Characterization Of Extended-spectrum Beta-lactamase Research Articles

Prevalence and molecular characterization of Multidrug-Resistant ESBL-Producing E. coli in commercial poultry

Background: Rural poultry farmers are gradually changing from the backyard poultry production to intensive production, which made poultry more vulnerable to diseases and lead to indiscriminate use of antimicrobials in poultry production. As per OIE, FAO and WHO, multiple spread antimicrobial resistant pathogenic bacteria are a serious global human and animal health problem. Hence the study has been carried out to know the antimicrobial resistance status of poultry in Tirunelveli, Tamil Nadu, India. Methods: The study was aimed to find the occurrence of extended spectrum beta lactamases (ESBLs) producing E. coli from poultry origin. Caecum samples from the broiler (n=180), desi chicken (n=180) and Japanese quail (n=180) were processed for the isolation and phenotypic identification of ESBL E. coli. The isolates were tested for antimicrobial susceptibility test and characterization of ESBL and virulence genes done by PCR. Result: On phenotypic confirmation of ESBL producing E. coli by combined disk diffusion test (CDDT), a total of 9.63% samples were positive for extended spectrum beta lactamase producer (ESBL). Multi drug resistance (MDR) was observed in 38.23% of the broiler isolates, 27.27% and 57.14% in desi chicken and Japanese quail isolates, respectively. All the phenotypically confirmed ESBL producing E. coli isolates (n=52) were positive for uspA gene by PCR confirming the isolates as E. coli. The overall presence of the blaTEM gene was 57.69%, with broiler isolates having the highest prevalence of 67.47%, followed by desi chicken 36.36% and Japanese quail 42.85%. In contrast, the blaSHV gene was found in only 17.64% of the broiler isolates, but none were positive for the blaCTXM and blaOXA-1 gene.

Antibiotypes and genetic characteristics of fluoroquinolone- and beta-lactam-resistant Escherichia coli isolated from food-producing animals

Background and Aim: Farm animals, including cattle, have been implicated as antimicrobial-resistant bacterial pathogen reservoirs. This study aimed to determine the antimicrobial resistance profiles and genetic characteristics of cattle colonized by fluoroquinolone-resistant and extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli in Ebonyi state, Nigeria. Materials and Methods: We randomly collected 100 fresh fecal samples from 100 cattle in major abattoirs and analyzed the samples using standard microbiological methods. Isolates were further characterized by polymerase chain reaction (PCR) using 16S rRNA sequence primers. Phenotypic detection of ESBL production was performed using the double disk synergy test. Antimicrobial susceptibility profiles of ESBL-producing Escherichia coli were determined using the disk diffusion method, whereas molecular characterization of ESBL- and fluoroquinolone-resistant genes was performed by PCR using specific primers. Results: A total of 20 (20%) ESBL-producing E. coli were isolated from 100 animal fecal samples. Isolates were generally multidrug-resistant (MDR) with a resistance rate of 100% to 45% to trimethoprim-sulfamethoxazole, tetracycline, amoxicillin, cephalosporins, and ciprofloxacin. The average multiple antibiotic resistance index values of the isolates ranged from 0.5 to 0.8. BlaTEM (75%), followed by blaCTX-M (20%) and blaSHV (5.0%) was the most predominant ESBL gene among the isolates. The Aac-lb-6-cr fluoroquinolone-resistant gene was harbored by 90% of the isolates, whereas Qnr was absent. Conclusion: This study showed a high frequency of MDR ESBL-producing E. coli harboring ESBL and fluoroquinolone-resistant genes in fecal samples of cattle with serious public health consequences if not adequately addressed. Keywords: Escherichia coli, extended-spectrum beta-lactamase genes, fluoroquinolone resistance genes, cattle, multidrug-resistance.

Characterization of extended-spectrum beta-lactamase and carbapenemase genes in bacteria from environment in Burkina Faso.

