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旨在分析养殖鱼塘水体中铜绿假单胞菌(Pseudomonas aeruginosa,PA)分离菌株的致病性、耐药性及其可能机制,为保障水产食品的安全提供科学依据。使用美国临床与实验室标准研究所的标准纸片扩散法,以及聚合酶链反应技术对PA分离菌株进行了抗菌素耐药性,以及毒性、固有和获得性耐药相关基因的检测与分析。结果显示,受试PA分离菌株的50%为exoS+/exoU-侵染型分子型,无临床分离菌株的exoS-/exoU+的细胞毒型分子型。PA菌株对6大类9种抗菌素的耐药性存在明显差异,其中甲氧胺苄嘧啶和利福平的耐药率最高为100%,其次是氨苄西林、卡那霉素和四环素,分别为90%、90%和80%,庆大霉素的耐药率最低为10%。多药抗性PA菌株均含有MexAB-OprM、MexXY-OprM和MexVW-OprM外排泵系统,其中20%菌株检测为β-内酰胺酶基因(ampC)阳性;而MexEF-OprN、MexJK-OprM、MexCD-OprJ和MexGHI-OpmD外排泵基因全部或部分缺失。此外,在PA菌株中均未检测到Ⅰ～Ⅲ类整合子的整合酶基因(comINT),但是整合接合元件(ICEs)保守模块功能基因(ICEint、soj、pilS2、pilD)均检测为阳性,提示PA菌株携带的ICEs具有潜在的转移活性,为进一步探讨PA多药抗性的散播奠定了基础。
The aim of this study is to analyze the pathogenicity, drug resistance and the possible mechanism of Pseudomonas aeruginosa (PA) isolates from the cultured fish ponds and provide a scientific basis for the safety of aquatic food. The antibacterial resistance of PA isolates and the detection and analysis of genes related to virulence, innate and acquired resistance were tested using the standard disk diffusion method of the American Institute of Clinical and Laboratory Standards and polymerase chain reaction. The results showed that 50% of the tested PA isolates were of the exoS + / exoU-infective molecular type and no exoS- / exoU + of the clinically isolated strains were cytotoxic. The antibacterial resistance of PA strains to 6 kinds of 9 kinds of antibiotics were significantly different, among which, the rates of resistance to methicillin and rifampin were 100%, followed by ampicillin, kanamycin and tetracycline, respectively 90%, 90% and 80%, the lowest rate of gentamicin resistance was 10%. Multi-drug resistant PA strains contained the MexAB-OprM, MexXY-OprM and MexVW-OprM efflux pump system, of which 20% were positive for beta-lactamase gene (ampC), while MexEF-OprN, MexJK-OprM, MexCD-OprJ and MexGHI-OpmD efflux pump genes were deleted in whole or in part. In addition, no integrants of class I ~ III integrants (comINT) were detected in the PA strains, but functional fragments of the ICE conserved modules (ICEint, soj, pilS2, pilD) were all detected as positive PA strains carrying ICEs have potential metastatic activity, which lays the foundation for further exploring the spread of PA multidrug resistance.