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The rise of β-Lactamase mediated antibiotic resistance is a major concern for public health; hence, there is an urgent need to find new treatment approaches. Structure-guided drug repurposing offers a promising approach to swiftly deliver essential therapeutics in the fight against escalating antibiotic resistance. Here, a structure-guided virtual screening approach was used involving drug profiling, molecular docking, and molecular dynamics (MD) simulation to identify existing drugs against β-Lactamase-associated drug resistance. We exploited a large panel of FDA-approved drugs to an extensive in silico analysis to ascertain their ability to inhibit β-Lactamase. First, molecular docking investigations were performed to assess the binding affinities and interactions of screened molecules with the active site of β-Lactamase enzymes. Out of all the screened candidates, Aristospan was identified to possess promising characteristics, which include appropriate drug profiles, high binding specificity, and efficiency towards the binding pocket of β-Lactamase. Further analysis showed that Aristospan possesses several desirable biological characteristics and tends to bind to the β-Lactamase binding site. To explore the interactions further, the best docking pose of Aristospan was selected for MD simulations to assess the thermodynamic stability of the drug-enzyme complex and its conformational changes over 500 ns. The MD simulations in independent replica runs demonstrated that the β-Lactamase-Aristospan complex was stable in the 500 ns trajectory. These enlightening results suggest that Aristospan may harbor the potential for further evolution into a possible β-Lactamase inhibitor, with potential applications in overcoming antibiotic resistance in both Gram-positive and Gram-negative bacteria. [ABSTRACT FROM AUTHOR]

AbstractPseudomonas aeruginosa, able to survive on the surfaces of medical devices, is a life-threatening pathogen that mainly leads to nosocomial infection especially in immunodeficient and cystic fibrosis (CF) patients. The antibiotic resistance in P. aeruginosa has become a world-concerning problem, which results in reduced and ineffective therapy efficacy. Besides intrinsic properties to decrease the intracellular content and activity of antibiotics, P. aeruginosa develops acquired resistance by gene mutation and acquisition, as well as adaptive resistance under specific situations. With in-depth research on drug resistance mechanisms and the development of biotechnology, innovative strategies have emerged and yielded benefits such as screening for new antibiotics based on artificial intelligence technology, utilizing drugs synergistically, optimizing administration, and developing biological therapy. This review summarizes the recent advances in the mechanisms of antibiotic resistance and emerging treatments for combating resistance, aiming to provide a reference for the development of therapy against drug-resistant P. aeruginosa. [ABSTRACT FROM AUTHOR]

Background and purpose: Infections caused by β-lactamase-producing strains of Staphylococcus aureus have become increasingly difficult to treat due to the expression of multiple virulence factors. This has heightened concerns about managing S. aureus-related infections. This study was conducted to characterize the blaZ gene and selected virulence determinants in β-lactam resistant S. aureus from human sources in three Nigerian tertiary hospitals. Materials and methods: Three hundred and sixty samples were collected for the study. S. aureus was isolated and characterized following standard microbiological protocols and nuc gene amplification. Antibiotic susceptibility and minimum inhibitory concentration tests were performed using the disk diffusion method and E-tests, respectively. Biofilm formation and β-lactamase production were assessed using Congo red agar and nitrocefin kits, while the blaZ gene was examined using conventional PCR. Capsular polysaccharide genotyping, accessory gene regulator (agr) detection, Panton-valentine leucocidin (PVL), and PVL proteins were performed using PCR and Western blotting. Results: S. aureus was recovered from 145 samples, 50 (34.5%) of these isolates exhibited multidrug resistance, with MICs ranging from 0.125 to 1.00 µg/mL, and showed significant resistance to aminoglycosides, fluoroquinolones, and β-lactams. Of these, 31 strains produced β-lactamases, 30 of which carried the blaZ gene in combination with cap8 (80%) or cap5 (20%). Biofilm formation and PVL gene were observed in 85% of the 20 randomly selected blaZ-positive multidrug-resistant (MDR) strains. The agr2 allele was predominant, found in 70% of the selected MDR strains. No significant difference in the occurrence of the blaZ gene was found among the three clinical sources (p ≤ α0.05). Conclusion: The co-occurrence of the blaZ gene with PVL, capsular polysaccharide genes, and agr alleles is associated with biofilm formation, indicating a high risk of β-lactam-resistant S. aureus infections. Our findings highlight the need for continuous molecular surveillance to enhance infection management, treatment options, and patient outcomes in the study locality. A limitation of this study is the random selection of MDR isolates, which may affect the comprehensiveness of the analyses. [ABSTRACT FROM AUTHOR]

Anti-microbial resistance has emerged as the leading cause of death worldwide with the rise of multidrug-resistant (MDR) bacteria, the need for novel anti-microbials to treat serious illnesses has become a great necessity. Hence, in this study, we aimed to design and synthesize benzothiazole-coupled azetidinone derivatives (GD1-GD12) as novel antibacterial agents. The synthesized compounds were elucidated by nuclear magnetic resonance, infrared and mass spectroscopy. The antibacterial activities of these compounds were tested against antibiotic-susceptible and MDR strains of bacteria. In addition, we performed ADME profiling, molecular docking and molecular dynamic simulations, principle component analysis, dynamic cross-correlation map and free-energy landscape to assess the binding of synthesized compounds with the β -lactamase. Among the synthesized compounds GD6 and GD5 displayed minimum inhibitory concentrations of 12.5 μ g/mL and 50 μ g/mL against MDR strains of E. coli; more effective than standard. The molecular docking of designed molecules was performed against μ -lactamase enzyme and the stability of the complex was vali-dated. The pharmacokinetic profile displayed the compounds to possess druggable properties within the suitable ranges. The in silico approach displayed compound GD6 to be stable with β -lactamase enzyme; indicating the mechanism for these compounds to be via inhibition of β -lactamase. The novel anti-microbial compounds assessed against susceptible and MDR strains of bacteria possess antibacterial potential via the inhibition of β -lactamase. The aforementioned data will be crucial to the development of novel broad-spectrum antibacterial compounds. A novel method was used to design the ligands: Benzothiazole-coupled azetidinone (GD1-12). Their binding affinity and stability to the β -lactamase enzyme inhibitor (3FV7) were assessed using molecular docking and dynamics. Subsequently, compounds (GD1-12) were synthesized, purified, characterized, and tested for antimicrobial activity. Among all the compounds, GD6 exhibited promising antimicrobial activity. [ABSTRACT FROM AUTHOR]

Background: Carbapenem-resistant Enterobacterales (CRE) have been identified as a public health problem. Treatment options for CRE are limited as they are mostly resistant to βeta-lactams, aminoglycosides, and fluoroquinolones as well as carbapenems. The present study aims to evaluate the performance of three phenotypic methods compared to a molecular-based technique for carbapenemase detection in Enterobacterales and determining their applicability in clinical and epidemiological settings. Methods: A total of 1,158 Enterobacterales were isolated from the urine samples in the microbiology laboratory of Alexandria main university hospital during the period from April 2020 to April 2021. Fifty randomly selected (39 Klebsiella and 11 E. coli) Enterobacterales were screened for carbapenem resistance by disc diffusion method. They were subjected to 3 phenotypic tests which are: Carba NP method, Modified carbapenem inactivation method (m CIM) and EDTA- modified carbapenem inactivation method (e CIM). Detection of 5 carbapenemase genes (blaKPC, blaIMP, blaVIM, blaOXA-48 and blaNDM-1) was performed using real time PCR. Results: CRE represented 33% of Enterobacterales isolates. Twenty-six cases (52%) were males and 94% of the cases were above 40 years old. Carba NP test was positive in 43/50 (86%) of the selected isolates, m CIM was positive in 35/50 (70%) and e CIM was positive in 30/50 (60%). The most common carbapenemase gene detected was blaNDM-1 (94%), followed by blaOXA-48 gene (72%) and blaVIM gene (24%). The blaKPC gene and blaIMP gene were not detected. Coexistence of the blaOXA-48 and the blaNDM-1 genes was detected in 48% isolates, while the blaNDM-1, the blaOXA-48 and the blaVIM genes were found in 22% isolates. The sensitivity of Carba NP, m CIM and e CIM was 87.5%, 72.9%, and 85.7% respectively. Conclusion: The study highlights the necessity of early detection of CRE. Carba NP test assists in the rapid identification of carbapenemase production. However, the genotypic test remains the gold standard for detection of CRE. [ABSTRACT FROM AUTHOR]

