Occurrence of K1 and K2 serotypes and genotypic characteristics of extended spectrumβ-lactamases-producing Klebsiella pneumoniae isolated from selected hospitals in Malaysia

Objective:To determine the distribution,phenotypic and genetic background of extended spectrumβ-lactamases(ESBL)-producing Klebsiella(K.)pneumoniae clinical isolates associated with K1 and K2 serotypes in two selected hospitals in Malaysia.Methods:A total of 192 K.pneumoniae isolates were collected and subjected to antibiotic susceptibility,hypermucoviscosity test and multiplex PCR to detect the presence of K1-and K2-serotype associated genes.Multilocus sequence typing(MLST)was performed on ESBL-producing K.pneumoniae isolates presented with K1 and K2 serotypes,followed by phylogenetic analysis.Results:A total of 87 out of 192(45.3%)of the K.pneumoniae isolates collected were ESBL producers.However,only 8.3%(16/192)and 10.9%(21/192)of the total isolates were detected to carry K1-and K2-serotype associated genes,respectively.Statistical analysis showed that K1 and K2 capsular serotypes were not significantly associated with ESBL phenotype(P=0.196).However,they were significantly associated with hypervirulent,as demonstrated by the positive string test(P<0.001).MLST analysis revealed that ST23 as the predominant sequence type(ST)in the K1 serotype,while the ST in the K2 serotype is more diverse.Conclusions:Although the occurrence of ESBL-producing isolates among the hypervirulent strains was low,their coexistence warrants the need for continuous surveillance.MLST showed that these isolates were genetically heterogeneous.

Microbiologic and Clinical Comparison of Patients Harboring <i>Escherichia coli</i>Blood Isolates with and without Extended-Spectrum <i>β</i>-Lactamases

The clinical and microbiologic characteristics of 34 patients with extended-spectrum β-lactamase (ESBL) positive E. coli isolated from blood were compared to 66 bacteremic patients with ESBL negative E. coli, from January 2007 through December 2009. Of the 21 ESBL positive isolates available for PCR analysis, 13 were positive for CTX-M, 8 for TEM, 4 for SHV β-lactamases, with 6 possessing multiple enzymes. Twenty of 34 (59%) ESBL-positive and 41 of 66 (62%) ESBL-negative blood isolates were considered community-associated. All but one isolate in both groups had MICs of ≤1.0 μg/ml to meropenem. However, when compared to ESBL-negative isolates, ESBL-positive isolates were more frequently resistant to levofloxacin, trimethoprim/sulfamethoxazole and had higher MICs to gentamicin, tobramycin and piperacillin/tazobactam. The use of intravenous and urinary catheters was strongly associated with the isolation of E. coli bloodstream isolates in both groups of patients. Although hospital stay was similar in both groups, appropriate therapy was given in 87% of patients with ESBL positive vs. 98% of patients with ESBL negative isolates and mortality was greater for patients with ESBL positive isolates (26% vs. 17%). Since a large proportion of E. coli blood isolates were ESBL-positive and community-associated, carbapenems should be considered as initial empiric therapy for such infections in our locale.

Evaluation of Disk Potentiation Test (DPT) and Double Disk Synergy Test (DDST) for The Detection of Metallo-β-Lactamases (MBLs) in Clinical Isolates of Bangladesh

