Molecular Diagnostic Techniques for the Characterisation of Escherichia coli

This study characterised Escherichia coli isolated from Creek Road/Bonny Estuary using molecular
techniques. One hundred and twenty (120) water samples were investigated for the presence of E.
coli in Creek Road/Bonny Estuary. Most Probable Number (MPN) Technique, Eijkman test and
molecular techniques were used for the isolation and detection of E. coli. The analysis was carried out
periodically (morning and evening) and seasonally (end of rainy season (November), the start of rainy
season (April) and in the middle of rainy season (July)). All E. coli isolates were screened for
resistance genes in the pathotypes of E. coli (EHEC, EPEC, EAEC, ETEC and EIEC), including
Sulfhydryl Variable (SHV), CTX-M, Temoniera (TEM) and MCR genes using the Polymerase chain
reaction Technique. The results showed that 100% of the water samples were positive for coliforms
and all the water samples harboured E. coli. The highest total coliforms count recorded was in the
morning of April (48 MPN/100 ml). The distribution of individual genes in the E. coli isolates are: SHV
(5.0), CTX-M (5.8), TEM (4.2), MCR (0.0%), stx1 and stx2 (4.2), esV and bfA (1.7), aaiC (4.2), elt
(3.3) and invE (2.5). The CTX-M was the most found of all the resistance genes. Siting of waste
dumps, discharge of sewage and the building of toilets, and the use of humans and animals excreta
as manure, may have contributed to the presence of the bacteria in the water body.