Β-lactamase Production Research Articles

Antibiotic susceptibility profiles and detection of genes mediating extended-spectrum β-lactamase (Esbl) production in escherichia coli isolates from National Hospital, Abuja.

Extended-spectrum beta-lactamases (ESBL) are the most widespread of the new beta-lactamases and are a significant threat to patient care in the hospital and the community. Aim: The study assessed the prevalence, antibiotic susceptibility profile, and major ESBL encoding genes among Escherichia coli isolated from clinical specimens of patients in the National Hospital, Abuja (NHA). E. coli isolated from diverse clinical specimens obtained from clinically proven cases of infection managed at the NHA were included in the study. The antimicrobial susceptibility was performed by the Kirby-Bauer method and E-test was used to confirm the ESBL phenotype. Multiplex polymerase chain reaction (PCR) was used to detect the genes mediating ESBL production. Meropenem, fosfomycin, and tigecycline demonstrated excellent activities against all isolates: of the 400 isolates, 392 (98%), 386 (96.5%), and 362 (90.5%) were susceptible, respectively. Similarly, 358 (89.5%) were susceptible to amikacin, 323 (80.3%) nitrofurantoin, 281 (70.3%) ceftazidime, and 279 (69.8%) cefotaxime. A total of 271 (67.8%), 219 (54.8%), and 208 (52.0%) were resistant to amoxicillin-clavulanate, ciprofloxacillin, and gentamicin, respectively. However, all the isolates were resistant to ampicillin. There was a significantly higher proportion of multidrug resistance among ESBL-producing isolates compared to non-ESBL-producing isolates (P = 0.0001). Of the 121 phenotypically detected ESBL isolates, 119 (98.3%) harbored genes mediating the production of Cefotaximase- Munich (CTX-M), Temoniera (TEM) or Sulfhydryl Variable (SHV) enzymes. The prevalence of ESBLs among E. coli was relatively high, at 30.2%. About 81% of all blood isolates were ESBL-producers. blaCTX-M is the predominant type of ESBL gene among E. coli. A high proportion of the ESBL-producing isolates expressed a combination of two or three genes together.

Genomic Characterization of International High-Risk Clone ST410 Escherichia coli Co-Harboring ESBL-Encoding Genes and blaNDM-5 on IncFIA/IncFIB/IncFII/IncQ1 Multireplicon Plasmid and Carrying a Chromosome-Borne blaCMY-2 from Egypt.

The accelerated dispersion of multidrug-resistant (MDR) Escherichia coli due to the production of extended-spectrum β-lactamases (ESBLs) or AmpC enzymes has been noted in Egypt, presenting a serious treatment challenge. In this study, we investigate the prevalence of ESBLs and AmpC enzymes among 48 E. coli isolates collected from patients with urinary tract infections admitted to a teaching hospital in Alexandria. Phenotypic and genotypic methods of detection are conducted. Isolates producing both enzymes are tested for the mobilization of their genes by a broth mating experiment. Whole genome sequencing (WGS) is performed for isolate EC13655. The results indicate that 80% of the isolates are MDR, among which 52% and 13% were ESBL and AmpC producers, respectively. Conjugation experiments fail to show the mobilization of blaCMY-2 in EC13655, which was chosen for WGS. In silico analysis reveals that the isolate belongs to a ST410-H24Rx high-risk clone. It coharbors the ESBL-encoding genes blaCTX-M-15, blaTEM-1, blaOXA-1 and blaNDM-5 on an IncFIA/IncFIB/IncFII/IncQ1 multireplicon plasmid. The chromosomal location of blaCMY-2 is detected with a flanking upstream copy of ISEcp1. This chromosomal integration of blaCMY-2 establishes the stable maintenance of the gene and thus, necessitates an imperative local surveillance to reduce further spread of such strains in different clinical settings.

Causative agents of bloodstream infections in two Croatian hospitals and their resistance mechanisms

Blood samples were collected alongside with routine blood cultures (BC) from patients with suspected sepsis, to evaluate the prevalence of different causative agents in patients with bacteraemia. Among 667 blood samples, there were 122 positive BC (18%). Haemoglobin content, platelet number, and systolic blood pressure values were significantly lower in patients with positive BC, whereas serum lactate levels, CRP, creatinine and urea content were significantly higher in patients with positive BC. The rate of multidrug (MDR) or extensively drug resistant (XDR) bacteria was 24% (n = 29): Klebsiella pneumoniae (9), Pseudomonas aeruginosa (9), Acinetobacter baumannii (4), Escherichia coli (1), vancomycin resistant Enterococcus spp (VRE) (3), and methicillin-resistant Staphylococcus aureus MRSA (3). The dominant resistance mechanisms were the production of extended-spectrum β-lactamases, OXA-48 carbapenemase, and colistin resistance in K. pneumoniae, VIM metallo-β-lactamases in P. aeruginosa and OXA-23-like oxacillinases in A. baumannii. The study revealed high rate of MDR strains among positive BCs in Zagreb, Croatia.