Objective: Increasing the emergence of Metallo-β-lactamase (MBL) producing gram-negative bacteria and their dexterous horizontal transmission demands rapid and accurate detection. This study was conducted to determine a suitable method to promptly detect MBL-producing gram-negative bacteria. Methods: A total of 103 gram-negative bacteria were identified from various clinical samples at a tertiary care hospital in Dhaka city. MBL producers were detected by two phenotypic methods, the Disk Potentiation Test (DPT) and the Double Disk Synergy Test (DDST) based on β-lactam chelator combinations where EDTA/SMA has been used as an inhibitor and Imipenem, Ceftazidime as substrates. Results: 103 isolates which were identified as Escherichia coli spp, Klebsiella spp, Pseudomonas spp, Acinetobacter spp, Proteus spp, Providencia spp were found to be multidrug-resistant in antibiogram test. Isolates showed complete resistance (100%) to Imipenem, Meropenem, and Amoxiclav. The highest carbapenem-resistant etiological agents were Acinetobacter spp 40 (38.8%) followed by Pseudomonas spp 27 (26.2%), Klebsiella spp 26 (25.2%), Escherichia coli 8 (7.8%), Proteus spp 1 (1%) and Providencia spp 1 (1%). DPT method detected significantly (p = 0.000009) a higher number of MBL-producers (Imipenem with 0.5 M EDTA n = 61, 59.2% & Ceftazidime with 0.5 M EDTA n = 56, 54.4%) compared to the DDST method (Imipenem -0.5 M EDTA n = 43, 41.7%, Imipenem – SMA n = 38, 36.9% & Ceftazidime -0.5 M EDTA n = 15, 14.6%). Conclusion: Pieces of evidence suggest that DPT is a more sensitive method than DDST and could be recommended for identifying MBL-producing bacteria in Bangladeshi hospitals for the proper management of patients, to reduce time constraints and treatment costs.

Characteristics of β-Lactamase Synthesis in E. coli and K. pneumanie Strains in Nosocomial Infections

Background: Recently micro-organisms that synthesize extended-spectrum β-lactamase (ESBLs) were increased. The peculiarities of ESBL synthesis of Escherichia coli and Klebsiella pneumoniae strains that cause nosocomial urinary tract infections, surgical site infections and pneumonia in surgical clinic were studied. ESBL synthesis were observed 38.9% of E. coli strains obtained from urine, 92.3% of strains obtained from surgical site infections, and 50% of strains obtained from sputum. ESBL synthesis were observed 37.5% of K. pneumoniae strains obtained from urine, 85.7% of strains obtained from surgical site infections, and 60% of strains obtained from sputum. Different levels of ESBL synthesize of E. coli and K. pneumoniae strains isolated from different pattern is discussed. Conclusion. ESBL synthesis is common in E. coli and K. pneumoniae strains, which cause nosocomial infections. The frequency of occurrence of ESBL s synthesis among of these strains depends on clinical forms of nosocomial infections.

Activity of Fosfomycin in Extended-Spectrum Beta-Lactamases Producing Klebsiella pneumonae from Hospital Acquired Urinary Tract Infections

Treatment of hospital acquired urinary tract infections (UTIs) caused by extended-spectrum beta-Lactamases producing Klebsiella pneumonae is a major problem. This organism expresses a high level of resistance to many groups of antibiotics. Fosfomycin is an agent which is recommended for treatment of UTIs caused by ESBLs producers. The aim of this study is to determine the sensitivity pattern of ESBLs producing urinary K. pneumonae to antimicrobial agents including fosfomycin in patients of MUHs and determine the prevalence of fosfomycin resistance mediated by plasmid mediated fosfomycin modifying enzymes fosA, fosB and fosA3. Methods: Klebsiella pneumonae urinary isolates were collected from patients with hospital acquired UTIs in Mansoura University Hospitals (MUHs). The susceptibility pattern was determined by Kirby Baur method. Isolates resistant to extended spectrum cephalosporins were tested for ESBLs production by double disc diffusion method. Fosfomycin resistance was determined by broth dilution method. Isolates resistant to fosfomycin were tested for fosA, fosB and fosA3 by PCR. Results: A total of 128 ESBLs producing K. pneumonae isolates were collected. The highest sensitivity was to imipenem (94.5%). The lowest was to trimethoprime-sulphamethoxazole (21.8%). Co-resistance of ESBLs isolates with fosfomycin was 23.2%. Eighteen fosfomycin resistant isolates (18/30) were positive to fosA. Conclusion: ESBLs producing urinary Klebsiella pneumonae express moderate sensitivity to fosfomycin. Resistance is mainly mediated by plasmid mediated fosfomycin modifying enzymes fosA.

