Prevalence Of Β-lactamase Genes Research Articles

Serovar and sequence type distribution and phenotypic and genotypic antimicrobial resistance of Salmonella originating from pet animals in Chongqing, China.

A total of 334 Salmonella isolates were recovered from 6,223 pet rectal samples collected at 50 pet clinics, 42 pet shops, 7 residential areas, and 4 plazas. Forty serovars were identified that included all strains except for one isolate that did not cluster via self-agglutination, with Salmonella Typhimurium monophasic variant, Salmonella Kentucky, Salmonella Enteritidis, Salmonella Pomona, and Salmonella Give being the predominant serovars. Fifty-one sequence types were identified among the isolates, and ST198, ST11, ST19, ST451, ST34, and ST155 were the most common. The top four dominant antimicrobials to which isolates were resistant were sulfisoxazole, ampicillin, doxycycline, and tetracycline, and 217 isolates exhibited multidrug resistance. The prevalence of β-lactamase genes in Salmonella isolates was 59.6%, and among these isolates, 185 harbored blaTEM, followed by blaCTX-M (66) and blaOXA (10). Moreover, six PMQR genes, namely, including qnrA (4.8%), qnrB (4.2%), qnrD (0.9%), qnrS (18.9%), aac(6')-Ib-cr (16.5%), and oqxB (1.5%), were detected. QRDR mutations (76.6%) were very common in Salmonella isolates, with the most frequent mutation in parC (T57S) (47.3%). Furthermore, we detected six tetracycline resistance genes in 176 isolates, namely, tet(A) (39.5%), tet(B) (8.1%), tet(M) (7.7%), tet(D) (5.4%), tet(J) (3.3%), and tet(C) (1.8%), and three sulfonamide resistance genes in 303 isolates, namely, sul1 (84.4%), sul2 (31.1%), and sul3 (4.2%). Finally, we found 86 isolates simultaneously harboring four types of resistance genes that cotransferred 2-7 resistance genes to recipient bacteria. The frequent occurrence of antimicrobial resistance, particularly in dogs and cats, suggests that antibiotic misuse may be driving multidrug-resistant Salmonella among pets.IMPORTANCEPet-associated human salmonellosis has been reported for many years, and antimicrobial resistance in pet-associated Salmonella has become a serious public health problem and has attracted increasing attention. There are no reports of Salmonella from pets and their antimicrobial resistance in Chongqing, China. In this study, we investigated the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella strains isolated from pet fecal samples in Chongqing. In addition, β-lactamase, QRDR, PMQR, tetracycline and sulfonamide resistance genes, and mutations in QRDRs in Salmonella isolates were examined. Our findings demonstrated the diversity of serovars and sequence types of Salmonella isolates. The isolates were widely resistant to antimicrobials, notably with a high proportion of multidrug-resistant strains, which highlights the potential direct or indirect transmission of multidrug-resistant Salmonella from pets to humans. Furthermore, resistance genes were widely prevalent in the isolates, and most of the resistance genes were spread horizontally between strains.

Antimicrobial Resistance Profile of Foodborne Salmonella spp. and E. coli Isolates from Rodents and Shrews in Morogoro Municipality, Tanzania

Background: Antimicrobial resistance (AMR) is a pressing global public health issue that affects both human and animal health. Small mammals, such as rodents and shrews, represent a significant reservoir of zoonotic infections. However, there is limited documented research specifically addressing Escherichia coli and Salmonella spp. resistant strains from small mammals. Purpose: This study was conducted to examin the occurrence of AMR E. coli and Salmonella spp. and their associated resistance genes in rodents and shrews. Methods: A total of 148 fecal samples from rodents and shrews were examined for E. coli and Salmonella spp. using culture methods and biochemical tests. Fifty isolates were subjected to antibiotic susceptibility testing using the disk diffusion method on Muller-Hinton agar. Genotypic analysis by PCR was used to confirm the bacterial strains and their resistance pattern genes. Results: Two bacteria were confirmed in 57 (38.5%) of the fecal samples. Specifically, E. coli and Salmonella spp. were identified in 54 (36.5%) and 3 (2%) fecal samples, respectively. Antimicrobial susceptibility testing revealed significant resistance in Rattus rattus. Molecular analysis confirmed that Salmonella spp. carry a larger proportion of resistance genes than E. coli. Specific resistance genes, including Sul1 and Sul2, were identified, constituting 15.4% of the total resistance genes. The prevalence of β-lactamase genes was remarkable, with a higher occurrence in Salmonella spp. Conclusion: In terms of human health, the implications of rodents and shrews serving as carriers and transmitters of various pathogens were highlighted. Given the possibility of unexpected zoonoses arising from the bacteria found in this study, these findings contribute to the understanding AMR in the context of bacterial infections in animals and humans.

