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Mzula, A.

Publications and source records attributed to Mzula, A..

2 recordsLinked to original sources
bioRxiv2025

One Health assessment of antimicrobial-resistant Enterobacterales and ESKAPE pathogens in little stints (Calidris minuta) and aquatic ecosystems of the Kenyan Rift Valley

Palearctic migratory little stints (Calidris minuta) can acquire resistant bacteria from anthropized environments and spread them across different hosts and borders. This two-year cross-sectional study assessed the prevalence of multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales and ESKAPE pathogens isolated from C. minuta and their aquatic foraging ecosystems at two Kenyan Rift Valley lakes, Bogoria (low anthropogenic activities) and Magadi (high impact). A total of 184 fecal samples from C. minuta and 48 water samples were collected during the birds arrivals (cohort 1) and departures (cohort 2). Samples were cultured, bacterial isolates were identified using MALDI-TOF MS platform and tested against 12 antimicrobials using the Kirby-Bauer disk method. Of the 294 isolates (16 genera and 33 species), Enterobacter species (31%) and Escherichia coli (17.3%) were predominant. Resistance was highest for ampicillin (50%), amoxicillin-clavulanic acid (36.4%), and tetracycline (32.7%), and lowest for meropenem (1.0%) and cefepime (3.4%). The predominant MDR phenotype was a combination of resistances to ampicillin, tetracycline, and trimethoprim-sulfamethoxazole. Enterobacter species showed the highest frequencies of MDR (8.5%) and ESBL-MDR (4.4%) phenotypes, while Acinetobacter species were the most frequent ESBL producers. Despite observing higher median resistances in isolates from Lake Magadi (7.1), C. minuta (8.0) and cohort 2 (7.1) than those from Lake Bogoria (6.7), water samples (5.9) and cohort 1 (6.5), these differences were statistically insignificant (p-values= 0.833, 0.147, 0.210). This suggests that while human activities drive AMR spread, resistant strains are pervasive even in minimal human-influenced environments. This is the first study to link C. minuta to the AMR epidemiological circuit. Our findings underscore the need to include migratory wild birds in AMR surveillance in the Kenyan Rift Valley, to implement stringent environmental stewardship measures to curb anthroponotic AMR transmissions and utilizing whole-genome sequencing to accurately trace the origin and dissemination pathways of AMR strains.

microbiology↗
bioRxiv2025

Molecular characterization and pathogenicity assessment of bacteria causing infectious diseases in cage-farmed fish in the Lake Victoria

Despite government initiatives in East African countries promoting cage fish farming to compensate for income losses from declining capture fisheries, disease-related mortalities have become a major challenge, causing significant economic losses for farmers. Due to inadequate screening of pathogens causing these mortalities, farmers have been left to rely on guesswork, frequently using treatments that are either ineffective or inappropriate. Therefore, this study aimed to identify and characterize the etiological agents responsible for infectious diseases in cage-farmed fish in Lake Victoria, Tanzania. Fish samples were collected from six districts in the Lake Victoria Basin (LVB), which are known for their extensive cage fish farming operations. A total of 81 samples of blood, liver, and kidney tissues were collected from morbid Nile tilapia and enriched in Buffered Peptone Water then cultured on various agar media to isolate pathogens. Gram staining and a series of biochemical tests were used to identify the bacterial isolates. Similarly genomic DNA were extracted from each isolate and fragments of the 16S rRNA gene amplified and sequenced. Three pathogenic bacteria namely Citrobacter freundii, Pseudomonas aeruginosa, and Streptococcus agalactiae were identified isolated and identified. Pathogenicity trials demonstrated that P. aeruginosa exhibited the highest mortality rate (86.7%), followed by C. freundii (66.7%) and S. agalactiae (40%). Clinical and post-mortem findings from the trials showed symptoms consistent with hemorrhagic septicemia and septicemia. Phylogenetic analysis grouped sequences of each pathogen into a single cluster, regardless of their geographical origins, suggesting a common source and subsequent dispersal to various locations. The study calls for harmonized efforts to enhance disease control strategies and reduce the impact on aquaculture operations, as farmers likely deal with the same bacterial strains.

microbiology↗