Background Klebsiella pneumoniae is capable of resistance to β-lactam antibiotics through expression of β-lactamases (both chromosomal and plasmid-encoded) and downregulation of outer membrane porins. However, the extent to which these mechanisms interplay in a resistant phenotype is not well understood. The purpose of this study was to determine the extent to which β-lactamases and outer membrane porins affected β-lactam resistance. Methods Minimum inhibitory concentrations (MICs) to β-lactams and inhibitor combinations were determined by agar dilution or Etest. Outer membrane porin production was evaluated by Western blot of outer membrane fractions. β-lactamase carriage was determined by whole genome sequencing and expression evaluated by real-time reverse-transcription polymerase chain reaction. Results Plasmid-encoded β--lactamases were important for cefotaxime and ceftazidime resistance. Elevated expression of chromosomal SHV was important for ceftolozane-tazobactam resistance. Loss of outer membrane porins was predictive of meropenem resistance. Extended-spectrum β-lactamases and plasmid-encoded AmpCs (pAmpCs) in addition to porin loss were sufficient to confer resistance to the third-generation cephalosporins, piperacillin-tazobactam, ceftolozane-tazobactam, and meropenem. pAmpCs (CMY-2 and DHA) alone conferred resistance to piperacillin-tazobactam. Conclusions Detection of a resistance gene by whole genome sequencing was not sufficient to predict resistance to all antibiotics tested. Some β-lactam resistance was dependent on the expression of both plasmid-encoded and chromosomal β-lactamases and loss of porins. [ABSTRACT FROM AUTHOR]

With the escalation of hospital-acquired infections by multidrug resistant bacteria, understanding antibiotic resistance is of paramount importance. This study focuses on the β-lactamase gene, bla OXA-58, an important resistance determinant identified in a patient-facing hospital wastewater system. This study aimed to characterize the behaviour of the OXA-58 enzyme when expressed using a non-native plasmid and expression host. bla OXA-58 was cloned using a pET28a(+)/ Escherichia coli BL21(DE3) expression system. Nitrocefin hydrolysis and antimicrobial susceptibility of OXA-58-producing cells were assessed against penicillin G, ampicillin, meropenem, and amoxicillin. bla OXA-58 conferred resistance to amoxicillin, penicillin G, and ampicillin, but not to meropenem. This was unexpected given OXA-58's annotation as a carbapenemase. The presence of meropenem also reduced nitrocefin hydrolysis, suggesting it acts as a competitive inhibitor of the OXA-58 enzyme. This study elucidates the phenotypic resistance conferred by an antimicrobial resistance gene (ARG) obtained from a clinically relevant setting and reveals that successful functional expression of ARGs is multifaceted. This study challenges the reliability of predicting antimicrobial resistance based solely on gene sequence alone, and serves as a reminder of the intricate interplay between genetics and structural factors in understanding resistance profiles across different host environments. [ABSTRACT FROM AUTHOR]

Background: Acinetobacter baumannii continued to be an important Gram-negative pathogen of concern in the clinical context. The resistance of this pathogen to carbapenems due to the production of carbapenemases is considered a global threat. Despite the efforts to track carbapenemase synthesis among A. baumannii in the Philippines, local data on its molecular features are very scarce. This study aims to characterize A. baumannii clinical isolates from a Philippine tertiary hospital through genotyping of the pathogen's carbapenemase genes. Methods: Antibiotic susceptibility profiling, phenotypic testing of carbapenemase production, and polymerase chain reaction assays to detect the different classes of carbapenemase genes (class A blaKPC, class B blaNDM, blaIMP, blaVIM, and class D blaOXA-23-like, blaOXA-24/40-like, blaOXA-48-like, blaOXA-51-like, ISAba1-blaOXA-51-like, blaOXA-58-like) were performed in all collected A. baumannii, both carbapenem resistant and susceptible (n = 52). Results: Results showed that the majority of the carbapenem-resistant strains phenotypically produced carbapenemases (up to 84% in carbapenem inactivation methods) and possessed the ISAba1-blaOXA-51-like gene complex (80%). Meanwhile, both carbapenem-resistant and carbapenem-susceptible isolates possessed multi-class carbapenemase genes including blaNDM (1.9%), blaVIM (3.9%), blaOXA-24/40-like (5.8%), blaOXA-58-like (5.8%), blaKPC (11.5%), and blaOXA-23-like (94.2%), which coexist with each other in some strains (17.3%). In terms of the intrinsic blaOXA-51-like (oxaAb) genes, 23 unique alleles were reported (blaOXA-1058 to blaOXA-1080), the majority of which are closely related to blaOXA-66. Isolates possessing these alleles showed varying carbapenem resistance profiles. Conclusions: In summary, this study highlighted the importance of molecular genotyping in the characterization of A. baumannii by revealing the carbapenemase profiles of the pathogen (which may not be captured accurately in phenotypic tests), in identifying potent carriers of transferrable carbapenemase genes (which may not be expressed straightforwardly in antimicrobial susceptibility testing), and in monitoring unique pathogen epidemiology in the local clinical setting. [ABSTRACT FROM AUTHOR]

Abstract Background and purpose Infections caused by β-lactamase-producing strains of Staphylococcus aureus have become increasingly difficult to treat due to the expression of multiple virulence factors. This has heightened concerns about managing S. aureus-related infections. This study was conducted to characterize the blaZ gene and selected virulence determinants in β-lactam resistant S. aureus from human sources in three Nigerian tertiary hospitals. Materials and methods Three hundred and sixty samples were collected for the study. S. aureus was isolated and characterized following standard microbiological protocols and nuc gene amplification. Antibiotic susceptibility and minimum inhibitory concentration tests were performed using the disk diffusion method and E-tests, respectively. Biofilm formation and β-lactamase production were assessed using Congo red agar and nitrocefin kits, while the blaZ gene was examined using conventional PCR. Capsular polysaccharide genotyping, accessory gene regulator (agr) detection, Panton-valentine leucocidin (PVL), and PVL proteins were performed using PCR and Western blotting. Results S. aureus was recovered from 145 samples, 50 (34.5%) of these isolates exhibited multidrug resistance, with MICs ranging from 0.125 to 1.00 µg/mL, and showed significant resistance to aminoglycosides, fluoroquinolones, and β-lactams. Of these, 31 strains produced β-lactamases, 30 of which carried the blaZ gene in combination with cap8 (80%) or cap5 (20%). Biofilm formation and PVL gene were observed in 85% of the 20 randomly selected blaZ-positive multidrug-resistant (MDR) strains. The agr2 allele was predominant, found in 70% of the selected MDR strains. No significant difference in the occurrence of the blaZ gene was found among the three clinical sources (p ≤ α0.05). Conclusion The co-occurrence of the blaZ gene with PVL, capsular polysaccharide genes, and agr alleles is associated with biofilm formation, indicating a high risk of β-lactam-resistant S. aureus infections. Our findings highlight the need for continuous molecular surveillance to enhance infection management, treatment options, and patient outcomes in the study locality. A limitation of this study is the random selection of MDR isolates, which may affect the comprehensiveness of the analyses.

Abstract Background Acinetobacter baumannii continued to be an important Gram-negative pathogen of concern in the clinical context. The resistance of this pathogen to carbapenems due to the production of carbapenemases is considered a global threat. Despite the efforts to track carbapenemase synthesis among A. baumannii in the Philippines, local data on its molecular features are very scarce. This study aims to characterize A. baumannii clinical isolates from a Philippine tertiary hospital through genotyping of the pathogen’s carbapenemase genes. Methods Antibiotic susceptibility profiling, phenotypic testing of carbapenemase production, and polymerase chain reaction assays to detect the different classes of carbapenemase genes (class A bla KPC, class B bla NDM, bla IMP, bla VIM, and class D bla OXA-23-like, bla OXA-24/40-like, bla OXA-48-like, bla OXA-51-like, ISAba1-bla OXA-51-like, bla OXA-58-like) were performed in all collected A. baumannii, both carbapenem resistant and susceptible (n = 52). Results Results showed that the majority of the carbapenem-resistant strains phenotypically produced carbapenemases (up to 84% in carbapenem inactivation methods) and possessed the ISAba1-bla OXA-51-like gene complex (80%). Meanwhile, both carbapenem-resistant and carbapenem-susceptible isolates possessed multi-class carbapenemase genes including bla NDM (1.9%), bla VIM (3.9%), bla OXA-24/40-like (5.8%), bla OXA-58-like (5.8%), bla KPC (11.5%), and bla OXA-23-like (94.2%), which coexist with each other in some strains (17.3%). In terms of the intrinsic bla OXA-51-like (oxaAb) genes, 23 unique alleles were reported (bla OXA-1058 to bla OXA-1080), the majority of which are closely related to bla OXA-66. Isolates possessing these alleles showed varying carbapenem resistance profiles. Conclusions In summary, this study highlighted the importance of molecular genotyping in the characterization of A. baumannii by revealing the carbapenemase profiles of the pathogen (which may not be captured accurately in phenotypic tests), in identifying potent carriers of transferrable carbapenemase genes (which may not be expressed straightforwardly in antimicrobial susceptibility testing), and in monitoring unique pathogen epidemiology in the local clinical setting.