Complete Genome Sequence of a Multidrug-Resistant Klebsiella pneumoniae Environmental Isolate from Zanzibar, Tanzania, Harboring Novel Insertion Elements and Two blaCTX-M-15 Genes.

ABSTRACTHere, we report the annotated whole-genome sequence of Klebsiella pneumoniae strain KP_3b, isolated in Zanzibar, Tanzania, from plastic litter. The strain is extended-spectrum β-lactamase (ESBL) producing and multidrug resistant, encoding 17 resistance genes, most of which are located on a 230,544-bp plasmid. The isolate contains two copies of the blaCTX-M-15 gene and novel insertion elements.

First report from supermarket chicken meat and genomic characterization of colistin resistance mediated by mcr-1.1 in ESBL-producing, multidrug-resistant Salmonella Minnesota

Plasmid-borne colistin resistance is considered one of the most complex public health concerns worldwide. Several studies reported the presence of the mcr-1.1 harboring Salmonella from the foodstuffs worldwide; still, there is a knowledge gap about the occurrence of these isolates in the Middle East. In this study, we report an mcr-1.1-mediated colistin resistance in two multidrug-resistant (MDR) S. Minnesota (denoted as Sal_2 and Sal_10), with both being also extended-spectrum β-lactamase (ESBL) producing. These isolates have been recovered from two independent samples out of 315 chilled chicken meat tested from retail supermarkets in the United Arab Emirates (UAE). Based on whole-genome sequencing (WGS) analysis, both isolates belonged to the same Sequence Type (ST) ST548. They shared the same genes encoding resistance to the following antimicrobials: polymyxin (mcr-1.1), phenicol (floR), quinolone (qnrB19), aminoglycoside (aac(6′)-Iaa), tetracycline (tet(A)), and sulfonamide (sul2). However, the isolates featured different patterns of β-lactamase resistance genes, which included blaCTX-M-55 (ESBL-β-lactamase) and blaCMY-2 (AmpC-β-lactamase) in the isolate Sal_2, and blaTEM-215 (ESBL-β-lactamase) in the isolate Sal_10. WGS analysis inferred that both S. Minnesota isolates in this study carry an IncX4 plasmid harboring the mcr-1.1 variant. To understand the possible origin of the two mcr-1.1 carrying S. Minnesota isolated from retail chicken meat in this study, we conducted a phylogenomic analysis using available genomes of S. enterica, which harbored mcr-1.1 gene (n = 240, from the Middle East and Asian countries) deposited in the NCBI database. We found that Sal_2 and Sal_10 independently clustered together with other isolates detected in China, mainly from the chicken origin and to a lesser extent from human clinical origin. The finding of mcr-producing colistin-resistant strains in retail chicken meat warrants a more comprehensive One Health investigations involving strains from animals, retail food chains, and human clinical isolates at the national level in the UAE.

Detection of Methicillin Resistance and β-Lactamase Production in Staphylococcus aureus Isolates: A Cross Sectional Study from a Tertiary Care Hospital

Nosocomial infections are proving to be a menace for the whole health care system, with methicillin resistant Staphylococcus aureus (MRSA) being a very notorious causative agent. Along with the role of mecA gene producing penicillin-binding protein (PBP2a), production of beta-lactamase enzyme by Staphylococcus aureus makes the organism resistant to all β-lactam agents. This study aims at phenotypic detection of methicillin resistance and β-Lactamase production in all S. aureus isolates by Cefoxitin disk diffusion test and Penicillin zone-edge test, respectively. In this prospective cross-sectional study, samples were obtained from patients admitted to different departments and were processed according to the standard laboratory protocols. As per the CLSI guidelines, phenotypic detection of resistance to methicillin was done by Cefoxitin Disk Diffusion test, whereas production of beta-lactamase enzyme was phenotypically detected by penicillin zone edge test. Among 179 isolates of S. aureus, 116 (64.8%) were MRSA, whereas the remaining 63 (35.2%) isolates were methicillin-sensitive Staphylococcus aureus (MSSA). Staphylococcus aureus infection among ICU and non-ICU patients were found to be 24(13%) and 155(86.6%) respectively. Among 24 ICU patients, 19 had MRSA infection, whereas among 155 non-ICU patients, 97 had MRSA infection. Out of 63 MSSA isolates, only 2 (3.17%) were found to be sensitive to Penicillin by Zone-edge test, 04 isolates showed presence of β-lactamase production, while remaining 57 isolates were resistant to Penicillin. At the same time, several class of antibiotics were found to be ineffective against these MRSA isolates. Cases of methicillin-resistant and b–lactamase producing Staphylococcus aureus infections are on the rise in our hospital settings.

