ABSTRACT
Purpose: This study was to identify and analyze the pathogen responsible for food poisoning in a tourist group traveling from Macao to Zhuhai. Patients and Methods: Samples were obtained from 27 patients of 96 cases, as well as samples of contaminated food in Macau. The collected samples were subjected to serological identification, drug sensitivity analysis, drug resistance gene identification, virulence factor analysis, and tracing. Results: Twenty-six isolates and the salad isolate were S. enteritidis ST11. Isolates from patients were exhibited significant resistance to Penicillin AMP (Ampicillin) and quinolones NAL (Nalidixic acid). Among these isolates, 21 strains were resistant to two or more antibiotics, indicating the multi-drug resistance (MDR). Genomic characteristics and phylogenetic analysis were performed on 9 of the isolates using whole genome sequencing (WGS). The analysis revealed that the resistance to AMP and NAL was primarily caused by a gryA mutation D87Y (9/9, 100%), and the presence of beta-lactam resistance genes blaOXA-1 (1/9, 11.11%), blaTEM-141 (1/9, 11.11%), and blaTEM-1B (8/9, 88.89%). It was also found a strains isolated from patients had two resistance genes to quinolones or beta-lactam drugs (1/8, 12.5%), respectively. The strains were found to possess 165 virulence genes, one adherence class virulence factor, one invasion class virulence factor and various pathogenicity islands, including SPI-1, SPI-2, SPI-3, SPI-4, SPI-5, SPI-9, SPI-10, SPI-13, SPI-14, SPI-15, SGI 1, CS54_island, and C63PI-1. Additionally, the virulence plasmids were detected, including IncFIB(s)-IncFII(s)-IncX1 (55.56%), IncFIB(s)-IncFII(s) (33.33%), and IncFIB(s)-IncFII(s)-IncHI2-IncHI2A (11.11%). PFGE (Pulsed Field Gel Electrophoresis) and phylogenetic tree analysis revealed a high degree of similarity between Salmonella isolates from patients and food samples from Macao. Conclusion: This study identified Salmonella enterica ST11 as the cause of the food poisoning outbreak. The findings highlight the importance of phenotypic characterization and next-generation sequencing (NGS) tools in epidemiological studies and emphasize the potential risk of a new emerging multi-antibiotic ST11 clone for S. enteritidis.
Subject(s)
Anti-Bacterial Agents , Azithromycin , Drug Resistance, Bacterial , Salmonella Infections , Salmonella paratyphi B/drug effects , Adult , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/therapeutic use , Australia , Azithromycin/pharmacology , Azithromycin/therapeutic use , Humans , Indonesia , Male , Microbial Sensitivity Tests , Salmonella Infections/drug therapy , Salmonella Infections/microbiology , TravelABSTRACT
OBJECTIVES: A field investigation was done to identify the level of epidemic and to evaluate the infection route of Salmonellosis occurred in a baby's first birthday banquet in Jeju Island. METHODS: Among participants in the banquet given on a baby's first birthday, persons showing gastrointestinal symptoms were conducted by the structured questionnaire and stool culture. The symptomless persons were also surveyed by self-responded structured questionnaire. The causal relationship between food items and gastrointestinal symptoms was proved by odds ratio and Wilcoxon rank-sum test. RESULTS: Salmonella london was identified in the stools of 12 subjects among 20 participants showing gastrointestinal symptoms, as well as in the boiled pork hock. CONCLUSIONS: This outbreak event is thought to happen after participants took the boiled pork hock that contaminated with S almonella london during the storage process.
