods: To compare consumption between regions, a standardized comparison using the Defined Daily Dose (DDD) was employed. The internal management system of each healthcare facility records all prescriptions and drug dispensations, and these data were extrapolated for this retrospective study. Results: A comparative assessment between the first half of 2022 and 2023 (January–June) highlighted a significant increase in beta-lactam antibiotic consumption, showing a twofold rise compared to the previous year's term. Regarding prescription averages, there was a noticeable increase of +29.00% in hospitalizations and +28.00% in hospital discharges within the ASL Napoli 3 South. Conversely, at Policlinico Umberto I, there was a marginal increase of +1.60% in hospitalizations and a decrease of −7.40% in hospital discharges. Conclusions: The study offers valuable insights into expenditure patterns and antibiotic consumption, underscoring the need for enhanced prescribing practices and awareness campaigns to address the issue of antibiotic resistance. The findings stress the importance of implementing international guidelines to combat the growing threat of antibiotic resistance and ensure the effective management of infectious diseases. [ABSTRACT FROM AUTHOR]

Background Streptococcus suis is an important pig pathogen and an emerging zoonotic agent. In a previous study, we described a high proportion of penicillin-resistant serotype 9 S. suis (SS9) isolates on pig farms in Italy. Objectives We hypothesized that resistance to penicillin emerged in some SS9 lineages characterized by substitutions at the PBPs, contributing to the successful spread of these lineages in the last 20 years. Methods Sixty-six SS9 isolates from cases of streptococcosis in pigs were investigated for susceptibility to penicillin, ceftiofur and ampicillin. The isolates were characterized for ST, virulence profile, and antimicrobial resistance genes through WGS. Multiple linear regression models were employed to investigate the associations between STs, year of isolation, substitutions at the PBPs and an increase in MIC values to β-lactams. Results MIC values to penicillin increased by 4% each year in the study period. Higher MIC values for penicillin were also positively associated with ST123, ST1540 and ST1953 compared with ST16. The PBP sequences presented a mosaic organization of blocks. Within the same ST, substitutions at the PBPs were generally more frequent in recent isolates. Resistance to penicillin was driven by substitutions at PBP2b, including K479T, D512E and K513E, and PBP2x, including T551S, while reduced susceptibility to ceftiofur and ampicillin were largely dependent on substitutions at PBP2x. Conclusions Here, we identify the STs and substitutions at the PBPs responsible for increased resistance of SS9 to penicillin on Italian pig farms. Our data highlight the need for monitoring the evolution of S. suis in the coming years. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have been widely used in metal-ion detection and are promising candidates for applications in chemical sensors and biomedicine. However, the abundant functional species on the surface of CDs often result in simultaneous response to multiple metal ions and poor selectivity. To realize the selective detection of metal ions, it is crucial to establish the correlation between the surface structure of CDs and metal-ion detection. Herein, CDs with different surface structures were synthesized under harsh thermal microwave reaction. The CDs have citric acid-like, polyethylene glycol-like (PEG-like), or polyethyleneimine-like (PEI-like) surfaces in combination with 4-hydroxy-1H-pyrrolo[3,4-c]pyridine-1,3,6(2H,5H)-trione (HPPT); and amide bonds were found in the lactam structure of HPPT. Different surface species can be distinguished to recognize Fe3+, Cu2+, and Hg2+ ions. Accordingly, organic species of PEG, HPPT, and PEI were used to functionalize carbon nanoparticles to prepare targeting functionalized CDs. The PEG/CDs and HPPT/CDs have high selectivity for Fe3+ and Hg2+ ions, while the PEI/CDs have high selectivity for Cu2+ ions, eliminating the interference of -NH combining Co2+, Mn2+, and Ni2+ ions. Our findings shed light on the correlation between the surface structure of CDs and selective detection of metal ions, which can expand the sensing applications of CDs. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) have recently become an emerging environmental contaminants. The aquatic environment, such as a river has already become the most polluted environment and can be a driver of ARGs. The water from irrigation canal has the potential to become a hotspot of ARGs through contamination from river pollutants carried along to the irrigation canal. However, the information regarding the cross-contamination of ARGs in fish farming systems integrated with irrigation canal in Indonesia needs further study. This study investigated the occurrence of ARGs sulfonamide (sul1), tetracycline (tetA), beta lactam (blaGES), and multi drug resistance (mexF) from body water samples along the irrigation canal and aquaculture ponds which utilize irrigation water for cultivation. Sampling sites are located in the Kulon Progo Regency (Indonesia) and samples were taken during the rainy season. Gene amplification was performed using Multiplex PCR. The results showed that sul1, tetA, and blaGES were detected in 67%, 63%, and 55% of all samples. Meanwhile, mexF was only found upstream and downstream irrigation canals, which accounted for 25% of the total samples. The results of this study indicated that the Sapon Irrigation Canal has the potential to cause the spread of antibiotic resistance genes. [ABSTRACT FROM AUTHOR]

The influence of anthropogenic pollution on the distribution of bacterial diversity, antibiotic-resistant bacteria (ARBs), and antibiotic resistance genes (ARGs) was mapped at various geo-tagged sites of Mini River, Vadodara, Gujarat, India. The high-throughput 16S rRNA gene amplicon sequencing analysis revealed a higher relative abundance of Planctomycetota at the polluted sites, compared to the pristine site. Moreover, the relative abundance of Actinobacteriota increased, whereas Chloroflexi decreased in the water samples of polluted sites than the pristine site. The annotation of functional genes in the metagenome samples of Mini River sites indicated the presence of genes involved in the defence mechanisms against bacitracin, aminoglycosides, cephalosporins, chloramphenicol, streptogramin, streptomycin, methicillin, and colicin. The analysis of antibiotic resistome at the polluted sites of Mini River revealed the abundance of sulfonamide, beta-lactam, and aminoglycoside resistance. The presence of pathogens and ARB was significantly higher in water and sediment samples of polluted sites compared to the pristine site. The highest resistance of bacterial populations in the Mini River was recorded against sulfonamide (≥ 7.943 × 103 CFU/mL) and ampicillin (≥ 8.128 × 103 CFU/mL). The real-time PCR–based quantification of ARGs revealed the highest abundance of sulfonamide resistance genes sul1 and sul2 at the polluted sites of the Mini River. Additionally, the antimicrobial resistance genes aac(6′)-Ib-Cr and blaTEM were also found abundantly at polluted sites of the Mini River. The findings provide insights into how anthropogenic pollution drives the ARG and ARB distribution in the riverine ecosystem, which may help with the development of antimicrobial resistance mitigation strategies. [ABSTRACT FROM AUTHOR]