Chemically synthesised flavone and coumarin based isoxazole derivatives as broad spectrum inhibitors of serine β-lactamases and metallo-β-lactamases: a computational, biophysical and biochemical study

The β-lactam antibiotics are the most effective medicines for treating bacterial infections. Resistance to them, particularly through the production of β-lactamases, which can hydrolyse all kinds of β-lactams, poses a threat to their continued use. The synthesised flavone and coumarin based isoxazole derivatives have the potential to be used as broad-spectrum inhibitors of the mechanistically different serine-(SBL) and metallo-β-lactamases (MBL). The synthesised compounds were discovered as potent β-lactamase inhibitors using molecular docking and in silico pharmacokinetic analysis. We studied the binding of chemically synthesised inhibitors to clinically significant β-lactamases of class A, B, and C using biophysical and biochemical approaches, and computational analyses. These molecules follow Lipinski’s rule of five and have acceptable solubility, permeability, and oral bioavailability. These molecules were found to be non-toxic and non-carcinogenic. MIC results suggest that these molecules restore the antibiotic efficacy against class A, B, and C β-lactamases. Kinetics data showed that these molecules reduce the catalytic efficiency of clinically relevant class A, B, and C β-lactamases. Fluorescence study showed significant interaction between these flavone-/coumarin-based isoxazole derivatives and class A/B/ C β-lactamases. This study showed promising effect of these new generation compounds as broad spectrum β-lactamase inhibitors of both SBLs and MBLs. Communicated by Ramaswamy H. Sarma

Disinfectant and heavy metal resistance profiles in extended spectrum β-lactamase (ESBL) producing Escherichia coli isolates from chicken meat samples

Biocidal compounds are frequently used as disinfectants in poultry industry and their widespread usage has risen concern due to the co-selection and persistence of antimicrobial resistance among bacteria. In this study, extended spectrum β-lactamase producing (ESBL) Escherichia coli isolates (n = 60) obtained from chicken meat were characterized by Pulsed Field Gel Electrophoresis (PFGE) and further tested for disinfectant and heavy metal resistance phenotypically and genotypically. Plasmid replicon types of these isolates were also determined. ESBL producing E. coli isolates were found to be resistant to ciprofloxacin (48.3 %) and gentamicin (15 %). The majority of these isolates (46.5 %) carried blaCTX-M-55 gene. The isolates showed higher minimal inhibitory concentrations to cetylpyridinium chloride (90 %), cetyltrimethylammonium bromide (50 %), hexadecyltrimethylammonium bromide (46.7 %), triclosan (38.3 %), benzalkonium chloride (28.3 %), chlorhexidine (21.7 %), acriflavine (3.3 %), benzethonium chloride (1.7 %) and N-alkyl dimethyl benzyl ammonium chloride (1.7 %), but 18.3 % of the isolates were resistant to triclosan. Of the quaternary ammonium compounds (QACs) tolerance genes, mdfA, sugE(c), ydgE and ydgF were most present in all isolates, but the qacE, qacG, oqxA and oqxB genes were not detected. Of genes mediating the heavy metal resistance, the zitB gene was detected in all isolates, whereas the copA and cueO genes were detected in 96.67 % and 95 % of isolates, respectively. The IncFIB plasmid was commonly present (93.3 %) in ESBL producing E. coli isolates. Consequently, given the detection of genes mediating disinfectant and heavy metal resistance commonly in ESBL producing E. coli isolates as well as high rate of MICs against disinfectant compounds, the use of QACs for decontamination of the facilities may not be as effective as expected in poultry sector in Turkey.