Abstract Objectives The emergence of multidrug-resistant (MDR) Salmonella strains, especially resistant ones toward critically important antimicrobial classes such as fluoroquinolones and third- and fourth-generation cephalosporins, is a growing public health concern. The current study, therefore, aimed to determine the prevalence, and existence of virulence genes (invA, stn, and spvC genes), antimicrobial resistance profiles, and the presence of β-lactamase resistance genes (bla OXA, bla CTX-M1, bla SHV, and bla TEM) in Salmonella strains isolated from native chicken carcasses in Egypt marketed in Mansoura, Egypt, as well as spotlight the risk of isolated MDR, colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars to public health. Methods One hundred fifty freshly dressed native chicken carcasses were collected from different poultry shops in Mansoura City, Egypt between July 2022 and November 2022. Salmonella isolation was performed using standard bacteriological techniques, including pre-enrichment in buffered peptone water (BPW), selective enrichment in Rappaport Vassiliadis broth (RVS), and cultivating on the surface of xylose-lysine-desoxycholate (XLD) agar. All suspected Salmonella colonies were subjected to biochemical tests, serological identification using slide agglutination test, and Polymerase Chain Reaction (PCR) targeting the invasion A gene (invA; Salmonella marker gene). Afterward, all molecularly verified isolates were screened for the presence of virulence genes (stn and spvC). The antimicrobial susceptibility testing for isolated Salmonella strains towards the 16 antimicrobial agents tested was analyzed by Kirby–Bauer disc diffusion method, except for colistin, in which the minimum inhibition concentration (MIC) was determined by broth microdilution technique. Furthermore, 82 cefotaxime-resistant Salmonella isolates were tested using multiplex PCR targeting the β-lactamase resistance genes, including bla OXA, bla CTX-M1, bla SHV, and bla TEM genes. Results Salmonella enterica species were molecularly confirmed via the invA Salmonella marker gene in 18% (27/150) of the freshly dressed native chicken carcasses. Twelve Salmonella serotypes were identified among 129 confirmed Salmonella isolates with the most predominant serotypes were S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively. All the identified Salmonella isolates (n = 129) were positive for both invA and stn genes, while only 31.8% (41/129) of isolates were positive for the spvC gene. One hundred twenty-one (93.8%) of the 129 Salmonella-verified isolates were resistant to at least three antibiotics. Interestingly, 3.9%, 14.7%, and 75.2% of isolates were categorized into pan-drug-resistant, extensively drug-resistant, and multidrug-resistant, respectively. The average MAR index for the 129 isolates tested was 0.505. Exactly, 82.2%, 82.2%, 63.6%, 51.9%, 50.4%, 48.8%, 11.6%, and 10.1% of isolated Salmonella strains were resistant to cefepime, colistin, cefotaxime, ceftazidime/clavulanic acid, levofloxacin, ciprofloxacin, azithromycin, and meropenem, respectively. Thirty-one out (37.8%) of the 82 cefotaxime-resistant Salmonella isolates were β-lactamase producers with the bla TEM as the most predominant β-lactamase resistance gene, followed by bla CTX-M1 and bla OXA genes, which were detected in 21, 16, and 14 isolates respectively). Conclusion The high prevalence of MDR-, colistin-, cefepime-, and levofloxacin-resistant Salmonella serovars among Salmonella isolates from native chicken is alarming as these antimicrobials are critically important in treating severe salmonellosis cases and boost the urgent need for controlling antibiotic usage in veterinary and human medicine to protect public health. Graphical Abstract

Antibiotic resistance has become a global threat as it is continuously growing due to the evolution of β‐lactamases diminishing the activity of classic β‐lactam (BL) antibiotics. Recent antibiotic discovery and development efforts have led to the availability of β‐lactamase inhibitors (BLIs) with activity against extended‐spectrum β‐lactamases as well as Klebsiella pneumoniae carbapenemase (KPC)‐producing carbapenem‐resistant organisms (CRO). Nevertheless, there is still a lack of drugs that target metallo‐β‐lactamases (MBL), which hydrolyze carbapenems efficiently, and oxacillinases (OXA) often present in carbapenem‐resistant Acinetobacter baumannii. This review aims to provide a snapshot of microbiology, pharmacology, and clinical data for currently available BL/BLI treatment options as well as agents in late stage development for CRO harboring various β‐lactamases including MBL and OXA‐enzymes. [ABSTRACT FROM AUTHOR]

The development of drugs to combat disease is a constantly evolving issue of great importance to the entire population. Among this group of molecules, broad‐spectrum antibiotics stand out as the clinical choice of physicians. The family of carbapenems are broad‐spectrum antibiotics used to treat diseases caused by gram‐positive and gram‐negative bacteria that have developed resistance to multiple antibiotics through enzyme production. This research focuses on the characterization of carbapenem enzyme systems using computational chemistry at the level of force field, artificial intelligence, and density functional theory. The computational results on antibiotic molecular structures have been compared with experimental references from UV‐vis spectroscopy, demonstrating high accuracy of several hybrid functionals. For the β‐Lactamase enzyme KPC2, the computational models of FF and AI agreed with the folded structure reported by X‐ray diffraction. Finally, the catalytic site calculated by Docking where the carbapenems‐enzyme interaction takes place was also in agreement with experimental data using water as medium and even in weak acids such as ethanol or methanol. Overall, the above computational characterization provides an understanding of how accurate current computational methods are for understanding the origin of bacterial resistance to one of the latest generation antibiotic families. [ABSTRACT FROM AUTHOR]

Background: Staphylococcus aureus has the ability to develop many efficient mechanisms to neutralize them and it has become difficult to control the virulent strains of S. aureus from causing staphylococcal diseases in animals and humans. Mostly Staphylococcal strains have become resistant to methicillin, β-lactamase and ESBL activity and sometime to vancomycin also. The present study investigated the phenotypic and genotypic characteristics of all the 62 S. aureus isolates for sensitivity towards methicillin, β-lactamase, ESBL production and vancomycin. Methods: The isolates were obtained by conventional microbiological methods, confirmed genotypically by 23S rRNA ribotyping and Maldi-Tof MS. Methicillin resistance activity among S. aureus isolates was detected by culturing them on MeReSa Agar. Extendedspectrum β-lactamase activity among S. aureus isolates was detected by the combined disc method. Result: On MeReSa agar, 53(85.48%) isolates were detected as methicillin resistant S. aureus (MRSA), but none of the isolates from any source or place of sampling was detected positive by the methicillin disk method. Extended-spectrum β-lactamase (ESBL) activity was exhibited by 51 (82.25%) isolates with 100% (maximum) isolates from human pus showing activity and 66.66% (least activity) was seen in isolates from unprocessed meat. All the isolates were susceptible to vancomycin. [ABSTRACT FROM AUTHOR]