This study aimed to characterize extended-spectrum beta-lactamase (ESBL) and carbapenemase genes in bacteria from the environment in Bobo-Dioulasso, Burkina Faso. This study was conducted from January 18 to December 31, 2019. Environmental samples were collected from the effluents of Souro Sanou University Hospital Center and the wastewater treatment plant at Bobo-Dioulasso. MacConkey agar media supplemented with 4 µg/mL cefotaxime was used for bacterial growth, and identification of bacteria was performed using API 20E system (BioMerieux SA, Lyon, France). Antibiotic susceptibility testing, synergy test, carbapenem inactivation method and molecular characterization were performed. A total of 180 bacterial isolates were identified from the different sites with a predominance of Klebsiella oxytoca and Klebsiella pneumoniae (27.5%). All 180 bacterial isolates were ESBL producers and 18 (10.0%) of them produced carbapenemases. Out of the 180 bacterial isolates, DNAs of 98.9% (178/180) bacterial isolates were extracted and tested through polymerase chain reaction (PCR) for characterization of resistant genes. The study showed that 89.8% (160/178) carried the bla-CTX-M genes including 54.4 (87/160) from hospital effluents and 45.6 (73/160) from the wastewater treatment plant. Regarding the carriage of carbapenemase genes, 7.9 (14/178) blaNDM-1 was found in all the sites including 71.4% (10/14) from hospital effluents and 28.6 (4/14) from the wastewater treatment plant. blaOXA-48-like was only found in bacteria from hospital effluents and represented 2.2% (4/178). This study highlights the need to build hospital effluent treatment plants to reduce the load of resistant bacteria before discharging the effluents into the urban wastewater system.

Characterization of Extended Spectrum Beta Lactamase Producing Escherichia coli from Calves

Background: Cephalosporins are major antimicrobials used to treat serious infections. However, their effectiveness is being compromised by the emergence of extended spectrum beta lactamases (ESBL). The present study was aimed to characterize ESBL producing Escherichia coli from healthy and diarrheic cattle calves. Methods: A total of 52 rectal swabs were collected from healthy and diarrheic cattle calves between August 2019 to March 2020. Phenotypically E. coli were characterized based on morphology, microscopy and biochemical tests. Extended Spectrum Beta Lactamases (ESBL) E. coli initial screening was performed by using cefpodoxime, ceftazidime, cefepime and aztreonam antibiotics. The confirmation of the ESBL producing strains was conducted through ESBL phenotypic identification kit and double disc diffusion test (DDDT). Molecular characterization of ESBL E. coli was conducted by PCR amplification of blaCTX-M, bla TEM and bla AmpC genes. Plasmid profiling of the ESBL E. coli isolates was carried out. Result: Phenotypically, out of the 51 E. coli isolated, 05 (9.8%) E. coli isolates were confirmed as ESBL strains. PCR amplification revealed 01 (20%), 04 (80%) and 03 (60%) isolates positive for blaCTX-M, bla TEM and bla AmpC genes, respectively. Plasmid profiling of the isolates showed that 60% isolates were harboring plasmids of varying size and number. The plasmid number among the isolates ranged from 0-4 plasmids per isolate and plasmid size varied from 900bp to greater than 10kb. The relatively high rates of ESBL producers in diarrheic calves were found than healthy calves. The study highlights the existence of ESBL producing E. coli isolates with certain strains carrying mobile genetic elements in livestock and probable disseminators of resistance, thus imposing public health threat.

Resistome characterization of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolated from wastewater treatment utilities in Oregon.

Infections resistant to broad spectrum antibiotics due to the emergence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is of global concern. This study characterizes the resistome (i.e., entire ecology of resistance determinants) of 11 ESBL-producing Escherichia coli isolates collected from eight wastewater treatment utilities across Oregon. Whole genome sequencing was performed to identify the most abundant antibiotic resistance genes including ESBL-associated genes, virulence factors, as well as their sequence types. Moreover, the phenotypes of antibiotic resistance were characterized. ESBL-associated genes (i.e., blaCMY, blaCTX, blaSHV, blaTEM) were found in all but one of the isolates with five isolates carrying two of these genes (four with blaCTX and blaTEM; one with blaCMY and blaTEM). The ampC gene and virulence factors were present in all the E. coli isolates. Across all the isolates, 31 different antibiotic resistance genes were identified. Additionally, all E. coli isolates harbored phenotypic resistance to beta-lactams (penicillins and cephalosporins), while 8 of the 11 isolates carried multidrug resistance phenotypes (resistance to three or more classes of antibiotics). Findings highlight the risks associated with the presence of ESBL-producing E. coli isolates in wastewater systems that have the potential to enter the environment and may pose direct or indirect risks to human health.

