Mobile Colistin-Resistant Genes mcr-1, mcr-2, and mcr-3 Identified in Diarrheal Pathogens among Infants, Children, and Adults in Bangladesh: Implications for the Future. - Related Documents




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89001.0000Mobile Colistin-Resistant Genes mcr-1, mcr-2, and mcr-3 Identified in Diarrheal Pathogens among Infants, Children, and Adults in Bangladesh: Implications for the Future. Colistin is a last-resort antimicrobial for treating multidrug-resistant Gram-negative bacteria. Phenotypic colistin resistance is highly associated with plasmid-mediated mobile colistin resistance (mcr) genes. mcr-bearing Enterobacteriaceae have been detected in many countries, with the emergence of colistin-resistant pathogens a global concern. This study assessed the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes with phenotypic colistin resistance in isolates from diarrheal infants and children in Bangladesh. Bacteria were identified using the API-20E biochemical panel and 16s rDNA gene sequencing. Polymerase chain reactions detected mcr gene variants in the isolates. Their susceptibilities to colistin were determined by agar dilution and E-test by minimal inhibitory concentration (MIC) measurements. Over 31.6% (71/225) of isolates showed colistin resistance according to agar dilution assessment (MIC > 2 μg/mL). Overall, 15.5% of isolates carried mcr genes (7, mcr-1; 17, mcr-2; 13, and mcr-3, with co-occurrence occurring in two isolates). Clinical breakout MIC values (≥4 μg/mL) were associated with 91.3% of mcr-positive isolates. The mcr-positive pathogens included twenty Escherichia spp., five Shigella flexneri, five Citrobacter spp., two Klebsiella pneumoniae, and three Pseudomonas parafulva. The mcr-genes appeared to be significantly associated with phenotypic colistin resistance phenomena (p = 0.000), with 100% colistin-resistant isolates showing MDR phenomena. The age and sex of patients showed no significant association with detected mcr variants. Overall, mcr-associated colistin-resistant bacteria have emerged in Bangladesh, which warrants further research to determine their spread and instigate activities to reduce resistance.202438927200
89110.9999Identification of mobile colistin resistance genes (mcr-1.1, mcr-5 and mcr-8.1) in Enterobacteriaceae and Alcaligenes faecalis of human and animal origin, Nigeria. Colistin is a last-resort drug used to treat infections caused by multidrug-resistant Gram-negative bacteria that have developed carbapenem resistance. Emergence and rapid dissemination of the nine plasmid-mediated mobile colistin resistance genes (mcr-1 to mcr-9) has led to fear of pandrug-resistant infections worldwide. To date, there is only limited information on colistin resistance in African countries where the drug is widely used in agriculture. In this Nigerian study, 583 non-duplicate bacterial strains were isolated from 1119 samples from humans, camels, cattle, dogs, pigs and poultry using colistin-supplemented MacConkey agar, among which 17.0% (99/583) were colistin-resistant. PCR (mcr-1 to mcr-9) and whole-genome sequencing (WGS) identified mcr in 21.2% (21/99) of colistin-resistant isolates: mcr-1.1 (n = 13), mcr-8.1 (n = 5), mcr-1.1 and mcr-8.1 (n = 2), and mcr-1.1 and mcr-5 (n = 1). Of the 21 mcr-positive strains, 9 were isolated from human samples, with 8 being Klebsiella pneumoniae, and 6 of these human K. pneumoniae had a high colistin MIC (>64 μg/mL). In contrast, 9 of the 12 mcr-positive animal isolates were Escherichia coli, of which only 2 had a colistin MIC of >64 μg/mL. This study is the first to report mcr-1 in Alcaligenes faecalis and the emergence of mcr-5 and mcr-8 in Nigeria. WGS determined that mcr-1 was localised on an IncX4 plasmid and that 95.2% of mcr-1 harbouring isolates (20/21) transferred colistin resistance successfully by conjugation. These findings highlight the global spread of colistin resistance and emphasise the urgent need for co-ordinated global action to combat resistant bacteria.202032721596
91520.9999Detection of Plasmid-Mediated Mobile Colistin Resistance Gene (mcr-1) in Enterobacterales Isolates from a University Hospital. PURPOSE: Colistin represents one of the last treatment options for infections caused by multi-drug resistant (MDR) Enterobacterales. The emergence of a plasmid-mediated mobile colistin resistance-1 (mcr-1) gene has raised serious concerns about its potential dissemination among bacteria. METHODS: In this study, we evaluated the chromogenic medium, CHROMID(®) Colistin Resistance (COLR) agar, for the rapid detection of colistin-resistant Enterobacterales using broth microdilution (BMD) as a reference method. We also attempted to detect mcr-1, -2, -3, -4, and -5 genes, as well as the insertion sequence ISApl1 via polymerase chain reaction (PCR), followed by sequencing of mcr gene(s). RESULTS: Among the 100 studied Enterobacterales isolates, 53% of them were colistin-resistant, with higher rate among Klebsiella pneumoniae (75%) as compared to Escherichia coli (44.4%). The COLR agar showed 83.2% sensitivity and 97.9% specificity for the detection of colistin resistance. Among colistin-resistant isolates, mcr-1 gene was only detected in four (7.5%) E. coli isolates. The ISApl1 was not found among mcr-1 positive isolates. Sequencing of mcr-1 gene revealed nucleotide sequence homogeneity with the wild-type mcr-1 gene in BLAST. CONCLUSION: The COLR agar is a promising phenotypic method for the detection of colistin-resistant Enterobacterales. Multiplex PCR followed by sequencing can be used for mcr genes' detection and characterization.202134408450
114230.9999Virulence Determinants and Plasmid-Mediated Colistin Resistance mcr Genes in Gram-Negative Bacteria Isolated From Bovine Milk. A major increase of bacterial resistance to colistin, a last-resort treatment for severe infections, was observed globally. Using colistin in livestock rearing is believed to be the ground of mobilized colistin resistance (mcr) gene circulation and is of crucial concern to public health. This study aimed to determine the frequency and virulence characteristics of colistin-resistant Gram-negative bacteria from the milk of mastitic cows and raw unpasteurized milk in Egypt. One hundred and seventeen strains belonging to Enterobacteriaceae (n = 90), Pseudomonas aeruginosa (n = 10), and Aeromonas hydrophila (n = 17) were screened for colistin resistance by antimicrobial susceptibility testing. The genetic characteristics of colistin-resistant strains were investigated for mcr-1-9 genes, phylogenetic groups, and virulence genes. Moreover, we evaluated four commonly used biocides in dairy farms for teat disinfection toward colistin-resistant strains. Multidrug-resistant (MDR) and extensive drug-resistant (XDR) phenotypes were detected in 82.91% (97/117) and 3.42% (4/117) of the isolates, respectively. Of the 117 tested isolates, 61 (52.14%) were colistin resistant (MIC >2 mg/L), distributed as 24/70 (34.29%) from clinical mastitis, 10/11 (90.91%) from subclinical mastitis, and 27/36 (75%) from raw milk. Of these 61 colistin-resistant isolates, 47 (19 from clinical mastitis, 8 from subclinical mastitis, and 20 from raw milk) harbored plasmid-borne mcr genes. The mcr-1 gene was identified in 31.91%, mcr-2 in 29.79%, mcr-3 in 34.04%, and each of mcr-4 and mcr-7 in 2.13% of the colistin-resistant isolates. Among these isolates, 42.55% (20/47) were E. coli, 21.28% (10/47) A. hydrophila, 19.12% (9/47) K. pneumoniae, and 17.02% (8/47) P. aeruginosa. This is the first report of mcr-3 and mcr-7 in P. aeruginosa. Conjugation experiments using the broth-mating technique showed successful transfer of colistin resistance to E. coli J53-recipient strain. Different combinations of virulence genes were observed among colistin-resistant isolates with almost all isolates harboring genes. Hydrogen peroxide has the best efficiency against all bacterial isolates even at a low concentration (10%). In conclusion, the dissemination of mobile colistin resistance mcr gene and its variants between MDR- and XDR-virulent Gram-negative isolates from dairy cattle confirms the spread of mcr genes at all levels; animals, humans, and environmental, and heralds the penetration of the last-resort antimicrobial against MDR bacteria. Consequently, a decision to ban colistin in food animals is urgently required to fight XDR and MDR bacteria.202134888259
86040.9999Investigation of Plasmid-Mediated Colistin Resistance Genes (mcr-1-8) in Enterobacterales Isolates. Background The escalating global rise in multidrug-resistant gram-negative bacteria presents an increasingly substantial threat to patient safety. Over the past decade, carbapenem-resistant Enterobacterales (CRE) have emerged as one of the most critical pathogens in hospital-acquired infections, notably within intensive care units. Colistin has become one of the last-resort antimicrobial agents utilized to combat infections caused by CRE. However, the use of colistin has been accompanied by a notable increase in the prevalence of colistin-resistant bacteria. This study aimed to investigate plasmid-mediated colistin resistance genes ranging from mcr-1 to mcr-8 among members of the Enterobacterales order. Materials and methods This prospective study was conducted in the microbiology laboratory of Afyonkarahisar Health Sciences University Health Research and Practice Center between May 1, 2021 and July 31, 2022. A total of 2,646 Enterobacterales isolates were obtained from all culture-positive clinical samples sent from various clinics. Of these, 79 isolates exhibiting resistance to carbapenem antibiotics were included in the study. Among the 79 isolates, the presence of mcr-1 to mcr-8 genes was investigated