Objectives: The emergence of multidrug-resistant (MDR) Salmonella strains, especially resistant ones toward critically important antimicrobial classes such as fluoroquinolones and third- and fourth-generation cephalosporins, is a growing public health concern. The current study, therefore, aimed to determine the prevalence, and existence of virulence genes (invA, stn, and spvC genes), antimicrobial resistance profiles, and the presence of β-lactamase resistance genes (blaOXA, blaCTX-M1, blaSHV, and blaTEM) in Salmonella strains isolated from native chicken carcasses in Egypt marketed in Mansoura, Egypt, as well as spotlight the risk of isolated MDR, colistin-, cefepime-, and levofloxacin-resistant Salmonella enterica serovars to public health. Methods: One hundred fifty freshly dressed native chicken carcasses were collected from different poultry shops in Mansoura City, Egypt between July 2022 and November 2022. Salmonella isolation was performed using standard bacteriological techniques, including pre-enrichment in buffered peptone water (BPW), selective enrichment in Rappaport Vassiliadis broth (RVS), and cultivating on the surface of xylose-lysine-desoxycholate (XLD) agar. All suspected Salmonella colonies were subjected to biochemical tests, serological identification using slide agglutination test, and Polymerase Chain Reaction (PCR) targeting the invasion A gene (invA; Salmonella marker gene). Afterward, all molecularly verified isolates were screened for the presence of virulence genes (stn and spvC). The antimicrobial susceptibility testing for isolated Salmonella strains towards the 16 antimicrobial agents tested was analyzed by Kirby–Bauer disc diffusion method, except for colistin, in which the minimum inhibition concentration (MIC) was determined by broth microdilution technique. Furthermore, 82 cefotaxime-resistant Salmonella isolates were tested using multiplex PCR targeting the β-lactamase resistance genes, including blaOXA, blaCTX-M1, blaSHV, and blaTEM genes. Results: Salmonella enterica species were molecularly confirmed via the invA Salmonella marker gene in 18% (27/150) of the freshly dressed native chicken carcasses. Twelve Salmonella serotypes were identified among 129 confirmed Salmonella isolates with the most predominant serotypes were S. Kentucky, S. Enteritidis, S. Typhimurium, and S. Molade with an incidence of 19.4% (25/129), 17.1% (22/129), 17.1% (22/129), and 10.9% (14/129), respectively. All the identified Salmonella isolates (n = 129) were positive for both invA and stn genes, while only 31.8% (41/129) of isolates were positive for the spvC gene. One hundred twenty-one (93.8%) of the 129 Salmonella-verified isolates were resistant to at least three antibiotics. Interestingly, 3.9%, 14.7%, and 75.2% of isolates were categorized into pan-drug-resistant, extensively drug-resistant, and multidrug-resistant, respectively. The average MAR index for the 129 isolates tested was 0.505. Exactly, 82.2%, 82.2%, 63.6%, 51.9%, 50.4%, 48.8%, 11.6%, and 10.1% of isolated Salmonella strains were resistant to cefepime, colistin, cefotaxime, ceftazidime/clavulanic acid, levofloxacin, ciprofloxacin, azithromycin, and meropenem, respectively. Thirty-one out (37.8%) of the 82 cefotaxime-resistant Salmonella isolates were β-lactamase producers with the blaTEM as the most predominant β-lactamase resistance gene, followed by blaCTX-M1 and blaOXA genes, which were detected in 21, 16, and 14 isolates respectively). Conclusion: The high prevalence of MDR-, colistin-, cefepime-, and levofloxacin-resistant Salmonella serovars among Salmonella isolates from native chicken is alarming as these antimicrobials are critically important in treating severe salmonellosis cases and boost the urgent need for controlling antibiotic usage in veterinary and human medicine to protect public health. [ABSTRACT FROM AUTHOR]

Antibiotic resistance genes (ARGs) benefit host bacteria in environments containing corresponding antibiotics, but it is less clear how they are maintained in environments where antibiotic selection is weak or sporadic. In particular, few studies have measured if the direct effect of ARGs on host fitness is fixed or if it depends on the host strain, perhaps marking some ARG–host combinations as selective refuges that can maintain ARGs in the absence of antibiotic selection. We quantified the fitness effects of six ARGs in 11 diverse Escherichia spp. strains. Three ARGs (blaTEM-116, cat and dfrA5, encoding resistance to β-lactams, chloramphenicol, and trimethoprim, respectively) imposed an overall cost, but all ARGs had an effect in at least one host strain, reflecting a significant strain interaction effect. A simulation predicts these interactions can cause the success of ARGs to depend on available host strains, and, to a lesser extent, can cause host strain success to depend on the ARGs present in a community. These results indicate the importance of considering ARG effects across different host strains, and especially the potential of refuge strains to allow resistance to persist in the absence of direct selection, in efforts to understand resistance dynamics. [ABSTRACT FROM AUTHOR]

Background Antimicrobial resistance (AMR) is a global threat to infectious disease control, particularly among recently hospitalized children. We sought to determine the prevalence and mitigating factors of resistance in enteric Escherichia coli among children discharged from health facilities in western Kenya. Methods Between June 2016 and November 2019, children aged 1 to 59 months were enrolled at the point of discharge from the hospital. E coli was isolated by microbiological culture from rectal swabs at baseline. β-Lactamases and macrolide resistance–conferring genes were detected by polymerase chain reaction. A modified Poisson regression model was used to assess the predictors mph (A) and CTX-M–type extended-spectrum β-lactamase (ESBL). Results Of the 238 children whose E coli isolates were tested, 91 (38.2%) and 109 (45.8%) had detectable CTX-M–type ESBL and mph (A) genes, respectively. Antibiotic treatment during hospitalization (adjusted prevalence ratio [aPR], 2.47; 95% CI, 1.12–5.43; P =.025), length of hospitalization (aPR, 1.42; 95% CI, 1.00–2.01; P =.052), and the practice of open defecation (aPR, 2.47; 95% CI, 1.40–4.36; P =.002) were independent predictors for CTX-M–type ESBL and mph (A) genes. Pneumococcal vaccination was associated with a 43% lower likelihood of CTX-M–type ESBL (aPR, 0.57; 95% CI,.38–.85; P =.005), while measles vaccination was associated with a 32% lower likelihood of mph (A) genes (aPR, 0.68; 95% CI,.49–.93; P =.017) in E coli isolates. Conclusions Among children discharged from the hospital, history of vaccination, shorter hospital stay, lack of in-hospital antibiotic exposure, and improved sanitation were associated with a lower likelihood of AMR genes. To mitigate the continued spread of AMR, AMR control programs should consider strategies beyond antimicrobial stewardship, including improvements in sanitation, increased vaccine coverage, and the development of novel vaccines. [ABSTRACT FROM AUTHOR]

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The rise of β-Lactamase mediated antibiotic resistance is a major concern for public health; hence, there is an urgent need to find new treatment approaches. Structure-guided drug repurposing offers a promising approach to swiftly deliver essential therapeutics in the fight against escalating antibiotic resistance. Here, a structure-guided virtual screening approach was used involving drug profiling, molecular docking, and molecular dynamics (MD) simulation to identify existing drugs against β-Lactamase-associated drug resistance. We exploited a large panel of FDA-approved drugs to an extensive in silico analysis to ascertain their ability to inhibit β-Lactamase. First, molecular docking investigations were performed to assess the binding affinities and interactions of screened molecules with the active site of β-Lactamase enzymes. Out of all the screened candidates, Aristospan was identified to possess promising characteristics, which include appropriate drug profiles, high binding specificity, and efficiency towards the binding pocket of β-Lactamase. Further analysis showed that Aristospan possesses several desirable biological characteristics and tends to bind to the β-Lactamase binding site. To explore the interactions further, the best docking pose of Aristospan was selected for MD simulations to assess the thermodynamic stability of the drug-enzyme complex and its conformational changes over 500 ns. The MD simulations in independent replica runs demonstrated that the β-Lactamase-Aristospan complex was stable in the 500 ns trajectory. These enlightening results suggest that Aristospan may harbor the potential for further evolution into a possible β-Lactamase inhibitor, with potential applications in overcoming antibiotic resistance in both Gram-positive and Gram-negative bacteria.

This study investigated the relationship between MiPs, antibiotic resistance genes (ARGs), and water quality in the Red River Delta. MiPs were collected from water samples at four locations: Hanoi, Ha Nam, Nam Dinh, and Cat Ba Island. Bacteria isolated from MiPs and the surrounding water were analyzed for β-lactamase genes. Polyethylene terephthalate (PET) and polytridecanolactone (PTDL) exhibited notable correlations with coefficients with microbial abundance on MiPs. Aeromonas (99.2 % of all isolates) were the most common bacteria isolated from MiPs, with a fewer Escherichia coli (0.83 %). Of 207 bacterial strains isolated from microplastic, 23 (~11 % of total) were found to carry antibiotic resistance genes, mostly blaTEM (13/23; 56.5 %), blaSHV (9/23; 39.1 %) and blaCTXM-9 (1/23; 4.3 %). All seven environmental factors measured were found to affect the distribution of ARGs and ARBs on MiP surfaces. Chlorophyll-a showed a strong positive correlation with ARB abundance, suggesting a potential link between primary productivity and bacterial colonization. This study is one of the first to report the association of MPs with antibiotic-resistant microbiota and genes. The presence of ARGs on MiPs in areas with high human population highlights the need for effective pollution management strategies to mitigate the risks associated with AMR.

