Occurrence and distribution of serovars in carcasses and foods in southern Italy: Eleven-year monitoring (2011-2021).

is one of the most common agents of foodborne illness. The genus includes two species ( and ) and six subspecies ( I, II, IIIa, IIIb, IV, and VI), each of which contains multiple serotypes associated with animal and human infections. The aim of the study was to evaluate the presence of spp. in carcasses of food-producing animals and foods in southern Italy and the serovar distribution among different sources. From 2011 to 2021, a total of 12,246 foods and 982 samples from animal carcasses were collected and analyzed. The overall percentage of positive samples was 5.84% ( = 773) and a significant increase in prevalence was observed by comparing the years 2011-2015 (257, 3.27%) and 2016-2021 (516, 9.61%; < 0.05). The highest percentage of positive food samples was observed in "Meat and Meat Products" ( = 327/2,438, 13.41%) followed by "Fish and fishery products" ( = 115/1,915, 6.01%). In carcasses, the highest percentage of positive samples was reported from broilers ( = 42/81, 51.85%) followed by buffalo ( 50/101, 49.50%) and pork ( 140/380, 36.84%). After typing, the isolates were assigned to the species and to the subspecies: ( 760, 98.32%), ( 8, 1.03%), ( 3, 0.39%) and ( 2, 0.26%). Infantis was the most frequently detected ( 177, 24.76%), followed by Derby ( 77, 10.77%), monophasic . Typhimurium ( 63, 8.81%), . Typhimurium ( 54, 7.55%), and Rissen ( 47, 6.57%). By comparing the sampling period 2011-2015 with that of 2016-2021, an increase in the prevalence of Infantis and monophasic . Typhimurium and a decrease of . Typhimurium were recorded ( < 0.05). Thus, present data suggest that, despite the implementation of national and European control strategies to protect against , the prevalence of this pathogen in southern Italy is still increasing and a change of national control programs to protect against are necessary.