Browsing by Author "Bindyo Phoebe Nzula"

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    Isolation, characterisation and in vivo efficacy of lytic bacteriophages from sewage-treatment plants against ciprofloxacin-resistant Salmonella Typhi in Mbarara District, Uganda
    (Kampala International University, 2023-10) Bindyo Phoebe Nzula
    The emergency of ciprofloxacin-resistant Salmonella Typhi infection among majority of the developing countries has elevated morbidity and mortality rate. The present study aimed at determining the in vivo efficacy against ciprofloxacin-resistant Salmonella Typhi of lytic bacteriophages from sewage treatment plants in Mbarara district, Southwestern Uganda. A laboratory based experimental study was conducted. Twelve samples obtained from two sewage treatment plants within Mbarara district, Southwestern Uganda; Kakoba and Taso were used for isolation of bacteriophages using the double agar overlay plaque assay. The isolated phages were assayed for both biological and physico-chemical characteristics. A mice infection model that included; bacteria + phage, bacteria + SM buffer, bacteria + ciprofloxacin antibiotic groups and phage only were used to assess the in vivo efficacy of bacteriophage cocktail against ciprofloxacin resistant Salmonella Typhi after intraperitoneal administration. The bacterial loads and phage titres from the lungs, intestines, liver, and kidney were determined using surface spreading and double agar overlay plaque assay. Data was analyzed using SPSS-26 to compute descriptive statistics and statistical significance was considered at P ≤ 0.05. The four isolated phages exhibited lytic activity against the ciprofloxacin-resistant S. Typhi with an average host range limited to S. Typhi species with exception of phage TA001 with activity against Shigella species. The adsorption time of phages ranged from 5-15 minutes, with latent period of 10 – 20 minutes and burst sizes ranged from 286 to 163 PFU/ml. The phages exhibited high stability at temperatures up to 60 oC and pH 4 -12. The phage had an average host range of 8.3% to 50.0%. The phage cocktail rapidly decreased the S. Typhi counts in blood, liver, spleen intestines and kidney to 0 CFU/mL within 48 h as compared to ciprofloxacin treated mice. The phages were completely cleared at a rapid rate in the spleen, kidney, and blood within 60h, 96 h and 120 h respectively. Treatment with phage cocktail caused a significant reduction in the weights of liver and intestines as compared to ciprofloxacin treated mice. Sewage harbored virulent lytic phages against ciprofloxacin resistant S. Typhi and the cocktail exhibited potent in vivo therapeutic efficacy in mice model. The study recommends molecular characterization, pharmacokinetic, histological effects and immunological responses in order to establish their safety for therapeutic usage in humans.