While most detailed analyses of antibiotic resistance plasmids focus on those found in clinical isolates, less is known about the vast environmental reservoir of mobile genetic elements and the resistance and virulence factors they encode. We selectively isolated three strains of cefotaxime-resistant Escherichia coli from a wastewater-impacted coastal wetland. The cefotaxime-resistant phenotype was transmissible to a lab strain of E. coli after one hour, with frequencies as high as 10-3 transconjugants per recipient. Two of the plasmids also transferred cefotaxime resistance to Pseudomonas putida, but these were unable to back-transfer this resistance from P. putida to E. coli. In addition to the cephalosporins, E. coli transconjugants inherited resistance to at least seven distinct classes of antibiotics. Complete nucleotide sequences revealed large IncF-type plasmids with globally distributed replicon sequence types F31:A4:B1 and F18:B1:C4 carrying diverse antibiotic resistance and virulence genes. The plasmids encoded extended-spectrum β-lactamases blaCTX-M-15 or blaCTX-M-55, each associated with the insertion sequence ISEc9, although in different local arrangements. Despite similar resistance profiles, the plasmids shared only one resistance gene in common, the aminoglycoside acetyltransferase aac(3)-IIe. Plasmid accessory cargo also included virulence factors involved in iron acquisition and defense against host immunity. Despite their sequence similarities, several large-scale recombination events were detected, including rearrangements and inversions. In conclusion, selection with a single antibiotic, cefotaxime, yielded conjugative plasmids conferring multiple resistance and virulence factors. Clearly, efforts to limit the spread of antibiotic resistance and virulence among bacteria must include a greater understanding of mobile elements in the natural and human-impacted environments.

Background. The situation regarding the prevalence of resistant pathogens, types of β-lactamase products, and, accordingly, the justification of rational approaches to antibacterial therapy in Ukraine remains insufficiently studied. Objective: based on the determination of the etiological structure of the causative agents of hospital infections in the Kharkiv region and the state of their resistance due to the production of β-lactamases, to propose rational approaches to antibacterial therapy and assess the feasibility of using aztreonam as a potentially effective mean of treating infections caused by resistant bacteria. Materials and methods. In 251 patients, samples of biomaterials were tested by the polymerase chain reaction for the presence of the following gram-negative pathogens: P.aeruginosa, Enterobacter, E.coli, K.pneumoniae, Proteus spp. and A.baumanii. A molecular genetic study was also conducted to identify certain types of β-lactamases. Results. In the structure of hospital pathogens, the absolute majority of gram-negative bacteria belong to the enterobacteria family. When determining the profile of β-lactamases, we found that in 59.38 % of cases, E.coli was able to produce metallo-β-lactamases, which makes the therapy with carbapenems or ceftazidime-avibactam impossible. An alternative in such cases is a combination of aztreonam and ceftazidime-avibactam. When the causative agent K.pneumoniae is detected, in some cases there may also be a need for combined therapy with the use of aztreonam. It was found that Enterobacter spp. in most cases is sensitive to carbapenems. A.baumanii is completely insensitive to carbapenems and requires alternative approaches to antibacterial therapy, including aztreonam, ceftazidime-avibactam, and polymyxins. P.aeruginosa was found only as part of polymicrobial associations, so it was impossible to analyze its β-lactamase production profile. Conclusions. The results of the conducted study demonstrate an extremely high detection of gram-negative antibiotic-resistant pathogens in patients of the intensive care units in the Kharkiv region. Microorganisms such as E.coli and A.baumanii have the most unfavorable profile of antibiotic resistance, which is due to the high frequency of production of serine carbapenemases and metallo-β-lactamases, whose presence makes the effective use of carbapenems impossible.

Abstract Background Antibiotics notoriously perturb the gut microbiota. We treated healthy volunteers either with cefotaxime or ceftriaxone for 3 days, and collected in each subject 12 faecal samples up to day 90. Using untargeted and targeted phenotypic and genotypic approaches, we studied the changes in the bacterial, phage and fungal components of the microbiota as well as the metabolome and the β-lactamase activity of the stools. This allowed assessing their degrees of perturbation and resilience. Results While only two subjects had detectable concentrations of antibiotics in their faeces, suggesting important antibiotic degradation in the gut, the intravenous treatment perturbed very significantly the bacterial and phage microbiota, as well as the composition of the metabolome. In contrast, treatment impact was relatively low on the fungal microbiota. At the end of the surveillance period, we found evidence of resilience across the gut system since most components returned to a state like the initial one, even if the structure of the bacterial microbiota changed and the dynamics of the different components over time were rarely correlated. The observed richness of the antibiotic resistance genes repertoire was significantly reduced up to day 30, while a significant increase in the relative abundance of β-lactamase encoding genes was observed up to day 10, consistent with a concomitant increase in the β-lactamase activity of the microbiota. The level of β-lactamase activity at baseline was positively associated with the resilience of the metabolome content of the stools. Conclusions In healthy adults, antibiotics perturb many components of the microbiota, which return close to the baseline state within 30 days. These data suggest an important role of endogenous β-lactamase-producing anaerobes in protecting the functions of the microbiota by de-activating the antibiotics reaching the colon. Video Abstract

Cyanobacteria in recent times have been touted to be a suitable source for the discovery of novel compounds, including antioxidants and antibiotics, due to their large arsenal of metabolites. This study presents the in vitro antioxidant and in silico evaluation of Cylindrospermum alatosporum NR125682 and Loriellopsis cavenicola NR117881, isolated from freshwater ponds around the campus of the University of Zululand, South Africa. The isolates were confirmed using 16S rRNA. Various crude extracts of the isolated microbes were prepared through sequential extraction using hexane, dichloromethane, and 70% ethanol. The chemical constituents of the crude extracts were elucidated by FTIR and GC-MS spectroscopy. The antioxidant potential of the extracts was determined by the free radical (DPPH, ABTS, •OH, and Fe2+) systems. Molecular docking of the major constituents of the extracts against β-lactamase was also evaluated. GC-MS analysis indicated the dominating presence of n-alkanes. The extracts exhibited varying degrees of antioxidant activity (scavenging of free radicals; an IC50 range of 8–10 µg/mL was obtained for ABTS). A good binding affinity (−6.6, −6.3 Kcal/mol) of some the organic chemicals (diglycerol tetranitrate, and 2,2-dimethyl-5-(3-methyl-2-oxiranyl)cyclohexanone) was obtained following molecular docking. The evaluated antioxidant activities, coupled with the obtained docking score, potentiates the antimicrobial activity of the extracts. [ABSTRACT FROM AUTHOR]

Background: Multi-Drug-ResistantKlebsiella pneumoniae (MDR K. pneumoniae) is considered as an important opportunistic pathogen, which causes life threatening infections. K. pneumoniae is known to causes life-threatening infections. Objective: The objective of this study is to detect some β-lactamase genes in Klebsiella pneumoniae. Methods: Thirty-five K. pneumoniae isolates were obtained from some hospitals in Baghdad City between October 2022 and February 2023. The identification of K. pneumoniae isolates was done phenotypically by the automated VITEK II system and genotypically by amplification of the rpob gene. The antibiotic susceptibility and detection of some β-lactamase genes were tested for all isolates. Results: The results showed that the K. pneumoniae isolates were resistant to most antibiotics used. A high percentage of K. pneumoniae isolates were resistant to cefixime, cefpodoxime, norfloxacin and doxycycline as 100% followed by ceftriaxone, ceftazidime, ticarcillin/clavulanate, ticarcillin, ceftazidime, tobramycin, and moxifloxacin (97.2%, 91.7%, 91.7%, 94.4%, 94.4%, and 94.4%, respectively). Furthermore, approximately 94.4% of the isolates were MDR. In addition, the molecular methods only detected the blaNDM and blaTEM genes as 33.3% and 75.6% of in the K. pneumoniae isolates, respectively, while the blaVIM, blaCTX−M, and blaKPC genes were not observed in K. pneumoniae isolates. Conclusions: β-lactam antibiotics, including carbapenems, are widely used to treat bacterial infections; however, an increase in antibiotic resistance due to β-lactamases limits the effectiveness of these antibiotics. Therefore, alternative treatment methods are required to control these resistant isolates. [ABSTRACT FROM AUTHOR]

The production of extended spectrum β-lactamases (ESBLs) in extensively drug-resistant (XDR) strains of Acinetobacter baumannii has created havoc amongst clinicians making the treatment procedure challenging. Carbapenem-resistant strains have displayed total ineffectiveness towards newer combinations of β-lactam-β-lactamase inhibitors (βL-βLI) in tertiary healthcare settings. Therefore, the present study was aimed to design potential β-lactamase antimicrobial peptide (AMP) inhibitors against ESBLs produced by the strains. We have constructed an AMP mutant library with higher antimicrobial efficacy (range: ~ 15 to 27%) than their parent peptides. The mutants were thoroughly screened based on different physicochemical and immunogenic properties revealing three peptides, namely SAAP-148, HFIAP-1, myticalin-C6 and their mutants with safe pharmacokinetics profile. Molecular docking highlighted SAAP-148_M15 displaying maximum inhibitory potential with lowest binding energies against NDM1 (− 1148.7 kcal/mol), followed by OXA23 (− 1032.5 kcal/mol) and OXA58 (− 925.3 kcal/mol). The intermolecular interaction profiles displayed SAAP-148_M15 exhibiting hydrogen bonds and van der Waals hydrophobic interactions with the crucial residues of metallo β-lactamase [IPR001279] and penicillin-binding transpeptidase [IPR001460] domains. Coarse-grained clustering and molecular dynamics simulations (MDS) further validated the stable backbone profile and minimal residue-level fluctuations of the protein-peptide complex that were maintained throughout the simulation timeframe. The present study hypothesised that the combination of sulbactam (βL) with SAAP-148_M15 (βLI) holds immense potential in inhibiting the ESBLs alongside restoration of sulbactam activity. The current in silico findings upon further experimental validations can pave path towards designing of successful therapeutic strategy against XDR strains of A. baumannii. [ABSTRACT FROM AUTHOR]

