1株泛耐药肺炎克雷伯菌耐药机制的研究

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。

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

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 β-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-lactamase(ESBL) were identified by modified Hodge test(MHT),ESBL confirmatory tests,inhibitor-potentiated double-disc diffusion test and modified ESBL confirmatory test.Results The strain was pan-resistant Kpn which carried blaKPC-2 and blaCTX-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-aminophenylboronic 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.