A diaminomethylenemalononitrile organocatalyst efficiently promoted the asymmetric conjugate addition of cyclic β‐keto esters to benzoyl acrylonitriles to afford the corresponding adducts. This was followed by the transformation of the nitrile group into an amide group, resulting in bicyclic γ‐lactam derivatives in good yields with excellent enantioselectivities (up to 99 % ee). As far as we know, this is the first study to synthesize chiral bicyclic γ‐lactam derivatives from cyclic β‐keto esters and benzoyl acrylonitriles. [ABSTRACT FROM AUTHOR]

Here we present a [3+2] cycloaddition of rationally designed trisubstituted cyclic α‐chloroamides, primarily those incorporating pharmacological pyrazolone cores, as potent synthons for synthesizing valuable spirocyclic γ‐lactam architectures. This protocol exhibits 52–96% yields, impressive substrate compatibility, and scale‐up capacity. Importantly, this study also represents one of the rare examples that harness enaminone C−N bond cleavage to engineer relevant spirocyclic γ‐lactam skeletons of biological interest. Moreover, we propose a plausible mechanistic explanation to elucidate the outstanding chemical outcomes observed, thereby enriching the synthetic toolbox for pyrazolone chemistry and α‐haloamide‐mediated reactions. [ABSTRACT FROM AUTHOR]

• Meta-analysis was conducted on the effects of beta-lactams in SUDs animal models. • Beta-lactams reduced the reinforcing effects as measured by drugs SA and CPP. • Beta-lactams attenuated drug-seeking, hyperlocomotion, and withdrawal symptoms. Introduction: Preclinical studies demonstrated that beta-lactams have neuroprotective effects in conditions involving glutamate neuroexcitotoxicity, including substance use disorders (SUDs). This meta-analysis aims to analyze the existing evidences on the effects of beta-lactams as glutamate transporter 1 (GLT-1) upregulators in animal models of SUDs, identification of gaps in the literature, and setting the stage for potential translation into clinical phases. Methods: Meta-analysis was conducted on preclinical studies retrieved systematically from MEDLINE and ScienceDirect databases. Abused substances were identified by refereeing to the National Institute on Drug Abuse (NIDA). The results were quantitatively described with a focus on the behavioral outcomes. Treatment effect sizes were described using standardized mean difference, and they were pooled using random effect model. I2 -statistic was used to assess heterogeneity, and Funnel plot and Egger's test were used for assessment of publication bias. Results: Literature search yielded a total of 71 studies that were eligible to be included in the analysis. Through these studies, the effects of beta-lactams were evaluated in animal models of nicotine, cannabis, amphetamines, synthetic cathinone, opioids, ethanol, and cocaine use disorders as well as steroids-related aggressive behaviors. Meta-analysis showed that treatments with beta-lactams consistently reduced the pooled undesired effects of the abused substances in several paradigms, including drug-self administration, conditioned place preference, drug seeking behaviors, hyperlocomotion, withdrawal syndromes, tolerance to analgesic effects, hyperalgesia, and hyperthermia. Conclusion: This meta-analysis revealed that enhancing GLT-1 expression in the brain through beta-lactams seemed to be a promising treatment approach in the context of substance use disorders, as indicated by results in animal models. [ABSTRACT FROM AUTHOR]

Background: Tigecycline and cefoperazone/sulbactam can cause coagulation disorders; tigecycline may also lead to hypofibrinogenemia, raising safety concerns. This study aimed to investigate whether tigecycline plus cefoperazone/sulbactam increases the risk of bleeding compared with other tigecycline-based combination therapies and identify risk factors for tigecycline-associated hypofibrinogenemia. Methods: In this multi-method, multicenter, retrospective study, coagulation and other baseline variables were compared using a cohort study, and risk factors for hypofibrinogenemia using a case-control study. Results: The 451 enrolled participants were divided into three group: tigecycline plus cefoperazone/sulbactam (Group A, 193 patients), tigecycline plus carbapenems (Group B, 200 patients) and tigecycline plus β-lactams without N-methylthio-tetrazole (NMTT) side chains (Group C, 58 patients). Activated partial thromboplastin time and prothrombin time were prolonged, and fibrinogen declined for all patients after tigecycline-based medication (all p < 0.05). Prothrombin time in Group B was significantly longer than in other groups (p < 0.05), but there were no significant differences in bleeding events between the three groups (p = 0.845). Age greater than 80 years (OR: 2.85, 95% CI: 1.07-7.60), treatment duration (OR: 1.29, 95% CI: 1.19-1.41), daily dose (OR: 2.6, 95% CI: 1.29-5.25), total bilirubin (OR: 1.01, 95% CI: 1.01-1.02) and basal fibrinogen (OR: 1.32, 95% CI: 1.14-1.63) were independent risk factors of hypofibrinogenemia. The optimal cut-off for treatment course was 6 days for high-dose and 11 days for lowdose. Conclusion: Tigecycline plus cefoperazone/sulbactam did not increase the risk of bleeding compared with tigecycline plus carbapenem, or tigecycline plus β-lactam antibiotics without NMTT-side-chains. Coagulation function should be closely monitored in patients receiving tigecycline treatment. [ABSTRACT FROM AUTHOR]

