Extended-spectrum Β-lactamase Research Articles

Genomic Profiling of Multidrug-Resistant Swine Escherichia coli and Clonal Relationship to Human Isolates in Peru.

The misuse of antibiotics is accelerating antimicrobial resistance (AMR) in Escherichia coli isolated from farm animals. The genomes of ten multidrug-resistant (MDR) E. coli isolates from pigs were analyzed to determine their sequence types, serotypes, virulence, and AMR genes (ARGs). Additionally, the relationship was evaluated adding all the available genomes of Peruvian E. coli from humans using the cgMLST + HierCC scheme. Two aEPEC O186:H11-ST29 were identified, of which H11 and ST29 are reported in aEPEC isolates from different sources. An isolate ETEC-O149:H10-ST100 was identified, considered a high-risk clone that is frequently reported in different countries as a cause of diarrhea in piglets. One ExPEC O101:H11-ST167 was identified, for which ST167 is an international high-risk clone related to urinary infections in humans. We identified many ARGs, including extended-spectrum β-lactamase genes, and one ETEC harboring the mcr-1 gene. CgMLST + HierCC analysis differentiated three clusters, and in two, the human isolates were grouped with those of swine in the same cluster. We observed that Peruvian swine MDR E. coli cluster with Peruvian E. coli isolates from healthy humans and from clinical cases, which is of great public health concern and evidence that AMR surveillance should be strengthened based on the One Health approach.

Impact of a hospital sepsis management protocol on the selection of empirical antibiotics in infectious disease consultations

It is well-established that Infectious Diseases consultation (IDC) enhances the prognosis of bloodstream infections. However, it is unclear if adoption of an institutional sepsis protocol would lead to any further improvement in a setting where IDC and infectious diseases approval (IDA) - available throughout 7 days/24 hours -are mandatory for administering broad spectrum antibiotics. We aimed to evaluate the influence of the institutional sepsis protocol developed by Department of Infectious Diseases and Clinical Microbiology on the selection of appropriate empirical antibiotics by IDC through focusing on patients who had bloodstream infections caused by Extended-spectrum β-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae, which poses a therapeutic challenge. One hundred and fifty-three adult patients (58 patients in the pre-protocol period and 95 patients in the post-protocol period), who received empirical antibiotic treatment for ESBL-producing E. coli and K. pneumoniae, in whom at least one systemic antibiotic was started either on the day blood cultures were drawn or not later than 24 hours were included in the study, retrospectively. The primary outcome was whether the empirical treatment regimen included a carbapenem that was accepted as the appropriate treatment based on the results of the MERINO trial. Secondary outcomes included empirical treatment based on pre-defined risk factors suggesting multidrug resistance (MDR), 30-day inpatient mortality, and appropriate antibacterial treatment according to antimicrobial susceptibility test (AST) results. The median age (Interquartile range) was 61 (48-70.5) years and 76 (49.7%) out of 153 patients were male. The patients in the post-protocol period were older compared to the pre-protocol period (54 years vs 64 years, p = 0.045). The Charlson Comorbidity Index was higher during the post-protocol period compared to the pre-protocol period (4 vs 5, p=0.038). At least one risk factor for MDR bacteria infection was present in 147 (96.1%) of the 153 patients. While the rate of risk factors for MDR bacteria infections did not differ significantly between the pre-protocol and post-protocol periods, the post-protocol period showed a significantly higher level of appropriate antibiotic treatment according to the presence of MDR risk factors compared to the pre-protocol period (44.8% vs 64.2%, p=0.019). There was a significant increase in the use of carbapenems in the post-protocol period compared to the pre-protocol period (34.5% vs. 56.8%, p=0.007). When the subgroup of patients who were likely to have infection caused by ESBL-producing bacteria is taken into consideration, the carbapenem use was more frequent in the post-protocol period (37.8% vs 68.9%, p=0.002). The rate of appropriate empirical treatment according to AST was not statistically different between pre-protocol and post-protocol period. The 30-day mortality rates were similar in both periods (24.1% vs 31.5, p=0.33). However, the rate of susceptibility to piperacillin-tazobactam was statistically higher in the pre-protocol period (82.6% vs 46.2%, p=0.016) when 39.7% of the patients received piperacillin-tazobactam as the empirical treatment. This study highlights the significance of using a structured protocol to attain appropriate empirical treatment for patients suspected of sepsis, even in a setting where IDC is readily available.

