Detection of E. coli Isolates in Water from Setumo Dam Mmabatho Area – North West Province, South Africa Using mdh Specific PCR Analysis

Abstract

KEYWORDS Coliform. E. coli mdh. Malate Dehydrogenase ABSTRACT Most countries including South Africa, process surface water from lakes, rivers, dams and ponds by filtration, chlorination, alum treatment before use for drinking purposes. In South Africa, the North West Province in particular, residents of most rural communities do not have access to treated water. This exposes them to contamination with pathogens such as Escherichia coli. The aim of the study was, therefore, to isolate, identify and characterize E. coli strains from water collected from Setumo Dam, located at the Modimola village, in the periphery of the Mmabatho suburban area using conventional microbiological methods and PCR analysis. Water samples were collected during the summer season from three different sites of the dam, viz; upstream, middle stream and the downstream of the dam. Tap water was used as a control during analysis. Bacterial loads were determined by spread plating on mFC and EMBA and incubating the plates aerobically at 45 o C and 37 o C, respectively for 24 hours. Blue colonies on mFC agar were counted and recorded while pure metallic sheen colonies on EMBA were identified using preliminary (oxidase test, TSI) and confirmatory (API 20E and mdh specific PCR) assays. The results obtained indicated that all the water samples were contaminated with faecal coliform bacteria. Samples from upstream had high colony counts (320 to 1624 cfu/50ml) than those from the mid-stream (56 to 90 cfu/50ml) and the downstream (26 to 44 cfu/50ml). There was no contamination from tap water. Of the 57 randomly selected E. coli colonies that satisfied the preliminary identification tests and API 20E, 46 (80.7%) were positively identified as E. coli since they possessed the mdh gene fragment. Water from the dam contained high E. coli load and it is recommended that the Local municipality makes informed decisions pertaining to the control and management of the pathogen. Improve- ment of the sanitary and water systems in the area is therefore necessary.