Bacteria have evolved numerous regulatory pathways to survive in changing environments. The SOS response is an inducible DNA damage repair system that plays an indispensable role in bacterial adaptation and pathogenesis. Here we report a discovery of the previously uncharacterized protein Lmo0946 as an SOS response interfering factor (Sif) in the human pathogen Listeria monocytogenes. Functional genetic studies demonstrated that sif is indispensable for normal growth of L. monocytogenes in stress-free as well as multi-stress conditions, and sif contributes to susceptibility to β-lactam antibiotics, biofilm formation and virulence. Absence of Sif promoted the SOS response and elevated expression of mobilome genes accompanied by mobilization of the A118 prophage and ICELm-1 mobile genetic elements (MGEs). These changes were found to be associated with decreased expression of general stress response genes from the σB regulon as well as virulence genes, including the PrfA regulon. Together, this study uncovers an unexpected role of a previously uncharacterized factor, Sif, as an inhibitor of the SOS response in L. monocytogenes. [ABSTRACT FROM AUTHOR]

Detection of correct oxidation state of a metal ion is important to understand its speciation and redox properties. Some of rhodamine derivatives can identify Al3+, Cr3+ and Fe3+ as the trivalent cations. We have synthesized a rhodamine derivative, HL‐qui, from the reaction of N‐(rhodamine‐6G)lactam‐ethylenediamine with quinoline‐2‐carboxaldehyde for the colorimetric as well as fluorogenic detection of all of metal ions with +3 oxidation state such as Al3+, Cr3+, Fe3+, Ga3+, In3+, Tl3+ and Gd3+. In the presence of these trivalent cations, colorless and nonfluorescent HL‐qui turns pink and strongly fluorescent in HEPES buffer (10 mM) in H2O/ethanol=1/9 (v/v) (pH 7.4) as its spirolactam ring gets open to show the changes in color and fluorescence properties. High sensitivity of the probe towards the cations is reflected from the limit of detection values that are in nM range. To the best of our knowledge, there is no such report where fluorescence sensing has been utilized to determine oxidation state. This multi‐ion sensing feature has been used for fabrication of multi input‐output based logic circuit using Boolean algebraic method. It has been used in imaging of metal ions in living cell (L6 cells). [ABSTRACT FROM AUTHOR]

Documentation of adverse drug reactions (ADRs) is a key factor in guiding future prescribing. However, incomplete documentation is common and often fails to distinguish implicated drugs as true allergies. This in turn leads to unnecessary avoidance of implicated drug classes and may result in sub-optimal prescribing. Pharmacovigilance (PV) programs utilize a systematic approach to clarify ADR documentation and are known to improve patient safety. Yet it remains unclear if PV alters prescribing. Or, if the existence of the ADR documentation itself continues to prompt avoidance of implicated drugs. To address this, our work presents a retrospective cohort study assessing if clarification of antibiotic ADRs by a hospital-wide PV team was associated with future, safe, re-prescribing at a freestanding pediatric hospital in the midwestern United States. First, we compared the likelihood of future prescribing in an antibiotic class with an active ADR, as compared to alternative drug classes, between PV-clarified and non-clarified patients. Second, we assessed differences in adverse event rates 30-days after future prescribing based on PV clarification status. For robustness, analyses were performed on patients with ADRs in four antibiotic classes: penicillin-based beta-lactams (n = 45,642), sulfonamides/trimethoprim (n = 5,329), macrolides (n = 3,959), and glycopeptides (n = 622). Results illustrate that clarification of an ADR by PV was associated with an increased odds of future prescribing in the same drug class (Odds Ratio [95%-CI]): penicillin-based beta-lactams (1.59 [1.36–1.89]), sulfonamides/trimethoprim (2.29 [0.89–4.91]), macrolides (0.77 [0.33–1.61]), and glycopeptide (1.85 [1.12–3.20]). Notably, patients clarified by PV experienced no increase in the rate of adverse events within 30-days following the prescribing of antibiotics in the same class as an active ADR. Overall, this study provides strong evidence that PV reviews safely increase the rate of re-prescribing antibiotics even in the presence of an existing implicated drug ADR. [ABSTRACT FROM AUTHOR]

We report an organocatalyst that combines a triazolium N-heterocyclic carbene (NHC) with a squaramide as a hydrogen-bonding donor (HBD), which can effectively catalyze the atroposelective ring-opening of biaryl lactams via a unique amide C–N bond cleavage mode. The free carbene species attacks the amide carbonyl, forming an axially chiral acyl-azolium intermediate. Various axially chiral biaryl amines can be accessed by this methodology with up to 99% ee and 99% yield. By using mercaptan as a catalyst turnover agent, the resulting thioester synthon can be transformed into several interesting atropisomers. Both control experiments and theoretical calculations reveal the crucial role of the hybrid NHC-HBD skeleton, which activates the amide via H-bonding and brings it spatially close to the carbene centre. This discovery illustrates the potential of the NHC-HBD chimera and demonstrates a complementary strategy for amide bond activation and manipulation. Developing efficient methods for the formation and cleavage of amide species is a primary research goal, but the amide C–N bond cleavage is exceptionally challenging. Here, the authors report the development of an organocatalyst that can effectively catalyze the atroposelective ring-opening of biaryl lactams via amide C–N bond cleavage. [ABSTRACT FROM AUTHOR]

An EDA complex comprising N‐allyl bromodifluoroacetamides and tertiary alkyl amine was exploited to facilitate annulative difunctionalization reaction under visible‐light irradiation. This external photocatalyst‐free methodology garners olefin‐olefin coupling featuring a radical Truce‐Smiles rearrangement and produced long‐chain functionalized gem‐difluoropyrrolidones from N‐substituted methacryloyl sulfonamides, while simple N‐aryl methacrylamides furnished pyrrolidinone‐oxindole hybrid lactams in high yields. Mechanistic investigations substantiate a combined reaction mechanism, involving charge‐transfer EDA complex‐based radical cascade, alongside an α‐aminoalkyl radical‐triggered XAT process, exhibiting a quantum yield value of 1.48. [ABSTRACT FROM AUTHOR]