Extended-spectrum β-lactamase controversies

G.A.Jacoby 教授毕业于美国哈佛医学院,为国际知名的传染病学、微生物学和免疫学专家,曾长期担任美国麻省总医院传染病科医师,现任麻省 Lahey 医学中心传染病实验室主任,中国感染与化疗杂志特邀编委。长期以来 Jacoby 教授对细菌耐药机制有深入研究,尤其对细菌(肺炎克雷伯菌、大肠埃希菌等)产生质粒介导的超广谱β内酰胺酶(ESBL)以及喹诺酮类的耐药机制研究。曾发表多篇有关上述专题的权威性论著。此次本刊特邀 Jacoby 教授撰写有关 ESBL 的新进展,文中阐述目前 ESBLs 除通常所指质粒介导β内酰胺酶中扩大了酶水解的底物谱导致细菌对头孢噻肟、头孢他啶、氨曲南等抗生素耐药外,还包括许多具有不同特点的β内酰胺酶,其中某些酶产自共生菌。除 ESBL 外,AmpC 酶和各种碳青霉烯β内酰胺酶也可导致细菌对上述抗生素耐药,因此临床微生物实验室准确检出和鉴别各种β内酰胺酶,对于临床选用适宜的抗茵药十分重要。美国 CLSI(过去称为 NCCLS)推荐采用两步法(筛选及确证)检测细菌产 ESBL;但有的学者认为测定抗茵药物对细菌的 MIC,如用药后 T>MIC 在50%以上即可达到满意疗效,无需检测细菌是否产 ESBL。目前认为碳青霉烯类抗生素治疗产 ESBL 菌感染的疗效最为满意,但由此可能引起细菌对该类药物耐药,值得关注。采用大剂量头孢吡肟或哌拉西林-三唑巴坦治疗产ESBL 菌感染是否有效尚有争论,临床上对β内酰胺类最为耐药的菌株往往对几乎所有现用抗菌药耐药。黏菌素(或多黏菌素 B)曾成功的用于治疗此种多重耐药菌感染。此外替莫西林(temocillin,一种对β内酰胺酶稳定的青霉素类)与替加环素(tigecvcline,为米诺环素衍生物)体外对产 ESBL 菌有抗菌作用,但尚无临床研究资料。

Post-appendectomy pelvic abscess with extended-spectrum beta-lactamase producing Escherichia coli : A case report and review of literature

BACKGROUND Appendicitis, the inflammation of the appendix, is the most common abdominal surgical emergency requiring expedient surgical intervention. Extendedspectrum beta-lactamases(ESBLs) are bacterial enzymes that catalyse the degradation of the betalactam ring of penicillins and cephalosporins(but without carbapenemase activity), leading to resistance of these bacteria to beta-lactam antibiotics. Recent increases in incidence of ESBL-producing bacteria have caused alarm worldwide. Proportion estimates of ESBLEnterobacteriaceae hover around 46% in China, 42% in East Africa, 12% in Germany, and 8% in the United States.CASE SUMMARY The impact of ESBL-producing bacteria on appendiceal abscesses and consequent pelvic abscesses are yet to be examined in depth. A literature review using the search words "appendiceal abscesses" and "ESBL Escherichia coli(E. coli)" revealed very few cases involving ESBL E. coli in any capacity in the context of appendiceal abscesses. This report describes the clinical aspects of a patient with appendicitis whodeveloped a postoperative pelvic abscess infected with ESBL-producing E. coli. In this report, we discuss the risk factors for contracting ESBL E. coli infection in appendicitis and post-appendectomy pelvis abscesses. We also discuss our management approach for postappendectomy ESBL E. coli pelvic abscesses, including drainage, pathogen identification, and pathogen characterisation. When ESBL E. coli is confirmed, carbapenem antibiotics should be promptly administered, as was done efficaciously with this patient. Our report is the first one in a developed country involving ESBL E. coli related surgical complications in association with a routine laparoscopic appendectomy.CONCLUSION Our report is the first involving ESBL E. coli and appendiceal abscesses, and that too consequent to laparoscopic appendectomy.

