Salmonella Alachua: causative agent of a foodborne disease outbreak

Abstract

Objectives: The aim of this study is to report the occurrence of the first outbreak of food poisoning caused by Salmonella Alachua in Brazil, as well as the antimicrobial susceptibility and the genetic relatedness of Salmonella Alachua strains isolated from clinical and food samples. Material and methods: To elucidate the outbreak, an epidemiological investigation was carried out, and two samples of common food were tested – mayonnaise salad and galinhada (a traditional Brazilian dish of chicken and rice) – according to the Compendium of methods for the microbiological examination of foods. Five stool samples were tested employing classic methods for the isolation and identification of enterobacteria. Strains of Salmonella were characterized for antibiotic susceptibility according to the Clinical and Laboratory Standards Institute guidelines (2013), and submitted to pulsed-field gel electrophoresis analysis, performed according to the Centers for Disease Control and Prevention PulseNet protocol. Results: A total of 94 people were interviewed after ingesting the food, 66 of whom had become ill. A 60-year old female patient who was hospitalized in a serious condition, developed septic shock and died two days after consuming the food. The presence of Salmonella Alachua was confirmed in all the analyzed stool samples, and in the two types of food. The five strains showed higher than minimum inhibitory concentration values of nalidixic acid (≥256 μg/mL) and reduced ciprofloxacin susceptibility (minimum inhibitory concentration = 0.5 μg/mL). The pulsed-field gel electrophoresis analysis revealed indistinguishable patterns in Salmonella Alachua strains isolated from clinical and food samples. Conclusion: The data presented herein confirm the foodborne disease outbreak. They also allowed for the identification of the source of infection, and suggest that products from poultry are potential reservoirs for this serotype, reinforcing the importance of warning consumers about the danger of possible contamination. Keywords: Foodborne diseases, Salmonella Alachua, Drug resistance, Brazil