Introduction: The rise in antimicrobial resistance (AMR) that is affecting humans, animals, and the environment, compromises the human immune system and represents a significant threat to public health. Regarding the impact on water sanitation, the risk that antimicrobial-resistant genes (ARGs) and antimicrobialresistant bacteria in surface water in cities pose to human health remains unclear. To determine the prevalence of AMR in environmental surface water in Japan, we used DNA sequencing techniques on environmental water DNA (eDNA) and the DNA of multidrug-resistant bacteria (mrDNA). Methods: The eDNA was extracted from four surface water samples obtained from the Tokyo area and subjected to high-throughput next-generation DNA sequencing using Illumina-derived shotgun metagenome analysis. The sequence data were analyzed using the AmrPlusPlus pipeline and the MEGARes database. Multidrug-resistant bacteria were isolated using a culture-based method from water samples and were screened by antimicrobial susceptibility testing (for tetracycline, ampicillin-sulbactam, amikacin, levofloxacin, imipenem, and clarithromycin). Of the 284 isolates, 22 were identified as multidrug-resistant bacteria. The mrDNA was sequenced using the Oxford nanopore MinION system and analyzed by NanoARG, a web service for detecting and contextualizing ARGs. Results and discussion: The results from eDNA and mrDNA revealed that ARGs encoding beta-lactams and multidrug resistance, including multidrug efflux pump genes, were frequently detected in surface water samples. However, mrDNA also revealed many sequence reads from multidrug-resistant bacteria, as well as nonspecific ARGs, whereas eDNA revealed specific ARGs such as pathogenic OXAtype and New Delhi metallo (NDM)-beta-lactamase ARGs. Conclusion: To estimate potential AMR pollution, our findings suggested that eDNA is preferable for detecting pathogen ARGs. [ABSTRACT FROM AUTHOR]

Detecting antibiotic residues is vital to minimize their impact. Yet, existing methods are complex and costly. Biosensors offer an alternative. While many biosensors detect various antibiotics, specific ones for beta‐lactams are lacking. To address this gap, a biosensor based on the AmpC beta‐lactamase regulation system (ampR–ampC) from Pseudomonas sp. IB20, an Antarctic isolate, was developed in this study. The AmpR–AmpC system is well‐conserved in the genus Pseudomonas and has been extensively studied for its involvement in peptidoglycan recycling and beta‐lactam resistance. To create the biosensor, the ampC coding sequence was replaced with the mCherry fluorescent protein as a reporter, resulting in a transcriptional fusion. This construct was then inserted into Escherichia coli SN0301, a beta‐lactam hypersensitive strain, generating a whole‐cell biosensor. The biosensor demonstrated dose‐dependent detection of penicillins, cephalosporins and carbapenems. However, the most interesting aspect of this work is the high sensitivity presented by the biosensor in the detection of carbapenems, as it was able to detect 8 pg/mL of meropenem and 40 pg/mL of imipenem and reach levels of 1–10 ng/mL for penicillins and cephalosporins. This makes the biosensor a powerful tool for the detection of beta‐lactam antibiotics, specifically carbapenems, in different matrices. [ABSTRACT FROM AUTHOR]

Objective: Staphylococcus aureus is a major human pathogen which is responsible for a wide variety of clinical manifestations both in nosocomial and community settings. The presence of methicillinresistant Staphylococcus aureus (MRSA) limits treatment options. There are major gaps in literature regarding the epidemiological and antimicrobial resistance characteristics of S. aureus in Northern Cyprus. This study aims to define the frequency of MRSA in a major hospital in Northern Cyprus and determine MRSA susceptibility to currently available antimicrobials in order to define the most effective regimen for the treatment of S. aureus infections. Methods: Four hundred and forty-nine clinical samples collected between January 2016 to December 2020 were retrospectively included in the study. Samples were cultured on Eosin-Methylene Blue (EMB) and 5% sheep blood agar and were incubated at 35°C for 24-48 h. Laboratory identification of isolates and antimicrobial susceptibility testing have been performed by Vitek-2 (bioMérieux, France) automated identification and susceptibility testing system. Antibiotic susceptibility was assessed according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Multi-drug resistance (MDR4) was determined by analyses of beta-lactam resistance plus nonsusceptibility to three additional classes of antimicrobial drugs. Data analysis was performed using SPSS Statistics Software version 23. A p value <0.05 was considered as statistically significant. Results: Of the 449 S. aureus isolates, 40.5% (n=182) were MRSA. In the inpatients group, MRSA infection rate was statistically higher (p=0.001) compared to outpatients. A significant correlation was observed between older age and MRSA infection. MRSA isolates exhibited higher resistance to erythromycin (85.4%), clindamycin (52.9%), ciprofloxacin (23.8%), levofloxacin (19.8%), tetracycline (68.0%), fosfomycin (13.0%), rifampicin (12.0%) and tobramycin (11.1%) compared to MSSA isolates (p<0.05). MDR was detected in 30.8% of the isolates. All isolates, MRSA and MSSA, showed high susceptibility to daptomycin, linezolid, vancomycin, fusidic acid, teicoplanin and gentamicin. The rate of MDR MRSA was observed to decrease statistically in the post-pandemic period compared to pre-pandemic period (p=0.0001). Conclusion: Over the five-year period, of the study, MRSA isolates have shown an increased resistance to several antibiotics. Therefore, the Infection Control Committee should work actively and inappropriate antibiotic use should be limited in order to prevent the spread of MDR pathogens. [ABSTRACT FROM AUTHOR]