The amino acid substitutions in Klebsiella pneumoniae carbapenemase 2 (KPC‐2) that have arisen in the clinic are observed to lead to the development of resistance to ceftazidime‐avibactam, a preferred treatment for KPC bearing Gram‐negative bacteria. Specific substitutions in the omega loop (R164‐D179) result in changes in the structure and function of the enzyme, leading to alterations in substrate specificity, decreased stability, and more recently observed, increased resistance to ceftazidime/avibactam. Using accelerated rare‐event sampling well‐tempered metadynamics simulations, we explored in detail the structural role of R164 and D179 variants that are described to confer ceftazidime/avibactam resistance. The buried conformation of D179 substitutions produce a pronounced structural disorder in the omega loop ‐ more than R164 mutants, where the crystallographic omega loop structure remains mostly intact. Our findings also reveal that the conformation of N170 plays an underappreciated role impacting drug binding and restricting deacylation. The results further support the hypothesis that KPC‐2 D179 variants employ substrate‐assisted catalysis for ceftazidime hydrolysis, involving the ring amine of the aminothiazole group to promote deacylation and catalytic turnover. Moreover, the shift in the WT conformation of N170 contributes to reduced deacylation and an altered spectrum of enzymatic activity. [ABSTRACT FROM AUTHOR]

[Display omitted] An all-fiber-optic system for rapid detection of antibiotic concentration, based on an optical enzyme biosensor with microfiber interferometer (MFI) and fiber gratings (FBGs) power variation, is proposed and experimentally validated. During the experiment, β-lactamase(β-LS) is fixed on the polyaniline (PANI)-coated optical fiber by cross-linking through glutaraldehyde (GA) covalent bonding. β-LS can hydrolyze β-lactam antibiotics to generate acidic by-products that transform polyaniline from the form of the emerald base to emerald salt, which results in the surface refractive index (RI) variation of MFI, to convert MFI wavelength and FBGs power macroscopic change for feedbackingly detecting the concentration of β-lactam antibiotics. The detection of amoxicillin (AMX) in deionized water at concentrations in the range of 0.01–100 nM resulted in a wavelength change sensitivity of 0.6 nm/nM, and FBGs power difference change sensitivity of 1.3 dB/nM, with a detection limit LOD = 0.04 nM in real food and urine samples. The sensing system by the same calibration technique can detect antibiotic concentrations in different substances (tap water, milk and artificial urine). This developed all-fiber-optic system can be used as a rapid solution for the measurement of β-lactam antibiotic residues in food and the environment. [ABSTRACT FROM AUTHOR]

Background: Antibiotics notoriously perturb the gut microbiota. We treated healthy volunteers either with cefotaxime or ceftriaxone for 3 days, and collected in each subject 12 faecal samples up to day 90. Using untargeted and targeted phenotypic and genotypic approaches, we studied the changes in the bacterial, phage and fungal components of the microbiota as well as the metabolome and the β-lactamase activity of the stools. This allowed assessing their degrees of perturbation and resilience. Results: While only two subjects had detectable concentrations of antibiotics in their faeces, suggesting important antibiotic degradation in the gut, the intravenous treatment perturbed very significantly the bacterial and phage microbiota, as well as the composition of the metabolome. In contrast, treatment impact was relatively low on the fungal microbiota. At the end of the surveillance period, we found evidence of resilience across the gut system since most components returned to a state like the initial one, even if the structure of the bacterial microbiota changed and the dynamics of the different components over time were rarely correlated. The observed richness of the antibiotic resistance genes repertoire was significantly reduced up to day 30, while a significant increase in the relative abundance of β-lactamase encoding genes was observed up to day 10, consistent with a concomitant increase in the β-lactamase activity of the microbiota. The level of β-lactamase activity at baseline was positively associated with the resilience of the metabolome content of the stools. Conclusions: In healthy adults, antibiotics perturb many components of the microbiota, which return close to the baseline state within 30 days. These data suggest an important role of endogenous β-lactamase-producing anaerobes in protecting the functions of the microbiota by de-activating the antibiotics reaching the colon. 64G36U-BwhYzB4Dx7Xcq3U Video Abstract [ABSTRACT FROM AUTHOR]

Background: Multi-Drug-Resistant Klebsiella pneumoniae (MDR K. pneumoniae) is considered as an important opportunistic pathogen, which causes life threatening infections. K. pneumoniae is known to causes life-threatening infections. Objective: The objective of this study is to detect some β-lactamase genes inKlebsiella pneumoniae. Methods: Thirty-five K. pneumoniae isolates were obtained from some hospitals in Baghdad City between October 2022 and February 2023. The identification of K. pneumoniae isolates was done phenotypically by the automated VITEK II system and genotypically by amplification of the rpob gene. The antibiotic susceptibility and detection of some β-lactamase genes were tested for all isolates. Results: The results showed that the K. pneumoniae isolates were resistant to most antibiotics used. A high percentage of K. pneumoniae isolates were resistant to cefixime, cefpodoxime, norfloxacin and doxycycline as 100% followed by ceftriaxone, ceftazidime, ticarcillin/clavulanate, ticarcillin, ceftazidime, tobramycin, and moxifloxacin (97.2%, 91.7%, 91.7%, 94.4%, 94.4%, and 94.4%, respectively). Furthermore, approximately 94.4% of the isolates were MDR. In addition, the molecular methods only detected the blaNDM and blaT EM genes as 33.3% and 75.6% of in the K. pneumoniae isolates, respectively, while the blaV IM, blaCTX−M, and blaKP C genes were not observed in K. pneumoniae isolates. Conclusions: β-lactam antibiotics, including carbapenems, are widely used to treat bacterial infections; however, an increase in antibiotic resistance due to β-lactamases limits the effectiveness of these antibiotics. Therefore, alternative treatment methods are required to control these resistant isolates.

Methicillin Resistance Staphylococcus aureus (MRSA) is a serious human disease also considered as a chronological developing zoonotic pathogen of common health and in term of veterinary concern. Pyoginic endocariditis, otitis media, food poisoning, pyogenic infection of the soft tissues and the skin, suppurative pneumonia, and osteomyelitis all are prevalent infection of MRSA in people. MRSA can induce botryomycosis and infected contamination in horses; severe mastitis and pyogenic infection in cattle and ewes with marked toxemia; pustular dermatitis in dogs and cats as well as food poisoning; greasy pig disease in pigs which also called exudative epidermatitis. A number of multilevel random-effects models were fitted to estimate mean occurrence rates of antibiotic-resistant S. aureus, and subgroup analyses were performed to compare antibiotic resistance rates of S. aureus throughout the years and among the methods to determine the antimicrobial susceptibility. This review provides a comprehensive illustration about MRSA including background, epidemiology, resistance, and others. On other hands, different types of antibiotics have been mentioned in which they have been utilized against S. aureus and their mechanism of action is explained as well. Therefore, this review is helpful by its simpleness and comprehensive contents.

