Molecular detection of serotype groups of Listeria monocytogenes isolated from gallbladder of cattle and sheep in Iraq

Aim: This study was designed to investigate the occurrence of serotypes of Listeria monocytogenes, an important foodborne pathogen, in gallbladder samples from cattle and sheep. Materials and Methods: Three hundred samples were collected and screened for the presence of L. monocytogenes. The identification of the isolates was confirmed by API-Listeria system and by the presence of hemolysin (hyl) gene. The isolates were subjected to polymerase chain reaction-based serotype identification with d1 (division 1), d2 (division 2), glt, mama (mismatch amplification mutation assay), andflaA (flagellin protein) genes. Results: A total of 8 (2.7%) L. monocytogenes were recovered from 6 (4.0%) samples of sheep and 2 (1.3%) samples of cattle. All isolates showed positive results with Hly primers. Four isolates carried d1 gene, did not possess glt gene and harbored mama gene. The serotypes of these isolates were identified as 4a or 4c. The other 4 isolates carried d2 gene, 3 of them were positive with the FlaA primers, and hence, determined to be a 1/2a or 3a serotype, and 1 isolate was determined to be 1/2c or 3 c serotype. Conclusion: This study concluded that the presence of 1/2a serotype in gallbladder samples indicates public health risk through cross-contamination of meat at slaughterhouses. Keywords: cattle, gallbladder, Listeria monocytogenes, molecular detection, sheep.