β-Lactams, such as penicillins and cephalosporins, have long been recognized as the most effective antibiotics for the treatment of infectious diseases. However, the major limitation to their effectiveness is the bacterial production of β-lactamase enzymes, which hydrolyze the β-lactam ring in these drugs, rendering them inactive. To overcome this resistance mechanism, β-lactamase inhibitors, such as clavulanic acid, are commonly used in combination with β-lactams. By inhibiting the action of β-lactamase enzymes, these inhibitors restore the efficacy of β-lactam antibiotics. In recent studies, researchers have employed docking techniques to investigate the interaction between β-lactamase enzymes and potential inhibitors. Specifically, the β-lactamases TEM-1 (1pzp) and IMP-1 (1JJE) were used as targets for designing new compounds. A series of novel compounds were generated by synthesizing 6 amides compounds as acid chloride derivatives and reacting them with p-aminodiphenylamine to form amide bonds. These compounds were then characterized by the use of various physical and spectroscopic methods to confirm their structures. Next, the synthesized compounds were subjected to biological testing to evaluate their efficacy against β-lactamase-producing Gram-positive and Gram-negative bacteria. This was accomplished by determining the minimum inhibitory concentration (MIC) of the compounds against three different strains of bacteria. Additionally, the possible anti β-lactamase activities of the compounds were compared to that of clavulanic acid. The results of this study revealed that five of the synthesized products exhibited effect similar to that of clavulanic acid for only one bacterial strain (Staph. aureus). Furthermore, the findings of the docking study suggest that the β-lactamase active pocket has a preference for hydrophobic substituents, as the synthesized products with these groups showed the highest binding score. In conclusion, the use of β-lactamase inhibitors, such as clavulanic acid, in combination with β-lactam antibiotics has proven effective in combating bacterial resistance. The development of novel compounds with anti β-lactamase activity holds promise for improving the treatment of infectious diseases. By understanding the preferences of the β-lactamase active pocket and designing compounds with hydrophobic substituents, researchers can enhance the affinity and efficacy of these inhibitors. This research contributes to the ongoing efforts to combat antibiotic resistance and improve patient outcomes in the field of infectious disease treatment. [ABSTRACT FROM AUTHOR]

Purpose: The duration of antibiotic treatment for prosthetic valve endocarditis caused by Streptococcus spp. is largely based on clinical observations and expert opinion rather than empirical studies. Here we assess the impact of a shorter antibiotic duration. Objectives: To assess the impact of antibiotic treatment duration for streptococcal prosthetic valve endocarditis on 12-month mortality as well as subsequent morbidity resulting in additional cardiac surgical interventions, and rates of relapse and reinfection. Methods: This retrospective multisite (N= 3) study examines two decades of data on patients with streptococcal prosthetic valve endocarditis receiving either 4 or 6 weeks of antibiotics. Overall mortality, relapse, and reinfection rates were also assessed for the entire available follow-up period. Results: The sample includes 121 patients (median age 72 years, IQR [53; 81]). The majority (74%, 89/121) received a ß-lactam antibiotic combined with aminoglycoside in 74% (89/121, median bi-therapy 5 days [1; 14]). Twenty-eight patients underwent surgery guided by ESC-guidelines (23%). The 12-month mortality rate was not significantly affected by antibiotic duration (4/40, 10% in the 4-week group vs 3/81, 3.7% in the 6-week group, p=0.34) or aminoglycoside usage (p=0.1). Similarly, there were no significant differences between the 2 treatment groups for secondary surgical procedures (7/40 vs 21/81, p=0.42), relapse or reinfection (1/40 vs 2/81 and 2/40 vs 5/81 respectively). Conclusions: Our study found no increased adverse outcomes associated with a 4-week antibiotic duration compared to the recommended 6-week regimen. Further randomized trials are needed to ascertain the optimal duration of treatment for streptococcal endocarditis. [ABSTRACT FROM AUTHOR]

In this work, we synthesized a family of three structurally related chiral oligothiophenes containing a 1,4‐diketo‐3,6‐diarylpyrrolo[3,4‐c]pyrrole (DPP) unit as the central core; functionalized with the same (S)‐3,7‐dimethyl‐1‐octyl chains on the nitrogen atoms of lactam moieties, they only differ in the number of lateral thiophene units. The aggregation modes of these π‐conjugated chiral systems were evaluated by means of UV–Vis absorption and ECD spectroscopies in conditions of solution aggregation (CHCl3/MeOH mixtures) and as thin films, describing in particular the impact of the π‐conjugation length on the chiroptical properties. Interestingly, we found that the variable number of thiophene units attached to the DPP core affects not only the propensity to aggregation but also the aggregates' helicity. ECD revealed information about the supramolecular arrangement of these molecules, that one would not obtain by using conventional optical spectroscopy and microscopy techniques. Thin film samples revealed very different aggregation modes with respect to solution aggregates, casting doubts on the common assumption that these latter may serve as simple models of the former ones. [ABSTRACT FROM AUTHOR]

Isoxazolidine, isoxazole, and isoquinolinone rings are present in the structure of several natural products and/or pharmaceutically interesting compounds. In this work, facile and efficient pathways have been developed for the preparation of fused frameworks bearing those heterocycles. The successful approaches for both isoxazolidine/isoquinolinone and isoxazole/isoquinolinone hybrid syntheses relied initially on 1,3-dipolar cycloadditions of nitrones and nitrile oxides to indenone and 2-propargylbenzamide, respectively. The construction of the isoquinolinone lactam system followed by performing a selective Schmidt reaction for isoxazolidine derivatives (two steps overall), whereas the isoxazole lactams were reached via an Ullmann-type cyclisation (three steps overall). Key observations were made regarding the stereo- and regioselectivities of the reactions employed, and small libraries of the targeted hybrids were prepared, demonstrating the general applicability of these strategies. [ABSTRACT FROM AUTHOR]

Bovine mastitis, a growing issue in dairy farms, with Klebsiella species being associated with severe mastitis. This study was designed to evaluate the prevalence, biochemical changes, antibiogram susceptibility profile, and biofilm-producing capacity of Klebsiella pneumoniae isolated from Holstein cows with clinical mastitis at a private farm in Alexandria, Egypt. The overall isolation rate of Klebsiella species was 28%, which was further characterized by polymerase chain reaction (PCR) targeting the 16S-23S internal transcribed spacer gene as K. pneumoniae. Clinical mastitis significantly impacted milk composition and blood biochemistry, causing a decline in milk composition, reduction of antioxidant capacity, and increased enzymatic levels compared to normal controls. K. pneumoniae isolates showed 100% resistance to beta-lactam antibiotics, followed by resistance rates of 57, 43 and 43% to chloramphenicol, streptomycin, and sulfamethoxazole--trimethoprim, respectively, while ciprofloxacin and ceftriaxone showed complete susceptibility. The study found that all K. pneumoniae strains expressed the fimA, mrkA, and mrkD fimbrial genes, and the ecpA gene. The study highlights the high prevalence of multidrug-resistant and biofilm-producing K. pneumoniae strains in bovine clinical mastitis, emphasizing the need for improved antimicrobial usage and antibiofilm approaches to overcome the poor treatment response, as well as measuring antioxidant level and enzymatic activity in milk improved milk health screening. [ABSTRACT FROM AUTHOR]