Outbreak of sexually transmitted, extensively drug-resistant Shigella sonnei in the UK, 2021–22: a descriptive epidemiological study

Shigellosis, traditionally a foodborne and waterborne infection, causes substantial morbidity globally. It is now a leading cause of sexually transmitted gastroenteritis among gay, bisexual, and other men who have sex with men (MSM). We describe an ongoing outbreak of extensively drug-resistant (XDR) Shigella sonnei in the UK. Routine laboratory surveillance (Second Generation Surveillance System, Gastrointestinal Data Warehouse) identified an exceedance of S sonnei clade 5 in England, first detected in September, 2021. Cases within this clade were subsequently reported from Scotland, Wales, and Northern Ireland. Confirmed cases in this outbreak were defined as individuals diagnosed with S sonnei clade 5 in the UK, with a specimen date between Sept 1, 2021, and Feb 9, 2022, who were genomically confirmed as part of a ten-single nucleotide polymorphism (SNP) linkage cluster. We used whole-genome sequencing with SNP typing to identify genomic clusters and antimicrobial-resistance determinants, analysing cases across the UK. We collected demographic, epidemiological, and clinical data from people infected with S sonnei clade 5 in England using questionnaires (standard and bespoke outbreak questionnaires). We used descriptive summary statistics to characterise cases. 72 cases (70 [97%] male, median age 34 years [IQR 27-39]) belonging to the ten-SNP single linkage cluster of S sonnei clade 5 were identified between Sept 4, 2021, and Feb 9, 2022. Isolates were predominantly XDR, with 66 (92%) of 72 harbouring bla_CTX-M-27, a plasmid-mediated gene for production of extended-spectrum β-lactamases (ESBLs). Of 33 cases with clinical data, 19 (58%) received antibiotics and eight (24%) were hospitalised. 21 (78%) of 27 cases with completed bespoke outbreak questionnaires were HIV-negative MSM taking HIV pre-exposure prophylaxis (PrEP) who reported sexual contacts in the UK and Europe within the incubation period. We highlight the rapid dissemination of XDR ESBL-producing S sonnei in sexual networks of MSM. We recommend strengthening shigella testing where clinically indicated, antimicrobial-resistance surveillance, and integrated health promotion messaging among all MSM, including PrEP users, to reduce the burden of shigellosis. National Institute for Health Research Health Protection Research Unit in Gastrointestinal Infections at the University of Liverpool in partnership with the UK Health Security Agency.

Synergistic Role of Plant Extracts and Essential Oils against Multidrug Resistance and Gram-Negative Bacterial Strains Producing Extended-Spectrum β-Lactamases.

Plants, being the significant and natural source of medication for humankind against several ailments with characteristic substances hidden on them, have been recognized for many centuries. Accessibility of various methodologies for the revelation of therapeutically characteristic items has opened new avenues to redefine plants as the best reservoirs of new structural types. The role of plant metabolites to hinder the development and movement of pathogenic microbes is cherished. Production of extended-spectrum β-lactamases is an amazing tolerance mechanism that hinders the antibacterial treatment of infections caused by Gram-negative bacteria and is a serious problem for the current antimicrobial compounds. The exploration of the invention from sources of plant metabolites gives sustenance against the concern of the development of resistant pathogens. Essential oils are volatile, natural, complex compounds described by a solid odor and are framed by aromatic plants as secondary metabolites. The bioactive properties of essential oils are commonly controlled by the characteristic compounds present in them. They have been commonly utilized for bactericidal, virucidal, fungicidal, antiparasitic, insecticidal, medicinal, and antioxidant applications. Alkaloids are plant secondary metabolites that have appeared to have strong pharmacological properties. The impact of alkaloids from Callistemon citrinus and Vernonia adoensis leaves on bacterial development and efflux pump activity was assessed on Pseudomonas aeruginosa. Plant-derived chemicals may have direct antibacterial activity and/or indirect antibacterial activity as antibiotic resistance modifying agents, increasing the efficiency of antibiotics when used in combination. The thorough screening of plant-derived bioactive chemicals as resistance-modifying agents, including those that can act synergistically with antibiotics, is a viable method to overcome bacterial resistance. The synergistic assessment studies with the plant extract/essential oil and the antibiotic compounds is essential with a target for achieving a redesigned model with sustainable effects which are appreciably noticeable in specific sites of the plants compared to the entirety of their individual parts.

