改良Hodge试验、CNPt及mCIM筛选肺炎克雷伯菌产碳青霉烯酶的价值

目的探讨改良Hodge试验(MHT)、Carba NP试验(CNPt)及改良碳青霉烯酶灭活试验(mCIM)检测肺炎克雷伯菌产碳青霉烯酶的价值。方法收集某院2016年12月—2017年11月临床分离的117株肺炎克雷伯菌,所有菌株进行药敏试验,其中碳青霉烯类耐药57株,敏感60株。以PCR法检测碳青霉烯酶基因为标准,评价3种方法检测肺炎克雷伯菌碳青霉烯酶的价值。结果 57株对碳青霉烯耐药的菌株中,PCR阳性40株,包括39株KPC,1株NDM-1,未检出其他耐药基因。MHT、CNPt、mCIM阳性率分别为87.7%(50/57)、89.5%(51/57)、91.2%(52/57)。60株敏感菌PCR均未检出碳青霉烯酶基因,3种表型筛选试验结果均为阴性。以PCR为金标准,MHT、CNPt、mCIM灵敏度分别为97.5%(39/40)、100%(40/40)和100%(40/40),特异度分别为85.7%(66/77)、85.7%(66/77)和84.4%(65/77)。结论 CNPt是一种可靠的表型筛选方法,可用于流行病学和医院感染的监测。mCIM操作简单,结果判断明确,更适合临床微生物实验室常规开展。

Value of modified Hodge test, Carba NP test, and modified carbapenem inactivation method for screening carbapenemase-producing Klebsiella pneumoniae

Objective To explore the value of modified Hodge test (MHT), Carba NP test (CNPt) and modified carbapenem inactivation test (mCIM) in detecting carbapenemase-producing Klebsiella pneumoniae(K. pneumoniae). Methods 117 clinically isolated strains of K. pneumoniae were collected from a hospital between December 2016 and November 2017, all strains were performed antimicrobial susceptibility testing, 57 strains were carbapenem -resistant and 60 strains were carbapenem-susceptible. Carbapenemase gene detected by PCR was as gold standard, value of three methods for detecting carbapenemase in K. pneumoniae was evaluated. Results Of 57 carbapenem-resistant K. pneumoniae strains, 40 were positive for PCR, including 39 KPC strains and 1 NDM-1 strain, no other resistance genes were detected. Positive rates of MHT, CNPt, and mCIM were 87.7% (50/57), 89.5% (51/57), and 91.2% (52/57) respectively. No carbapenemase gene was detected among 60 strains of susceptible bacteria by PCR, results of three phenotypic screening tests were all negative. Taking PCR as the gold standard, sensitivity of MHT, CNPt, and mCIM were 97.5% (39/40), 100% (40/40), and 100% (40/40) respectively, specificity were 85.7% (66/77), 85.7% (66/77), and 84.4% (65/77) respectively. Conclusion CNPt is a reliable phenotypic screening method, which can be used in epidemiology and healthcare-associated infection surveillance. mCIM has the advantages of simple operation, easy to make a judgment and is more suitable for clinical microbiology laboratory to carry out routinely.