The role of marine environments in the global spread of antibiotic resistance still remains poorly understood, leaving gaps in the One Health-based research framework. Antibiotic resistance genes (ARGs) encoding resistance to five major antibiotic classes, including sulfonamides (sul1, sul2), tetracyclines (tetA, tetB), β-lactams (blaCTX-M, blaTEM blaVIM), macrolides (ermB, mphA), aminoglycosides (aac3-2), and integrase gene (intl1) were quantified by RT-qPCR, and their distribution was investigated in relation to environmental parameters and the total bacterial community in bottom layer and surface waters of the central Adriatic (Mediterranean), over a 68 km line from the wastewater-impacted estuary to coastal and pristine open sea. Seasonal changes (higher in winter) were observed for antibiotic resistance frequency and the relative abundances of ARGs, which were generally higher in eutrophic coastal areas. In particular, intl1, followed by blaTEM and blaVIM, were strongly associated with anthropogenic influence and Gammaproteobacteria as their predominant carriers. Water column stratification and geographic location had a significant influence on ARGs distribution in the oligotrophic zone, where the bacterial community exhibited a seasonal shift from Gammaproteobacteria in winter to Marine group II in summer. [ABSTRACT FROM AUTHOR]

Ureaplasma species (Ureaplasma spp.) are commonly found as commensals in the human urogenital tracts, although their overgrowth can lead to infection in the urogenital tract and at distal sites. Furthermore, ureaplasmas lack a cell wall and do not synthesize folic acid, which causes all β-lactam and glycopeptide antibiotics, and sulfonamides and diaminopyrimidines, to be of no value. The antibiotics used in therapy belong to the fluoroquinolone, tetracycline, chloramphenicol and macrolide classes. However, the growing incidence of antibiotic-resistant Ureaplasma spp. in the population becomes a problem. Thus, there is a need to search for new drugs effective against these bacteria. Since 1951, the FDA-approved, well-tolerated, inexpensive, orally administered drug disulfiram (DSF) has been used in the treatment of chronic alcoholism, but recently, its antimicrobial effects have been demonstrated. The main biological metabolite of DSF, i.e., N,N-diethyldithiocarbamate (DDC), is generally believed to be responsible for most of the observed pharmacological effects of DSF. In the presented studies, the effect of DDC at concentrations of 2 µg/mL, 20 µg/mL and 200 µg/mL on the growth and survival of Ureaplasma urealyticum and Ureaplasma parvum was tested for the first time. The results indicated that all the used DDC concentrations showed both bacteriostatic and bactericidal activity against both tested strains. [ABSTRACT FROM AUTHOR]

Background Limited comparative data exist on acute kidney injury (AKI) risk and AKI-associated outcomes in hospitalized patients with carbapenem-resistant Gram-negative infections (CR-GNIs) treated with a newer β-lactam/β-lactam-β-lactamase inhibitor (BL/BL-BLI)-, polymyxin (PB)- or aminoglycoside (AG)-containing regimen. This study quantified the risk of AKI and AKI-related outcomes among patients with CR-GNIs treated with a newer BL/BL-BLI-, PB- or AG-containing regimen. Methods A multicentre, retrospective, observational study was performed (2016–20). The study included adult hospitalized patients with (i) baseline estimated glomerular filtration rates ≥30 mL/min/1.73 m2; (ii) CR-GN pneumonia, complicated urinary tract infection or bloodstream infection; and (iii) receipt of newer BL/BL-BLI, PG or AG within 7 days of index CR-GN culture for ≥3 days. Outcomes included AKI, in-hospital mortality and hospital costs. Results The study included 750 patients and most (48%) received a newer BL/BL-BLI. The median (IQR) treatment duration was 8 (5–11), 5 (4–8) and 7 (4–8) days in the newer BL/BL-BLI group, AG group and PB group, respectively. The PB group had the highest adjusted AKI incidence (95% CI) (PB: 25.1% (15.6%–34.6%) versus AG: 8.9% (5.7%–12.2%) versus newer BL/BL-BLI: 11.9% (8.1%–15.7%); P = 0.001). Patients with AKI had significantly higher in-hospital mortality (AKI: 18.5% versus 'No AKI': 5.6%; P = 0.001) and mean hospital costs (AKI: $49 192 versus 'No AKI': $38,763; P = 0.043). Conclusions The AKI incidence was highest among PB patients and patients with AKI had worse outcomes. Healthcare systems should consider minimizing the use of antibiotics that augment AKI risk as a measure to improve outcomes in patients with CR-GNIs. [ABSTRACT FROM AUTHOR]

Agrobacterium tumefaciens is a plant pathogen, broadly known as the causal agent of the crown gall disease. The soil bacterium is naturally resistant to beta‐lactam antibiotics by utilizing the inducible beta‐lactamase AmpC. Our picture on the condition‐dependent regulation of ampC expression is incomplete. A known regulator is AmpR controlling the transcription of ampC in response to unrecycled muropeptides as a signal for cell wall stress. In our study, we uncovered the global transcriptional regulator LsrB as a critical player acting upstream of AmpR. Deletion of lsrB led to severe ampicillin and penicillin sensitivity, which could be restored to wild‐type levels by lsrB complementation. By transcriptome profiling via RNA‐Seq and qRT‐PCR and by electrophoretic mobility shift assays, we show that ampD coding for an anhydroamidase involved in peptidoglycan recycling is under direct negative control by LsrB. Controlling AmpD levels by the LysR‐type regulator in turn impacts the cytoplasmic concentration of cell wall degradation products and thereby the AmpR‐mediated regulation of ampC. Our results substantially expand the existing model of inducible beta‐lactam resistance in A. tumefaciens by establishing LsrB as higher‐level transcriptional regulator. [ABSTRACT FROM AUTHOR]

