Srisrattakarn Arpasiri, Lulitanond Aroonlug, Wilailuckana Chotechana, Charoensri Nicha, Wonglakorn Lumyai, Piyapatthanakul Sirikan, Supajeen Ampai, Chanawong Aroonwadee
Medical Sciences Programme, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
Centre for Research and Development of Medical Diagnostic Laboratories, Faculty of Associated Medical Sciences, Khon Kaen University, Khon Kaen, 40002, Thailand.
World J Microbiol Biotechnol. 2016 Jul;32(7):117. doi: 10.1007/s11274-016-2064-x. Epub 2016 Jun 4.
Carbapenemase-producing Enterobacteriaceae (CPE) isolates have now emerged worldwide. We therefore modified the phenotypic Carba NP test by use of a filter paper strip for easily and rapidly identifying CPE in routine laboratory. A collection of 56 CPE and carbapenemase-producing Pseudomonas spp. isolates (including 28 NDM-1, 11 IMP-14a, 1 IMP-1, 1 IMP-4, 1 IMP-9, 1 IMP-15, 4 VIM-2, 1 VIM-1, 1 IMP-14a with VIM-2, 3 OXA-48, 3 OXA-181 and 1 KPC-2 producers) and 41 non-CPE isolates (including 19 ESBL, 7 pAmpC, 3 AmpC, 9 ESBL with pAmpC and 3 non-ESBL & non-AmpC producers) as confirmed by the PCR methods were tested by the paper strip method using pharmaceutical imipenem/cilastatin as a substrate. Bacterial colonies of each isolate were applied directly on filter paper strips dropped with either imipenem-phenol red (test strip) or phenol red solution alone (control strip). The reaction was read within 5 min. This test failed to detect 3 OXA-181, 2 OXA-48 and 3 IMP-14a producers (85.7 % sensitivity), whereas no false positives were seen (100 % specificity). Further evaluation of the paper strip test in 267 CPE screening-positive isolates from three hospitals by their medical technologists showed 92.0 % sensitivity (100 % for NDM producers) and 100 % specificity compared with the PCR methods. Because of its ease, rapidness and cost effective, the paper strip test has a potential for routine CPE testing in low-resource laboratories particularly in areas with high prevalence of NDM enzymes, leading to appropriate antimicrobial therapy and infection control strategy.
产碳青霉烯酶肠杆菌科细菌（CPE）分离株现已在全球出现。因此，我们对表型Carba NP试验进行了改良，使用滤纸条在常规实验室中轻松快速地鉴定CPE。收集了56株CPE和产碳青霉烯酶的假单胞菌属分离株（包括28株NDM-1、11株IMP-14a、1株IMP-1、1株IMP-4、1株IMP-9、1株IMP-15、4株VIM-2、1株VIM-1、1株带有VIM-2的IMP-14a、3株OXA-48、3株OXA-181和1株KPC-2产生菌）以及41株非CPE分离株（包括19株超广谱β-内酰胺酶（ESBL）、7株质粒介导的AmpC酶（pAmpC）、3株AmpC酶、9株ESBL合并pAmpC和3株非ESBL及非AmpC产生菌），经PCR方法确认后，以药用亚胺培南/西司他丁为底物，采用纸条法进行检测。将每个分离株的细菌菌落直接接种在滴有亚胺培南-酚红（试验条）或仅酚红溶液（对照条）的滤纸条上。在5分钟内读取反应结果。该试验未能检测出3株OXA-181、2株OXA-48和3株IMP-14a产生菌（灵敏度为85.7%），而未出现假阳性结果（特异性为100%）。医学技术人员对三家医院的267株CPE筛查阳性分离株进行纸条试验的进一步评估显示与PCR方法相比，灵敏度为92.0%（NDM产生菌为100%），特异性为100%。由于其操作简便、快速且成本效益高，纸条试验在资源匮乏的实验室，特别是在NDM酶高流行地区进行常规CPE检测具有潜力，可据此制定适当的抗菌治疗和感染控制策略。