An increase in antibiotic resistance and a corresponding decrease in antimicrobial drug discovery have resulted in researchers focussing on alternative therapies, including plant based medicines. The development of bacterial strains resistant to β-lactam, including resistance to the second generation drugs methicillin, is particularly concerning and has rendered many common therapies ineffective or of substantially decreased efficacy. New antibiotic therapies are urgently needed. The antibacterial activity of selected southern African Combretum spp. leaf extracts towards β-lactam resistant and sensitive bacterial strains was investigated by disc diffusion assays and quantified by broth microdilution Minimum inhibitory concentration (MIC) assays. Toxicity was evaluated by testing Artemia nauplii mortality and human dermal fibroblast (HDF) cytotoxicity assays. The gas chromatography coupled to Mass spectrometry (GC-MS) headspace analysis was used to identify volatile terpenoid components. The leaf extracts of all Combretum spp. displayed noteworthy growth inhibitory activity against all of the bacteria tested, including against Methicillin resistant Staphylococcus aureus MRSA, and the extended spectrum β-lactamase (ESBL) strains of E. coli and K. pneumoniae. Combretum heroense leaf extract had particularly good (MICs = 170-680 μg/mL) antibacterial activity against all bacterial strains. Notably, this extract was a better inhibitor of MRSA than of the β-lactam sensitive strain of S. aureus. The Combretum vendae extract was also a good inhibitor of the MRSA and ESBL strains. Noteworthy antibacterial activity (MICs 120-890 μg/mL) was also noted for Combretum collinum and Combretum molle extracts against all bacteria, and for the Combretum bracteosum and Combretum erythrophyllum extracts against the MRSA and ESBL strains (500-1625 μg/mL). All extracts were non-toxic in the Artemia nauplii lethality assay (ALA) and HDF assays and the calculated therapeutic indexes (TIs) indicated their safety for use as antibiotic chemotherapies. The GC-MS headspace analysis identified and highlighted several noteworthy monoterpenoids which had antibacterial properties. In particular, cineole, terpineol, camphor, borneol and limonene were present in relative abundance in all Combretum spp. extracts. Further phytochemical and mechanistic studies of these extracts are warranted. [Display omitted] • Selected southern African Combretum spp. leaf extracts were screened for the ability to inhibit the growth of MRSA and ESBL E. coli and K. pneumoniae. • The antibacterial activity of the extracts was quantified by broth dilution MIC assays. • The MIC values of the extracts against the β-lactam resistant bacterial strains was compared to their activity against antibiotic sensitive strains. • Toxicity of the Combretum spp. extracts was determined using the Artemia nauplii and HDF cell viability toxicity bioassays. • GC-MS headspace analysis was used to identify volatile monoterpenoid components across all Combretum spp. extracts. [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]

The combination of aztreonam (ATM) and ceftazidime–avibactam (CAZ-AVI; CZA) has shown therapeutic potential against serine-β-lactamase (SBL)- and metallo-β-lactamase (MBL)-producing Enterobacterales. However, the ability of CZA to restore the antibiotic activity of ATM is severely limited in MBL-producing multidrug-resistant (MDR) Pseudomonas aeruginosa strains because of the myriad of intrinsic and acquired resistance mechanisms associated with this pathogen. We reasoned that the simultaneous inhibition of multiple targets associated with multidrug resistance mechanisms may potentiate the antibiotic activity of ATM against MBL-producing P. aeruginosa. During a search for the multitarget inhibitors through a molecular docking study, we discovered that di-F-Q, the previously reported efflux pump inhibitor of MDR P. aeruginosa, binds to the active sites of the efflux pump (MexB), as well as various β-lactamases, and these sites are open to the 3-O-position of di-F-Q. The 3-O-substituted di-F-Q derivatives were thus synthesized and showed hereto unknown multitarget MDR inhibitory activity against various ATM-hydrolyzing β-lactamases (AmpC, KPC, and New Delhi metallo-β-lactamase (NDM)) and the efflux pump of P. aeruginosa, presumably by forming additional hydrophobic contacts with the targets. The multitarget MDR inhibitor 27 effectively potentiated the antimicrobial activity of ATM and reduced the MIC of ATM more than four-fold in 19 out of 21 MBL-producing P. aeruginosa clinical strains, including the NDM-producing strains which were highly resistant to various combinations of ATM with β-lactamase inhibitors and/or efflux pump inhibitors. Our findings suggest that the simultaneous inhibition of multiple MDR targets might provide new avenues for the discovery of safe and efficient MDR reversal agents which can be used in combination with ATM against MBL-producing MDR P. aeruginosa. [ABSTRACT FROM AUTHOR]

The production of carbapenemases is a significant mechanism contributing to carbapenem resistance in Enterobacteriaceae. Among these carbapenemases, OXA-48 presents a distinct challenge and threat, as most β-lactamase inhibitors do not effectively inhibit its activity. In this study, we investigated the inhibitory potential of α-mangostin against OXA-48 with an IC50 value of 0.52 μM. Enzyme activity assays demonstrated that α-mangostin inhibited OXA-48 reversibly through a non-competitive and dose-dependent inhibition mode. The docking analysis revealed that the 7-hydroxyl group of α-mangostin formed hydrogen bonds with Thr197 and Trp222, whereas the 5-hydroxyl group and the 4-carbonyl group interacted with Lys116 and Met115. Our study indicates that α-mangostin exhibits significant inhibition against OXA-48 and holds promise as a potential compound for the development of β-lactamase inhibitors. [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]

The spread of multidrug-resistant bacteria from humans or livestock is a critical issue. However, the epidemiology of resistant pathogens across wastewater pathways is poorly understood. Therefore, we performed a detailed comparison of third-generation cephalosporin-resistant Escherichia coli (3GCREC) from wastewater treatment plants (WWTPs) to analyze dissemination pathways. A total of 172 3GCREC isolated from four WWTPs were characterized via whole genome sequencing. Clonal relatedness was determined using multi-locus sequence typing (MLST) and core genome MLST. Resistance genotypes and plasmid replicons were determined. A total of 68 MLST sequence types were observed with 28 closely related clusters. Resistance genes to eight antibiotic classes were detected. In fluoroquinolone-resistant isolates, resistance was associated with three-or-more point mutations in target genes. Typing revealed high genetic diversity with only a few clonal lineages present in all WWTPs. The distribution paths of individual lines could only be traced in exceptional cases with a lack of enrichment of certain lineages. Varying resistance genes and plasmids, as well as fluoroquinolone resistance-associated point mutations in individual isolates, further corroborated the high diversity of 3GCREC in WWTPs. In total, we observed high diversity of 3GCREC inside the tested WWTPs with proof of resistant strains being released into the environment even after treatment processes. [ABSTRACT FROM AUTHOR]

A total number of 150,86 samples (57.3%) of samples were females, and 64 (42.7%) of samples were males, so from total specimens of 150 showed significant bacterial growth. The most common pathogen was proteus spp (50%), Staphylococcus spp (8.3%) Klebsiella pneumoniae (11.7 %), streptococcus spp (16.7%), Serratia marcescens (13,3%), Antibacterial susceptibility test was conducted for 30 proteus spp isolates against 20 commonly used antibacterial agents by using the disk diffusion method, the highest rate of resistance was seen with Ampicillin 30/30(100%) followed Amoxicillin- clavulanic Acid 29/30 (97.5%) and colistin 27/30 (90 %) and the low rate resistance was seen with Meropenem 0/30 (0%) and imipenem was 1/30 (7.5%), the results showed presence of integron-1 in Proteus spp isolates, from the 30 (100%) isolates of Proteus spp was 5 (16.65 %) is positive and integron-2 was ( 83.25 %) 25 positive for 30 proteus spp isolates. The results showed that the (blaOXA-1) gene was detected in Proteus spp isolates, from the 30 (100%) isolates 9 (30.3 %) were positive. where have blaTEM gene, the result was (40%) positive, and bla SHV gene was found in 2 isolates (6.66%), and finally the bla AMP-c gene was positive in 6 isolates (19%). [ABSTRACT FROM AUTHOR]

This article discusses a study conducted in Amritsar, Punjab, India, to evaluate the prevalence and antibiotic resistance rate of uropathogens in women with urinary tract infections (UTIs). The study found that E. coli was the most common uropathogen, followed by Klebsiella spp and Enterobacter spp. The study also reported multi-drug resistance in some isolates, but found that gentamicin, imipenem, and meropenem were effective antibiotics against the uropathogens. Additionally, all ESBL-positive isolates possessed the quinolone-resistant gene qnrB. The study concludes that understanding the epidemiological data of UTIs is crucial for appropriate treatment. [Extracted from the article]

Metallo-β-lactamases (MBLs), also known as class B β-lactamases (BBLs), are Zn(II)-containing enzymes able to inactivate a broad range of β-lactams, the most commonly used antibiotics, including life-saving carbapenems. They have been known for about six decades, yet they have only gained much attention as a clinical problem for about three decades. The naming conventions of these enzymes have changed over time and followed various strategies, sometimes leading to confusion. We are summarizing the naming strategies of the currently known MBLs. These enzymes are quite diverse on the amino acid sequence level but structurally similar. Problems trying to describe conserved residues, such as Zn(II) ligands and other catalytically important residues, which have different numbers in different sequences, have led to the establishment of a standard numbering scheme for BBLs. While well intended, the standard numbering scheme is not trivial and has not been applied consistently. We revisit this standard numbering scheme and suggest some strategies for how its implementation could be made more accessible to researchers. Standard numbering facilitates the comparison of different enzymes as well as their interaction with novel antibiotics and BBL inhibitors. [ABSTRACT FROM AUTHOR]