Detection of extended spectrum β-Lactamase (ESBL) and Metallo β-Lactamase (MBL) in Pseudomonas aeruginosa isolated from various clinical samples

Introduction: β-Lactamase production is considered one of the most important resistance mechanisms among virulent Pseudomonas aeruginosa isolates. The aim of the study was to detect Extended Spectrum β-Lactamase (ESBL) and Metallo β-Lactamase (MBL) in Pseudomonas aeruginosa obtained from various clinical samples. Materials and Methods: The study was conducted in the Department of Microbiology, Govt. Medical College, Shahdol. All clinical specimens were processed and P. aeruginosa isolates were identified by standard protocols. Antibiotic sensitivity testing for all isolates was done using Kirby-Bauer disc diffusion method. Detection of ESBL and MBL was done by Disc potentiation test. Results: Among 347(27.2%) isolates of P. aeruginosa, 284(88.2%) were MDR, 139(40%) and 73(21%) were ESBL and MBL producers respectively where 39(11.2%) isolates produced both ESBL and MBL. Conclusion: A high prevalence of MDR, ESBL, MBL positive isolates among P. aeruginosa is increasing at an alarming rate. Thus, proper antibiotic policy and measures to restrict the indiscriminative use of cephalosporins and carbapenems should be taken to minimize the emergence of this MDRPA.

In vitro activity of aztreonam/avibactam against isolates of Enterobacterales collected globally from ATLAS in 2019

Objectives: Infections caused by drug-resistant Enterobacterales including those producing metallo-β-lactamases (MBLs) are particularly challenging due to limited therapeutic options. The drug combination aztreonam/avibactam (ATM-AVI) is under clinical development for treating serious infections caused by these strains. This study assessed the in vitro activity of ATM-AVI against Enterobacterales isolates collected globally in the ATLAS surveillance programme in 2019. Methods: Clinical isolates of Enterobacterales (N = 18 713) including Citrobacter freundii, Citrobacter koseri, Enterobacter cloacae complex, Escherichia coli, Klebsiella aerogenes, Klebsiella oxytoca, Klebsiella pneumoniae, Proteus mirabilis, and Serratia marcescens collected from 232 sites in 2019 were analysed. Antimicrobial susceptibility testing was performed by reference broth microdilution. A pharmacokinetic/pharmacodynamic based breakpoint of 8 mg/L was considered for ATM-AVI activity. Results: ATM-AVI demonstrated potent antimicrobial activity against all Enterobacterales, with 99.9% isolates inhibited at MIC ≤8 mg/L (MIC90, 0.25 mg/L). MICs ≤8 mg/L (>99.0%) were noted for ATM-AVI across regions worldwide. Among other antimicrobials, amikacin, colistin, imipenem, meropenem, and tigecycline were also active (susceptibility >85.0%) against Enterobacterales. Activity of ATM-AVI was sustained against multidrug-resistant, extended-spectrum β-lactamase producing, and carbapenem-resistant isolates (susceptibility >99%; MIC90, 0.25–0.5 mg/L). Importantly, potent activity for ATM-AVI (>99.0%; MIC90, 0.5 mg/L) was noted among MBL-positive isolates and those producing other carbapenemases, such as KPC and OXA-48. Conclusion: Our results demonstrated that ATM-AVI was highly active against a recent collection of Enterobacterales isolates, including those producing MBLs either alone or in combination with other carbapenemases. Thus, ATM-AVI represents a potential option for treating infections caused by antibiotic-resistant Enterobacterales including MBL-producing strains.

Detection of beta-lactamase-producing Enterobacteriaceae in a veterinary hospital environment

Due to the strong selective pressure resulting from the misuse of antibiotics, the natural process of bacterial resistance has been accelerated, leading to the increasingly constant appearance of multiresistant isolates. The high number of multiresistant bacteria is a one health problem. Enterobacteriaceae are usually commensal bacteria of the gastrointestinal tract. However, they can cause infections, and the most important resistance characteristic among them is the production of β-lactamases. This study aimed to identify ESBL-producing Enterobacteriaceae of types of TEM, SHV, and the CTX-M groups. To isolate the enterobacteria, swabs were collected by swiping objects that had contact with the patients and professionals, and the water of the hospital environment. Ten collections were carried out, yielding 306 samples, from which 118 enterobacteria were identified: Escherichia coli, Enterobacter spp., Klebsiella spp., Proteus mirabilis, Serratia spp., and Citrobacter spp. Isolates. The genes TEM and CTX-M, for the production of β lactamases, were detected in 12.7% of the 118 enterobacterial isolates. It is very important to know the bacterial population circulating in the veterinary hospital environment and its resistance to antimicrobials so that professionals can take appropriate measures to minimize the risks of transmission, especially from cages and consultation tables. In addition, the correct control of the microbiological quality of the supply water, as well as environmental cleaning procedures, are essential to prevent the transmission of these microorganisms.