in 27 isolates that were shown to be resistant to colistin. The identification of bacteria at the species level and antibiotic susceptibility tests were conducted using the VITEK 2 automated system (bioMérieux, USA). Colistin resistance among Enterobacterales strains exhibiting carbapenem resistance was evaluated using the broth microdilution technique (ComASP™ Colistin, Liofilchem, Italy), in accordance with the manufacturer's instructions. Results In our in vitro investigations, the minimum inhibitory concentration (MIC) values for meropenem were determined to be >8 µg/ml, whereas for colistin, the MIC50 value was >16 µg/ml and the MIC90 value was 8 µg/ml. A total of 27 colistin-resistant strains were identified among the 79 carbapenem-resistant Enterobacterales strains analyzed. The most prevalent agent among colistin-resistant strains was Klebsiella pneumoniae (K. pneumoniae), representing 66.7% of the isolates. This was followed by Proteus mirabilis (P. mirabilis) with 29.6% and Escherichia coli (E. coli) with 3.7%. The colistin resistance rate among carbapenem-resistant strains was found to be 34.2%, with colistin MIC values in strains tested by the broth microdilution method ranging from 4 to >16 µg/ml concentrations. In polymerase chain reaction (PCR) studies, the mcr-1 gene region was successfully detected by real-time PCR in the positive control isolate. Nevertheless, none of the gene regions from mcr-1 to mcr-8 were identified in our study investigating the presence of plasmid-mediated genes using a multiplex PCR kit. Conclusion Although our study demonstrated the presence of increased colistin resistance rates in carbapenem-resistant Enterobacterales isolates, it resulted in the failure to detect genes from mcr-1 to mcr-8 by the multiplex PCR method. Therefore, it is concluded that the colistin resistance observed in Enterobacteriaceae isolates in our region is not due to the mcr genes screened, but to different resistance development mechanisms.202438957246
86250.9999Emergence of plasmid-mediated mcr genes from Gram-negative bacteria at the human-animal interface. BACKGROUND: The global emergence of plasmid-mediated colistin resistance (Col-R) conferred by mcr genes in gram-negative rods (GNRs) has jeopardized the last treatment option for multidrug-resistant bacterial infections in humans. This study aimed to assess the emergence of mcr gene-mediated Col-R in GNRs isolated from humans and animals in Pakistan. METHODS: Animal and clinical specimens collected from various sources were prospectively analysed using standard microbiological procedures. Pathogens were identified using the API 20E and API 20NE systems (bioMerieux). Minimum inhibitory concentration (MIC) against colistin was determined using the MIC detection methods, and multiplex polymerase chain reaction (PCR) was used to amplify the mcr-1 to mcr-5 genes. RESULTS: We isolated 126 (88.1%) animal and 17 (11.9%) human Col-R phenotypes, among which there was a significant association (P < 0.01) of Escherichia coli and Proteus mirabilis with animals and of Acinetobacter baumannii with humans. Animal strains exhibited statistically significant (P < 0.05) resistance to co-trimoxazole, chloramphenicol, and moxifloxacin, and the human pathogens exhibited statistically significant (P < 0.05) antibiotic resistance to cephalosporins, carbapenems, and piperacillin-tazobactam. For Col-R strains, MIC(50) values were > 6 µg/mL and > 12 µg/mL for human and animal isolates, respectively. mcr genes were detected in 110 (76.9%) bacterial strains, of which 108 (98.2%) were mcr-1 and 2 (1.8%) were mcr-2. CONCLUSIONS: The detection of a considerable number of mcr-1 and mcr-2 genes in animals is worrisome, as they are now being detected in clinical pathogens. The acquisition of mcr genes by colistin-susceptible bacteria could leave us in a post-antibiotic era.202033292525
108560.9999The occurrence and molecular detection of mcr-1 and mcr-5 genes in Enterobacteriaceae isolated from poultry and poultry meats in Malaysia. The advent of antimicrobials-resistant (AMR), including colistin-resistant bacteria, poses a significant challenge to animal and human health, food safety, socio-economic growth, and the global environment. This study aimed to ascertain the colistin resistance prevalence and molecular mechanisms of colistin resistance in Enterobacteriaceae. The colistin resistance was determined using broth microdilution assay, PCR; and Sanger sequencing of mcr genes responsible for colistin resistance in Enterobacteriaceae (n = 627), including Escherichia coli (436), Salmonella spp. (n = 140), and Klebsiella pneumoniae (n = 51), obtained from chicken and chicken meats. Out of 627 Enterobacteriaceae, 8.6% of isolates exhibited colistin resistance phenotypically. Among these colistin resistant isolates, 9.3% (n = 37) were isolated from chicken meat, 