Antimicrobial Resistance and Genotype Analysis of Extended-Spectrum-β-Lactamase-Producing Proteus Mirabilis

To analyse the genotypes of clinical isolates of Extended-Spectrum-β-Lactamase-Producing (ESBL-producing) Proteus mirabilis (P. mirabilis) and the mechanisms of antimicrobial resistance, to guide reasonable use of antibiotics and to avoid nosocomial outbreak infections by ESBL-producing P. mirabilis. 125 clinical isolates of P. mirabilis were collected from the Drug-Resistant Bacteria Surveillance Center of Anhui Province (from Jan 2009 to May 2010). Searching for the genotypes of ESBLs was perfomed by PCR amplification and DNA sequencing, and performed conjugation test simultaneously. Among ESBL-producing strains, CTX-M was the major genotype (3 CTX-M-13 and 1 CTX-M-3). TEM-1b spectrum β-lactamase was also prevalence in P. mirabilis. The diversity of β-lactamases in P. mirabilis and the emergency of multi-drug-resistance clinical strains will present serious threat to clinical therapy and even will lead to outbreak of nosocomial infections. Our study emphasizes the need for enhanced supervision of ESBL-producing P. mirabilis. Timely and reasonable drug-resistance data are indispensable to clinical therapy.

Appendical Perforation by Infection with Extended-Spectrum Beta-Lactamase (ESBL)-Producing <i>Escherichia coli</i>: Case Report

We report the very rare case of a huge appendical abscess with extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli (E. coli) as the pathogen. There have been several reports of appendical infections such as appendicitis and appendical abscess caused by ESBL-producing bacteria in adults. The treatment of ESBL-producing E. coli infection is specific, and ESBL-producing bacteria have recently been reported as pathogens associated appendicitis in children. To the best of our knowledge, this is the second report of perforated appendicitis with abscess due to ESBL-producing E. coli. We discuss the diagnostic modalities and treatments for appendical abscess with ESBL-producing E. coli. and propose that the patients with perforated appendicitis and abscess formation due to ESBL-producing E. coli should be administered the antibiotic MEPM within 2 weeks to treat the abscess more effec-tively without producing other multidrug-resistant bacteria.

Antibiogram of Extended-Spectrum <i>β</i>-Lactamase (ESBL) Producing <i>Escherichia coli</i>

Background: Extended-spectrum β-lactamases (ESBLs) are enzymes capable of hydrolyzing extended-spectrum cephalosporins, penicillins and monobactams but inactive against cephamycins and carbapenems. The ESBL-producing organisms are a breed of multidrug-resistant pathogens. Objectives: This study was aimed to determine the susceptibility pattern of ESBL-producing Escherichia coli to ciprofloxacin, amikacin and imipenem. Methods: A total of 75 ESBL-producing E. coli, were obtained from the tertiary care hospitals of Bangladesh and were studied for susceptibility pattern from October, 2010 to December, 2011. These isolates were identified by double disc synergy test (DDST) and were confirmed phenotypically as ESBL-producer by phenotypic confirmatory disc diffusion test (PCDDT). Minimum inhibitory concentrations (MICs) of ciprofloxacin, amikacin and imipenem among ESBL-producing E. coli were determined using agar dilution method. Results: Out of 75 DDST positive ESBL-producing E. coli, 71 (94.67%) were also positive by PCDDT. All ESBL-producing E. coli, were susceptible to imipenem. About 92.95% ESBL-producing E. coli were susceptible to amikacin but only 14.08% were susceptible to ciprofloxacin. Conclusion: In this study, ESBL-producing E. coli, showed high resistance to ciprofloxacin. Imipenem and amikacin were most effective against ESBL positive strains.

Distribution of extended-spectrum β-lactamase genes in antibiotic-resistant strains of Pseudomonas aeruginosa obtained from burn patients in Ahvaz, Iran

Objective: To evaluate the drug susceptibility profiles and the frequency of beta-lactamase encoding genes in Pseudomonas aeruginosa (P. aeruginosa) obtained from burn patients. Methods: Totally 93 non-duplicate clinical isolates of P. aeruginosa were recovered from burn patients of Taleghani Burn Hospital of Ahvaz. Antibiotic susceptibility testing was conducted by disk diffusion method according to the CLSI 2017 recommendations. PCR assay was performed by to find beta-lactamase encoding genes. Results: In this study, most clinical specimen was obtained via wound swabs [65 (69.9%)], followed by blood [14 (15.1%)] and biopsy (7 (7.5%))Forty-two (45.16%) patients were male and 51(54.84%) were female. High resistance was observed for most of antibiotics especially for gentamicin and ciprofloxacin (Up to 85%), whereas the highest susceptibility was reported for colistin (100.0%), followed by ceftazidime (66.7%). According to PCR results, 16.1% (15), 9.7% (9) and 14.0% (13) of isolates carried blaDHA, blaVEB and blaGES genes, respectively. It also revealed that the blaVEB gene was found to coexist within 2 isolates (2.2%). Conclusions: Antibacterial resistance is high among P. aeruginosa isolates. Colistin is highly active against multi-drug resistant P. aeruginosa isolates. Antimicrobial susceptibility testing can confine indiscriminate uses of antibiotics and resistance increase, and can improve management of treatment.