Antimicrobial Resistance Profiles of Multidrug-Resistant Enterobacteria Isolated from Feces of Weaned Piglets.

Nosocomial infections caused by multidrug-resistant enterobacteria have become a major challenge in global public health. Previous studies have indicated that use of antibiotics in livestock production chains is linked to the rising threat of antibiotic resistance in humans. In this study, we aimed to evaluate the distribution of genes encoding resistance to tetracycline, β-lactams, and colistin in multidrug-resistant enterobacteria isolated from feces of weaned pigs. Ninety-four enterobacteria isolates were submitted to antibiotic susceptibility test by minimum inhibitory concentration (MIC). In addition, we performed conjugation experiments to verify if plasmid-bearing isolates containing the mcr-1 gene could transfer their resistance determinant to a colistin-sensitive recipient strain. Our results demonstrated a positive association between the detection of antibiotic resistance genes in enterobacteria and the phenotypic resistance profiles of the bacterial isolates. At least one of the extended-spectrum β-lactamases (ESBL) genes (blaCTX-M, blaTEM, or bla SHV) and tetA was found among most bacterial genera analyzed. In addition, results revealed that the mcr-1 gene can be transferred from E. coli UFV-627 isolate to an F- recipient (Escherichia coli K12) by conjugation. Our findings support the hypothesis that swine represents an important reservoir of antibiotic resistance genes and suggest that horizontal transfer mechanisms (e.g., conjugation) may mediate the spread of these genes in the swine gastrointestinal tract.

Isolation and Characterization of Extended-Spectrum β-Lactamase Producing Escherichia coli from Pig Farms and Slaughterhouse.

Extended-spectrum β-lactamase (ESBL) producing Escherichia coli represents a formidable challenge in the field of microbiology and public health due to its resistance to commonly used antibiotics. These strains pose a serious threat to human and animal health, underscoring the urgency of comprehensive research and surveillance. The ongoing investigation seeks ESBL producing E. coli strains from pig farms and slaughterhouses in West Bengal and Assam, India. A total of 309 samples were collected: nasal swabs (25), rectal swabs (25) from healthy pigs, pig pen soil (45), faeces (55), slaughterhouse effluents (115), and cleaning water (44). In these samples, 154 tested positive for E. coli, indicating a 49.8% prevalence. Among 154 E. coli isolates, 23 (14.9%) produced ESBLs, sourced from pig rectal swabs (7.1%), faeces (10.7%), slaughterhouse effluents (26.1%), and cleaning water (11.7%). Significantly, 4 ESBL E. coli isolates (6.6%) exclusively emerged from pig slaughterhouse effluents, displaying imipenem-resistant properties. The majority of ESBL E. coli primarily produced CTX-M and CMY, with consistent genetic markers bla CTX-M (100%) and bla CMY (82.6%). Remarkably, 2 (8.6%) of 17 ESBL E. coli isolates from pig slaughterhouse effluents carried the genetic marker bla NDM1. These findings stress implementing thorough surveillance in pig farms and local slaughterhouses. This proactive approach is crucial to identify ESBL E. coli strains, enhancing public health protection.

IS26 drives the dissemination of bla CTX-M genes in an Ecuadorian community.

The horizontal gene transfer events are the major contributors to the current spread of CTX-M-encoding genes, the most common extended-spectrum β-lactamase (ESBL), and many clinically crucial antimicrobial resistance (AMR) genes. This study presents evidence of the critical role of IS26 transposable element for the mobility of bla CTX-M gene among Escherichia coli isolates from children and domestic animals in the community. We suggest that the nucleotide sequences of IS26-bla CTX-M could be used to study bla CTX-M transmission between humans, domestic animals, and the environment, because understanding of the dissemination patterns of AMR genes is critical to implement effective measures to slow down the dissemination of these clinically important genes.

Spatiotemporal distribution of community-acquired phenotypic extended-spectrum beta-lactamase Escherichia coli in United States counties, 2010-2019.