PB2256: BACTERIAL BLOODSTREAM INFECTIONS AND ANTIMICROBIAL SUSCEPTIBILITY PATTERN IN PATIENTS WITH ACUTE LEUCAEMIA

Background: Currently, there is a trend towards an increasing proportion of Gram-negative microorganisms, including Enterobacterias. Escherichia coli and Klebsiella pneumoniae constitute the major part in the structure of bloodstream pathogens. One important mechanism of Enterobacterias’ resistance is the production of extended-spectrum beta-lactamases (ESBL), AmpC β-lactamases and carbapenemases. Aims: Determination of the antibiotic resistance profile of bloodstream pathogens in patients with acute leukaemia and evaluation of the efficacy of starting antibiotic therapy regimens. Methods: The study included 69 cases of bloodstream infections, confirmed by bacteriological blood testing in patients with acute leukaemia between January 2020 and January 2022, 46.4% of which were male and 53.6% were female, with a median age of 44 years. All patients had myelotoxic agranulocytosis at the time of infectious complications. Results: During the study period and according to the bacteriological examination of blood, 58 strains of E. coli and Kl. pneumoniae were detected. The antibiotic sensitivity pattern is shown in the figure. Bloodstream infection caused by E. coli was detected in 23 cases (32.8%), herewith ESBL production was detected in 47.8% of E. coli strains. In the scope of the empirical antibiotic therapy, the 4th generation cephalosporin (cefepime) was used in 39.1% of cases or carbapenem (meropenem) in 60.9% of cases in combination with the 3rd generation aminoglycoside (amikacin). Herewith the empirical antibiotic therapy was considered as rational in 78.3% of cases, whereas in the remaining cases escalation was essential. The use of the 4th generation cephalosporin (cefepime) in the scope of the empirical therapy was ineffective in 55.6% of cases. Due to the therapy in 95.7% of cases the patient’s condition was stable, and in 4.3% of cases led to a fatal outcome. Bloodstream infection caused by Kl. pneumoniae was detected in 35 cases (50%), and resistance to carbapenems was reported in 68.6% of strains of the Kl. pneumoniae. The share of ESBL-producing Kl. pneumonias trains was 40%, while the proportion of Enterobacteriaceae strains, susceptible to extended-spectrum cephalosporins and carbapenems, reached only 8.8%. During the therapy in 72.4% of cases the patient’s condition stabilised, and in 27.6% of cases a fatal outcome was recorded. In all cases of fatality сarbapenem-resistant strains, including panresistant strains (5.9%) acted as a causative agent. Summary/Conclusion: The most frequent causative agents of bloodstream infections in acute leukaemia patients during myelotoxic agranulocytosis are the Gram-negative bacteria E. coli and Kl. pneumoniae. The empirical antibiotic therapy regimens including 3rd generation cephalosporins (cefepime) was ineffective in 55.6% of cases, as 47.8% of isolated E. coli strains were generating ESBL. This increases the relevance of using carbapenems. Resistance to carbapenems was reported in 68.6% of strains of Kl. pneumoniae. This indicates a high prevalence of carbapenem-resistant strains in the haematological hospital, as well as the low efficacy of empirical antibiotic therapy, including both cephalosporins and carbapenems.

Assessment of well water as a reservoir for extended-spectrum β-lactamases (ESBL) and carbapenem resistant Enterobacteriaceae from Iwo, Osun state, Nigeria.

Unsafe water supplies are of public health concern, especially in developing countries. This article aims to investigate the microbiological quality of water from eight Wells in Iwo and to explore for the extended-spectrum β-lactamase (ESBL) and carbapenemase genes contained in isolated enteric bacteria from in the water samples. Bacterial isolation and identification were done using standard conventional methods. Antibiotic susceptibility testing was conducted using the Kirby-Bauer method. Ten phenotypically carbapenem-resistant isolates were further subjected to genotypic analysis (PCR amplification) for the detection of ESBL and carbapenemase gene. A total of 148 Enterobacteriaceae isolates belonging to seven (7) genera were isolated and identified which included E. coli, Enterobacter spp., Klebsiella spp., Salmonella, Citrobacter sp, Proteus, and Shigella. Results showed that 55% of isolates were resistant to tetracycline, 28% to cefepime, the least resistance was shown in moxifloxacin and gentamicin which had 6% and 9%, respectively, of the total isolates. For the two carbapenems used, results showed meropenem and imipenem had resistant values of 14% each, respectively. Two isolates carried the bla CTX-M gene while the carbapenemase gene (bla KPC, bla NDM, and bla OXA) was not detected in all the ten isolates. There was also negative chromosomal detection of carbapenemase in MDR isolates from well waters in Iwo town. Consequently, resistance to carbapenem antibiotics in these isolates may not be mediated by carbapenemase but by the production of extended-spectrum β-lactamases and through other mechanisms of resistance.

