Antimicrobial susceptibility pattern of Salmonella isolates from clinical, environmental and food sources in Lagos, Nigeria Profil de sensibilité aux antimicrobiens des isolats de Salmonella provenant de sources cliniques, environnementales et alimentaires à Lagos, au Nigéria

Abstract

Background: Salmonellosis persists in Lagos, Nigeria, despite interventions. This study investigated antimicrobial resistance patterns of Salmonella species from clinical, food, and environmental samples in Lagos.
Methodology: From June to December 2018, 276 samples (86 blood, 80 stool, 40 hospital effluents, and 70 food) were collected for microbiological analysis. Clinical samples (blood and stool) were collected from patients in General Hospital Igando and Lagos State University Teaching Hospital Ikeja. Food samples were collected from food vendors in the urban periphery of Lagos State, and hospital effluents were collected from Gbagada General Hospital and Ojo Health Centre. The samples were processed using standard microbiological procedures. Antimicrobial susceptibility of isolated bacteria was done using the Kirby-Bauer disk diffusion method.
Results: Of the 276 samples, an overall prevalence of Salmonella spp from all sources was 9.1% (25/276), with 7.0% from blood, 17.5% from stool, 10.0% from hospital effluents, and 1.4% from food samples. Salmonella strains showed multidrug resistance (MDR) to at least four of nine antibiotics, with 98.0% resistance to ampicillin, nitrofurantoin and augmentin, and 99.0% sensitivity to imipenem. Five unique resistance patterns (A1-A5) were identified, with pattern A1 (AMP AUG GEN OFX CXM CTZ CIP NIT) observed in 72.0% of the Salmonella isolates, followed by A5 (AMP AUG GEN CXM CTZ NIT) in 8.0% of the isolates from two sources (stool and hospital effluent). The remaining patterns (A2, A3, and A4) were exhibited by Salmonella isolates from a single source.
Conclusion: The findings of this study suggest potential multi-source transmission dynamics of the investigated Salmonella species. It highlights the circulation of MDR Salmonella species from food and environmental sources with possible transmission to humans, emphasizing the need for continuous surveillance and control strategies. The persistence of Salmonella species and antimicrobial resistance in Lagos underscores the importance of targeted public health interventions to mitigate this public health threat.