Using data from the Veterans' Health Administration from 2010 to 2019, we examined the distribution and prevalence of community-acquired phenotypic extended-spectrum β-lactamase (ESBL) E. coli in the United States. ESBL prevalence slowly increased during the study period, and cluster analysis showed clustering in both urban and rural locations.

Genomic data of global clones of CTX-M-65-producing Escherichia coli ST10 from South American llamas inhabiting the Andean Highlands of Peru

The global spread of extended-spectrum β-lactamase (ESβL)-producing Escherichia coli has been considered a One Health issue that demands continuous genomic epidemiology surveillance in humans and non-human hosts. To report the occurrence and genomic data of ESβL-producing E. coli strains isolated from South American llamas inhabiting a protected area with public access in the Andean Highlands of Peru. Two ESβL-producing E. coli strains (E. coli L1LB and L2BHI) were identified by MALDI-TOF. Genomic DNAs were extracted and sequenced using the Illumina NextSeq platform. De novo assembly was performed by CLC Genomic Workbench and in silico prediction was accomplished by curated bioinformatics tools. SNP-based phylogenomic analysis was performed using publicly available genomes of global E. coli ST10. Escherichia coli L1LB generated a total of 4 000 11 and L2BHI a total of 4 002 54 paired-end reads of ca.164 × and ca. 157 ×, respectively. Both E. coli strains were assigned to serotype O8:H4, fimH41, and ST10. The blaCTX-M-65 ESβL gene, along with other medically important antimicrobial resistance genes, was predicted. Broad virulomes, including the presence of the astA gene, were confirmed. The phylogenomic analysis revealed that E. coli L1LB and L2BHI strains are closely related to isolates from companion animals and human hosts, as well as environmental strains, previously reported in North America, South America, Africa, and Asia. Presence of ESβL-producing E. coli ST10 in South American camelids with historical and cultural importance supports successful expansion of international clones of priority pathogens in natural areas with public access.

Comparison of the inoculum effect of in vitro antibacterial activity of Imipenem/relebactam and Ceftazidime/avibactam against ESBL-, KPC- and AmpC-producing Escherichia coli and Klebsiella pneumoniae

ObjectiveTo evaluate effect of inoculum size of extended-spectrum β-Lactamase (ESBL)-producing-, AmpC-producing-, and KPC-producing Escherichia coli and Klebsiella pneumoniae on the in vitro antibacterial effects of imipenem/relebactam (IMR) and ceftazidime/avibactam (CZA).MethodsWe compared the impact of inoculum size on IMR and CZA of sixteen clinical isolates and three standard isolates through antimicrobial susceptibility tests, time-kill assays and in vitro PK/PD studies.ResultsWhen inoculum size increased from 105 to 107 CFU/mL, an inoculum effect was observed for 26.3% (5/19) and 52.6% (10/19) of IMR and CZA, respectively; time-kill assays revealed that the concentration of CZA increased from ≥ 4 × MIC to 16 × MIC to reach 99.9% killing rate against K. pneumoniae ATCC-BAA 1705 (KPC-2-, OXA-9- and SHV-182-producing) and 60,700 (SHV-27- and DHA-1-producing). While for IMR, a concentration from 1 × MIC to 4 × MIC killed 99.9% of the four strains. When the inoculum size increased to 109 CFU/mL, neither IMR nor CZA showed a detectable antibacterial effect, even at a high concentration. An in vitro PK/PD study revealed a clear bactericidal effect when IMR administered as 1.25 g q6h when inoculum size increased.ConclusionAn inoculum effect on CZA was observed more frequent than that on IMR. Among the β-lactamase-producing strains, the inoculum effect was most common for SHV-producing and KPC-producing strains.