The Status of Extended-spectrum β-lactamase and AmpC β-lactamase production in uropathogenic isolates of Escherichia coli and Klebsiella pneumonia in Bangladesh

Background: The rapid dissemination of antibiotic resistance as extended-spectrum beta-lactamases (ESBLs) and AmpC β-lactamases in bacteria became a major public health concern worldwide. Hence, this study was carried out to evaluate the status of uropathogenic isolates of Bangladesh especially Escherichia coli and Klebsiella pneumoniae in terms of ESBL and AmpC β-lactamases enzymes production. Methods: A laboratory-based cross-sectional survey was conducted with 553 urine samples at the Department of Microbiology, Popular Diagnostic Centre Ltd. Dhaka, Bangladesh for a period of 2.5 years from July 2017 to December 2019. Pathogens were obtained upon culture, and screened for ESBL production following the cephalosporin disk diffusion method and cephalosporin-clavulanate combination disc test (confirmatory) method. For AmpC β-lactamases enzymes, cefoxitin disc diffusion, and AmpC disc test (confirmatory) methods were performed. The positive isolates were further genotyped for the presence of blaTEM, blaSHV, blaOXA, and blaCTX-M β-lactamases genes in case of ESBL and blaFOX, blaCMY, and blaDHA genes for AmpC β-lactamases by polymerase chain reaction. Results: Of all urine samples, uropathogens were detected among 28.57% (158, n=553) samples. Among them, 46.20% (73) were E. coli and 20.25% (32) were K. pneumoniae. The prevalence of ESBL and AmpC β-lactamases production in E. coli was 34.24% (25) and 17.80% (13) respectively whereas it was 43.75% (14) and 21.87% (7) in Klebsiella pneumoniae isolates respectively. These resistance properties were further confirmed by phenotypic disc test. In case of ESBLs, most typical isolates possessed two or more resistance genes. Overall, the most prevalent gene was blaCTX-M (84.61%) followed by blaTEM (64.10%), blaOXA (46.15%) and blaSHV (25.64%). In case of AmpC β-lactamases FOX gene was most prevalent (45%) followed by CMY (20%) and DHA 3 (15%). Conclusion: The high prevalence of ESBL and AmpC β-lactamases production in our study emphasizes the judicious use of antibiotics in controlling urinary tract infections in Bangladesh.

Prevalence and Molecular Characterization of Metallo β-Lactamase Producing Gram-Negative Pathogens Causing Eye Infections.

Purpose:Metallo β-lactamases (MβL) production is a worldwide problem, particularly in gram-negative bacteria. As scanty data is available on the prevalence of MBL, the present study is being undertaken to determine the prevalence, antibacterial sensitivity patterns, and molecular characterization of MβL associated resistant genes in gram-negative bacteria isolated from ocular infections.Material and MethodsAt a tertiary eye care center in south India, 359 gram-negative pathogens, 200 isolates from eye infections, and 159 isolates from normal flora of the eye were studied. A gold standard microbiology method was used to identify the isolates. An antibiotic double disc synergy test and a combination disc test were used to detect MβL production. Multiplex PCR was used to investigate the molecular characteristics of the MβL encoding genes blaVIM, blaIMP, and blaNDM.ResultsOf the 359 gram-negative bacterial pathogens, Pseudomonas aeruginosa 108 (30.1%) and Enterobacter agglomerans 46 (12.8%) were commonly isolated. High prevalence of P. aeruginosa 81% (17 strains) was detected as an MβL producer and it shows 100% resistance to 2nd and 3rd generation cephalosporins and meropenem. Multiplex PCR detected only the blaVIM gene in 56 (28%) of various eye infections and 27 (17%) of normal flora of the gram-negative bacteria (GNB). The blaVIM gene is detected predominantly in 51.8% of keratitis and 21.4% of postoperative endophthalmitis. High prevalence of the gene was detected in P. aeruginosa 42.9% (24 of 56) and Alcaligens denitrificans 10.7% (6 of 56) from eye infections. Whereas, in the control group, P. aeruginosa and E. coli each had 14.8% (4 of 27) that were shown positive.ConclusionThe emerging MβLs mediated resistance among P. aeruginosa is a challenging task for ophthalmologists, especially in patients with endophthalmitis and bacterial keratitis. This local knowledge will aid in advising appropriate antibiotic use and avoiding unnecessary antibiotic prescriptions, which are highly warranted.

