Seromolecular typing of Listeria monocytogenes isolated from raw and frozen chicken nuggets

Listeria monocytogenes has been identified as a major cause of human Listeriosis, which has now become a major public health concern. So the main purpose of this study was to screen Listeria monocytogenes from ready-to-eat nugget samples to determine the seromolecular typing of the isolates. For this purpose, 40 chicken nuggets were bought from different area of Shiraz city and had transferred to the microbiological laboratory. 25 gram of each nugget was transferred to Palcom Broth medium and subsequently Palcam Agar. Then the isolates were identified by biochemical tests, also specific primers were used for seromolecular typing. For determination of antibiotic susceptibility of the isolates, effect of Oxacillin (OX1), Erythromycin (E15), Amikacin (AN30), Penicillin (P10), Tobramycin (Tob10), Gentamicin (Gm10), Ceftriaxone (CRO30), Clindamycin (CC2), Vancomycin (V30), Ciproflexocacin (CP5), Tetracycline (TE30) and Trimethoprim Sulfomethoxazole (SXT23) were checked on the isolates by using disk diffusion method and Vet01-A4 CLSI protocol. Data were analyzed by SPSS software and ANOVA test. Out of all isolated bacteria, 4 isolates from chicken nugget belong to Listeria monocytogenes was identified by biochemical tests. Based on molecular testing, Seromoleculartyping including 1/2a, 3a and 1/2b, 3b were identified and their frequency was 50%. Out of all the most antibiotics resistant belong to the (OX), (CRO), (P) were100 percent, 100 percent and 58/3 percent respectively and the less belong to (TE), (GM), (CP), (V), (SXT), (TOB), (AN), all of them was 100 percent.