Magnitude of extended-spectrum β-lactamase and carbapenemase producing Enterobacteriaceae among commonly vended street foods in Arba Minch town, southern Ethiopia

BackgroundThe rising prevalence of extended-spectrum beta-lactamase and carbapenemase-producing Enterobacteriaceae (ESβL-PE) in street foods poses a significant risk to human health due to its epidemiological significance. Thus, the aim of this study was to determine the magnitude of foodborne Enterobacteriaceae that produce carbapenemase and ESβL, as well as their patterns of antibiotic resistance, in the studied area.MethodsA community-based cross-sectional study was carried out from January 1st, 2023, to February 30th, 2023. One hundred randomly chosen street-vended food items (one hundred grams of each food item) were aseptically collected, and aliquots of 0.1 ml from the homogenized (25 g of samples into 225 ml of buffered peptone water (BPW)) were inoculated on MacConkey agar and Xylose Lysine Deoxycholate Agar (XLD). Enterobacteriaceae isolates were identified using various biochemical tests. ESβL and carbapenemase were first screened by indicator cephalosporins and carbapenem antibiotics, respectively. ESβL and carbapenemase were confirmed by a double-disc synergy test and modified carbapenem inactivation methods, respectively. Kirby-Bauer disc diffusion method was used for the antimicrobial-resistant test.ResultsA total of 112 Enterobacteriaceae belonging to six different genera were isolated. E. coli was attributed 39 (34.8%), followed by Citrobacter spp. 22 (19.6%) and K. pneumoniae 18 (16.1%), with only 8 (7.1%) isolated Salmonella spp. About 15.2% (n = 17) and 8.9% (n = 10) of Enterobacteriaceae were phenotypically confirmed to be extended-spectrum beta-lactamase (ESβL) and carbapenemase producers, respectively. The highest percentage of ESβL-producing isolates was attributed to K. pneumoniae (n = 5), E. coli (n = 4), and Enterobacter spp. (n = 3). Proteus spp. and Salmonella spp. isolates were carbapenemase-negative. All carbapenemase-positive isolates were found to be ESβL-producers. 70.6% (12/17) of ESβL-producing Enterobacteriaceae were found to be multidrug-resistant (MDR).ConclusionA considerable number of multidrug-resistant ESβL and carbapenemase-producing Enterobacteriaceae were identified, suggesting that street foods may be a potential source of MDR foodborne infections. Consequently, it is important to conduct routine examinations of street food items and track trends in medication resistance.

Characterization of ESBL/AmpC-producing extraintestinal Escherichia coli (ExPEC) in dogs treated at a veterinary hospital in Brazil

The clinical aspects and lineages involved in Extraintestinal pathogenic Escherichia coli (ExPEC) infections in dogs remain largely unknown. In this study, we investigated the antimicrobial resistance and molecular structures of ExPECs isolated from infected dogs in Brazil. Samples were obtained from dogs (n = 42) with suspected extraintestinal bacterial infections. Phylogroup B2 was predominant (65.1%). No association was observed between the site of infection, phylogroups, or virulence factors. Almost half of the isolates (44.2%) were MDR, and 20.9% were extended-spectrum β-lactamase (ESBL)-positive. E. coli isolates that were resistant to fluoroquinolones (27.9%) were more likely to be MDR. The CTX-M-15 enzyme was predominant among the ESBL-producing strains, and seven sequence types were identified, including the high-risk clones ST44 and ST131. Single SNPs analysis confirmed the presence of two clonal transmissions. The present study showed a high frequency of ExPECs from phylogroup B2 infecting various sites and a high frequency of ESBL-producing strains that included STs frequently associated with human infection. This study also confirmed the nosocomial transmission of ESBL-producing E. coli, highlighting the need for further studies on the prevention and diagnosis of nosocomial infections in veterinary settings.

The phylogenomic landscape of extended-spectrum β-lactamase producing Citrobacter species isolated from surface water

