Monophasic variant of Salmonella Typhimurium 4,[5],12:i:- outbreak: an investigation by the Competent Authority

Abstract

Foodborne diseases represent a significant public health issue, regarding both collective health and the economy, with implications for healthcare costs and agribusiness. This paper shows the description and results of the investigation of a Salmonella enterica subsp. enterica foodborne outbreak that occurred in the Marche Region (Italy) in 2022, which was linked to the consumption of a roasted pork product (porchetta). As part of the outbreak investigations discussed in this article, molecular analysis to evaluate the genomic correlation between clinical, food, and environmental origin strains was carried out. All Salmonella strains of different origins were serotyped as monophasic variant of Salmonella Typhimurium with an antibiotic-resistance pattern and an allelic profile such as to define the "cluster strain" allowing the correlation between clinical and food/environmental strains, definitively confirmed by whole genome sequencing analysis. Following the laboratory evidence, corrective measures at the porchetta processing plant and at the retail stores involved were carried out by the Local Animal Based Food Hygiene Service. The results of this study show that effective intervention is only possible if efficient data exchange, standardized procedures, and staff training are guaranteed. The latter aspect also concerns the food business operator, who must take appropriate measures to minimize the risk.

Keywords: foodborne disease outbreaks; monophasic variant of Salmonella Typhimurium; official control; porchetta.

Figure 1.

Flowchart of single case and outbreak investigation as proposed by the regional foodborne diseases investigation guidelines. Source: Marche Region, (Decree No. 98/2022). FHNS, Food Hygiene and Nutrition Service; ABFHS, Animal Based Food Hygiene Service; LHU, Local Health Unit; HPHS, Hygiene and Public Health Service; FCD, foodborne disease; FBO, food business operators.

Figure 2.

Flowchart of the food safety measures adopted by the competent authority as proposed by the regional foodborne diseases investigation guidelines. Source: Marche Region, (Decree No. 98/2022). FHNS, Food Hygiene and Nutrition Service; ABFHS, Animal Based Food Hygiene Service.