Escherichia coli from Human Wounds: Analysis of Resistance to β-Lactams and Expression of RND Efflux Pumps.

Resistance of pathogenic strains of Escherichia coli to β-lactams, particularly to ampicillin, is on the rise and it is attributed to intrinsic and acquired mechanisms. One important factor contributing to resistance, together with primarily resistance mechanisms, is a mutation and/or an over-expression of the intrinsic efflux pumps in the resistance-nodulation-division (RND) superfamily. Among these efflux pumps, AcrA, AcrB, TolC, and AcrD play an important role in antimicrobial co-resistance, including resistance to β-lactams. Twelve E. coli isolates obtained from patients' wounds and the control strain of E. coli ATCC 25922 were analyzed. The phenotypic resistance of these isolates to selected β-lactams was assessed by determination of the minimal inhibitory concentration. Additionally, the prevalence of β-lactamase genes (blaTEM, blaCTX-M, blaSHV, and blaAmpC) was screened by PCR. Real-time qPCR was used to determine the expression of the selected efflux pumps acrA, acrB, tolC, and acrD and the repressor acrR after the exposure of E. coli to ampicillin. Phenotypic resistance to β-lactams was detected in seven isolates, mainly to ampicillin and piperacillin. This was corroborated by the presence of at least one acquired bla gene in each of these isolates. Although E. coli strains varied in the expression of RND-family efflux pumps after the ampicillin exposure, their gene expression indicated that these pumps did not play a major role in the phenotypic resistance to ampicillin. Each E. coli isolate displayed unique characteristics, differing in minimum inhibitory concentration (MIC) values, prevalence of acquired blaTEM and blaCTX-M genes, and expression of the RND-family pumps. This together demonstrates that these clinical isolates employed distinct intrinsic or acquired resistance pathways for their defense against ampicillin. The prevalence and spread of ampicillin resistant E. coli has to be monitored and the search for ampicillin alternatives is needed.

Analyses of Extended-Spectrum-β-Lactamase, Metallo-β-Lactamase, and AmpC-β-Lactamase Producing Enterobacteriaceae from the Dairy Value Chain in India.

The consumption of milk contaminated with antibiotic-resistant bacteria poses a significant health threat to humans. This study aimed to investigate the prevalence of Enterobacteriaceae producing β-lactamases (ESBL, MBL, and AmpC) in cow and buffalo milk samples from two Indian states, Haryana and Assam. A total of 401 milk samples were collected from dairy farmers and vendors in the specified districts. Microbiological assays, antibiotic susceptibility testing, and PCR-based genotyping were employed to analyze 421 Gram-negative bacterial isolates. The overall prevalence of β-lactamase genes was 10% (confidence interval (CI) (7-13)), with higher rates in Haryana (13%, CI (9-19)) compared to Assam (7%, CI (4-11)). The identified β-lactamase genes in isolates were blaCMY, blaMOX, blaFOX, blaEBC, and blaDHA, associated with AmpC production. Additionally, blaCTX-M1, blaSHV, and blaTEM were detected as ESBL producers, while blaVIM, blaIMP, blaSPM, blaSIM, and blaGIM were identified as MBL producers. Notably, Shigella spp. were the dominant β-lactamase producers among identified Enterobacteriaceae. This study highlights the presence of various prevalent β-lactamase genes in milk isolates, indicating the potential risk of antimicrobial-resistant bacteria in dairy products. The presence of β-lactam resistance raises concern as this could restrict antibiotic options for treatment. The discordance between genotypic and phenotypic methods emphasizes the necessity for comprehensive approaches that integrate both techniques to accurately assess antibiotic resistance. Urgent collaborative action incorporating rational and regulated use of antibiotics across the dairy value chain is required to address the global challenge of β-lactam resistance.

BlaTEM-positive Salmonella enterica serovars Agona and Derby are prevalent among food-producing animals in Chongqing, China.

