Serotype identification of listeria monocytogenes isolated from ground turkey by multiplex PCR and relation between serotype distribution and antibiotic resistance profiles

ABSTRACT
The objectives of this study were to determine the serotype distribution of L. monocytogenes isolated from packaged fresh ground turkey using multiplex PCR, to find out the antibiotic resistance profiles of the isolates by disc diffusion method and to suggest the relation between serotype distribution and antibiotic resistance profiles.
From 78 isolates, 35 (44.9 %), 29 (37.2 %), 7 (9.0 %) and 7 (9.0 %) were identified by multiplex PCR, as 1/2a, 4b, 1/2b and 1/2c, respectively. According to the disc diffusion test, all of the isolates (100.00 %) were found to be resistant to nalidixic acid, 63 (80.8 %) to penicillin G and 53 (67.9 %) to ampicillin. According to the serotypes, all of the 1/2c (7/7) serotypes were found to be resistant to penicillin G and ampicillin and also all the 1/2b (7/7) serotypes were resistant to penicillin G. In the study, 91.4 % (32/35) of 1/2a, 57.1 % (4/7) of 1/2b and 37.9 % (11/29) of 4b serotypes were resistant to ampicillin. In addition, 87.7 % (30/35) of 1/2a and 65.5 % (19/29) of 4b serotypes were resistant to penicillin G.
The results of this study showed that most of the L. monocytogenes isolates were identified as serotype 1/2a and 4b which were generally related with foodborne listeriosis worldwide. Relatively high numbers of the L. monocytogenes isolates were found to be resistant to widely used antibiotics. In addition, serotypes 1/2b and 1/2c were higly resistant to antibiotics, compared with 1/2a and 4b.