BackgroundCitrobacter species are Gram-negative opportunistic pathogens commonly reported in nosocomial-acquired infections. This study characterised four Citrobacter species that were isolated from surface water in the North West Province, South Africa.ResultsPhenotypic antimicrobial susceptibility profiles of the isolates demonstrated their ability to produce the extended-spectrum β-lactamase (ESBL). Whole genomes were sequenced to profile antibiotic resistance and virulence genes, as well as mobile genetic elements. In silico taxonomic identification was conducted by using multi-locus sequence typing and average nucleotide identity. A pangenome was used to determine the phylogenomic landscape of the Citrobacter species by using 109 publicly available genomes. The strains S21 and S23 were identified as C. braakii, while strains S24 and S25 were C. murliniae and C. portucalensis, respectively. Comparative genomics and sequenced genomes of the ESBL-producing isolates consisted of n = 91; 83% Citrobacter species in which bla-CMY−101 (n = 19; 32,2%) and bla-CMY−59 (n = 12; 38,7%) were prevalent in C. braakii, and C. portucalensis strains, respectively. Macrolide (acrAB-TolC, and mdtG) and aminoglycoside (acrD) efflux pumps genes were identified in the four sequenced Citrobacter spp. isolates. The quinolone resistance gene, qnrB13, was exclusive to the C. portucalensis S25 strain. In silico analysis detected plasmid replicon types IncHI1A, IncP, and Col(VCM04) in C. murliniae S24 and C. portucalensis S25, respectively. These potentially facilitate the T4SS secretion system in Citrobacter species. In this study, the C. braakii genomes could be distinguished from C. murliniae and C. portucalensis on the basis of gene encoding for cell surface localisation of the CPS (vexC) and identification of genes involved in capsule polymer synthesis (tviB and tviE). A cluster for the salmochelin siderophore system (iro-BCDEN) was found in C. murliniae S24. This is important when it comes to the pathogenicity pathway that confers an advantage in colonisation.ConclusionsThe emerging and genomic landscapes of these ESBL-producing Citrobacter species are of significant concern due to their dissemination potential in freshwater systems. The presence of these ESBL and multidrug-resistant (MDR) pathogens in aquatic environments is of One Health importance, since they potentially impact the clinical domain, that is, in terms of human health and the agricultural domain, that is, in terms of animal health and food production as well as the environmental domain.

High-risk clonal lineages among extended-spectrum β-lactamase producing Escherichia coli and Klebsiella pneumoniae from urban and rural stagnant water samples in Tunisia

AbstractThis study sought to investigate the occurrence and subsequently to characterize extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae from urban and rural stagnant water samples during the wet season (December to February) in several regions of northern Tunisia. From 56 stagnant water samples, 14 ESBL-producing Enterobacteriaceae were recovered, including 9 Escherichia coli, 3 Klebsiella pneumoniae, and 2 K. oxytoca. Most isolates were multidrug-resistant, with ESBL production primarily encoded by blaCTX-M-15 (n = 8) and blaCTX-M-1 (n = 4) followed by blaCTX-M-55 (n = 1) and blaTEM-26 (n = 1). One K. pneumoniae isolate co-harbored blaKPC and blaCTX-M-15 genes. Class 1 integrons were detected in 4 isolates, however, sul1, sul2, and aac(6′)-Ib-cr genes were detected in eleven, two, and four isolates, respectively. The nine E. coli isolates belonged to seven sequence types namely, B2/ST131 (3 isolates), A/ST164, A/ST10, A/ST224, A/ST38, A/ST155, and A/ST69 (each of them one isolate). The three K. pneumoniae isolates were assigned to three sequence types: ST101, ST405 (harboring CTX-M-15 and KPC), and ST1564. Overall, the phenotypic and genotypic traits of collected isolates mirror the molecular epidemiology of ESBL-producing enterobacteria in Tunisia and highlight the potential role of stagnant water in both urban and rural areas as a reservoir of ESBL-producing Enterobacteriaceae.

Prevalence, extended-spectrum β-lactamase and biofilm production ability ofEscherichia coli isolated from buffalo mastitis

This study aimed to determine the prevalence, antibiotic resistance pattern, extended-spectrum, beta-lactamase production and biofilm forming ability of isolated E. coli strains from buffaloes mastitis milk. Out of 549 bacterial isolates from mastitis milk of buffaloes (n, animal level= 472) between 2019 and 2022, a total of 43 E. coli strains were isolated with an overall prevalence of 9.11% at animal level. Prevalence of E coli was high in unorganised buffalo herd (11.36%) from villages of Farmer FIRST project (ICAR-FFP) compared with organised buffalo farms (6.73%). The highest resistance was against Penicillin 43 (100%) followed by Ceftriaxone 18 (41.86%), Amoxycillin/Sulbactam 8 (18.60%) and Enrofloxacin 7 (16.27%). Additionally, all were sensitive to gentamycin 43 (100%) followed by Cefoperazone/Sulbactam 34 (79.06%). Cephalosporins are frequently used antibiotics to treat bovine mastitis. However, their therapeutic effectiveness is being compromised by bacterial resistant to β-lactams. In present study, a total of 32 (6.78% %) extended-spectrum β-lactamase (ESBL) producing E coli were isolated from mastitic buffalo milk (n=43/472). In total, 17 (39.5%) isolates were biofilm producers by microtiter-plate method. There was statistically non-significant relationship between biofilm production and antibiotic resistance as well as between ESBL production and biofilm formation in E coli strains. Present study demonstrated a high occurrence of ESBL and biofilm producing E. coli in buffalo mastitis milk, implementing a significant challenge to treat mastitis in buffaloes, necessitates judicious use of antimicrobials and to explore potential therapeutic agents as substitutes forantibiotics to treat bovine mastitis effectively.