Prevalence and antimicrobial susceptibility profiles of ESBL-producing Klebsiella Pneumoniae from broiler chicken farms in Shandong Province, China

Klebsiella pneumoniae (K. pneumoniae) is a conditionally pathogenic bacterium present in the intestinal or the respiratory tract of animals, and it is a common factor in acquired infections and a major threat to public health. Increased production of extended-spectrum β-lactamases (ESBLs) has become a serious issue in the treatment of K. pneumoniae infections. In this study, we examined the serotypes and antibiotic resistance profiles of K. pneumoniae isolated from broiler chickens on farms in Shandong Province, China. The K. pneumoniae isolation rate was 4.67% (33/707), and the serotype Capsular K54 (42.42%, 14/33) was the most prevalent serotype in broilers in Shandong. The antimicrobial susceptibility assay revealed that the 33 isolates were resistant to 28 antimicrobial drugs to varying degrees; among these, the highest resistance rate was observed for tetracyclines (90.91%), and the lowest rate of resistance was observed for moxifloxacin and fosfomycin (0%). The multidrug resistance (MDR) rate was 87.88% (29/33). The carrying rate of β-lactam-resistance genes was as high as 100%, with blaSHV having the highest rate (93.94%). It is worth noting that one carbapenem-resistant K. pneumoniae (CRKP) isolate carrying blaNDM-1 and one colistin-resistant K. pneumoniae (COLR-KP) isolate carrying mcr-3 were found in broiler chickens. This study indicates that ESBL-producing CRKP isolates and COLR-KP isolates have emerged on poultry farms in Shandong and could be a potential threat to food safety and public health.

Crystal structures of the molecular class A β-lactamase TEM-171 and its complexes with tazobactam

The resistance of bacteria to β-lactam antibiotics is primarily caused by the production of β-lactamases. Here, novel crystal structures of the native β-lactamase TEM-171 and two complexes with the widely used inhibitor tazobactam are presented, alongside complementary data from UV spectroscopy and fluorescence quenching. The six chemically identical β-lactamase molecules in the crystallographic asymmetric unit displayed different degrees of disorder. The tazobactam intermediate was covalently bound to the catalytic Ser70 in the trans-enamine configuration. While the conformation of tazobactam in the first complex resembled that in published β-lactamase-tazobactam structures, in the second complex, which was obtained after longer soaking of the native crystals in the inhibitor solution, a new and previously unreported tazobactam conformation was observed. It is proposed that the two complexes correspond to different stages along the deacylation path of the acyl-enzyme intermediate. The results provide a novel structural basis for the rational design of new β-lactamase inhibitors.

Phenotypic and genotypic distribution of ESBL, AmpC β-lactamase and carbapenemase-producing Enterobacteriaceae in community-acquired and hospital-acquired urinary tract infections in Sri Lanka

Although Sri Lanka belongs to a region with a high prevalence of extended-spectrum β-lactamase (ESBL), AmpC β-lactamase and carbapenemase-producing Enterobacteriaceae, data regarding antimicrobial resistance (AMR) is limited. We studied the prevalence and diversity of β-lactamases produced by Enterobacteriaceae urinary pathogens from two hospitals in the Western Province of Sri Lanka. ESBL, AmpC β-lactamase and carbapenemase production was detected by phenotypic testing followed by genotyping. The species responsible for urinary tract infections (UTI) were Escherichia coli (69%), Klebsiella pneumoniae (16%) and Enterobacter sp (6%). The prevalence of ESBL (50%), AmpC β-lactamase (19%) and carbapenemase (11%) phenotypes was high, and greater in hospital-acquired (HA-UTI) (75%) than in community-acquired UTI (CA-UTI) (42%). Identification of CA-UTI caused by carbapenemase-producing Enterobacteriaceae (5%) is alarming. Only one ESBL gene, blaCTX-M-15, was detected. AmpC β-lactamase genes found in E.coli and K. pneumoniae were blaCMY-2, blaCMY-42 and blaDHA-1, while Enterobacter sp. carried blaACT-1. Carbapenemase genes were blaNDM-1, blaNDM-4, blaOXA-181 and blaOXA-232, while blaKPC, blaIMP and blaVIM were absent. Co-occurrence of multiple bla genes, with some isolates harbouring six different bla genes, was common. Carbapenem-resistant isolates without carbapenemase genes displayed mutations in the outer membrane porin genes, ompF of E. coli and ompK36 of K.pneumoniae. Factors associated with UTI with β-lactamase-producing Enterobacteriaceae were age ≥50 years, previous hospitalization, presence of an indwelling urinary catheter, history of diabetes mellitus or other chronic illness and recurrent urinary tract infections. This study adds to the currently scarce data on AMR in Sri Lanka.