Epidemiological Analysis Using Pulsed-Field Gel Electrophoresis of Salmonella enteritidis Outbreak in Factory Workers

Salmonellosis is still being reported as the second most common food-borne infection of bacterial origin. The most common serotypes worldwide as salmonellosis agents are Salmonella enterica subsp. enterica serotype enteritidis (S. enteritidis) and S. enterica subsp. enterica serotype typhimurium (S. typhimurium).
In the current study, the researchers investigated food associated S. enteritidis outbreak in factory workers of Turkey.
The same meatball preparation that was consumed by the patients for lunch and dinner was responsible for the food poisoning on July 2014, when 257 workers in the same factory sought medical care. Among 257 individuals with diarrhea, abdominal pain, headache, fever, and vomiting, 48 (19%) were hospitalized. Stool samples were plated on Salmonella-Shigella agar and Eosine Methylene Blue agar plates and incubated at 37°C. Colonies morphologically resembling Salmonellae were selected for further identification on the next day using API 20E.
During the outbreak, 10 out of 48 (21%) stool samples and 1 out of 25 (4%) blood culture from patients were positive. On serotyping, the isolates were identified as S. enteritidis (9,12; g,m;-) by the agglutination test. Pulsed field gel electrophoresis (PFGE) used for epidemiological analysis of the isolates showed a similar PFGE pattern. Pulsed field gel electrophoresis analysis was performed by XbaI enzymes. The antibiotic susceptibility tests of isolates were studied according to clinical and laboratory standards institute (CLSI) suggestions by using the disc diffusion method. All isolates were susceptible to ampicillin, nalidixic acid, ciprofloxacin, trimethoprim/sulfamethoxazole, tetracycline, kanamycin, chloramphenicol, gentamicin, ceftazidime, and cefotaxime.
All patients in the study were treated with ciprofloxacin 2 × 750 mg/day and returned to work on the 7th day.