7.2% (n = 11) from the cloacal swab of chicken and 7.9% (n = 6) from the litter samples. Overall, 12.96% of colistin-resistant isolates were positive with mcr genes, in which mcr-1 and mcr-5 genes were determined in 11.11% and 1.85% of colistin-resistant isolates, respectively. The E. coli isolates obtained from chicken meats, cloacal swabs and litter samples were found positive for mcr-1, and Salmonella spp. originated from the chicken meat sample was observed with mcr-5, whereas no mcr genes were observed in K. pneumoniae strains isolated from any of the collected samples. The other colistin resistance genes, including mcr-2, mcr-3, mcr-4, mcr-6, mcr-7, mcr-8, mcr-9, and mcr-10 were not detected in the studied samples. The mcr-1 and mcr-5 genes were sequenced and found to be 100% identical to the mcr-1 and mcr-5 gene sequences available in the NCBI database. This is the first report of colistin resistance mcr-5 gene in Malaysia which could portend the emergence of mcr-5 harboring bacterial strains for infection. Further studies are needed to characterize the mr-5 harbouring bacteria for the determination of plasmid associated with mcr-5 gene.202337601372
108670.9999Antimicrobial Resistance Profiles and Co-Existence of Multiple Antimicrobial Resistance Genes in mcr-Harbouring Colistin-Resistant Enterobacteriaceae Isolates Recovered from Poultry and Poultry Meats in Malaysia. The co-existence of the colistin resistance (mcr) gene with multiple drug-resistance genes has raised concerns about the possibility of the development of pan-drug-resistant bacteria that will complicate treatment. This study aimed to investigate the antibiotic resistance profiles and co-existence of antibiotic resistance genes among the colistin-resistant Enterobacteriaceae isolates recovered from poultry and poultry meats. The antibiotic susceptibility to various classes of antibiotics was performed using the Kirby-Bauer disk diffusion method and selected antimicrobial resistance genes were detected using PCR in a total of 54 colistin-resistant Enterobacteriaceae isolates including Escherichia coli (E. coli) (n = 32), Salmonella spp. (n = 16) and Klebsiella pneumoniae (K. pneumoniae) (n = 6) isolates. Most of the isolates had multi-drug resistance (MDR), with antibiotic resistance against up to seven classes of antibiotics. All mcr-harbouring, colistin-resistant Enterobacteriaceae isolates showed this MDR (100%) phenotype. The mcr-1 harbouring E. coli isolates were co-harbouring multiple antibiotic resistance genes. The seven most commonly identified resistance genes ((bla)TEM, tetA, floR, aac-3-IV, aadA1, fosA, aac(6_)-lb) were detected in an mcr-1-harbouring E. coli isolate recovered from a cloacal swab. The mcr-5 harbouring Salmonella spp. isolate recovered from poultry meats was positive for (bla)TEM, tetA, floR, aac-3-IV, fosA and aac(6_)-lb genes. In conclusion, the colistin-resistant Enterobacteriaceae with mcr genes co-existing multiple clinically important antimicrobial resistance genes in poultry and poultry meats may cause potential future threats to infection treatment choices in humans and animals.202337370378
114580.9999Abundance of Mobilized Colistin Resistance Gene (mcr-1) in Commensal Escherichia coli from Diverse Sources. Aims: Antimicrobial resistance (AMR) spreads not only by pathogenic but also by commensal bacteria, and the latter can become a reservoir for resistance genes. This study was aimed to investigate the AMR patterns along with the presence of mobilized colistin resistance (mcr) genes in commensal Escherichia coli circulating in chickens, farm environments, street foods, and human patients. Materials and Methods: By a cross-sectional survey, isolates obtained from 530 samples were tested for their AMR profiles against 9 antimicrobials. Minimum inhibitory concentration (MIC) of the phenotypically colistin-resistant isolates was determined and screened for a set of mcr genes followed by sequencing of mcr-1 gene in the multidrug-resistant (MDR) isolates. Results: A total of 313 E. coli strains were isolated and confirmed by polymerase chain reaction. Antimicrobial susceptibility testing revealed that about 98% (confidence interval [95% CI] 95-99) of the isolates were MDR, and 58% (95% CI 52-63) isolates exhibited resistance to colistin. MIC values of colistin against the isolates ranged from 4 to 64 mg/L. Except for human patients, 20.4% colistin-resistant isolates from other sources of isolation had mcr-1 gene. Conclusions: There is abundance of commensal MDR E. coli strains with the acquisition of mcr-1 gene circulating in chickens and farm environments in Bangladesh.202133909471
