1株泛耐药肺炎克雷伯菌耐药机制的研究

The drug-resistant mechanism of a pan-resistant Klebsiella pneumoniae stain

目的研究1株泛耐药肺炎克雷伯菌(Kpn)的耐药机制。方法用Vitek-2系统进行细菌鉴定,纸片扩散法和肉汤稀释法进行药敏试验;PCR和DNA测序检测β-内酰胺酶基因和7个管家基因,多位点序列分型(MLST)进行7个管家基因的序列分析;改良Hodge试验、超广谱β-内酰胺酶(ESBLs)确证试验、利用抑制剂的双纸片增效试验和改良ESBLs确证试验检测β-内酰胺酶表型。结果该菌株呈泛耐药性,携带KPC-2和CTX-M-15基因,MLST显示ST11型;改良Hodge试验检出碳青霉烯酶;ESBLs确证试验呈假阴性结果,改良ESBLs确证试验呈阳性结果;用3-氨基-苯酚硼酸(APBA)的双纸片增效试验呈阳性结果,显示产KPC型A类碳青霉烯酶。结论该菌株的泛耐药性可能是由于产KPC酶,利用抑制剂的表型试验能简便准确地检出KPC和ESBL。

Objective To study the drug-resistant mechanism of a pan-resistant Klebsiella pneumoniae （Kpn） strain. Methods The isolated strain was identified by using Vitek-2 compact automatic system, and antibiotic susceptibility was tested by Kirby-Bauer disc diffusion method and microbroth dilution method. The ^-lactamase genotypes and 7 housekeeping genes were detected by PCR and DNA sequencing. The nucleotide sequences of 7 housekeeping genes were determined by multilocus sequence typing （MLST）. The phenotypes of extended-spectrum β-1actamase （ESBL） were identified by modified Hodge test （MHT）, ESBL confirmatory tests, in- hibitor-potentiated double-disc diffusion test and modified ESBL confirmatory test. Results The strain was pan-resistant Kpn which carried bla_KPC-2 and bla_CTx-M-15. The sequence type was ST11. The result of modified Hedge test was positive. ESBL confirmatory test showed false negative results, but the modified ESBL confirmatory test was positive. The positive result of potentiated double-disc test using 3-aminophenylboronie acid （APBA） indicated Klebsiella pneumoniae carbapenemase （KPC） -producing strain. Conclusion The pan-resistance of the Kpn strain in this study may be aroused by production of KPC. The inhibitor-potentiated double-disc diffusion test for identification of phenotype should be available to detect KPC and ESBL easily and correctly.