C S Swetha1, K Porteen2, A Elango3, B S M Ronald4, T M A Senthil Kumar5, A P Milton6, S Sureshkannan2. 1. Ph.D. Student in Veterinary Public Health, Department of Veterinary Public Health and Epidemiology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University, Chennai-600 007, Tamil Nadu, India. 2. Department of Veterinary Public Health and Epidemiology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University, Chennai-600 007, Tamil Nadu, India. 3. Veterinary College and Research Institute, Tamil Nadu Veterinary and Animal Sciences University, Salem-636 112, Tamil Nadu, India. 4. Department of Veterinary Microbiology, Madras Veterinary College, Tamil Nadu Veterinary and Animal Sciences University, Chennai-600 007, Tamil Nadu, India. 5. Translational Research Platform for Veterinary Biologicals (TRPVB), Madhavaram Milk Colony, Tamil Nadu Veterinary and Animal Sciences University, Chennai-600 051, Tamil Nadu, India. 6. Division of Animal Health, ICAR Research Complex for North Eastern Hill Region, Meghalaya-793 103, India.
Abstract
BACKGROUND: Listeria monocytogenes is an opportunistic intracellular foodborne pathogen and is ubiquitous in nature. The occurrence of L. monocytogenes in animal production units coupled with their presence in milk, faeces, feed, water, sewage, and soil is a contributory factor for foodborne listeriosis in humans and animals. AIMS: The study was aimed to characterize genotype and serogroup of L. monocytogenes recovered from different types of samples and also to study antimicrobial patterns by phenotypic and genotypic methods. METHODS: Multiplex polymerase chain reaction (PCR) was used for the confirmation of L. monocytogenes, the identification of its serogroup and lineage, and the detection of virulence markers. Enterobacterial repetitive intergenic consensus (ERIC), and randomly amplified polymorphic DNA (RAPD)-PCR were used to characterize those isolates, and antimicrobial patterns were studied phenotypically by Kirby-Bauer method and genotypically by PCR. RESULTS: Out of the screened 474 samples (274 milk and 50 each of soil, feed, sewage, and beef), ten L. monocytogenes isolates (milk=8, soil=1, and beef=1) were confirmed by PCR targeting the hlyA gene and found to belong to the 1/2a, 3a serogroup and fall under type II lineage. Virulence potential assessment revealed that all the ten isolates harbored the iap gene while the presence of plcA and plcB genes were noticed in seven and eight isolates respectively. Six isolates from milk were found to group in the same cluster by ERIC and RAPD fingerprinting, suggesting both methods to be efficient molecular typing tools for L. monocytogenes. Genotypic characterization of antimicrobial resistance (AMR) genes revealed that seven isolates were positive for tetM, five for mefA, four for msrA, and one for lnuA genes while none of the isolates showed tetK, ermA, ermB, and lnuB genes. CONCLUSION: The presence of L. monocytogenes in bovine farm environments coupled with virulence markers, and multidrug resistance from the study area suggest a possible transmission from the environment to humans and animals which needs to be monitored regularly to ensure food safety and the well-being of animals and humans.
BACKGROUND: Listeria monocytogenes is an opportunistic intracellular foodborne pathogen and is ubiquitous in nature. The occurrence of L. monocytogenes in animal production units coupled with their presence in milk, faeces, feed, water, sewage, and soil is a contributory factor for foodborne listeriosis in humans and animals. AIMS: The study was aimed to characterize genotype and serogroup of L. monocytogenes recovered from different types of samples and also to study antimicrobial patterns by phenotypic and genotypic methods. METHODS: Multiplex polymerase chain reaction (PCR) was used for the confirmation of L. monocytogenes, the identification of its serogroup and lineage, and the detection of virulence markers. Enterobacterial repetitive intergenic consensus (ERIC), and randomly amplified polymorphic DNA (RAPD)-PCR were used to characterize those isolates, and antimicrobial patterns were studied phenotypically by Kirby-Bauer method and genotypically by PCR. RESULTS: Out of the screened 474 samples (274 milk and 50 each of soil, feed, sewage, and beef), ten L. monocytogenes isolates (milk=8, soil=1, and beef=1) were confirmed by PCR targeting the hlyA gene and found to belong to the 1/2a, 3a serogroup and fall under type II lineage. Virulence potential assessment revealed that all the ten isolates harbored the iap gene while the presence of plcA and plcB genes were noticed in seven and eight isolates respectively. Six isolates from milk were found to group in the same cluster by ERIC and RAPD fingerprinting, suggesting both methods to be efficient molecular typing tools for L. monocytogenes. Genotypic characterization of antimicrobial resistance (AMR) genes revealed that seven isolates were positive for tetM, five for mefA, four for msrA, and one for lnuA genes while none of the isolates showed tetK, ermA, ermB, and lnuB genes. CONCLUSION: The presence of L. monocytogenes in bovine farm environments coupled with virulence markers, and multidrug resistance from the study area suggest a possible transmission from the environment to humans and animals which needs to be monitored regularly to ensure food safety and the well-being of animals and humans.
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