Identification of CTX-M Type ESBL E. coli from Sheep and Their Abattoir Environment Using Whole-Genome Sequencing.

Widespread dissemination of extended-spectrum beta-lactamase (ESBL) Escherichia coli (E. coli) in animals, retail meats, and patients has been reported worldwide except for limited information on small ruminants. Our study focused on the genotypic characterization of ESBL E. coli from healthy sheep and their abattoir environment in North Carolina, USA. A total of 113 ESBL E. coli isolates from sheep (n = 65) and their abattoir environment (n = 48) were subjected to whole-genome sequencing (WGS). Bioinformatics tools were used to analyze the WGS data. Multiple CTX-M-type beta-lactamase genes were detected, namely blaCTX-M-1, blaCTX-M-14, blaCTX-M-15, blaCTX-M-27, blaCTX-M-32, blaCTX-M-55, and blaCTX-M-65. Other beta-lactamase genes detected included blaCMY-2, blaTEM-1A/B/C, and blaCARB-2. In addition, antimicrobial resistance (AMR) genes and/or point mutations that confer resistance to quinolones, aminoglycosides, phenicols, tetracyclines, macrolides, lincosamides, and folate-pathway antagonists were identified. The majority of the detected plasmids were shared between isolates from sheep and the abattoir environment. Sequence types were more clustered around seasonal sampling but dispersed across sample types. In conclusion, our study reported wide dissemination of ESBL E. coli in sheep and the abattoir environment and associated AMR genes, point mutations, and plasmids. This is the first comprehensive AMR and WGS report on ESBL E. coli from sheep and abattoir environments in the United States.

Molecular characterization of ESBL- producing uropathogenic Escherichia coli recovered from urine samples of patients attending a University Teaching hospital in Nigeria.

Infection of the urinary tract ranks as one of the most common infections affecting people worldwide and its treatment is made complicated by the rising incidence of antibiotic resistance. This study aimed to detect extended spectrum beta-lactamase (ESBL) genes and antibiotic resistance profile of uropathogenic Escherichia coli (E. coli) recovered from patients attending a University Teaching hospital in Nigeria. Uropathogenic E. coli isolates were obtained from the culture collection of Department of Microbiology and Parasitology of the University Teaching hospital for a period of four months (October 2019-January, 2020). Antibiotic susceptibility testing was done using the disc diffusion method while phenotypic ESBL production was detected using double disc synergy test (DDST). Detection of β-lactamase genes was done using Real-Time PCR. Forty-nine E. coli isolates were recovered from 120 urine samples, with 24 (49%) being ESBL positive. The resistance to antibiotics in the ESBL producers was: ciprofloxacin (100%), cefotaxime (100%), cefpodoxime (100%), tetracycline (95.7%), ceftazidime (56.7%), amoxicillin-clavulanate (50%), gentamicin (33.3%), and imipenem (0%). All the ESBL producers carried blaTEM, blaCTX-M-1 and blaCTX-M-9, 75% (18/24) carried blaSHV, while blaCTX-M-2, blaCTX-M-8 and blaCTX-M-25 groups were detected in 20.8% (5/24) of the isolates. There was co-occurrence of CTX-M, SHV and TEM β-lactamases in 79.2% (19/24) isolates, while five isolates (20.8%) co-harbored blaCTX-M and blaTEM. This study showed a high level of multidrug resistance and ESBL gene carriage in uropathogenic E. coli obtained in this study, suggesting a likely review of therapeutic options in the treatment of UTI to clamp down on the rising cases of antibiotic resistance.