Various types of extended spectrum β-lactamases: a literature review

The inappropriate use of antibacterials causes the spread of resistance in bacteria and increases the health burden of infection due to the nature of resistance to many classes of antibiotics which are referred to as multi-resistant (multidrug resistant). Extended spectrum β-lactamase (ESBL) is one of the enzymes that cause multi-resistance, where bacteria with this enzyme become resistant to third-generation cephalosporin antibiotics which are often used to treat gram-positive and gram-negative bacterial infections in humans with minimal side effects. β -lactamase is an enzyme capable of hydrolyzing the β-lactam ring in β -lactam class antibiotics so that antibiotics become inactive. Mutations in the gene that encodes this enzyme produce a β-lactamase enzyme which can break down the β-lactam ring in all penicillin and cephalosporin antibiotics. The classification of β-lactamases is complex due to genetic, biochemical properties, and substrate affinity for β-lactamase inhibitors. There are also various types of ESBL enzyme-coding genes including TEM, SHV, CTX-M, VEB, PER, OXA, SFO-1, BEL-1, BES-1, TLA-1, and GES. This study aims to review various types of extended-spectrum β-lactamases.

National genomic surveillance integrating standardized quantitative susceptibility testing clarifies antimicrobial resistance in Enterobacterales

Antimicrobial resistance is a global health concern; Enterobacterales resistant to third-generation cephalosporins (3GCs) and carbapenems are of the highest priority. Here, we conducted genome sequencing and standardized quantitative antimicrobial susceptibility testing of 4,195 isolates of Escherichia coli and Klebsiella pneumoniae resistant to 3GCs and Enterobacterales with reduced meropenem susceptibility collected across Japan. Our analyses provided a complete classification of 3GC resistance mechanisms. Analyses with complete reference plasmids revealed that among the blaCTX-M extended-spectrum β-lactamase genes, blaCTX-M-8 was typically encoded in highly similar plasmids. The two major AmpC β-lactamase genes were blaCMY-2 and blaDHA-1. Long-read sequencing of representative plasmids revealed that approximately 60% and 40% of blaCMY-2 and blaDHA-1 were encoded by such plasmids, respectively. Our analyses identified strains positive for carbapenemase genes but phenotypically susceptible to carbapenems and undetectable by standard antimicrobial susceptibility testing. Systematic long-read sequencing enabled reconstruction of 183 complete plasmid sequences encoding three major carbapenemase genes and elucidation of their geographical distribution stratified by replicon types and species carrying the plasmids and potential plasmid transfer events. Overall, we provide a blueprint for a national genomic surveillance study that integrates standardized quantitative antimicrobial susceptibility testing and characterizes resistance determinants.

Treated municipal wastewater as a source of high-risk and emerging multidrug-resistant clones of E. coli and other Enterobacterales producing extended-spectrum β-lactamases