Intestinal carriage of methicillin resistant Staphylococcus aureus and extended-spectrum β-Lactamase-producing Enterobacteriacae in hospitalized and nonhospitalized patients and their clinical implications

Objective:To determine the clinical implication of and intestinal carriage with methicillin resistant Staphylococcus aureus(MRSA) and extended spectrumβ-lactamase(ESBL)-producing Enterobacteriacae.Methods: A total of 180 stool specimens were screened for MRSA and ESBL-producing enterobacteria.Identification of ESBL- producing Enterobacteriacae was done by MicroScan Walk Away 96 system(Dade Behring Inc.,West Sacramento,CA 95691,USA ) and confirmation by double-disc synergy test.MRSA was identified by disc diffusion using 30μg cefoxitin disc and the MicroScan.Results:The rate of fecal MRSA carriage was 7.8% (14/180),35.7%(5 /14) were recovered from surgical wards.Three patients(21,4%) had MRSA recovered from other body sites,and 2(14.2%) had in addition ESBL -producing Escherichia coli(E.coli) and Klebsiella pneumoniae(K.pneumoniae) respectively.Four(28.5%) patients with MRSA fical carriage died. MRSA fecal carriage was recovered from both inpatients and outpatients.Four(2.2%) cases carried ESBL-producing Enterobacteriacae in feces.Three(75%) were from intensive care unit(ICU).One patient had both ESBL-producing E.coli and K.pneumoniae from stool as well as E.coli from tracheal aspirate.Two ICU patients with fecal ESBL died.Conclusion:Fecal screening for MRSA and ESBL of all patients at high risk admitted to different hospital wards and ICUs and implementing infection control measures were recommended.

Unravelling Antimicrobial Resistance Phenotypes and Carriage of Extended-Spectrum β-Lactamase Genes in Escherichia coli Isolated from Dairy Farms in Kiambu County, Kenya

The use of antibiotics for prophylaxis and growth enhancement in livestock farming is on the increase globally. This practice has led to the emergence and spread of antimicrobial-resistant bacteria in livestock. Only limited research has been done to establish the role of cattle farming in antimicrobial resistance. The current study sought to establish the carriage of multi-drug resistance and extended-spectrum beta-lactamase genes in Escherichia coli from farmers, their cattle, and cattle slurry within Kiambu County. A total of 286 (81%) E. coli isolates were recovered from 352 samples analysed. Antibiotic resistance profiles showed 114 (40%) isolates were resistant to ≥3 antimicrobial classes and were considered multidrug-resistant. Among multidrug-resistant (MDR) E. coli strains, 40 (14%) were resistant to 3 different antimicrobial classes, while 71 (25%) were resistant to between 4 and 7 antibiotic classes. Extended-spectrum β-lactamase resistance was found in 18 isolates: human (n = 14), cattle (n = 2), and environmental (n = 2). Both the blaCTX-M and blaTEM genes were detected in 10 and 15 strains, respectively. Sequence analysis showed that the isolates carried the blaTEM-116 (n = 7), blaTEM-1 (n = 5), and blaCTX-M-15 (n = 8) genes. Genotyping MDR isolates using (GTG) 5 PCR demonstrated that the isolates were not clonal. This data shows antimicrobial resistance profiles and different types of resistance genes in the E. coli population on dairy farms. As a result, more effective, targeted public health policies and measures need to be put in place to control and prevent the emergence and spread of resistant bacteria.