Molecular characterization of extended-spectrum beta-lactamase producing bacteria isolated from a river in Dhaka, Bangladesh

Molecular characterization of extended-spectrum beta-lactamase producing bacteria isolated from a river in Dhaka, Bangladesh

Occurrence of ESBLs in Clinical Isolates of Klebsiella Species and Comparative Analysis of Phenotypic Detection Methods

Aims:Drug resistance enzymes like beta-lactamases and Extended-Spectrum Beta- Lactamases (ESBLs) are mostly produced in the response of mutation and a few other factors. These enzymes are plasmid-mediated that can confer resistance against several β-lactam agents including cephalosporin and extended-spectrum cephalosporin. This study is conducted to determine the frequency of ESBL producing Klebsiella strains and to compare the phenotypic detection methods among various clinical samples collected from a commercial centralized Microbiology diagnostic laboratory.Materials and Methods:125 Klebsiella strains were collected for this study. After identification and susceptibility testing, the phenotypic characterization of ESBL producing K. pneumoniae (n=89) and K. oxytoca (n=36) species was performed by using the double disc synergy test and the combination disc test.Results:In our study, 80 (64%) Klebsiella isolates were found to be ESBL positive due to their ability to produce an extended zone of inhibition with combination disc whereas 45 (36%) isolates were ESBL negative with no extended zone of inhibition. The phenotypic findings obtained by using the combination disc method and double disc synergy method were re-confirmed by molecular methods. By comparing the phenotypic finding with the genotypic results, we identified 80 (64%) Klebsiella isolates as ESBL positive and 45 (36%) isolates as ESBL negative. These genotypic findings of the ESBL producing strains were similar to the results obtained from the combination disc method. It also confirmed that the double disc synergy test was unable to detect 47 ESBL producing klebsiella strains.Conclusion:For implementing strict infection control policy and to stop the spread of resistant strains, it is important to detect ESBL producing isolates more rapidly. A suitable antimicrobial therapy can be started timely with the early detection of resistance enzymes either phenotypically or genotypically. It has been proved that the combination disc test can be used more reliably and preferably as compared to the double disc synergy test for the detection of ESBL enzymes produced by Klebsiella strains.

Occurrence of Extended Spectrum Beta Lactamase Encoding Genes among Urinary Pathogenic <i>Escherichia coli</i> and <i>Klebsiella pneumoniae</i> Isolates Obtained from a Tertiary Hospital in Gombe Nigeria

This study was conducted to assess the occurrence and nature of extended-spectrum beta lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae isolates from patients who presented with urinary tract infection at Federal Teaching Hospital Gombe. Isolates collected were recovered on MacConkey agar at 35°C and were identified as members of Enterobacteriaceae, and further screened for antimicrobial susceptibility and resistance by disc diffusion method. Isolates resistant to oxyimino-cephalosporins were confirmed as ESBL producers using Double Disks Synergy Test (DDST). The study shows 66% resistance to ceftriaxone (30 μg) in K. pneumoniae, which was the highest value recorded and a 51% resistance to cefpodoxime (10 μg) in E. coli. The sensitivity of E. coli and K. pneumoniae isolates to cefpodoxime (10 μg) were 49% and 33.9% respectively. ESBLs were detected among 40% (40/100) of E. coli and 54.13% (59/109) of K. pneumoniae isolates. Molecular characterization of ESBL encoding genes among E. coli isolates using multiplex-PCR showed 10% prevalence of SHV gene and 5% prevalence for CTX-M gene while TEM gene was not detected. In K. pneumoniae isolates, 5% prevalence was recorded for each of the three genes screened. The study revealed a co-occurrence of SHV and CTX-M in 75% of the E. coli and 70% of the K. pneumoniae isolates; the occurrence of all the three genes was seen in 10% and 5% of K. pneumoniae and E. coli respectively. Multiplex-PCR method provided an efficient and rapid detection of ESBL related genes, hence could be used in epidemiological studies among ESBL isolates. Monitoring dissemination and transmissions of ESBL producers are highly recommended for optimum patient care and preventing the spread of multidrug resistant (MDR) pathogens.

Molecular Characterization of Extended Spectrum β-lactamase and Carbapenemase Producing Klebsiella pneumoniae from a Tertiary Care Hospital.

