Fomda Bashir Ahmad, Khan Asiya, Zahoor Danish
Department of Microbiology, Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu & Kashmir, India.
Indian J Med Res. 2014 Nov;140(5):672-8.
BACKGOUND & OBJECTIVES: Resistance to carbapenems in Gram-negative bacteria conferred by NDM-1 is a global health problem. We investigated the occurrence of NDM-1 in clinical isolates of Gram-negative bacilli in a tertiary care hospital in Kashmir valley, India.
Gram-negative bacilli from different clinical isolates were included in the study. Antimicrobial susceptibility was performed by Kirby Bauer disk diffusion method and interpreted using Clinical Laboratory Standards Institute (CLSI) guidelines. Isolates resistant to carbapenems were subjected to different phenotypic test such as modified Hodge test (MHT), boronic acid and oxacillin based MHT ( BA-MHT and OXA-MHT), combined disk test and minimum inhibitory concentration (MIC) with imipenem and imipenem -EDTA for determination of class B metallo enzymes. Presence of blaNDM-1 gene was established by PCR and confirmed by sequencing.
Of the total 1625 Gram-negative isolates received, 100 were resistant to imipenem. Of the 100 isolates, 55 (55%) were positive by modified Hodge test indicating carbapenemase production. Of the 100 isolates tested by MHT, BA-MHT and OXA-MHT, 29 (29%) isolates belonged to Class A and 15 (15%) to Class B, while 56 (56%) isolates were negative. Of the 15 class B metallo beta lactamase producers, nine carried the bla(NDM-1) gene. NDM-1 was found among Escherichia coli (2 isolates), Klebsiella pneumoniae (2 isolates), Citrobacter freundii (3 isolates), Acinetobacter spp (1 isolate), and one isolate of Pseudomonas aeruginosa. Isolates were resistant to all antibiotic tested except polymyxin B and tigecycline.
INTERPRETATION & CONCLUSIONS: Our study showed the presence of clinical isolates expressing NDM-1 in Srinagar, Jammu & Kashmir, India. These isolates harbour plasmid mediated multiple drug resistant determinants and can disseminate easily across several unrelated genera. To halt their spread, early identification of these isolates is mandatory.
背景与目的：NDM - 1介导的革兰氏阴性菌对碳青霉烯类抗生素的耐药性是一个全球性的健康问题。我们调查了印度克什米尔山谷一家三级护理医院革兰氏阴性杆菌临床分离株中NDM - 1的出现情况。
本研究纳入了来自不同临床分离株的革兰氏阴性杆菌。采用 Kirby Bauer 纸片扩散法进行药敏试验，并按照临床实验室标准协会（CLSI）指南进行解读。对耐碳青霉烯类抗生素的分离株进行不同的表型试验，如改良 Hodge 试验（MHT）、基于硼酸和苯唑西林的 MHT（BA - MHT 和 OXA - MHT）、联合纸片试验以及亚胺培南和亚胺培南 - EDTA 的最低抑菌浓度（MIC）测定，以确定 B 类金属酶。通过 PCR 确定 blaNDM - 1 基因的存在，并通过测序进行确认。
在总共收到的1625株革兰氏阴性分离株中，有100株对亚胺培南耐药。在这100株分离株中，55株（55%）改良 Hodge 试验呈阳性，表明产生了碳青霉烯酶。在通过 MHT、BA - MHT 和 OXA - MHT 检测的100株分离株中，29株（29%）属于 A 类，15株（15%）属于 B 类，而56株（56%）为阴性。在15株产生 B 类金属β-内酰胺酶的菌株中，9株携带 bla(NDM - 1)基因。在大肠杆菌（2株）、肺炎克雷伯菌（2株）、弗氏柠檬酸杆菌（3株）、不动杆菌属（1株）和一株铜绿假单胞菌中发现了 NDM - 1。除多粘菌素 B 和替加环素外，分离株对所有测试抗生素均耐药。
我们的研究表明，在印度查谟和克什米尔的斯利那加存在表达 NDM - 1 的临床分离株。这些分离株携带质粒介导的多重耐药决定簇，并且可以很容易地在几个不相关的属之间传播。为了阻止它们的传播，必须尽早识别这些分离株。