Antimicrobial resistance (AMR) is a global health threat requiring urgent attention and effective strategies for containment. AMR is fueled by wastewater mismanagement and global mobility, disseminating multidrug-resistant (MDR) strains worldwide. While global estimates of AMR burden have been informative, community-level understanding has received little attention despite reports of high AMR prevalence in healthy communities. We assessed the "invasion" of antibiotic resistance genes (ARGs) into the normal human flora by characterizing AMR Escherichia coli in local wastewaters contributed by a healthy youth population. This study estimated 26% (out of 300 isolates) resistant and 59% plasmid-bearing E. coli in local wastewater. Of the 78 AMR isolates, the frequency of mono-resistance was higher against tetracycline (32%), followed by kanamycin (17%) and chloramphenicol (9%). Five isolates were potentially MDR. We further sequenced four MDRs and four sensitive strains to comprehend the genome and resistome diversity in comparison to the global wastewater E. coli (genomes from the PATRIC database). The whole-genome analysis revealed extensive genome similarity among global isolates, suggesting global dissemination and colonization of E. coli. Global wastewater resistome majorly comprised ARGs against aminoglycosides (26%), beta-lactam (17%), sulfonamide (11%), and trimethoprim (8%). Resistance to colistin, a last-resort antibiotic, was prevalent in MDRs of European and South Asian isolates. A systems approach is required to address the AMR crisis on a global scale, reduce antibiotic usage, and increase the efficiency of wastewater management and disinfection. [ABSTRACT FROM AUTHOR]

Introduction: New combinations of old β-lactam drugs with novel β-lactamase inhibitors, approved in recent years by the US Food and Drug Administration and the European Medicines Agency, are a promising alternative for the treatment of infections caused by multidrug-resistant strains. Due to limited availability and increasing resistance to antibacterial drugs, they should be used with caution, especially in patients with limited treatment options. It should be noted that both diazobicycloctane and boron inhibitors are inactive against metallo-β-lactamase (MBL) producing strains. The aim of this study was to evaluate the in vitro susceptibility of carbapenemase-producing Gram-negative bacilli to meropenem/vaborbactam, imipenem/relebactam and ceftazidime/avibactam in clinical samples from hospitalized patients. Materials and methods: The analysis included 102 clinical strains of carbapenemase-producing Enterobacterales and nonfermenters from hospital centers in Łódź, Poland. A minimum inhibitory concentration test strip method was used to determine antimicrobial susceptibility. Results: Seventy-one percent of Escherichia coli, 40% of Klebsiella pneumoniae, and 67% of Pseudomonas aeruginosa were resistant to meropenem/vaborbactam, 57%, 66%, and 60% to imipenem/relebactam, and 71%, 74%, and 60% to ceftazidime/avibactam, respectively. Considering carbapenemase resistance mechanisms, the highest efficacy was observed in Klebsiella pneumoniae carbapenemases (KPC) strains for each drug combination tested. Conclusions: The results of our study confirm the conclusions of the studies evaluating the susceptibility of Gram-negative, fermenting, and non-fermenting bacilli to ceftazidime/avibactam, meropenem/vaborbactam and imipenem/relebactam and indicate that there are reasonable grounds for using these antibiotics in the treatment of patients hospitalized with serious infections. However, limitations in their use against MBL-producing strains are highlighted. [ABSTRACT FROM AUTHOR]

Klebsiella pneumoniae carbapenemase 2 (KPC-2) is an important source of drug resistance as it can hydrolyze and inactivate virtually all ß-lactam antibiotics. KPC-2 is potently inhibited by avibactam via formation of a reversible carbamyl linkage of the inhibitor with the catalytic serine of the enzyme. However, the use of avibactam in combination with ceftazidime (CAZ-AVI) has led to the emergence of CAZ-AVI-resistant variants of KPC-2 in clinical settings. One such variant, KPC-44, bears a 15 amino acid duplication in one of the active-site loops (270-loop). Here, we show that the KPC-44 variant exhibits higher catalytic efficiency in hydrolyzing ceftazidime, lower efficiency toward imipenem and meropenem, and a similar efficiency in hydrolyzing ampicillin, than the WT KPC-2 enzyme. In addition, the KPC-44 variant enzyme exhibits 12-fold lower AVI carbamylation efficiency than the KPC-2 enzyme. An X-ray crystal structure of KPC-44 showed that the 15 amino acid duplication results in an extended and partially disordered 270-loop and also changes the conformation of the adjacent 240-loop, which in turn has altered interactions with the active-site omega loop. Furthermore, a structure of KPC-44 with avibactam revealed that formation of the covalent complex results in further disorder in the 270-loop, suggesting that rearrangement of the 270-loop of KPC-44 facilitates AVI carbamylation. These results suggest that the duplication of 15 amino acids in the KPC-44 enzyme leads to resistance to CAZ-AVI by modulating the stability and conformation of the 270-, 240-, and omega-loops. [ABSTRACT FROM AUTHOR]

