Distribution of Listeria monocytogenes serogroups in food of animal origin produced in Poland during 2013–2022

Abstract

Listeria monocytogenes is an important food-borne pathogen that causes severe disease in humans. Many different foods products may be vehicles of these pathogenic strains. The aims of this study were to identified serogroups L. monocytogenes isolates by using PCR and analyze the distribution of serogroups in different food products of animal origin. L. monocytogenes isolates from ready-to-eat (RTE) meat products (n = 1,571), non-meat RTE food (n = 237), and non-RTE products (n = 189) were collected during years 2013-2020. A total of 899 (45.0%) isolates, irrespective of the origin, were classified to serogroup IIa. The remaining 1,098 strains belonged either to serogroups IVb (478; 23.9%), IIc (347; 17.4%) or IIb (273; 13.7%), respectively. In the predominant group products, i.e. RTE food of meat origin, serogroup IIa (702; 44.7%) was the most common followed by IVb (334; 21.3%), IIc (300; 19.1%), and IIb (235; 14.9%), respectively. The statistical differences were observed between the prevalence of L. monocytogenes serogroup IIb in sausages and cold cuts (P < 0.0001), cold cuts and delicatessen food (P < 0.001), as well as strains of serogroup IVb from sausages and cold cuts (P < 0.001). The prevalence of serogroup IIa was statistically higher among strains of milk and milk products origin than RTE fish and fish products (P < 0.05). The differences (P < 0.0001) were also observed in the distribution of L. monocytogenes of serogroup IIa from mixed food and milk as well as fish products. Additionally, the occurrence of serogroup IVb in mixed food differed compared to other food categories, i.e. milk and fish products (P < 0.0001). The obtained results confirmed the presence of L. monocytogenes serogroups IIa and IVb in food of animal origin, including RTE products, that are responsible for listeriosis in humans and suggested that these food products may pose a potential health problem, particularly to sensitive groups of people.