Phenotypic and genotypic characterization of antibiotic-resistant Salmonella isolated from humans, aquaculture, and poultry in Sri Lanka: A retrospective study.

BACKGROUND: In Sri Lanka, foodborne diseases caused by nontyphoidal Salmonella are of increasing concern. We therefore aimed to characterize the dominant Salmonella serovars in humans, poultry, and aquaculture through a One Health approach. METHODS: We collected isolates from different sectors, confirmed their identities using PCR, screened their antibiotic resistance profiles, and determined their antibiotic resistance genes based on whole-genome sequencing. RESULTS: Of the 75 Salmonella isolates identified, the majority of serotypes were unidentified. Both Salmonella enterica serovar Enteritidis (S. Enteritidis) and Salmonella enterica serovar Typhimurium (S. Typhimurium) could be isolated from human sources and were also found prevalent in the poultry sector. ST36, ST11 and ST1541 were the dominant serotypes of S. Typhimurium and S. Enteritidis, respectively. Alarmingly, 4% (1/25) of poultry Salmonella isolates were resistant to ciprofloxacin, suggesting an emergence of this phenotype. Moreover, virulence genes were very diverse among S. Enteritidis and S. Typhimurium isolates. CONCLUSIONS: With the diversity of unidentified serotypes found and the detection of emerging resistances, our study highlights the importance of a One Health approach to monitoring antibiotic resistance. For public health initiatives in Sri Lanka to be successful in mitigating salmonellosis, all three sectors - humans, aquaculture, and poultry - must be tackled concomitantly in a coordinated manner under the One Health approach because antibiotic resistance genes, and even specific sequence types, may be able to spread across the aforementioned sectors. We anticipate that our results will inform public health policies in Sri Lanka to tackle foodborne illnesses.

One Health Surveillance of Antimicrobial Use and Resistance: Challenges and Successes of Implementing Surveillance Programs in Sri Lanka.

BACKGROUND: Sri Lanka is a low-income country, as defined by the World Bank. The country suffered further economic downturn during the COVID-19 pandemic. This situation adversely affected the prioritization of policies and programs around healthcare and public health. In particular, inflation, fuel prices, and shortage of food supplies increased struggles to implement antimicrobial resistance (AMR) programs. However, in the long run, it is crucial to gather data and evidence to plan AMR policies and track interventions. (1) Aim: To establish and reiterate the importance of prioritizing AMR programs in the One Health framework, the Fleming Fellows collected and studied antimicrobial use/consumption (AMU/AMC) and resistance (AMR) in humans, food-producing animals, and the environment. (2) Methods: A systematic and cross-sectional study was conducted between 2019 and 2021. By way of coordinating an AMU/AMC and AMR prevalence study across six agencies from human health and food-producing animal sectors, the authors established a field epidemiology study, laboratory testing, and data processing at their institutions. AMU/AMC patterns were surveyed using questionnaires and interviews, while AMR samples were collected for antibiotic susceptibility tests and genomic tests. Samples were tested for phenotypic and genotypic resistance. (3) Results: In human samples, resistance was highest to beta-lactam antibiotics. In non-human samples, resistance was highest to erythromycin, a highest-priority, critically important antibiotic defined by the World Health Organization. From government records, tylosin was sold the most in the food-producing animal sector. (4) Conclusions: Sri Lanka AMU and AMR trends in human and non-human sectors can be ascertained by a One Health framework. Further coordinated, consistent, and sustainable planning is feasible, and can help implement an AMU/AMR surveillance system in Sri Lanka.