Browsing by Author "Rediet Guta"

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    Isolation and Characterization of Lytic Bacteriophages Against Multidrug-Resistant Salmonella Typhimurium Atcc 13311 From Poultry Farms and Rivers in Addis Ababa, Ethiopia
    (Addis Abeba University, 2026) Rediet Guta; Tesfaye Sisay; Alemayehu Godana; Tesfaye Admasu
    Antimicrobial resistance (AMR) is a growing worldwide challenge, treatment options for bacterial infections are increasingly limited. Non-typhoidal Salmonella (NTS), particularly Salmonella enterica serovar Typhimurium, poses a serious threat to public health due to rising antimicrobial resistance and can causes invasive bloodstream infections that have a high death rate. This study aimed to identify and isolate exclusively lytic bacteriophages that target multidrug-resistant Salmonella Typhimurium (ATCC 13311) from river water and poultry farm environments in Addis Ababa, Ethiopia, and to assess their potential as alternative treatment. In this study a total of 38 environmental samples were collected from poultry farms and rivers, from 38 samples 22 different bacteriophages were successfully isolated using S. Typhimurium ATCC 13311 as the host strain, with the majority (63.6%) isolated from river water samples. Spot assay were used to isolate phages, and the double Layer agar method (DLA) was used for purification of isolated phages. PCR-based identification and classification, latent period determination, plating efficiency, burst size, stability testing, and assessment of in vitro bactericidal activity were all included in the characterization. According to host range analysis, all isolates were active against the primary host, and four isolates showed cross-genus efficacy against specific pathotypes of Escherichia coli. The latent periods of the isolated phages ranged from 10 to 20 minutes, indicating a wide range of infection kinetics. Peak titers as high as 10¹³ PFU/mL were attained by some of the most productive isolates, indicating a significant ability for replication. Additionally, the ideal multiplicity of infection differed significantly amongst isolates, ranging from 0.001 to 100. Regarding environmental stability, all phages were activein a pH range of 5 to 9 and withstood temperatures ranging from 4°C to 37°C. The majority of the isolates were classified by molecular analysis into the T4-like and T7-like lineages, two distinct phage groups with known lytic characteristics. This study demonstrates that multidrug-resistant Salmonella Typhimurium ATCC 13311 can be effectively inhibited by locally isolated lytic bacteriophages and supports their potential as safe and effective biocontrol agents for combating MDR S. Typhimurium infection. Furthermore, clinical trials, in vivo research, and genome sequencing are necessary to confirm these phages' effectiveness and safety.