Evaluation of Oxidative Stress Adaptability of Typhoidal Salmonella from Patients Suspected of Enteric Fever in Bauchi, Nigeria

Introduction. Salmonella typhi has the ability to effectively resist stress damage due to exposure to stressors, it may also be observed in may bacteria in their response to some cytotoxic agents. The aim of the study was to evaluate the oxidative stress adaptability of typhiodal salmonella and molecular detection of the regulon gene involved in adaption of the oxidative stress in clinical specimen in Tertiary Hospital of Bauchi State, Nigeria. Methodology. The blood specimens were cultured in thioglycollate broth and subcultured onto deoxycholate citrate agar (DCA), Salmonella-Shigella agar (SSA) followed by confirmation of presumptive colonies using different biochemical tests. Serologic identification of Salmonella was performed by slide agglutination test using polyvalent O and H Salmonella antisera. Stress effect on growth was done with the supplementation of 2.5ml hydrogen peroxide (H2O2) at the late log phase and the cell viability was simultaneously retraced through culture in agar plates for up to 72hr Subsequent changes in cell morphology and arrangements were monitored. HotStart Polymerase chain reaction (PCR) was also done to detect the gene involve in the stress adaptability. Result. Seven isolates of salmonella typhi employed and impact of H2O2 were insignificant on their growth measuring the turbidity. Growth and colony morphology was also observed by culture after treatment of H2O2 and was found to be unaffected by the H2O2 treatment. Molecularly, the gene (RpoE) was detected in the seven isolates suggestive of a stringent defense mechanism against oxidative stress. Conclusion. Data obtained clearly showed new information on the defense strategies of Salmonella typhi against oxidative stress. Salmonella formed CFUs with the absence of aggregates in culture media, the cell morphology of the salmonella found to be completely unaffected by the oxidant which supported the maintenance of cell culturability of Salmonella. While the bacteria resist the oxidative stress, molecular detection on rpoE in all the seven salmonella typi isolates shows the presence of the regulatory gene in them.