Clostridioides difficile is the leading cause of antibioticassociated diarrhea worldwide with significant morbidity and mortality. This organism is naturally resistant to several betalactam antibiotics that inhibit the polymerization of peptidoglycan, an essential component of the bacteria cell envelope. Previous work has revealed that C. difficile peptidoglycan has an unusual composition. It mostly contains 3-3 cross-links, catalyzed by enzymes called L,D-transpeptidases (Ldts) that are poorly inhibited by beta-lactams. It was therefore hypothesized that peptidoglycan polymerization by these enzymes could underpin antibiotic resistance. Here, we investigated the catalytic activity of the three canonical Ldts encoded by C. difficile (LdtCd1, LdtCd2, and LdtCd3) in vitro and explored their contribution to growth and antibiotic resistance. We show that two of these enzymes catalyze the formation of novel types of peptidoglycan cross-links using meso-diaminopimelic acid both as a donor and an acceptor, also observed in peptidoglycan sacculi. We demonstrate that the simultaneous deletion of these three genes only has a minor impact on both peptidoglycan structure and resistance to beta-lactams. This unexpected result therefore implies that the formation of 3-3 peptidoglycan cross-links in C. difficile is catalyzed by as yet unidentified noncanonical Ldt enzymes. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is a bacterium that holds significant clinical and epidemiological significance. It serves as the principal etiological cause of opportunistic infections in individuals with impaired immune systems. Integrons are known to have a notable impact on Gram-negative bacteria, particularly in the context of P. aeruginosa, a bacterium recognized for its ability to develop resistance to antimicrobial drugs. Aim. To systematically characterize and detect integron genes (intI, intII, intIII) with antibiotic-resistant and biofilm-forming capabilities in isolated P. aeruginosa. Methods. A total of 209 samples were collected from Al Yarmouk Teaching Hospital in Baghdad City, Iraq to isolate P. aeruginosa. The process of bacterial identification was carried out phenotypically and by biochemical tests. Antibiotic susceptibility was measured using the Vitek2 system. Biofilm quantification was done by the microtiter method. The PCR approach was employed to assess the presence of class 1, 2, and 3 integrons. Results. P. aeruginosa was identified in 83 isolates by using a combination of morphological and biochemical examinations where all isolates showed the ability to grow a selective medium on cetrimide agar for P. aeruginosa. The results also showed significant variances (p < 0.05) among the percentage of a number of samples and isolated P. aeruginosa. The burn and wound infection scored the highest percentages (25% and 19%) based on the positivity of P. aeruginosa, whereas burn and ear sites scored the highest percentage (58% and 50%). Also, the isolates show the ability to form biofilm at a percentage of 68.7% with resistance to a high number of antibiotics. The multidrug-resistant and sensitive P. aeruginosa isolates scored high percentages (49.4% and 34.9%) whereas potentially pan drug-resistant and extensively drug-resistant isolates scored low percentages (2.4% and 13.3%). PCR results showed that integron I scored the highest percentage (100%) compared to integron 2 found in 3 (10%) isolates, and no intI3 gene was detected in any of the P. aeruginosa isolates. Conclusions. Overall, the findings of the present investigation indicate that integrons and biofilm development are recognized as significant factors contributing to antibiotic resistance in P. aeruginosa. The prevalence of class 1 integrons is shown to be significantly high in all bacterial isolates, with a complete occurrence rate of 100%. Th is high incidence of class 1 integrons is associated with the development of resistance to crucial antibiotics, including β-lactams, aminoglycosides, and cephalosporins. [ABSTRACT FROM AUTHOR]

Background and Objective: Ceftaroline fosamil is a β-lactam antibiotic approved as a 600 mg twice daily dose (≤1 h infusion, 'standard dosing') or a 600 mg thrice daily dose (2 h infusion) to treat complicated skin and soft tissue infections caused by Staphylococcus aureus (minimum inhibitory concentration [MIC] 2–4 mg/L). We sought to systematically evaluate the relative impact of the three key components of the intensified dosing regimen (i.e. shortened dosing interval, prolonged infusion duration and increased total daily dose [TDD]) on the pharmacokinetic/pharmacodynamic (PK/PD) target attainment given different grades of bacterial susceptibility. Methods: A population PK model was developed using data from 12 healthy volunteers (EudraCT-2012-005134-11) receiving standard or intensified dosing. PK/PD target attainment (ƒT>MIC = 35% and 100%) after 24 h was compared following systematically varied combinations of the (1) dosing interval (every 12 h [q12h]→ every 8 h [q8h]); (2) infusion duration (1 h→2 h); and (3) individual and total daily dose (400→900 mg, i.e. TDD 1200→1800 mg), as well as for varying susceptibility of S. aureus (MIC 0.032–8 mg/L). Results: A two-compartment model with linear elimination adequately described ceftaroline concentrations (n = 274). The relevance of the dosing components dosing interval/infusion duration/TDD for ƒT>MIC systematically changed with pathogen susceptibility. For susceptible pathogens with MIC ≤1 mg/L, shortened dosing intervals appeared as the main driver of the improved target attainment associated with the intensified dosing regimen, followed by increased TDD and infusion duration. For less susceptible pathogens, the advantage of q8h dosing and 2 h infusions declined, and increased TDD improved ƒT>MIC the most. Conclusion: The analysis calls to mind consideration of dose increases when prolonging the infusion duration in the case of low bacterial susceptibility. [ABSTRACT FROM AUTHOR]

β-Lactams are the most widely prescribed class of antibiotics that inhibit penicillin-binding proteins (PBPs), particularly transpeptidases that function in peptidoglycan synthesis. A major mechanism of antibiotic resistance is the production of β-lactamase enzymes, which are capable of hydrolyzing β-lactam antibiotics. There have been many efforts to counter increasing bacterial resistance against β-lactams. These studies have mainly focused on three areas: discovering novel inhibitors against β-lactamases, developing new β-lactams less susceptible to existing resistance mechanisms, and identifying non-β-lactam inhibitors against cell wall transpeptidases. Drug discovery in the β-lactam field has afforded a range of research opportunities for academia. In this review, we summarize the recent new findings on both β-lactamases and cell wall transpeptidases because these two groups of enzymes are evolutionarily and functionally connected. Many efforts to develop new β-lactams have aimed to inhibit both transpeptidases and β-lactamases, while several promising novel β-lactamase inhibitors have shown the potential to be further developed into transpeptidase inhibitors. In addition, the drug discovery progress against each group of enzymes is presented in three aspects: understanding the targets, screening methodology, and new inhibitor chemotypes. This is to offer insights into not only the advancement in this field but also the challenges, opportunities, and resources for future research. In particular, cyclic boronate compounds are now capable of inhibiting all classes of β-lactamases, while the diazabicyclooctane (DBO) series of small molecules has led to not only new β-lactamase inhibitors but potentially a new class of antibiotics by directly targeting PBPs. With the cautiously optimistic successes of a number of new β-lactamase inhibitor chemotypes and many questions remaining to be answered about the structure and function of cell wall transpeptidases, non-β-lactam transpeptidase inhibitors may usher in the next exciting phase of drug discovery in this field. [ABSTRACT FROM AUTHOR]