114090.9999High abundance of the colistin resistance gene mcr-1 in chicken gut-bacteria in Bangladesh. Colistin is considered a last-resort reserved drug for the treatment of critical human infections by Gram-negative bacteria. Phenotypic colistin-resistance is strongly associated with plasmid-mediated mobile colistin resistance (mcr) genes. The mcr-bearing Enterobacteriaceae have been detected in many countries from environments, animals, and humans. This study investigated phenotypic colistin-resistance and the distribution of mcr-1, mcr-2, mcr-3, mcr-4, and mcr-5 genes in chicken-gut bacteria in Bangladesh. Bacteria were isolated from poultry- and native-chicken droppings, and their susceptibilities to colistin were determined by agar dilution and E-test minimal inhibitory concentration (MIC) measurements. Multiplex polymerase chain reactions detected mcr-1 to mcr-5 genes. Overall, 61.7% (92/149) of the isolates showed colistin resistance by agar dilution assessment (MIC > 2.0 μg/mL). The phenotypic resistance was observed considerably higher in poultry-chicken isolates (64.6%, 64/99) than in native-chicken isolates (56%, 28/50; p = 0.373). All the resistant isolates showed MIC levels between > 2 and > 128 μg/mL. The mcr-genes (mcr-1and mcr-2 combined) were detected more in poultry gut bacteria (36.4%) than native-chicken isolates (20%, p = 0.06). Despite bacteria sources, mcr-genes appeared to be significantly associated with phenotypic colistin-resistance phenomena (p < 0.001). Prior colistin usage led to a substantial increase in the proportion of bacteria with mcr-genes and phenotypic resistance (p < 0.001).202033057111
883100.9998Detection of plasmid-mediated colistin resistance, mcr-1 gene, in Escherichia coli isolated from high-risk patients with acute leukemia in Spain. BACKGROUND: Bacterial infections in immunocompromised patients are associated with a high mortality and morbidity rate. In this high-risk group, the presence of multidrug-resistant (MDR) bacteria, particularly bacteria that harbor a transferable antibiotic resistance gene, complicates the management of bacterial infections. In this study, we investigated the presence of the transferable colistin resistance mcr genes in patients with leukemia in Spain. METHODS: 217 fecal samples collected in 2013-2015 from 56 patients with acute leukemia and colonized with MDR Enterobacteriaceae strains, were screened on September 2017 for the presence of the colistin resistance mcr genes (mcr-1 to -5) by multiplex PCR. mcr positive strains selected on LBJMR and MacConkey supplemented with colistin (2 μg/ml) media were phenotypically and molecularly characterized by antimicrobial susceptibility testing, minimum inhibitory concentration, multilocus sequence typing and plasmid characterization. RESULTS: Among 217 fecal samples, 5 samples collected from 3 patients were positive for the presence of the mcr-1 colistin-resistance gene. Four Escherichia coli strains were isolated and exhibited resistance to colistin with MIC = 4 μg/ml. Other genes conferring the resistance to β-lactam antibiotics have also been identified in mcr-1 positive strains, including bla(TEM-206) and bla(TEM-98). Three different sequence types were identified, including ST1196, ST140 and ST10. Plasmid characterization allowed us to detect the mcr-1 colistin resistance gene on conjugative IncP plasmid type. CONCLUSION: To the best of our knowledge, we have identified the mcr-1 gene for the first time in leukemia patients in Spain. In light of these results, strict measures have been implemented to prevent its dissemination.201931023570
1144110.9998Identification of mcr-2 and mcr-3 Genes in Colistin-Resistant E. coli O157:H7 Isolated From Raw Meat Samples in Beirut, Lebanon. Colistin is a last-resort antibiotic used to treat multidrug-resistant Gram-negative bacterial infections. The global emergence of colistin resistance has been attributed to plasmid-mediated mobile colistin resistance (mcr) genes. In Lebanon, bacteria carrying the mcr-1 gene have increasingly been identified in food animal sources. This study is aimed at detecting colistin-resistant Shiga toxigenic Escherichia coli O157:H7 in raw meat samples from local markets in the suburbs of Beirut and evaluating their antimicrobial resistance profiles. A total of 50 meat samples, including 25 minced beef and 25 burger samples, were collected and analyzed. Antimicrobial resistance patterns were determined using the Kirby-Bauer method, while colistin resistance and the presence of mcr-2 and mcr-3 genes were assessed using broth microdilution and PCR amplification techniques. Among these samples, 23 (46%) tested positive for E. coli O157:H7. Resistance to ampicillin and amoxicillin/clavulanic acid was observed in 96% of the samples, while 61% were resistant to trimethoprim/sulfamethoxazole, and 43% to chloramphenicol. Notably, 87% of the samples displayed colistin resistance, with a minimum inhibitory concentration (MIC) of ≥ 4 μg/mL. The mcr-2 gene was present in four isolates (17.4%), and the mcr-3 gene was identified in 10 isolates (43.4%). This study is the first to document the presence of plasmid-mediated colistin resistance genes, mcr-2 and mcr-3, in E. coli O157:H7 strains in Lebanon. These findings highlight a serious public health concern for the Lebanese community. Therefore, the responsible use of antibiotics across all healthcare sectors, combined with strict hygiene measures in food handling, is essential to control the spread of colistin-resistant genes.202540226838