ABSTRACTObjectiveThe extended-spectrum beta-lactamase (ESBL) and carbapenemase producing gram-negative bacteria among the members of Enterobacteriaceae are of major health concern globally. The present study was carried out to determine proportion and genetic characterization of ESBL and carbapenemase producing Klebsiella pneumoniae strains isolated from intensive care units of a tertiary care hospital.Materials and methodsA total of 250 non-duplicate K. pneumoniae isolates were recovered from various clinical specimens from our intensive care units from May 2014 to May 2015. Antibiotic susceptibility testing was performed as recommended by Clinical and Laboratory Standard Institute. Phenotypic identification of ESBL and carbapenemase producing isolates were confirmed by the double-disk synergy test, modified Hodge test, imipenem and imipenem-EDTA combined test, respectively. Molecular characterization of β-lactamase genes were performed by polymerase chain reaction.ResultsOut of 250 Klebsiella pneumonaie, 84% isolates were ESBL producers, 66% were carbapenem resistant based on their reduced susceptibility to imipenem, meropenem and ertapenem. Among these 165 carbapenem resistant isolates, 9.7% were positive for bla NDM-1 and these isolates were also found to be positive for one or more bla genes. Co-carriage of AmpC in ESBL and carbapenem resistant isolates were 7.8% and 3.6%, respectively and were negative for blaKPC genes.ConclusionThe study indicated the prevalence of ESBLs and blaNDM-1, with additional bla genes and AmpC among the K. pneumoniae isolates in our intensive care units. NDM-1 producing Enterobacteriaceae is a growing health care problem. Detection of the prevalence of antibacterial resistance pattern helps towards improved antibiotic policy and empirical antibiotic treatment.How to cite this articleBeena HB, Shenoy SM, et al. Molecular Characterization of Extended Spectrum β-lactamase and Carbapenemase Producing Klebsiella pneumoniae from a Tertiary Care Hospital. Indian J of Crit Care Med 2019;23(2):61-66.

Detection and characterization of extended-spectrum beta-lactamase genes ( bla TEM and bla SHV ) among beta-lactam-resistant fecal coliforms of dairy cattle from Chhattisgarh, India

The aim of this study was to isolate the antimicrobial-resistant enterobacteria from cattle feces and to identify the extended-spectrum beta-lactamase (ESBL) and carbapenemase gene among them. A total of 70 cattle fecal swab samples were collected from Durg, Chhattisgarh, India, and cultured in nutrient broth. Bacterial isolation recovered 120 gram-negative bacteria. Antimicrobial susceptibility testing showed 90 (75%) coliform isolates (66 Escherichia coli , 20 Klebsiella sp., and two each of Enterobacter sp. and Citrobacter sp.) resistant to amoxicillin, amoxicillin-clavulanic acid, cefixime, ceftazidime, imipenem, or meropenem. Bacterial isolates showed the highest resistance rate for ceftazidime (61.6%), followed by cefixime and amoxicillin-clavulanic acid (60%). The ESBL phenotype, assessed by combination disk method, was shown by 36 (40%) of the resistant isolates. PCR amplification revealed 20% and 31.6% positivity of bla T E M role=presentation> T E M T E M _{TEM} and bla S H V role=presentation> S H V S H V _{SHV} genes, respectively. bla T E M role=presentation> T E M T E M _{TEM} and bla S H V role=presentation> S H V S H V _{SHV} coexpression was recorded among eight (12.1%) E. coli and two (10%) Klebsiella sp. isolates. Restriction endonuclease analysis indicated clonal blaTEM and clonal and nonclonal blaSHV genes. Nucleotide sequencing confirmed the bla T E M role=presentation> T E M T E M _{TEM} and bla S H V role=presentation> S H V S H V _{SHV} genotypes. None of the isolates showed amplification of the carbapenemase gene. Phenotypic and genetic detection and characterization of ESBLs among Enterobacteriaceae bacteria illustrate the importance of planning and execution of effective control programs for emerging antimicrobial-resistant pathogens.

Dissemination and genetic support of broad-spectrum beta-lactam-resistant Escherichia coli strain isolated from two Tunisian hospitals during 2004-2012.

