Survey of Listeria monocytogenes and other Listeria sp. contamination in different common ready-to-eat food products in Jordan

Abstract

Incidence and contamination levels of different Listeria monocytogenes serovars and different Listeria sp. in 360 samples of common ready-to-eat food products in Jordan were investigated. The presence of L. monocytogenes was determined using EN ISO protocol and confirmed using PCR technique. Five Listeria sp.: L. monocytogenes, L. innocua, L. ivanovvi, L. welshimeri and L. seeligeri were isolated. L. monocytogenes was isolated from 19 samples (5.3%), from 6 RTE dairy samples; 6 RTE vegetables samples and 4 traditional dishes samples and 3 miscellaneous samples. L. innocua and L. ivanovvi were the most and least frequently isolated species, 24 and 3 samples, respectively. L. welshimeri was isolated from 8 samples and L. seeligeri from 7 samples. The contamination levels of L. monocytogenes were found to be < or = 100 CFU g(-1) in 84.2% (16 samples) of the positive samples. Only 15.8% (3 samples; 1 vegetable, 1 traditional dish and 1 miscellaneous samples) of the positive samples were found with counts >100 CFU g(-1). L. monocytogenes strains isolated fell into 2 serotype, 1 and 4 and to 5 different serovars, 1/2a, 1/2b, 1/2c, 4a, 4c.