863120.9998Colistin-resistance genes in Escherichia coli isolated from patients with urinary tract infections. BACKGROUND: The incidence of antimicrobial resistance is alarmingly high because it occurs in humans, environment, and animal sectors from a "One Health" viewpoint. The emergence of plasmid-carried mobile colistin-resistance (MCR) genes limits the efficacy of colistin, which is the last-line treatment for multidrug resistance (MDR) against gram-negative infections. OBJECTIVES: The current study aimed to investigate emergence of colistin-resistance (MCR 1-5) genes in E. coli isolated from patients with urinary tract infections (UTIs) in Jordan. METHODS: E. coli (n = 132) were collected from urine specimens. The E. coli isolated from human UTI patients were examined the resistance to colistin based on the presence of MCR (1-5). All isolates were tested against 20 antimicrobials using the standard disk diffusion method. The broth microdilution technique was used to analyze colistin resistance. In addition, the MCR (1-5) genes were detected using multiplex PCR. RESULTS: Out of the 132 isolates, 1 isolate was colistin-resistant, having a minimum inhibitory concentration of 8 μg/mL and possessing MCR-1. All the E. coli isolates showed high resistance to penicillin (100%), amoxicillin (79.55%), cephalexin (75.76%), nalidixic acid (62.88%), tetracycline (58.33%), or cefepime (53.79). CONCLUSION: To our knowledge, this is the first report on the presence of plasmid-coded MCR-1 in E. coli from a patient with UTIs in Jordan. This is a problematic finding because colistin is the last-line drug for the treatment of infections caused by MDR gram-negative bacteria. There is a crucial need to robustly utilize antibiotics to control and prevent the emergence and prevalence of colistin-resistance genes.202438865304
861130.9998The Prevalence Rates of Colistin Resistance Among Third-Generation Cephalosporin-Resistant E. coli Isolates From Thai Patients. Drug-resistant infections, such as colistin resistance, are reportedly increasing due to the inappropriate use of antibiotics, lack of good control, and the use of excessive quantities of antibiotics. Colistin resistance has been observed in bacteria of the order Enterobacterales exhibiting resistance to third-generation cephalosporins or carbapenems. Currently, the prevalence of colistin resistance in third-generation cephalosporin-resistant E. coli obtained from patients at Nopparat Rajathanee Hospital, Thailand, in 2023 was determined by broth microdilution. Among 343 isolates, 1.45% (95% CI: 0.19%-2.73%, n = 5/343) exhibited a minimum inhibitory concentration (MIC) of colistin between 4 and 8 μg/mL, indicating colistin-resistant E. coli. Nevertheless, five isolates were positive for resistant genes by multiplex PCR: two isolates for mcr-1, two isolates for mcr-3, and one isolate for both mcr-1 and mcr-3. This study reveals crucial data on resistance genes, informing surveillance of antibiotic resistance, treatment decisions, and public health initiatives to combat resistant bacteria.202541170286
919140.9998Molecular Characteristics of Carbapenem-Resistant Enterobacter cloacae in Ningxia Province, China. The emergence of carbapenem-resistant Enterobacteriaceae (CRE) has become a major public health concern worldwide and a new challenge in the treatment of infectious diseases. The molecular characteristics of Enterobacter cloacae in Ningxia China are unknown. In this study, we reported 10 carbapenem-resistant E. cloacae isolates from the General Hospital of Ningxia Medical University, the largest university hospital in Ningxia between January 2012 and December 2013. Bacteria isolates were identified by Vitek2 compact and the identity of non-duplicate E. cloacae isolates was further confirmed by PCR and sequencing. The drug susceptibility and phenotype identification of these isolates were analyzed by agar dilution method, modified Hodge test (MHT), and EDTA synergy test. Beta-lactamase (bla) genes bla(NDM-1) was found in 8 out of 10 isolates. Most isolates harbored multiple resistance genes including bla(ESBL), bla(AmpC), quinolones, aminoglycosides, and disinfectant resistance genes. Pulsed field gel electrophoresis (PFGE) showed that these E. cloacae isolates were grouped into 6 clusters based on a cutoff of 80% genetic similarity. In conjugative assay, 9 out of 10 isolates transferred carbapenem-resistant genes to Escherichia coli. Our study has revealed that NDM-1-producing isolates are the most prevalent carbapenem-resistant E. cloacae in Ningxia. These isolates also carry several other carbapenem-resistant genes and can transfer these genes to other bacteria through conjugation. These findings highlight an urgent need to monitor these isolates to prevent their further spread in this region.201728197140