The dissemination of extended-spectrum β-lactamase (ESBL)-producing bacteria presented a great concern worldwide. Gram-negative organisms such as Escherichia coli and Klebsiella pneumoniae are the most frequently isolated pathogens responsible for nosocomial infections. The aim of this study was to investigate and to follow the emergence of resistance and the characterization of Extended-Spectrum Beta-Lactamases (ESBL) among broad-spectrum beta-lactam-Escherichia coli clinical isolates recovered from the military hospital and Habib Thameur hospital in Tunisia. A total of 113 E.coli isolates obtained during the period 2004 through 2012 showed a significant degree of multi-resistance. Among these strains, the double-disk synergy test confirmed the ESBL phenotype in 46 isolates. These included 32(70%) strains from Hospital A and 14(30%) from Hospital B. The ESBL was identified as CTX-M-15. The ESBL resistance was transferred by a 60 kb plasmid CTXM-15-producing isolates were unrelated according to the PFGE analysis and characterization of the regions surrounding the blaCTX-M-15 showed the ISEcp1 elements located in the upstream region of the bla gene and 20 of them truncated by IS26. ESBL producing E. coli strains are a serious threat in the community in Tunisia and we should take into consideration any possible spread of such epidemiological resistance.

A Study on Isolation and Antibiotic Sensitivity Testing of <i>Pseudomonas aeruginosa</i> Isolated from Patients with Respiratory Tract Infection with Special Reference to Phenotypic and Genotypic Characterization of Extended Spectrum Beta Lactamases (ESBL)

Backgrounds: Pseudomonas aeruginosa is a classic opportunistic pathogen with innate resistance to many antibiotics and disinfectants. The lung is a main target for colonization and infection by the bacteria either in the context of a chronic, progressively deteriorating infectious and inflammatory pulmonary disease such as cystic fibrosis (CF) or in a more acute setting such as severe pneumonia in immunocompromised patients [1]. Aim and Objectives: To study the prevalence, virulence and the resistance pattern, phenotypic and genotypic characterization of P. aeruginosa from sputum samples. Materials and Methods: The present study was carried out with a total of 500 clinical sputum samples, which were received from patients, admitted to the various departments of Rajah Muthiah Medical College & Hospital, Annamalai University, Chidambaram. Result: Of the 500 samples subjected for isolation and identification of P. aeruginosa, 116 (23.20%) were positive. The isolated strains were tested for antibiotic sensitivity patterns. 93.10% of P. aeruginosa showed a maximum sensitivity to Ofloxacin, Norfloxacin and 86.20% of strains were highly resistant to Cefotaxime. The same isolates were also tested for phenotypic characterization of Extended Spectrum of Beta Lactamases by double disc synergy method against Cefotaxime and Clavulanic acid, according to the criteria of Hi-Media [2]. Of the resistant strains of P. aeruginosa isolated from sputum, 59% were positive for ESBL. The genotype characterization of ESBL P. aeruginosa showed 40% of CTX-M and 46.66% SHV gene. Conclusion: The present study strongly recommends for further checking of the antibiotic resistant strains of P. aeruginosa for phenotypic characterization of ESBL for effective treatment.

Prevalence and antibacterial resistance patterns of extended-spectrum beta-lactamase producing Gram-negative bacteria isolated from ocular infections.

Purpose:Extended-spectrum beta-lactamases (ESBLs) mediated resistance is more prevalent worldwide, especially among Gram-negative bacterial isolates, conferring resistance to the expanded spectrum cephalosporins. As limited data were available on the prevalence of ESBLs in this area, the current study was undertaken to determine the prevalence, antibacterial resistance patterns, and molecular detection and characterization of ESBL encoding resistance genes among ocular Gram-negative bacterial isolates from ocular infections.Materials and Methods:A prospective study was done on 252 ocular Gram-negative bacterial isolates recovered from ocular infections during a study period from February 2011 to January 2014. All isolates were subjected to detection of ESBLs by cephalosporin/clavulanate combination disc test and their antibacterial resistance pattern was studied. Molecular detection and characterization of ESBL encoding blaTEM-, blaSHV, blaOXA-, and blaCTX-M (phylogenetic groups 1, 2, 9, and 8/25) resistance genes by multiplex polymerase chain reaction and DNA sequence analysis.Results:Of all Gram-negative bacteria, Pseudomonas aeruginosa (44%) was the most common strain, followed by Enterobacter agglomerans and Klebsiella pneumoniae each (10%). Among the 252, 42 (17%) were ESBL producers. The major source of ESBL producers were corneal scraping specimens, highest ESBL production was observed in P. aeruginosa 16 (38%) and Escherichia coli 7 (16.6%). Among ESBL-producing genes, the prevalence of blaTEM-gene was the highest (83%) followed by blaOXA-gene (35%), blaSHV-gene (18.5%), and blaCTX-M-1-gene (18.5%) alone or together.Conclusion:The higher rate of prevalence of ESBLs-encoding genes among ocular Gram-negative bacteria is of great concern, as it causes limitation to therapeutic options. This regional knowledge will help in guiding appropriate antibiotic use which is highly warranted.