Metallo-β-Lactamases:A Major Threat to Human Health

Antibiotic resistance is one of the most significant challenges facing global healthcare. Since the 1940s, antibiotics have been used to fight infections, initially with penicillin and subsequently with various derivatives including cephalosporins, carbapenams and monobactams. A common characteristic of these antibiotics is the four-memberedβ-lactam ring. Alarmingly, in recent years an increasing number of bacteria have become resistant to these antibiotics. A major strategy employed by these pathogens is to use Zn(II)-dependent enzymes, the metallo-β-lactamases (MBLs), which hydrolyse theβ-lactam ring. Clinically useful MBL inhibitors are not yet available. Consequently, MBLs remain a major threat to human health. In this review biochemical properties of MBLs are discussed, focusing in particular on the interactions between the enzymes and the functionally essential metal ions. The precise role(s) of these metal ions is still debated and may differ between different MBLs. However, since they are required for catalysis, their binding site may present an alternative target for inhibitor design.

Prevalence and Potential Risk Factors of Hospital Acquired Extended-Spectrum Beta-Lactamase—Producing <i>Proteus</i>Species

Background: Multidrug resistance and production of extended spectrum β-lactamases (ESBLs) by a large group of bacterial agents in hospitals are to be a matter of scientific concern. Objective: This cross-sectional study was aimed to investigate the prevalence of ESBL producing Proteus species and risk factors associated with hospital acquired infection in addition to study the antibiotics susceptibility patterns of all bacterial isolates from inpatients of four Yemeni general hospitals. Methods: A total of 740 consecutive non-repeat culture isolates were obtained from admitted patients of Al-Kuwait University Hospital, Al-Thowra General Hospital, Al-Jumhori Teaching Hospital, and Military General Hospitals Sana’a city. We used Kirby-Bauer disk diffusion method to detect antimicrobial susceptibility and establish the presence of ESBLs-producing bacteria according to the Clinical and Laboratory Standards Institute guidelines. Results: Out of 740 isolate, 233 (31.5%) were Escherichia coli followed by Staphylococcus aureus 188 (25.4%), Pseudomonas aeruginosa 149 (20.1%), Klebsiella sp. 107 (14.5%), Enterococcus faecalis 25 (3.4%) and Proteus spp. 38 (5.1%). The highest frequencies of ESBLs producing among Proteus sp. were Proteus mirabilis 26 out 38 (68.4%) and Proteus vulgaris 12 out 38 (31.6%). The most effective of antimicrobial susceptibility pattern among Proteus spp. were Imipenem (100%) followed by Pipracillin-Tazobactam (92.3%) for P. mirabilis and (83.3%) for P. vulgaris, while the Amikacin (80.8%) for P. mirabilis and P. vulgaris with (91.7%). Amoxicillin and Cefotaxime were the highest for both species (100%). Conclusion: The prevalence of ESBL-producing Proteus spp. detected in this study is of great concern for public health authorities and a strict adherence of infection control policies and procedures with continuous antibiotics resistance surveillance including antimicrobial management and routine detection of ESBL-producing isolates are very important to prevent nosocomial infections.

Phenotypic and Genotypic Characterization of Metallo-Beta-Lactamase and Extended-Spectrum Beta-Lactamase among Enterobacteria Isolated at National Public Health Laboratory of Brazzaville

The improper use of antimicrobials against infectious diseases has allowed microorganisms to develop defense mechanisms that give them insensitivity to these agents. All bacteria are concerned by this phenomenon. This work aimed to assess prevalence of beta-lactamase produced by enterobacterial isolates. Then, disc diffusion, double disc synergy test (DDST) and combined disc test (CDT) were respectively used for antimicrobial resistance, detection of Extended-Spectrum Beta-Lactamases (ESBL) and Metallo-Beta-Lactamases (MBL). bla genes were detected by PCR. A total of 132 enterobacterial strains were studied. Resistance to antibiotic families was observed with a greater frequency than 50%. Gentamicin was the least active beta-lactam antibiotic, with a resistance rate of 88%. 40.9% of strains show an ESBL phenotype and 16.6% were MBL. An overall prevalence of 74% (40/54) and respectively rates of 29.6%, 27.7% and 16.7% for blaSHV, blaCTX and blaTEM genes were observed. SHV, CTX, CTX/SHV/TEM, CTX/TEM, SHV/TEM and CTX/SHV were different ESBL genotypes observed. ESBL-producing enterobacteria isolation worried about the future of antimicrobial therapy in the Republic of Congo. This is a public health problem that requires careful monitoring and implementation of a policy of rational antibiotics use.