859150.9998Analysis of mcr family of colistin resistance genes in Gram-negative isolates from a tertiary care hospital in India. AIM: Colistin serves as the drug of last resort for combating numerous multidrug-resistant (MDR) Gram-negative infections. Its efficacy is hampered by the prevalent issue of colistin resistance, which severely limits treatment options for critically ill patients. Identifying resistance genes is crucial for controlling resistance spread, with horizontal gene transfer being the primary mechanism among bacteria. This study aimed to assess the prevalence of plasmid-mediated mcr genes associated with colistin resistance in Gram-negative bacteria, utilizing both genotypic and phenotypic tests. METHODS AND RESULTS: The clinical isolates (n = 913) were obtained from a tertiary care center in Chennai, India. Colistin resistance was seen among Gram-negative isolates. These strains underwent screening for mcr-1, mcr-3, mcr-4, and mcr-5 genes via conventional PCR. Additionally, mcr-positive isolates were confirmed through Sanger sequencing and phenotypic testing. The bacterial isolates predominantly comprised Klebsiella pneumoniae (62.43%), Escherichia coli (19.71%), Pseudomonas aeruginosa (10.73%), and Acinetobacter baumannii (4.81%), along with other species. All isolates exhibited multidrug resistance to three or more antibiotic classes. Colistin resistance, determined via broth microdilution (BMD) using CLSI guidelines, was observed in 13.08% of the isolates studied. Notably, mcr-5 was detected in K. pneumoniae in PCR, despite its absence in Sanger sequencing and phenotypic tests (including the combined-disk test, colistin MIC in the presence of EDTA, and Zeta potential assays). This finding underscores the importance of employing multiple diagnostic approaches to accurately identify colistin resistance mechanisms.202438986507
1051160.9998Multi-drug Resistance, β-Lactamases Production, and Coexistence of bla (NDM-1) and mcr-1 in Escherichia coli Clinical Isolates From a Referral Hospital in Kathmandu, Nepal. The ability of pathogenic Escherichia coli to produce carbapenemase enzymes is a characteristic that allows them to resist various antibiotics, including last-resort antibiotics like colistin and carbapenem. Our objectives were to identify rapidly developing antibiotic resistance (AR), assess β-lactamases production, and detect mcr-1 and bla (NDM-1) genes in the isolates. A prospective cross-sectional study was carried out in a referral hospital located in Kathmandu from November 2019 to December 2020 using standard laboratory and molecular protocols. Among 77 total E. coli isolates, 64 (83.1%) of them were categorized as MDR. Phenotypically 13 (20.3%) colistin-resistant, 30 (46.9%) ESBL and 8 (12.5%) AmpC producers, and 5 (7.8%) ESBL/AmpC co-producers were distributed among MDR-E. coli. Minimum inhibitory concentrations (MIC) against the majority of MDR isolates were exhibited at 1 g/L. Of these 77 E. coli isolates, 24 (31.2%) were carbapenem-resistant. Among these carbapenem-resistant bacteria, 11 (45.9%) isolates were reported to be colistin-resistant, while 15 (62.5%) and 2 (8.3%) were MBL and KPC producers, respectively. Out of 15 MBL producers, 6 (40%) harbored bla (NDM-1), and 8 (61.5%) out of 13 colistin-resistant pathogens possessed mcr-1. The resistance by colistin- and carbapenem were statistically associated (P < .001). However, only 2 (18.2%) of the co-resistant bacteria were found to have both genes. Our study revealed the highly prevalent MDR and the carbapenem-resistant E. coli and emphasized that the pathogens possess a wide range of capabilities to synthesize β-lactamases. These findings could assist to expand the understanding of AR in terms of enzyme production.202336741474