Prevalence and characterization of extended-spectrum beta-lactamase-producing Enterobacteriaceae in spring waters.

The purpose of this study was to investigate the prevalence and characterization of extended-spectrum beta-lactamases (ESBL)-producing Enterobacteriaceae from spring waters in Mountain Tai of China. ESBL-producing Enterobacteriaceae were found in four out of 50 sampled spring waters (4/50, 8·0%) and a total of 16 non-duplicate ESBL-producing Enterobacteriaceae were obtained, including 13 Escherichia coli (E. coli) and three Klebsiella pneumoniae (Kl. pneumoniae). All 16 nonduplicate ESBL-producing Enterobacteriaceae isolates harboured genes encoding CTX-M ESBLs, among which six expressed CTX-M-15, five produced CTX-M-14, three produced CTX-M-55 and two expressed CTX-M-27. Four multilocus sequence types (ST) were found and ST131 was the dominant type (8/16, 50·0%). Taken together, the contamination of ESBL-producing Enterobacteriaceae were present in spring waters of Mountain Tai. The results indicated that spring waters could become a reservoir of antibiotic resistant bacteria and contribute to the spread of antimicrobial-resistant bacteria via drinking water or food chain. In addition, wastewater discharge of restaurants or hotels may be an important contribution source of antibiotic resistant bacteria in spring waters.

Risk factors for extended-spectrum β-lactamases-producing Escherichia coli urinary tract infections in a tertiary hospital.

To assess the risks factors for urinary tract infections (UTIs) caused by Extended-Spectrum Beta-Lactamases (ESBLs)-producing E. coli and the molecular characterization of ESBLs. A case-control study was performed to identify risk factors in consecutively recruited patients with UTIs caused by ESBLs or non-ESBLs-producing E. coli in a tertiary hospital in Mexico. ESBLs-producing E. coli were isolated from 22/70 (31%) patients with E. coli UTIs over a three month period. All isolates were resistant to cephalosporins and quinolones but susceptible to carbapenems, amikacin and nitrofurantoin. Prior antibiotic treatment with more than two antibiotic families (OR=6.86; 95%CI 1.06-157.70; p=0.028), recurrent symptomatic UTIs (OR=5.60; 95%CI 1.88-17.87; p=0.001) and previous hospitalization (OR=5.06; 95%CI 1.64-17.69; p=0.002) were significant risk factors. Sixteen isolates harbored the beta-lactamase (bla)CTX-M-15 gene and five the blaTEM-1 gene. One of every three patients presented UTIs with ESBLs-producing beta-lactams and fluoroquinolone resistant E. coli. Risk factors and resistance patterns must be taken into account for developing antibiotic use policies in these settings.

Characterization of extended-spectrum beta-lactamase, carbapenemase, and plasmid quinolone determinants in Klebsiella pneumoniae isolates carrying distinct types of 16S rRNA methylase genes, and their association with mobile genetic elements.

