Rahman Helina, Deka Manab
Department of Biotechnology, Gauhati University, Guwahati, India.
Indian J Med Res. 2014 Apr;139(4):632-7.
BACKGROUND & OBJECTIVES: Urinary tract infections (UTI) are a serious health problem affecting millions of people each year. Although appreciable work on various aspects of UTI including aetiology per se has been done, information on the emerging pathogens like necrotoxigenic Escherichia coli (NTEC) is largely lacking in India. In the present study E. coli isolates from patients with urinary tract infection from northeastern India were investigated for detection and characterization of NTEC.
E. coli isolated and identified from urine samples of patients with UTI were serotyped. Antibiogram was determined by disc diffusion test. Plasmid profile was also determined. Virulence genes of NTEC (cnf1, cnf2, pap, aer, sfa, hly, afa) were detected by PCR assay. E.coli isolates carrying cnf gene (s) were identified as NTEC.
A total of 550 E. coli were isolated and tested for the presence of cnf genes. Of these, 84 (15.27%) belonged to NTEC. The cnf1 gene was present in 52 (61.9%) isolates, cnf2 in 23 (27.4%) and 9 (10.7%) carried both cnf1 and cnf2 genes. All the NTEC strains were found to harbour the pap and aer genes. Serogroup O4 was found to be the most common among the 12 serogroups identified amongst the NTEC isolates. Majority of the isolates (96.4%) were sensitive to furazolidone and were highly resistant to ampicillin. NTEC were found to harbour different numbers of plasmids (1 to 7). No association was observed between the number of plasmids and the antibiotic resistance of the isolates.
INTERPRETATION & CONCLUSIONS: The results of the present study showed that about 15 per cent of E. coli isolates associated with UTI belonged to NTEC. More studies need to be done from other parts of the country.
尿路感染（UTI）是一个严重的健康问题，每年影响数百万人。尽管在UTI的各个方面，包括其病因本身，已经开展了大量工作，但在印度，关于诸如产坏死毒素大肠杆菌（NTEC）等新出现病原体的信息却非常匮乏。在本研究中，对来自印度东北部尿路感染患者的大肠杆菌分离株进行了检测和鉴定，以确定NTEC的存在并对其进行特征分析。
对从UTI患者尿液样本中分离并鉴定出的大肠杆菌进行血清分型。通过纸片扩散试验测定抗菌谱。同时也测定了质粒图谱。通过聚合酶链反应（PCR）检测NTEC的毒力基因（cnf1、cnf2、pap、aer、sfa、hly、afa）。携带cnf基因的大肠杆菌分离株被鉴定为NTEC。
共分离出550株大肠杆菌，并检测其cnf基因的存在情况。其中，84株（15.27%）属于NTEC。52株（61.9%）分离株含有cnf1基因，23株（27.4%）含有cnf2基因，9株（10.7%）同时含有cnf1和cnf2基因。所有NTEC菌株均被发现含有pap和aer基因。在NTEC分离株鉴定出的12个血清群中，O4血清群最为常见。大多数分离株（96.4%）对呋喃唑酮敏感，对氨苄青霉素高度耐药。发现NTEC含有不同数量的质粒（1至7个）。未观察到质粒数量与分离株抗生素耐药性之间的关联。
本研究结果表明，与UTI相关的大肠杆菌分离株中约15%属于NTEC。该国其他地区需要开展更多研究。