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a major public health problem, and wastewater from municipal wastewater treatment plants (WWTPs) is a potential means of spreading them into the environment and community. Our objective was to isolate ESBL-producing E. coli and other Enterobacterales from wastewater after treatment at Croatia's largest WWTP and to characterize these isolates by phenotypic and genotypic testing. Of the 200 bacterial isolates, 140 were confirmed as Enterobacterales by MALDI-TOF MS, with Escherichia coli and Klebsiella spp. predominating (69% and 7%, respectively). All 140 enterobacterial isolates were multidrug-resistant (MDR) and produced ESBLs. The most prevalent ESBL genes among the isolates tested were blaCTX-M-15 (60%), blaTEM-116 (44%), and blaCTX-M-3 (13%). Most isolates (94%) carried more than one ESBL gene in addition to blaCTX-M. Genes encoding plasmid-mediated AmpC, most notably blaEBC, were detected in 22% of isolates, whereas genes encoding carbapenemases (blaOXA-48, blaNDM-1, blaVIM-1) were less represented (10%). In E. coli, 9 different sequence types (ST) were found, with the emerging high-risk clones ST361 (serotype A-O9:H30) and pandemic ST131 (serotype B2–O25:H4) predominating (32% and 15%, respectively). Other high-risk E. coli clones included ST405 (3%), ST410 (3%), CC10 (3%), ST10 (3%), and ST38 (2%), and emerging clones included ST1193 (2%) and ST635 (2%). Whole-genome sequencing of three representative E. coli from two dominant clone groups (ST361 and ST131) and one extensively drug-resistant K. oxytoca revealed the presence of multiple plasmids and resistance genes to several other antibiotic classes, as well as association of the blaCTX-M-15 gene with transposons and insertion sequences. Our findings indicate that treated municipal wastewater contributes to the spread of emerging and pandemic MDR E. coli clones and other enterobacterial strains of clinical importance into the aquatic environment, with the risk of reintroduction into humans.

Detection of chromosome-mediated blaNDM-1-carrying Aeromonas spp. in the intestinal contents of fresh water river fish in Ho Chi Minh City, Vietnam

The spread of antibiotic-resistant bacteria is a global problem that should be addressed through the perspective of the “one health” concept. The purpose of this study was to determine the contamination rate of antibiotic-resistant Aeromonas spp. in fresh water river fish purchased from a fish market in Vietnam. We then defined the pattern of antibiotic resistance to assess antibiotic-resistant contamination. Antibiotic-resistant Aeromonas spp. were detected in the intestinal contents of 32 of 80 fish. blaNDM-1 was detected in seven strains. Extended-spectrum β-lactamase and AmpC β-lactamase-related genes were detected in 28 strains, including blaCTX-M-55, blaCTX-M-15, blaCTX-M-1, and blaDHA,blaFOX, and blaMOX. The blaNDM-1 detected in the seven Aeromonas spp. strains were found chromosomally. This finding suggests that the blaNDM gene is stable in the natural environment and may spread widely into animals and humans via Aeromonas spp. with a transposon. Our results suggest the importance of continuing to monitor carbapenemase genes in Aeromonas spp. to evaluate the possibility that they may spread in other Enterobacterales, and to elucidate the mechanism of spread.

An insight into genes responsible for fosfomycin resistance among uropathogens of asymptomatic bacteriuria during pregnancy: A North Indian study.

Asymptomatic bacteriuria (ASB) is a common finding during pregnancy. Effective antibiotic treatment could reduce its adverse effects on both mother and fetus. However, emerging antimicrobial resistance limits the treatment options. Fosfomycin might be a promising drug in this regard, as its resistance is still low. The aim of the study was to determine the antimicrobial susceptibility pattern of fosfomycin in isolates causing ASB by disc diffusion and agar dilution (in selected isolates), determine minimum inhibitory contribution (MIC) by agar dilution in isolates resistant by disc diffusion and detect the genes responsible for fosfomycin resistance. This was a 2-year study carried in the Department of Microbiology, Jawaharlal Nehru Medical College and Hospital (JNMCH), Aligarh Muslim University (AMU), Aligarh. A total of 10 252 urine samples from asymptomatic pregnant females (18-45 years) attending the antenatal care (ANC) outpatient department (OPD) were submitted. Identification of pathogen and antimicrobial susceptibility testing (AST) was carried out as per standard methods of CLSI. There was phenotypic detection of methicillin-resistant Staphylococcus aureus (MRSA) and other Staphylococcus species (MRSS), high-level aminoglycoside resistance (HLAR), vancomycin resistant Enterococci (VRE) and S. aureus (VRSA), extended spectrum β-lactamase (ESBL) and carbapenem-resistant Enterobacterales (CRE). All the fosfomycin-resistant isolates (by disk diffusion) were tested by agar dilution. Conventional PCR was performed for murA, fosA, uhpT and glpT genes on all resistant isolates. In this study, the prevalence of ASB among pregnant females was 1173(11.4 %), in which Escherichia coli 495(42 %) was the predominant organism. The overall sensitivity of fosfomycin among Gram-positive cocci (GPC) and Gram-negative bacilli (GNB) was 99 % and 97.6 %, respectively. MRSA and MRSS accounted for 50 (66.6 %) and 71 (76 %), respectively. The highest rates of MIC >2048 µg ml-1 were shown by most isolates (mainly E. coli ) on agar dilution. PCR studies revealed four E. coli strains possessed both murA (also present in one K. pneumoniae strain) and glpT genes. While only one isolate ( E. faecalis ) was positive for fosA gene. But none of the strain possessed the uhpT gene. According to this study, murA and glpT genes were more frequent than fosA. We cannot comment on the prevalence and regional distribution of fosfomycin-resistant genes based on this preliminary study. Therefore, more Indian studies should be carried out to create awareness about the presence of genes in a particular area.

