Abundance of colistin-resistant Escherichia coli harbouring mcr-1 and extended-spectrum β-lactamase-producing E. coli co-harbouring bla(CTX-M-55) or (-65) with bla(TEM) isolates from chicken meat in Vietnam.

Although the spread of plasmid-mediated antibiotic-resistant bacteria is a public health concern, food contamination with plasmid-mediated antibiotic-resistant Escherichia coli in Vietnam has not been well investigated. This study aimed to describe the prevalence of colistin-resistant, carbapenem-resistant, and endemic blaCTX-M in extended-spectrum β-lactamase (ESBL) producing E. coli isolates. Colistin and carbapenem-resistant ESBL-producing E. coli were isolated from chickens in Vietnam and Japan. Colistin-resistant and AmpC/ESBL-producing E. coli (52% and 93%, respectively) were detected in chickens from Vietnam, in comparison to 52.7%, AmpC/ESBL-producing E. coli found in chicken from Japan. Carbapenem-resistant E. coli has not been isolated in Vietnam and Japan. Genotyping revealed that colistin-resistant E. coli harboured mcr-1, and most of the AmpC/ESBL-related genes were blaCTX-M-55 and blaCTX-M-65 together with blaTEM in Vietnamese chickens and blaCMY-2 in Japanese chickens. Multi-drug resistance analysis showed that ESBL-producing E. coli isolates had greater resistance to quinolones, streptomycin, and chloramphenicol than colistin-resistant E. coli isolates from Vietnam, suggesting the selection of multiple antibiotic resistance genes in ESBL-producing E. coli. In conclusion, colistin-resistant E. coli was detected in approximately half of the chicken samples, the majority of which harboured mcr-1. The high prevalence of ESBL-producing E. coli has remained constant in the last 5 years. The predominant blaCTX-M in ESBL-producing E. coli was blaCTX-M-55 or blaCTX-M-65, with the coexistence of blaTEM in Vietnam. These results can be implemented in monitoring systems to overcome the development of antimicrobial resistance.

Nakayama T ，Le Thi H ，Thanh PN ，Minh DTN ，Hoang ON ，Hoai PH ，Yamaguchi T ，Jinnai M ，Do PN ，Van CD ，Kumeda Y ，Hase A ... -  《-》

High prevalence of mcr-1 encoding colistin resistance and first identification of bla(CTX-M-55) in ESBL/CMY-2-producing Escherichia coli isolated from chicken faeces and retail meat in Tunisia.

Avian industries have been reported as an important contributor in the worldwide spread of antibiotic resistance owing to some particular practices especially the overuse of antibiotics. Thus in this study, we aimed to characterize extended-spectrum-beta-lactamase (ESBL) and acquired-AmpC-beta-lactamase (aAmpC)-producing Escherichia coli isolates from chicken faeces and raw meat in Tunisia. During the year 2018, 286 faecal chicken swabs and 47 raw chicken meat samples were collected and processed to recover cefotaxime-resistant E. coli. Antimicrobial susceptibility was performed by disk-diffusion and/or broth-microdilution. blaTEM, blaSHV, blaCTX-M, and blaCMY genes were investigated by PCR/sequencing. Genes encoding resistance to colistin (mcr-1 to mcr-8), tetracycline (tetA/tetB), sulfonamide (sul1/sul3), and chloramphenicol (cmlA), were analysed by PCR. Class 1 integrons were investigated by PCR/sequencing. Phylogenetic groups of all isolates were determined. PFGE and MLST were performed for representative isolates. PCR-based replicon typing was performed in mcr1-harbouring isolates. Cefotaxime-resistant E. coli was detected in 22.4% (64/286) and 63.8% (30/47) of faeces and meat samples, respectively. Ninety isolates were ESBL-producers and harboured the genes: blaCTX-M-1 +/- blaTEM-1 (n = 65), blaCTX-M-55 +/- blaTEM-1 (n = 21), blaCTX-M-14 (n = 1), and blaSHV-12 (n = 3). The blaCMY-2 gene was detected in four ESBL-negative isolates. Isolates belonged to phylogroups D (50%), A (36.2%), B1 (9.6%), and B2 (4.3%). Fifty-four were colistin-resistant and 52 carried the mcr-1 gene. The tetA, sul1/sul3 and cmlA genes were detected among resistant isolates and 76 harboured class 1 integrons. MLST analysis revealed 13 sequence types (STs). The isolates were classified into 28 PFGE types. The IncP, IncFIB, and IncI1 replicons were detected among mcr-1-positive strains. We report a high frequency of ESBL-producers and colistin-resistant E. coli in chicken and derived food and the detection for the first time of blaCTX-M-55 in poultry in Tunisia.

Hassen B ，Abbassi MS ，Ruiz-Ripa L ，Mama OM ，Hassen A ，Torres C ，Hammami S ... -  《-》

Occurrence of the Colistin Resistance Gene mcr-1 and Additional Antibiotic Resistance Genes in ESBL/AmpC-Producing Escherichia coli from Poultry in Lebanon: A Nationwide Survey.

Mikhayel M ，Leclercq SO ，Sarkis DK ，Doublet B ... -  《Microbiology Spectrum》

Prevalence of colistin resistance and mcr-1/mcr-2 genes in extended-spectrum β-lactamase/AmpC-producing Escherichia coli isolated from chickens in Canada, Senegal and Vietnam.

