Isolation and Characterization of Bacteriophages with Lytic Activity against Multidrug-Resistant Non-Typhoidal Salmonella from Nairobi City County, Kenya
| dc.contributor.author | Mugo, Michael Muraya | |
| dc.date.accessioned | 2026-03-12T06:37:23Z | |
| dc.date.available | 2026-03-12T06:37:23Z | |
| dc.date.issued | 2025-12 | |
| dc.description | A Research Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Master of Science in Medical Laboratory Sciences (Medical Bacteriology) in the School of Health Sciences of Kenyatta University, December, 2025 Supervisor: 1.Abednego Musyoki 2.Angela Makumi | |
| dc.description.abstract | Non-typhoidal Salmonella (NTS) commonly cause self-limiting gastroenteritis; however, severe invasive infections occur in vulnerable populations and high-burden regions. In Kenya, multidrug-resistant (MDR) and extended spectrum β-lactamase (ESBL)-producing NTS with reduced susceptibility to third-generation cephalosporins present a growing public health challenge. Rising antimicrobial resistance (AMR), coupled with slow development of new antibiotics, highlights the urgent need for alternative treatment strategies. Bacteriophages offer a promising option, yet phage data targeting MDR and ESBL-producing NTS in Kenya remain limited. This study aimed to isolate and characterize lytic bacteriophages against MDR NTS. Sampling was conducted in Nairobi City County between April and October 2022, targeting informal settlements and Ruai Sewage Treatment Plant using a purposive approach to maximize phage recovery. Water samples from open drains, rivers, and a dam across seven sampling points were collected in sterile Whirl-Pak bags and transported under chilled conditions to the Kenya Medical Research Institute for same-day processing. Four NTS strains were used in phage enrichment, spot tests, and plaque purification, while a panel of 12 Salmonella isolates was used to assess host range and efficiency of plating (EOP). Ten broad-host-range phages were further evaluated for thermal and pH stability, ability to disrupt pre-formed biofilms, genomic features (Illumina sequencing), potential allergenicity and morphology (Transmission Electron Microscopy). Data analysis combined descriptive summaries with Mann–Whitney tests for biofilm assays and standard genomic and TEM evaluations. Thirty-one phages with host ranges varying from 8% to 100% were isolated. Ten phages demonstrating the ability to lyse more than 10 Salmonella strains tested were selected for physicochemical and genome characterization. Except for KE26 and KE28, the study phages exhibited high production efficiency EOP in at least one bacterial strain. Phages were stable at temperature from -80°C to 40°C and pH 5 to 11, and showed noticeable but statistically insignificant biofilm disruption. Genomic analysis revealed linear doublestranded DNA genomes size ranging from 23,215 bp to 159,981 bp, with no virulence genes, AMR genes or lysogeny genes detected. Allergenicity screening identified no allergenic hits across most phages, with exception of KE23, which showed potential allergenic regions in its tail fiber and endolysin proteins. All phages belonged to class Caudoviricetes, with KE23, KE26, and KE28 exhibiting a myovirus-like morphotype, and KE15 displaying a siphovirus morphotype. This study identifies safe and promising lytic phages with strong potential for development as therapeutic candidates against MDR and ESBL-producing NTS infections in Kenya, and recommends further preclinical evaluation using appropriate animal models | |
| dc.description.sponsorship | Kenyatta University | |
| dc.identifier.uri | https://ir-library.ku.ac.ke/handle/123456789/32714 | |
| dc.language.iso | en | |
| dc.publisher | Kenyatta University | |
| dc.title | Isolation and Characterization of Bacteriophages with Lytic Activity against Multidrug-Resistant Non-Typhoidal Salmonella from Nairobi City County, Kenya | |
| dc.type | Thesis |