Eighty-four multidrug-resistant Klebsiella pneumoniae (MDR-KP) isolates from a Chinese hospital from January to October 2012 were evaluated to characterize the coexistence of 16S rRNA methylase, extended-spectrum β-lactamase, carbapenemase, and plasmid-mediated quinolone resistance determinants and their association with mobile genetic elements. Among the 84 MDR-KP isolates studied, 19 isolates exhibited high-level resistance to amikacin mediated by the production of the 16S rRNA methylase. They carried 19 armA genes (22.9%) and three rmtB genes (3.6%). CTX-M genes were found in all of the isolates. Among these armA- or rmtB/CTX-M-producing K. pneumoniae isolates, 31.6% carried the carbapenemase genes (blaKPC-2 [26.3%], blaIMP-4 [10.5%], and blaNDM-1 [5.3%]), which made them resistant to imipenem (minimum inhibitory concentration [MIC] ≥16 mg/L). All positive strains possessed qnr-like genes (16 qnrA1, 10 qnrS1, and 7 qnrB4 genes) and 18 harbored an aac(6')-Ib-cr gene. Mobile elements ISEcp1, IS26, ISCR1, ISAba125, and sul-1 integrons were detected in 19/19 (100%), 16/19 (84.2%), 18/19 (94.7%), 9/19 (47.4%), and 18/19 (94.7%) isolates, respectively. The mobilizing elements occurred in different combinations in the study isolates. Majority of armA and qnr genes were in MDR-KP strains carrying integrons containing the ISCR1. Close to 80% of blaTEM-1 and blaSHV-12 were linked to IS26 while ≥90% of blaCTX-Ms and blaCMYs were linked to ISEcp1. ISAba125 was located upstream of blaNDM-1 and some blaCMY-2 genes. In addition, seven transconjugants were available for further analysis, and armA, qnrS1, acc(6')-Ib-cr, blaCTX-M-15, blaTEM-1, and blaNDM-1 were cotransferred. This study points to the dissemination of 16S rRNA methylase genes and the prevalence of selected elements implicated in evolution of resistance determinants in collection of clinical K. pneumoniae in China.

Molecular and phylogenetic characterization of multidrug resistant extended spectrum beta-lactamase producing Escherichia coli isolated from poultry and cattle in Odisha, India

The present study was undertaken to determine the occurrence and characterization of extended spectrum beta-lactamase (ESBL) producing Escherichia coli isolated from cattle and poultry in Odisha, India. Of 316 E. coli isolated from 305 samples (170 fecal samples from poultry and 135 milk samples from cattle), a total of 18 E. coli isolates were confirmed as ESBL producers by combination disc method and ESBL E-test. The isolates were resistant to oxyimino cephalosporins and monobactam as revealed by disc diffusion assay and determination of minimum inhibitory concentration. Resistance against other antibiotics was frequently noted as well. Further, beta-lactamase genes viz., blaSHV, blaCTXM, blaTEM and blaampC were detected in 17, 13, 9 and 2 isolates, respectively in PCR. Of the 18 ESBL strains, 16 were positive for class I integron (int1), nine of them carried sulphonamide resistance gene (sul1) and one harbored quinolone resistance gene (qnrB). Virulence markers for extraintestinal pathogenic E. coli like astA, tsh and iucD were also present in 4, 3 and 3 isolates, respectively. All the PCR amplified products were cloned and subjected to sequencing for homology analysis and data were submitted to gene bank. Sequence analysis of the amplified variable regions of class 1 integron of four representative isolates revealed the presence of aadA2 and dfrA12 gene cassettes conferring resistance to aminoglycosides and trimethoprim, respectively. Most of the ESBL producing strains emerged as single lineage through phylogenetic analysis by RAPD and ERIC PCR. This is the first ever systemic study on multidrug resistant ESBL producing E. coli in food producing animals from India.

ESBL, plasmidic AmpC, and associated quinolone resistance determinants in coliforms isolated from hospital effluent: first report of qnrB2, qnrB9, qnrB19, and blaCMY-4 in Algeria

The characterization of extended-spectrum beta-lactamases , plasmidic AmpC (pAmpC), and associated plasmid-mediated quinolone resistance (PMQR) determinants in cefotaxime-resistant coliforms isolated from hospital effluent in Algiers showed blaCTX-M genes in 89%, blaTEM-1 in 79·8%, and pAmpC genes (blaCIT) in 2·7% isolates. Association of ISEcp1B with blaCTX-M was found in all CTX-M+ isolates, and 97·2% harboured class 1 integrons. Sequencing showed blaCTX-M-15, blaCTX-M-3, and blaCMY-4 genes. blaCTX-M-3 and blaCTX-M-15 were located in Inc L/M conjugative plasmids. The PMQR determinants identified were qnrB1, qnrB2, qnrB9, qnrB19, qnrS2, and aac(6')-Ib-cr. qnrB2, qnrB9, qnrB19, and blaCMY-4 are described for the first time in Algeria and qnrB19 for the first time in non-clinical environments. This study highlights the major potential role of hospital effluents as providers of resistance genes to natural environments.