1624170.9998Detection of chromosomal and plasmid-mediated mechanisms of colistin resistance in Escherichia coli and Klebsiella pneumoniae from Indian food samples. OBJECTIVES: Numerous previous publications on the detection of bacterial isolates harbouring the mcr-1 gene from animals and humans strongly suggest an underlying route of transmission of colistin resistance via the food chain. The aim of this study was to investigate the presence of colistin-resistant (Col-R) bacteria in Indian food samples and to identify the underlying mechanisms conferring colistin resistance. METHODS: Raw food material, including poultry meat, mutton meat, fish, fruit and vegetables, collected from food outlets in Chennai, India, were processed to identify Col-R bacteria using eosin methylene blue agar supplemented with colistin. Colistin minimum inhibitory concentrations (MICs) were determined by the broth microdilution method. PCR for the mcr-1 and mcr-3 genes was performed on Col-R Escherichia coli and Klebsiella pneumoniae isolates. Mutations in the mgrB gene were analysed in K. pneumoniae isolates. One representative mcr-1-positive E. coli was subjected to whole-genome sequencing. RESULTS: Of 110 food samples tested, 51 (46.4%) were positive for non-intrinsic Col-R Gram-negative bacteria. Three E. coli isolates were found to harbour mcr-1, whereas none were positive for mcr-3. Ten K. pneumoniae isolates had alterations in mgrB, with mutations in four and insertional inactivation in six. CONCLUSION: The presence of Col-R bacteria and the mcr-1 gene in raw food samples further complicates the antimicrobial resistance scenario in India. To the best of our knowledge, this is the first report in the global literature on mgrB mutation and its insertional inactivation conferring Col-R in K. pneumoniae from food samples.201930244040
884180.9998Fecal carriage and molecular epidemiology of mcr-1-harboring Escherichia coli from children in southern China. BACKGROUND: The increase of multidrug-resistant Enterobacteriaceae bacteria has led to the reintroduction of colistin for clinical treatments, and colistin has become a last resort for infections caused by multidrug-resistant bacteria. Enterobacteriaceae bacteria carrying the mcr-1 gene are majorly related to colistin resistance, which may be the main reason for the continued increase in the colistin resistance rate of Enterobacteriaceae. The study aimed to investigate the sequence type and prevalence of Escherichia coli (E. coli) harboring the mcr-1 gene in the gut flora of children in southern China. METHODS: Fecal samples (n = 2632) of children from three medical centers in Guangzhou were cultured for E. coli. The mcr-1-harboring isolates were screened via polymerase chain reaction (PCR). The colistin resistance transfer frequency was studied by conjugation experiments. DNA sequencing data of seven housekeeping genes were used for multi-locus sequence typing analysis (MLST). RESULTS: PCR indicated that 21 of the 2632 E. coli (0.80%) isolates were positive for mcr-1; these strains were resistant to colistin. Conjugation experiments indicated that 18 mcr-1-harboring isolates could transfer colistin resistance phenotypes to E. coli J53. MLST analysis revealed that the 21 isolates were divided into 18 sequence types (STs); E. coli ST69 was the most common (14.3%), followed by E. coli ST58 (9.5%). CONCLUSION: These results demonstrate the colonization dynamics and molecular epidemiology of E. coli harboring mcr-1 in the gut flora of children in southern China. The mcr-1 gene can be horizontally transmitted within species; hence, it is necessary to monitor bacteria that harbor mcr-1 in children.202337196369
1143190.9998Antimicrobial Resistance and Virulence Profiles of mcr-1-Positive Escherichia coli Isolated from Swine Farms in Heilongjiang Province of China. ABSTRACT: The emergence and global distribution of the mcr-1 gene for colistin resistance have become a public concern because of threats to the role of colistin as the last line of defense against some bacteria. Because of the prevalence of mcr-1-positive Escherichia coli isolates in food animals, production of these animals has been regarded as one of the major sources of amplification and spread of mcr-1. In this study, 249 E. coli isolates were recovered from 300 fecal samples collected from swine farms in Heilongjiang Province, People's Republic of China. Susceptibility testing revealed that 186 (74.70%) of these isolates were colistin resistant, and 86 were positive for mcr-1. The mcr-1-positive isolates had extensive antimicrobial resistance profiles and additional resistance genes, including blaTEM, blaCTX-M, aac3-IV, tet(A), floR, sul1, sul2, sul3, and oqxAB. No mutations in genes pmrAB and mgrB were associated with colistin resistance. Phylogenetic group analysis revealed that the mcr-1-positive E. coli isolates belonged to groups A (52.33% of isolates), B1 (33.72%), B2 (5.81%), and D (8.14%). The prevalence of the virulence-associated genes iutA, iroN, fimH, vat, ompA, and traT was moderate. Seven mcr-1-positive isolates were identified as extraintestinal pathogenic. Among 20 mcr-1-positive E. coli isolates, multilocus sequence typing revealed that sequence type 10 was the most common (five isolates). The conjugation assays revealed that the majority of mcr-1 genes were transferable at frequencies of 7.05 × 10-7 to 7.57 × 10-4. The results of this study indicate the need for monitoring and minimizing the further dissemination of mcr-1 among E. coli isolates in food animals, particularly swine.202032730609