In the present study, we analyzed the genome of two S. enterica strains TS1 and TS2 from stool and blood cultures, respectively, and one strain of C. freundii TS3, isolated from a single hospitalized patient with acute myeloid leukemia. The S. enterica Goldcoast ST358 (O:8 (C2-C3) serogroup), sequenced by the MiSeq Illumina system, showed the presence of β-lactamase genes (blaVIM-1, blaSHV-12 and blaOXA-10), aadA1, ant(2″)-Ia, aac(6′)-Iaa, aac(6′)-Ib3, aac(6′)-Ib-cr, qnrVC6, parC(T57S), and several incompatibility plasmids. A wide variety of insertion sequences (ISs) and transposon elements were identified. In C. freundii TS3, these were the blaVIM-1, blaCMY-150, and blaSHV-12, aadA1, aac(6′)-Ib3, aac(6′)-Ib-cr, mph(A), sul1, dfrA14, ARR-2, qnrVC6, and qnrB38. IncA plasmid isolated from E.coli/K12 transconjugant and C. freundii exhibited a sequence identity >99.9%. The transfer of IncA plasmid was evaluated by conjugation experiments. [ABSTRACT FROM AUTHOR]

ABSTRACT: Riemerella anatipestifer (R. anatipestifer) is a highly pathogenic and complex serotypes waterfowl pathogen with inherent resistance to multiple antibiotics. This study was aimed to investigate the antibiotic resistance characteristics and genomic features of R. anatipestifer isolates in Anhui Province, China in 2023. A total of 287 cases were analysed from duck farms and goose farms, and the R. anatipestifer isolates were subjected to drug resistance tests for 30 antimicrobials. Whole genome sequencing (WGS) and bioinformatics analysis were performed on the bacterial genomes, targeting the β-lactam resistance genes. The results showed that a total of 74 isolates of R. anatipestifer were isolated from 287 cases, with a prevalence of 25.8%. The antimicrobial susceptibility testing (AST) revealed that all the 74 isolates were resistant to multiple drugs, ranging from 13 to 26 kinds of drugs. Notably, these isolates showed significant resistance to aminoglycosides and macrolides, which are also commonly used in clinical practices. Data revealed the presence of several β-lactamase-related genes among the isolates, including a novel blaRASA-1 variant (16.2%), the class A extended-spectrum β-lactamase blaRAA-1 (12.2%), and a blaOXA-209 variant (98.6%). Functional analysis of the variants blaRASA-1 and blaOXA-209 showed that the blaRASA-1 variant exhibited activity against various β-lactam antibiotics while their occurrence in R. anatipestifer were not common. The blaOXA-209 variant, on the other hand, did not perform any β-lactam antibiotic resistance. Furthermore, we observed that blaRAA-1 could undergo horizontal transmission among different bacteria via the insertion sequence IS982. In conclusion, this study delves into the high prevalence of R. anatipestifer infection in waterfowl in Anhui, China. The isolated strains exhibit severe drug resistance issues, closely associated with the prevalence of antibiotic resistance genes (ARG). Additionally, our research investigates the β-lactam antibiotic resistance mechanism in R. anatipestifer.

β-lactam resistance is a serious problem that the hospitals face worldwide; particularly in the developing countries. The widespread of this resistance is attributed to various mechanisms used by the nosocomial bacteria. The aims of this study were to monitor the spread of the β-lactam resistant bacteria in the different provinces of Egypt; to create a biocontrol strategy by producing the β-lactamase inhibitory protein from the Streptomyces bacteria, and to knowing its suitability for the human use. Seventy β-lactam resistant bacterial isolates were sampled randomly from several hospital laboratories across ten governorates of Egypt. The isolates were screened against six different antibiotics; mainly Amoxicillin; Amoxicillin-Clavulanate, Penicillin, Ampicillin-Sulbactam, Cefepime, and Piperacillin-Tazobactam at 250 µg/ ml, and their Minimum inhibitory concentration (MIC) was recorded. The Bn67 isolate was the most promising isolate, which was molecularly identified using 16SrRNA partial sequence as Pseudomonas aeruginosa (LC710315.1). So in order to overcome this bacterial resistance; eighty actinobacteria were isolated from several soil samples collected from Giza governorate, Egypt, and were screened for their effectiveness against Bn67. The actinobacterial isolate (Stn-01) showed the maximum inhibitory efficacy against Bn67 and was identified using 16SrRNA partial sequence as Streptomyces katsurahamanus (LC710314.1). The inhibitor protein (β-LIP-n) was isolated; precipitated, and purified to give 35 kDa with 17 amino acid sequences. The β-LIPn exhibited no cytotoxic potential against the Human Skin Fibroblast (HSF) cell line at 200 µg/ ml. This approach of using the bacterial soil-based inhibitor protein to biocontrol the β-lactam resistant bacteria is considered as novel and as a promising start-up to using the environmental bacteria to overcome this problem of β-lactam resistance.

Antimicrobial Resistance (AMR) has been regarded as a major public health concern as a reason of millions of deaths. Extended-spectrum β-lactamase (ESBL) is considered as a leading factor contributing to this and limiting its treatment. Thus, ESBL producing Enterobacteriaceae should be discriminated from those having other mechanism conferring resistance. Several phenotypic methods have been evaluated for this purpose. Some of these are based on conventional method (DDST, CDT, ESBL E-test, Cica-β test) while others depend on automated systems (VITEK 1, VITEK 2, Phoenix, MicroScan). All the conventional methods have been found to be more specific, sensitive and cost effective than any of the automated system though they are easy to perform and interpret. Automated system also fails to detect ESBL in presence of other interfering enzymes such as AmpC, MBL or K1 enzyme. ESBL can be detected by using third-generation cephalosporin (cefotaxime or ceftazidime) or monobactam (aztreonam) in combination with clavulanate. AmpC can be distinguished by using cloxacillin-containing agar, fourth-generation cephalosporin (cefepime) or phenylboronic acid. MBL producers remain unaffected in presence of clavulanate but gets inhibited by carbapenems (imipenem, meropenem) in combination with EDTA. Cefpodoxime-clavulanate and ceftazidime- clavulanate combinations are reliable for K1 enzyme detection but are not suitable for distinguishing blaCTX–M1.

Despite the advances in β-lactamase inhibitor development, limited options exist for the class D carbapenemase known as OXA-48. OXA-48 is one of the most prevalent carbapenemases in carbapenem-resistant Enterobacteriaceae infections and is not susceptible to most available β-lactamase inhibitors. Here, we screened various low-molecular-weight compounds (fragments) against OXA-48 to identify functional scaffolds for inhibitor development. Several biphenyl-, naphthalene-, fluorene-, anthraquinone-, and azobenzene-based compounds were found to inhibit OXA-48 with low micromolar potency despite their small size. Co-crystal structures of OXA-48 with several of these compounds revealed key interactions with the carboxylate-binding pocket, Arg214, and various hydrophobic residues of β-lactamase that can be exploited in future inhibitor development. A number of the low-micromolar-potency inhibitors, across different scaffolds, synergize with ampicillin to kill Escherichia coli expressing OXA-48, albeit at high concentrations of the respective inhibitors. Additionally, several compounds demonstrated micromolar potency toward the OXA-24 and OXA-58 class D carbapenemases that are prevalent in Acinetobacter baumannii. This work provides foundational information on a variety of chemical scaffolds that can guide the design of effective OXA-48 inhibitors that maintain efficacy as well as potency toward other major class D carbapenemases.

Backbone chemical shift assignments for the Toho-1 β-lactamase (263 amino acids, 28.9 kDa) are reported based on triple resonance solution-state NMR experiments performed on a uniformly 2H,13C,15N-labeled sample. These assignments allow for subsequent site-specific characterization at the chemical, structural, and dynamical levels. At the chemical level, titration with the non-β-lactam β-lactamase inhibitor avibactam is found to give chemical shift perturbations indicative of tight covalent binding that allow for mapping of the inhibitor binding site. At the structural level, protein secondary structure is predicted based on the backbone chemical shifts and protein residue sequence using TALOS-N and found to agree well with structural characterization from X-ray crystallography. At the dynamical level, model-free analysis of 15N relaxation data at a single field of 16.4 T reveals well-ordered structures for the ligand-free and avibactam-bound enzymes with generalized order parameters of ~ 0.85. Complementary relaxation dispersion experiments indicate that there is an escalation in motions on the millisecond timescale in the vicinity of the active site upon substrate binding. The combination of high rigidity on short timescales and active site flexibility on longer timescales is consistent with hypotheses for achieving both high catalytic efficiency and broad substrate specificity: the induced active site dynamics allows variously sized substrates to be accommodated and increases the probability that the optimal conformation for catalysis will be sampled.