Salmonella is one of the most important foodborne zoonotic pathogens, causing global morbidity and mortality in both humans and animals. Due to the extensive use of antimicrobials in food-producing animals, the antimicrobial resistance of Salmonella has attracted increasing attention globally. There have been many reports concerning the antimicrobial resistance of Salmonella from food-producing animals, meats and the environment. However, few studies on Salmonella from food-producing animals have been reported in Chongqing municipality, China. The aim of the present study was to determine the prevalence, serovar diversity, sequence types, and antimicrobial resistance of Salmonella isolated from livestock and poultry in Chongqing. Meanwhile, we also want to know the presence of β-lactamase genes, plasmid-mediated quinolone resistance (PMQR) genes and quinolone resistance-determining region (QRDR) mutations of Salmonella isolates. A total of 129 Salmonella strains were recovered from 2,500 fecal samples at 41 farms from pigs, goats, beef cattle, rabbits, chickens, and ducks. Fourteen serovars were identified, with S. Agona and S. Derby being the dominant serovars. The 129 isolates had high resistance to doxycycline (87.6%), ampicillin (80.6%), tetracycline (79.8%), trimethoprim (77.5%), florfenicol (76.7%) chloramphenicol (72.9%), and trimethoprim-sulfamethoxazole (71.3%), but were susceptible to cefepime. A total of 114 (88.4%) isolates showed multidrug resistant phenotypes. The prevalence of β-lactamase genes in Salmonella isolates was 89.9% (116/129), and among these isolates, 107 (82.9%) harbored blaTEM, followed by blaOXA (26, 20.2%), blaCTX-M (8, 6.2%), and blaCMY (3, 2.3%). In addition, qnrB, qnrD, qnrS, oqxA, oqxB, and aac(6')-Ib-cr were detected in 11, 2, 34, 34, 43, and 72 PMQR-producing isolates, respectively. Moreover, QRDR mutations were very common in PMQR-positive Salmonella isolates (97.2%, 70/72) with mutation(s) in parC or combinative mutations in gyrA and parC. More significantly, 32 extended spectrum beta-lactamase (ESBL)-producing isolates were identified, and 62.5% of them were found to harbor one to four PMQR genes. Furthermore, 11 sequence types were identified from the isolates, and most of ESBL-producing isolates were attributed to ST34 (15.6%) and ST40 (62.5%). The coexistence of PMQR genes with β-lactamase genes and the extensive mutations in QRDR present in Salmonella isolates from food-producing animals suggest a potential threat to public health. Reasonable utilization and strict control strategies for antimicrobials in animal husbandry and animal treatment are necessary to reduce the emergence and dissemination of drug-resistant Salmonella isolates.

Molecular Analysis of KPC and GES Beta-Lactamase Genes in Clinical Isolates of Klebsiella pneumoniae by PCR Method

Background: Carbapenem-resistant Klebsiella pneumonia (K. pneumoniae) has been recently identified as the major class of pathogens and the treatment became the biggest challenge in this bacterium. We assessed the antibiotic resistance patterns of K. pneumoniae, the frequency of resistant strains to imipenem, meropenem, and ertapenem, and the frequency of K. pneumoniae carbapenemases (KPC), and Guiana-Extended-Spectrum (GES) metallo-β-lactamase genes. Methods: The phenotypes of 200 strains of K. pneumonia, collected from 650 clinical samples, were isolating and identified in Qom, Iran. The antibiotic resistance pattern of the strains was analyzed against different antibiotics. The imipenem, meropenem, and ertapenem-resistant strains, were isolated and the frequency of KPC and GES genes were evaluated. Results: K. pneumoniae strains had different resistance patterns against various antibiotics. The isolated strains with the highest and lowest antibiotic resistance were related to ampicillin, and meropenem, respectively. Investigation of the KPC and GES β lactamase showed that none of 48 imipenem, meropenem, and ertapenem-resistance isolates had the KPC gene. In addition, the GES gene was detected in 3(2.7%) of 110 ceftazidime-resistant specimens. Conclusions: Carbapenem is useful in the treatment of K. pneumoniae infections. Due to the importance of the mechanisms of resistance is by β-lactamase genes, investigating the prevalence of β-lactamase genes can help to increase the necessity of choosing the appropriate treatment for K. pneumoniae.

Clinical and molecular characteristics of Chryseobacterium indologenes isolates at a teaching hospital in Shanghai, China.

BackgroundChryseobacterium indologenes (C. indologenes) has recently emerged as a cause of life-threatening nosocomial infections in humans. This study aims to investigate the clinical characteristics, homology, and antimicrobial patterns of C. indologenes clinical isolates at a teaching hospital in Shanghai, China.MethodsA total of 135 consecutive non-replicate clinical C. indologenes isolates from January 2010 to December 2018 were collected at a tertiary care university hospital in Shanghai, China. Genetic relatedness of the isolates was performed by pulsed-field gel electrophoresis (PFGE). The antimicrobial susceptibility of these isolates was measured by the microdilution broth method. The prevalence of β-lactamase genes was investigated by polymerase chain reaction (PCR), while the quinolone resistance-determining regions (QRDRs) were sequenced.ResultsAll 135 C. indologenes isolates were collected from hospitalized patients with an average age of 55 years. Most of these clinical isolates were derived from ascites (59.3%) or urine (23.7%) specimens. Eighty (80/135) of the strains were classified as clone D by PFGE. In vitro drug susceptibility tests showed that minocycline and trimethoprim-sulfamethoxazole had sound antibacterial effects. However, more than 86% of the tested strains were resistant to cephalosporins (ceftazidime, cefotaxime), β-lactamase/β-lactamase inhibitors (cefoperazone-sulbactam), and carbapenems (meropenem, imipenem). Metallo-β-lactamase blaIND and type A broad-spectrum β-lactamase genes blaCIA were present in 135 and 103 isolates, respectively. The clinical strains in our hospital mainly carried blaIND-2 (89.6%, 121/135). Compared with previous studies, these strains had a high rate of resistance to quinolones. The resistance rates to levofloxacin, ciprofloxacin, norfloxacin, gatifloxacin, and nemonoxacin were as high as 83.7–94.8%. The mutations at Ser83Val, Ser83Tyr, and Asp87Gly in the QRDRs of GyrA were significantly related to the resistance of C. indologenes to levofloxacin. All but one quinolone-resistant strain contained at least one significant mutation.ConclusionsThis study showed a clonal dissemination of C. indologenes isolates in infections at a tertiary care university hospital in Shanghai, China. Minocycline and trimethoprim-sulfamethoxazole had favorable in vitro antibacterial effects. However, the high resistance rate to β-lactams and quinolones was due to carrying β-lactamase (blaIND, blaCIA), and mutations in the QRDRs of GyrA.

