比較Modified-Hodge Test及Modified Carbapenem Inactivation Method二種方式偵測可產生碳青黴烯酶的腸內菌

Comparison of the modified-Hodge Test and Modified Carbapenem Inactivation Method for Detection of Carbapenemase-Producing Enterobacteriaceae

可產生碳青黴烯酶的腸內菌（carbapenemase-producing carbapenem-resistant Enterobacteriaceae; CP-CRE）如大腸桿菌及克雷白氏肺炎桿菌等，是造成院內感染的常見致病菌，且伴隨著較高的發病率及死亡率，故若能早期且正確的偵測CP-CRE，對於菌株蔓延及院內感染的控制而言是十分重要的。本研究利用PCR方式偵測CP-CRE的抗藥基因，包括blaKPC、blaNDM、blaVIM、blaIMP及blaOXA-48-type等所得之結果為黃金標準，分析以Modified Hodge Test（MHT）及modified carbapenem inactivation method（mCIM）二種方法偵測CP-CRE的正確性。研究中共收集99株對Carbapenem類的藥物包括Ertapenem或Imipenem，為不具感受性之腸內菌，同時操作PCR、MHT及mCIM三種方式偵測CP-CRE。研究結果顯示：99株CRE菌株中有78株PCR偵測結果為陽性，分別是43株bla KPC；28株bla NDM；6株bla OXA-48及1株bla VIM，其餘21株則不帶有任一抗藥基因。以MHT檢測結果有63株為陽性，敏感性為80.8%（63/78）；以mCIM檢測則有77株為陽性，敏感性為98.7%（77/78）；MHT檢測偽陰性結果主要發生於Escherichia coli菌株。21株PCR結果為陰性的菌株，以MHT及mCIM檢測分別有19及21株為陰性，MHT及mCIM特異性為90.5%及100%。綜合以上結果，mCIM之敏感性及特異性皆優於MHT方式，建議臨床實驗室以mCIM方式偵測CP-CRE，提供訊息供臨床醫師用藥參考，並藉以有效的感控隔離措施，降低此類菌株的蔓延。

Carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) are common pathogens of nosocomial infections associated with significant morbidity and mortality. Early identification of CP-CRE is essential to prevent their dissemination within health care settings. To achieve this goal, several carbapenemase genes like blaKPC, blaNDM, blaVIM, blaIMP and blaOXA-48-type genes were detected by PCR method as a golden standard, and these results will further evaluate the accuracy of Modified Hodge Test (MHT) and modified Carbapenem Inactivation Method (mCIM). Nity-nine CP-CRE isolates were collected and processed by above three diagnostic methods. Our results showed that 78 isolates were PCR positive (43 blaKPC, 28 blaNDM, 6 blaOXA-48 and 1 blaVIM), and the other 21 PCR negative isolates cannot detect any carbapenemase genes. Sixty-three and 77 isolates were MHT and mCIM positive, the CP-CRE detection sensitivities were 80.8% (63/78) and 98.7% (77/78), and most of the MHT false negative results were came from Escherichia coli. Twenty-one PCR negative isolates further verified by MHT and mCIM were found that 19 and 21 isolates showed negative results, and the specificities of MHT and mCIM were 90.5% and 100%. Based on above analysis results, mCIM is better than MHT method, which is suggested using for CP-CRE diagnosis in clinical laboratory. We believed this data will be useful for physicians and which may effectively reducing the CP-CRE spreading in hospital.