Distribution And Molecular Characteristics Of Antibiotic Resistance Bacteria In Chilled Livestock Meats In Supermarkets Of Beijing

Over the past few decades,antibiotic resistance caused by antibiotics abuse has drawn great public concern and seriously harm for human health.A lot of research groups around the world are working with the drug resistant pathogenic bacteria.Whereas,limited information are available about distribution of commensal bacteria and antibiotic resistance characteristics in chilled meat.In this study,antibiotic resistance microbial diversity in chilled fresh livestock meats were analyzed by metagenomic.At the same time,the prevalence of antibiotic resistance isolates and genes in chilled fresh meats sold in supermarkets of Beijing from winter to spring were investigated by isolation and identification,and characteristics of antibiotic resistance isolates were analyzed.This paper aims to reveal and discuss the distribution and molecular characteristics in general level of antibiotic resistance bacteria in chilled livestock meats from supermarkets of Beijing.In the analysis of antibiotic resistance bacterial community diversity of chilled fresh livestock meats on metagenomic,the fresh livestocck meat samples?beef,pork and mutton?were preprocessed by 14 different antibiotic,then the DNA of samples in experimental and contral groups were extracted,the V3-V4 region of the 16S rRNA genes were sequenced by Illumina MiSeq.Finally,the date were analyzed by bioinformatics.The indexes of alpha diversity shown that the total number of species and species diversity in samples were declined in certain degree which processed by antibiotic compared with control groups.The result of clustering and bacterial abundance shown there was high similarity in the same groups and the microbial community structure were changed in varying degrees compared with contral groups.In these groups,the predominant microflora were Aeromonas spp.and pseudomonas spp..In the study of distribution of antibiotic resistance bacteria and genes,a total of 96samples?44 pork,41 beef and 11mutton?were purchased from supermarkets in eight regions of Beijing from winter of 2015 to spring of 2016.The number of total bacteria and antibiotic resistance bacteria of all samples were counted,antibiotic resistance bacteria were also identified by MALDI-TOF MS,the result shown that the values of samples collected in spring were all obvious higher than which collected in winter,and contamination rate of antibiotic resistance bacteria in samples was differ significant?P value?.Meanwhile,586 antibiotics resistance bacteria of 26 different genus were obtained,pseudomonas spp.?43.36%,n=254?and serratia spp.?34.30%,n=201?hold a strong majority in antibiotic resistance isolates.In 96 samples,erythromycin resistance determinants ermA,ermB,ermC,ereA,ereB,mef?A/E?,mphA,tetracycline resistance genes tetM,tetO,tetK,tetL and colistin resistance gene mcr-1 were 24?25%?,60?62.5%?,20?20.8%?,66?68.8%?,0?0%?,77?80.2%?,0?0%?,82?85.4%?,13?13.5%?,67?69.8%?,87?90.6%?and 0?0%?.In the study of characteristics of antibiotic resistance isolates,160 isolates were tested antibiotic susceptibility,while,all isolates were resistant to at least one antimicrobial,131?81.88%?isolates were multidrug-resistant.A lot of isolates?61.5%⁸2.4%?resistant to ampicillin,tetracycline,amoxicillin,clavulanic acid,penicillin G,erythromycin and Oxacillin,some isolates?13.1%⁴4.8%?resistant to gentamicin,colistin,sulfamethoxazole-trimethoprim,aztreonam cefazolin,ampicillin-salbactam,piperacillin,cefoxitin and clindamycin.Finally,an isolate?Acinetobacter baumannii?produced extended spectrum?-lactamases were identified,and PCR showed that Acinetobacter baumannii positive for bla_TEM.