Prevalence of β-lactamase genes, class 1 integrons, major virulence factors and clonal relationships of multidrug-resistant Pseudomonas aeruginosa isolated from hospitalized patients in southeast of Iran.

Objective(s): Pseudomonas aeruginosa is one of the most important nosocomial pathogens causing a high rate of mortality among hospitalized patients. Herein, we report the prevalence of antibiotic resistance genes, class 1 integrons, major virulence genes and clonal relationship among multidrug- resistant (MDR) P. aeruginosa, isolated from four referral hospitals in the southeast of Iran.Materials and Methods:In this study, 208 isolates of P. aeruginosa were collected from four referral hospitals in southeast of Iran. Disk diffusion method was used to determine susceptibility to 13 antibacterial agents. AmpC was detected by phenotypic method and β-lactamase genes, virulence genes and class 1 integrons were detected by PCR. Clonal relationship of the isolates was determined by RAPD-PCR.Results:All the isolates were susceptible to polymyxin-B and colistin. Overall, 40.4% of the isolates were MDR, among which resistance to third generation cephalosporins, aminoglycosides, and carbapenems was 47.5%, 32.3% and 40%, respectively. None of the isolates was positive for blaNDM-1 genes, while 84.5% and 4.8% were positive for the blaIMP-1 and blaVIM, metallo-β-lactamase genes, respectively. Incidence of class 1 integrons was 95% and AmpC was detected in 33% of the isolates. Prevalence of exoA, exoS, exoU, pilB and nan1 were 98.8%, 44%, 26%, 8.3% and 33.3%, respectively. RAPD profiles identified four large clusters consisting of 77 isolates, and two small clusters and three singletons.Conclusion: :The rate of MDR P. aeruginosa isolates was high in different hospitals in this region. High genetic similarity among MDR isolates suggests cross-acquisition of infection in the region.

Emergence of blaCTX-M-15, blaTEM-169 and blaPER-1 extended-spectrum β-lactamase genes among different Salmonella enterica serovars from human faecal samples

Background: Broad-spectrum β-lactams are used for empirical therapy of severe infections with non-typhoid Salmonella serotypes; however, activities of these drugs against the strains producing different β-lactamase is not so clear. This study investigated the prevalence of β-lactamase genes among isolates of S. enterica serovars from human faecal samples and determined their diversity in activity against different β-lactams.Methods: Antimicrobial resistance of faecal isolates of S. enterica to extended-spectrum cephalosporins was analysed and MIC values were determined for the strains presenting extended-spectrum β-lactamases (ESBLs) phenotypes. The β-lactamase genes were identified by PCR and sequencing. β-lactamase activity of the Salmonella strains exhibiting ESBL phenotype was detected by biological, iodometric, spectrophotometry and nitrocefin assays.Results: Out of 202 S. enterica isolates, ESBLs phenotype was detected among 3.4% (7/202) of the strains. blaTEM-1 and blaCTX-M-15 were among the frequent β-lactamase genes. Detection of blaTEM-169 in S. enterica serovar Typhimurium and S. enterica serovar Bredeney and blaPER-1 in S. enterica serovar Infantis was a new finding in this experiment. Location of blaCTX-M-15/blaTEM-169/blaPER-1 genes on plasmid was confirmed in a transformation experiment. While crude extracts of the enzymes from each strain showed higher activity against cephalothin and cefotaxime, the lowest activity was detected against ceftazidime. The greatest synergistic activity was seen in a strain of S. enterica that carried blaCTX-M-15 and blaPER-1 genes compared with those presenting blaCTX-M-15/blaTEM-169 or blaCTX-M-15/blaTEM-1 genotypes.Conclusions: The results show dissemination of ESBLs encoding genes and their combined activity among different serovars of S. enterica that are a threat for future treatment options.