研究食品中克罗诺杆菌分离菌株的生物被膜形成、耐药性以及携带毒力基因情况。在成都市周边农贸市场和路边小摊采集食品样品129份,采用DFI 阪崎肠杆菌显色培养基分离克罗诺杆菌;通过16S rRNA序列比对分析鉴定分离菌株;采用试管法和微孔板法分析菌株生物被膜形成能力,同时研究温度对细菌成膜能力影响;采用纸片法检测分离菌株对18种抗生素的耐药性;采用PCR方法检测分离菌株携带cpa、hly、sip 和ompX毒力基因情况。结果发现从129份食品样本中共检出克罗诺杆菌43株,检出率为33.3%。43株克罗诺杆菌食品分离菌株的成膜率为90.7%,并且温度对细菌成膜影响明显。四种毒力基因中,ompX检出率为100%;cpa检出率为13.9%;hly检出率为11.6%;sip基因未检出。耐药表型检测发现43株克罗诺杆菌食品分离菌株对青霉素、克林霉素、万古霉素、苯唑西林和杆菌肽B的耐药率为100%,对利福平的耐药率达97.7%;对红霉素的耐药率为7%;对环丙沙星、庆大霉素、四环素、氯霉素、亚胺培南、磺胺甲恶挫、呋喃妥因、头孢西丁、链霉素、阿米卡星、氧氟沙星等100%敏感。本研究表明克罗诺杆菌食品分离菌株具有较好的形成生物被膜能力,对常见的抗生素耐药率较高,并且分离菌株携带一定的毒力基因,对食品安全造成潜在威胁。
In this study, Cronobacter spp. food isolates were identified, and the biofilm formation ability, antimicrobial susceptibility and virulence genes were investigated. All 129 food samples were collected from food markets and food stands from Chengdu city in 2016.Cronobacter spp. were isolated and identified by DFI selective medium and 16S rRNA sequencing analysis. The 96-well microplate and tube test were used to detect biofilm formation ability. The influence of temperature on the biofilm formation was also explored. The antimicrobial susceptibility of Cronobacter spp. isolates to 18 antibiotics was detected by disk diffusion method. The virulence genes (cpa, hly, sip, and ompX) were detected by PCR. The results showed 43 Cronobacter spp. strains were identified from 129 food samples. The Cronobacter spp. isolation rate was 33.3%. The biofilm formation rate was 90.7% and the temperature had a significant effect on bacterial biofilm formation. The detection rate of ompX gene in 43 Cronobacter spp. strains was 100%;cpa was 13.9%, hly was 11.6%, and the sip gene was not detected in all isolates. The drug resistance rates to penicillin, clindamycin, vancomycin, oxacillin and bacitracin B for all 43 Cronobacter were 100%. The drug resistance rate to rifampicin was 97.7%. For erythromycin, the resistance rate was 7%. All the Cronobacter food isolates were sensitive to ciprofloxacin, gentamicin, tetracycline, chloramphenicol, imipenem, sulfamethoxazole, nitrofurantoin, cefoxitin, streptomycin, amikacin, and ofloxacin, completely. The study indicated Cronobacter spp. food isolates had better biofilm formation ability and had some resistance to most antibiotics. The food safety were threatened by Cronobacter spp. isoaltes with virulence genes.