Detection of Virulence Genes of DiarrheagenicEscherichia coli Strains, Isolated fromDrinking Water in Khartoum State

Abstract

Diarrheagenic E. coli (DEC) strains are an important cause of intestinal syndromes in developing countries mainly affecting children, DEC strains are typically transmitted by contaminated food and water. This study was aimed to determine the prevalence of virulence genes in the diarrheagenic E. coli (DEC) isolated from drinking water in Khartoum State from April to May 2016. A total of 46 isolates of E. coli were obtained from Central Public Health Lab in Khartoum. These isolates were isolated from drinking water in Khartoum State and subcultures in Eosin Methylene Blue (EMB) media, the isolates were then identified by routine biochemical tests. Antimicrobial susceptibility testing was then done by using the following antibiotics; Chloramphenicol, Ceftriaxone, Ciprofloxacin, Gentamicin, and Tetracycline. Bacterial genomic DNA was extracted by boiling centrifugation method, and Multiplex Polymerase Chain Reaction (MPCR) was performed to detect the virulence genes (IPaH, Stx, AggR, and eae). Most of the isolated bacteria were from tap water 86.9% (40/46), and the rest from cooler 10.9% (5/46) and tanks 2.2% (1/46). In addition to, the majority of them were from houses 36 (78.3%), most of them in Khartoum province 20(43.5%). Most of the isolates were resistant to Tetracycline 45(97.8%), 8 (17.4%) were resistant to Chloramphenicol, 4 (87.0%) were resistant to Ceftriaxone, 11 (23.9%) were resistant to Ciprofloxacin and 11 (23.9%) were resistant to Gentamicin. The multiplex PCR assays confirmed the presence of E. coli virulence genes in 58.6% (27/46) of all the isolates; IPaH gene 41.3% (19/46), AggR gene 30.4% (14/46) and Stx gene 10 .8% (5/46). There were 9(19.5%) isolates positive for both AggR and IPaH. Also, AggR and Stx genes were detected both in 2(4.3%) isolates. All isolates were negative for eae (EPEC). There were 19 (41.4%) negative for all genes. V This study confirmed for the first time the presence of DEC strains in drinking water in Khartoum State in different resources and different locations. Also, Detection of diarrheagenic E. coli by Multiplex PCR method was quite satisfactory. We recommended that the drinking water should be treated before use and also, using of the filters in tap’s spouts of a great importance.