生牛乳中高黏液型肺炎克雷伯菌耐药、毒力及生物被膜形成能力分析

Analysis of drug resistance,virulence and biofilm formation ability in hypermucoviscous Klebsiella pneumoniae from raw milk

  • 摘要: 【目的】评估分离自生牛乳及其环境中高黏液型肺炎克雷伯菌(hypermucoviscous Klebsiella pneumoniae,hmKP)的生物被膜形成能力及耐药毒力风险,对其可能引起的潜在风险提出警示,进而为肺炎克雷伯菌(KP)的科学防治提供理论参考。【方法】采用药敏纸片法鉴定32株hmKP产超广谱β-内酰胺酶(ESBLs)表型,以半定量结晶紫法检测其生物被膜形成能力,并通过PCR对hmKP携带的耐药基因和毒力基因进行检测分析。【结果】从32株hmKP中共鉴定出ESBLs阴性菌株(non-ESBLs-KP)24株(占75.00%)、ESBLs阳性菌株(ESBLs-KP)8株(占25.00%),均可形成生物被膜,其中,10株具有强生物被膜形成能力,17株具有中等生物被膜形成能力,5株表现为弱生物被膜形成能力。在10株具有强生物被膜形成能力的hm KP中有7株来自生牛乳样本,且ESBLs-KP中具有强生物被膜形成能力的菌株检出率(37.50%)高于non-ESBLs-KP中的检出率(29.17%)。所有hmKP至少携带4种以上的耐药基因,其耐药风险排序依次为四环素类=氨基糖苷类>β-内酰胺类>磺胺类>喹诺酮类>氯霉素类,其中ESBLs-KP均携带8种以上的耐药基因;32株hmKP共表现出30种基因谱类型,无明显的优势耐药基因谱类型。在32株hmKP中共检出wabGfimHmrkDentBybtS等5种毒力基因,其中,wabGentBfimHmrkD基因检出率均为100.00%,ybtS基因检出率为21.88%,未检出rmpAiutA基因;存在2种毒力基因谱型(fimH-mrkD-wabG-entB和fimH-mrkD-wabG-entB-ybtS),二者的区别在于是否携带ybtS基因;虽然ESBLs-KP和non-ESBLs-KP间在毒力基因检出率方面无显著差异(P>0.05),但ESBLs-KP中的ybtS基因检出率高于non-ESBLs-KP。【结论】生牛乳中hmKP存在高毒力和多重耐药风险,是临床KP感染的主要潜在来源,建议居民切勿直接饮用生牛乳,且相关部门应加强对牛乳中hmKP的耐药及毒力监测,兼顾其分布规律,以便对其潜在风险进行精准防御。

     

    Abstract: 【Objective】To assess biofilm formation ability and risk of drug resistance and virulence of hypermucoviscous Klebsiella pneumoniae(hmKP)from raw milk and its environment,to propose a warning of potential risks posed by hmKP,so as to provide a theoretical basis for the appropriate prevention and control of Klebsiella pneumoniae(KP).【Method】Phenotypes of extended-spectrum β-lactamase(ESBLs)in 32 strains of hmKP were identified by drug sensitive slips method. Biofilm formation ability was detected by the semi-quantitative crystal violet method. Drug resistance genes and virulence genes carried by hm KP were detected through PCR.【Result】Twenty-four ESBLs-negative strains(non-ESBLs-KP,75.00%)and 8 ESBLs-positive strains(ESBLs-KP,25.00%)were identified from 32 hmKP strains,all of which could form biofilm,among which 10 had strong biofilm formation ability,17 had moderate biofilm formation ability,and 5 had weak biofilm formation ability. Among the 10 hm KP strains with strong biofilm formation ability,7 strains were from raw milk samples. Detection rate of ESBL-KP with strongly biofilm formation ability(37.50%)was higher than that of non-ESBL-producing strains(29.17%). All hm KP carried at least 4 kinds of drug resistance genes,and the sequence of drug resistance risk was tetracyclines = aminoglycosides > β-lactams > sulfonamides > quinolones > chloramphenicols,in which ESBLs-KP carried more than 8 kinds of drug resistance genes. 30 types of gene profiles were found in32 strains of hmKP,but no dominant drug resistance gene profiles were found. Five virulence genes including wabG,fimH,mrkD,entB and ybtS were detected in 32 hm KP strains. The detection rates of wabG,entB,fimH and mrkD was100.00%,followed by that of ybtS(21.88%). None of the strains carried iutA and rmpA genes. Two virulence gene profiles(fimH-mrkD-wabG-entB and fimH-mrkD-wabG-entB-ybtS)were found,and difference was whether they carried the ybtS gene. Although there was no significant difference in the detection rate of virulence genes between ESBLs-KP and non-ESBLs-KP(P>0.05),the detection rate of ybtS gene in ESBLs-KP was higher than that in non-ESBLs-KP.【Conclusion】hmKP from raw milk has a high risk of virulence and multiple drug resistance and is a major potential source of clinical KP infection. People are advised not to drink raw milk directly. Competent departments should strengthen the monitoring of drug resistance and virulence of hm KP in raw milk to grasp the distribution pattern of virulence,thus accurately preventing potential risk.

     

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