A Preliminary Phylogenetic Analysis and Comparative Study on the Molecular and Conventional Identities of Bacteria Isolated from Typhoid Fever Patients Attending Some Hospitals in Ondo State, Nigeria

Abstract

Aim: This study aimed at determining the molecular and conventional identities of bacteria associated with presumptive typhoid fever patients in Ondo State, Nigeria. Study Design: The study attempted a comparative study of the conventional and molecular identities of bacteria isolated from presumptively diagnosed typhoid patients. Place and Duration of the Study: The study was conducted in three different hospitals in Ondo State, Nigeria viz; State Specialists’ Hospital, Akure, Don Bosco Clinic, Akure and Federal Medical Centre, Owo, between February and May, 2013. Methodology: A total of 520 blood samples were collected from presumptively diagnosed typhoid fever patients attending Don Bosco Clinic Akure, Federal Medical Center, Owo and State Specialists’ Hospital, Akure, Ondo State, Nigeria. The samples were screened for the presence of Salmonella typhi and other co-existing bacteria through blood culture. Initial identification of the isolates was carried using their culture morphology, Gram stain and biochemical tests, while their identities were verified using molecular techniques like PCR analysis, gene sequencing and blasting. The genetic relatedness of the bacterial isolates was investigated by constructing a phylogenetic tree using neighbor-joining (NJ) method. Results: The traditional identities of the bacteria were Salmonella typhi, Escherichia coli, Staphylococcus aureus, Shigella flexneri, Klebsiella pneumoniae, Enterobacter aerogenes, Serratia marcescens and Pseudomonas aeruginosa while their molecular identities were Enterobacter cloacae, Shigella flexneri, Enterococcus casseliflavus, Achromobacter xylosoxidans, Bacterium species clone BAO 14, Serratia marcescens and Pseudomonas aeruginosa respectively. Most of the isolates fell within the same clade on the phylogenetic tree signifying that they had a common ancestor. Conclusion: Molecular biology techniques are more reliable, sensitive and accurate for bacterial identification than the conventional methods.