This study investigated the prevalence of Escherichia coli (E. coli) colistin resistance and mcr-1 and mcr-2 genes among extended-spectrum β-lactamase (ESBL)/AmpC-producing E. coli isolates recovered from chicken feces in Canada (Quebec), Senegal and Vietnam, and evaluated the susceptibility pattern of the colistin-resistant E. coli isolates to other clinically relevant antimicrobials. A total of 327 potential ESBL/AmpC-producing E. coli isolates from chicken farms in Canada (Quebec), Senegal and Vietnam were analysed for colistin susceptibility by broth microdilution method and for the presence of mcr (1-2) genes by PCR. The pmrA and pmrB genes of colistin-resistant E. coli isolates, in the absence of mcr (1-2) genes, were sequenced. Antimicrobial resistance phenotypes of colistin-resistant E. coli isolates were determined by disk diffusion. None of the 108 potential ESBL/AmpC-producing E. coli isolates from seven farms in Canada were colistin-resistant or possessed mcr-1 or mcr-2 gene. A low prevalence of 2.2% of colistin resistance was observed in 93 Senegalese isolates from the 15 sampled farms, although neither mcr-1 nor mcr-2 gene was found. A prevalence of 8.7% of colistin resistance was observed among 126 Vietnamese isolates from two of the four sampled farms. The mcr-1 gene was detected in 85% of the 13 phenotypically colistin-resistant isolates. Moreover, all colistin-resistant isolates presented a multidrug-resistant phenotype. The co-existence of the mcr-1 and ESBL/AmpC genes and the very high level of multiple drug resistance in all colistin-resistant E. coli isolates obtained from sampled chicken farms in Vietnam is a major concern.

Vounba P ，Rhouma M ，Arsenault J ，Bada Alambédji R ，Fravalo P ，Fairbrother JM ... -  《-》

Prevalence of mobile colistin resistance (mcr) genes in extended-spectrum β-lactamase-producing Escherichia coli isolated from retail raw foods in Nha Trang, Vietnam.

The aim of the study was to assess the presence of genes in ESBL-producing E. coli (ESBL-Ec) isolated from retail raw food in Nha Trang, Vietnam. A total of 452 food samples comprising chicken (n = 116), pork (n = 112), fish (n = 112) and shrimp (n = 112) collected between 2015 and 2017 were examined for the prevalence of ESBL-Ec. ESBL-Ec were detected in 46.0% (208/452) of retail food samples, particularly in 66.4% (77/116), 55.4% (62/112), 42.0% (47/112) 19.6% (22/112) of chicken, pork, fish and shrimp, respectively. Sixty-five out of the 208 (31.3%) ESBL-Ec isolates were positive for mcr genes including mcr-1, mcr-3 and both mcr-1 and mcr-3 genes in 56/208 (26.9%), 1/208 (0.5%) and 8/208 (3.9%) isolates, respectively. Particularly, there was higher prevalence of mcr-1 in ESBL-Ec isolates from chicken (53.2%, 41/77) in comparison to shrimp (22.7%, 5/22), pork (11.3%, 7/62) and fish (6.4%, 3/47). mcr-3 gene was detected in co-existence with mcr-1 in ESBL-Ec isolates from shrimp (9.1%, 2/22), pork (8.1%, 5/62) and fish (2.1%, 1/47) but not chicken. The 65 mcr-positive ESBL-Ec (mcr-ESBL-Ec) were colistin-resistant with the MICs of 4-8 μg/mL. All mcr-3 gene-positive isolates belonged to group A, whereas phylogenetic group distribution of isolates harboring only mcr-1 was B1 (44.6%), A (28.6%) and D (26.8%). PFGE analysis showed diverse genotypes, although some isolates demonstrated nearly clonal relationships. S1-PFGE and Southern hybridization illustrated that the mcr-1 and mcr-3 genes were located either on chromosomes or on plasmids. However, the types of mcr genes were harbored on different plasmids with varied sizes of 30-390 kb. Besides, the ESBL genes of CTX-M-1 or CTX-M-9 were also detected to be located on plasmids. Noteworthy, co-location of CTX-M-1 with mcr-1 or mcr-3 genes on the same plasmid was identified. The conjugation experiment indicated that the mcr-1 or mcr-3 was horizontally transferable. All mcr-ESBL-Ec isolates were multidrug resistance (resistance to ≥3 antimicrobial classes). Moreover, β-Lactamase-encoding genes of the CTX-M-1 (78.5%), CTX-M-9 (21.5%), TEM (61.5%) groups were found in mcr-ESBL-Ec. The astA gene was detected in 27 (41.5%) mcr-ESBL-Ec isolates demonstrating their potential virulence. In conclusion, mcr-1 and mcr-3 genes existed individually or concurrently in ESBL-Ec isolates recovered from retail raw food in Nha Trang city, which might further complicate the antimicrobial-resistant situation in Vietnam, and is a possible health risk for human.

Le PQ ，Awasthi SP ，Hatanaka N ，Hinenoya A ，Hassan J ，Ombarak RA ，Iguchi A ，Tran NTT ，Dao KVT ，Vien MQ ，Le HX ，Do HT ，Yamamoto Y ，Yamasaki S ... -  《-》