Identification and preliminary characterization of novel B3-type metallo-β-lactamases

Antibiotic resistance has emerged as a major global threat to human health. Among the strategies employed by pathogens to acquire resistance the use of metallo-β-lactamases (MBLs), a family of dinuclear metalloenzymes, is among the most potent. MBLs are subdivided into three groups (i.e. B1, B2 and B3) with most of the virulence factors belonging to the B1 group. The recent discovery of AIM-1, a B3-type MBL, however, has illustrated the potential health threat of this group of MBLs. Here, we employed a bioinformatics approach to identify and characterize novel B3-type MBLs from Novosphingobium pentaromativorans and Simiduia agarivorans. These enzymes may not yet pose a direct risk to human health, but their structures and function may provide important insight into the design and synthesis of a still elusive universal MBL inhibitor.

Unusual metallo-β-lactamases may constitute a new subgroup in this family of enzymes

Metallo-β-lactamases (MBLs) are a family of Zn2+-dependent enzymes that have contributed strongly to the emergence and spread of antibiotic resistance. Novel members as well as variants of existing members of this family are discovered continuously, compounding their threat to global health care. MBLs are divided into three subgroups, i.e. B1, B2 and B3. The recent discovery of an unusual MBL from Serratia proteamaculans (SPR-1) suggests the presence of an additional subgroup, i.e. B4. A database search reveals that SPR-1 has only one homologue from Cronobacter sakazakii, CSA-1.These two MBLs have a unique active site and may employ a mechanism distinct from other MBLs, but reminiscent of some organophosphate-degrading hydrolases.

Prevalence and Risk Factors of Penicillinase-Type β-Lactamase Producing Neisseria gonorrhoeae Isolated from Patients Attending Health-Facilities in Yaounde, Cameroon

Background and Objectives: Mitigation of antibiotic resistant Neisseria gonorrhoeae has become a priority due to considerable health and economical disabilities it generates. In order to tackle the emergence of resistant Neisseria gonorrhoeae, this study aimed to determine the prevalence and risk factors of penicillinase type β-lactamase-producing Neisseria gonorrheae among patients consulting for genital infectious disorders in two health-facilities in Yaounde, Cameroon. Materials and Method: A cross-sectional descriptive and analytical study was conducted over a 3-month period, from July 2nd to October 2nd, 2022. Vaginal and urethral secretions were collected. Biochemical identification tests were performed on colonies grown on chocolate agar + polyvitex using the Api NH gallery. The detection of penicillinases was equally performed using the API NH gallery and confirmed using the antimicrobial susceptibility testing. The Minimum Inhibitory Concentrations of some antibiotics were determined using the E-Test. Results: The results showed that out of the 198 patients sampled, 16 (8.08%) were positive for Neisseria gonorrhoeae, among which 13/16 (81.25%) were penicillinase-type β-lactamase producers. Antimicrobial susceptibility testing results showed high co-resistances to antibiotics, mainly ciprofloxacin (100%), nalidixic acid (92.31%) and azithromycin (84.62%). Moreover, high Minimum Inhibitory Concentrations of ceftriaxone (ranging from 6 to 24 mg/L) was observed toward Neisseria gonorrhoeae isolates. The risk factors of the carriage of penicillinase-type β-lactamase producing Neisseria gonorrhoeae identified were: a history of Sexually Transmitted infections (p = 0.01) and unprotected sexual intercourse (p = 0.01). Conclusion: The emergence of penicillinase-type β-lactamase producing Neisseria gonorrhoeae is increasing and the situation is becoming worrisome. The identified risk factors can constitute a basic outlook to tackle resistant Neisseria gonorrhoeae, and therefore sustain antibiotic stewardship.

L1 β-Lactamase催化反应机理研究

用混合量子力学和分子力学(QM/MM)方法和密度泛函理论讨论了L1β-Lactamase催化Nitrocefin水解的过程,研究结果表明,反应为多步反应:第一步亲核进攻反应为反应的决速步骤,并且伴随着酰胺键的断裂,第二步反应为质子迁移反应.同时讨论了金属锌在反应中的作用.