Incidence and Characterization of Carbapenem Resistance Mediated by Acquired Beta-Lactamases in Pseudomonas aeruginosa Isolates from a Bulgarian Cancer Hospital

Detection of clinical isolates of Pseudomonas aeruginosa producing metallo-𝛽-lactamases (MBL) and extended-spectrum 𝛽-lactamases (ESBL) is essential to adequately treat patients and control the spread of resistance. We investigated the frequency of carbapenem resistance mediated by acquired 𝛽-lactamases in P. aeruginosa isolates from a tertiary cancer hospital in Bulgaria. The prevalence of P. aeruginosa infec¬tions was relatively low - approximately 2% of all hospital-acquired infections, while the carbapenem re¬sistance rate was estimated at 25% in 2023. Carbapenem resistance due to VIM and NDM MBL types was observed in 8/54 (14.81%) isolates. PER, VEB, or GES ESBLs were detected in a total of 8/54 (14.81%) isolates including 3 isolates co-harbouring NDM and GES enzymes. The overall frequency of 24.07% (13/54) of acquired carbapenemase and ESBL genes in our study reflects the multicomponent nature of carbapenem resistance in P. aeruginosa and highlights the need for reliable screening.

Detection of clinically relevant antibiotic-resistant bacteria in shared fomites, waste water and municipal solid wastes disposed near residential areas of a Nigerian city.

Studies investigating environmental hotspots of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) in Nigeria are limited. This study was designed to assess various environmental sources and commonly touched surfaces as potential carriers of ARB and ARGs with implications for public health. A total of 392 samples, including sewage (36), sludge (36), diapers (20), plastics (20), water sachet polythene bags (20), food wastes (20), soil beneath dump sites (20), and frequently touched surfaces such as restroom floors (80), corridors (24), door handles (56), and room floors and walls (60), were collected and screened for the presence of resistant bacteria carrying genes such as bla KPC, bla NDM-1, bla CMY-2, bla IMP, bla OXA66 and MecA. Additionally, we employed standard techniques to detect methicillin-resistant Staphylococcus aureus (MRSA) and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii . We also evaluated the effectiveness of routine disinfection procedures in eliminating ARB from restroom floors. Our findings revealed that sewage, sludge, diapers, food wastes and restroom floors are frequently contaminated with highly and moderately resistant strains of E. coli, K. pneumoniae, P. aeruginosa and MRSA. Notably, we identified two variants of the bla OXA51-like gene (bla OXA-66 and bla OXA-180) in A. baumannii isolated from these environmental sources. Furthermore, we detected seven ESBL- K. pneumoniae , five ESBL- A. baumannii , two ESBL- E. coli and one ESBL- P. aeruginosa , all carrying one or more ARGs (bla KPC, bla NDM-1, bla CMY-2), in isolates recovered from sewage, sludge, restroom floors and plastics. It is of note that ARB persisted on restroom floors even after disinfection procedures. In conclusion, this study highlights that environmental wastes indiscriminately discarded in residential areas and shared surfaces among individuals are heavily colonized by ARB carrying ARGs of significant public health importance.