RESUMO
BACKGROUND AND AIM: Listeria monocytogenes is a ubiquitous, intracellular pathogen which has been implicated as a cause of several foodborne outbreaks. This study aimed to generate information on the prevalence and antibiotic resistance profile of Listeria species isolated from seafood. MATERIALS AND METHODS: A total of 400 samples of fresh fish, 100 samples of dry fish and 200 samples each of crustaceans and mollusks were collected from the fish catchment areas. All the samples were subjected to isolation and identification of Listeria spp. by two-step enrichment in UVM broth and plating on selective agar media (PALCAM) and then subjected to molecular characterization. L. monocytogenes isolates obtained during the study were subjected to serotyping by multiplex polymerase chain reaction. The isolates were also subjected to antibiotic sensitivity test. RESULTS: The prevalence of L. monocytogenes in seafoods in the present study was 0.55%. The isolates of L. monocytogenes were found to possess all virulence genes, namely, iap, hlyA, actA, prfA, plcA, and inlA. All the isolates belonged to serotype 4b. The occurrence of Listeria innocua was found to be more and was detected in 16.77% of seafood samples. Antibiotic sensitivity test revealed that all isolates were resistant to cefixime but were sensitive to almost all other commonly used antibiotics. CONCLUSION: The presence of Listeria spp. in raw seafood samples augments the need for implementation of good hygienic practices during the handling and processing of seafoods to safeguard the health of the consumers.
RESUMO
BACKGROUND AND AIM: Food of animal origin such as milk is vital for nutritional security and should be free of any antibiotic residues due to its public health significance. We designed a study aiming to determine the occurrence of antibiotic residues and in further levels of oxytetracycline residues in pooled raw milk samples from Palakkad district, Kerala. MATERIALS AND METHODS: We collected pooled raw milk samples were collected from Alathur, Chittoor, and Palakkad blocks of Palakkad district, Kerala. A total of 215 samples were screened for antibiotic residues by microbial inhibition assay (MIA) and the positive samples were subjected to enzyme-linked immunosorbent assay (ELISA) to determine oxytetracycline residues, this was further confirmed using high-performance liquid chromatography (HPLC). RESULTS: We found that out of the 215 pooled raw milk samples screened for antibiotic residues using MIA, 22 samples (10.23%) were positive for antibiotic residues from Palakkad, Kerala. Out of these 22 samples, five (2.33%) were positive for oxytetracycline residues. We further calculated the mean concentration of oxytetracycline residues in these five samples and estimated it to be 201.00±41.25 ng/mL and 272.11±53.21 ng/mL using ELISA and HPLC, respectively. On analyzing these five samples, we found that four samples (1.86%) exceeded the maximum residue limits level of 100 ng/mL for oxytetracycline residues in milk as specified by Codex Alimentarius Commission/Food Safety and Standards Authority of India (FSSAI). CONCLUSION: This study revealed that the occurrence of oxytetracycline residues in pooled raw milk samples in the Palakkad district of Kerala. Hence, there is a need for surveillance and monitoring of antibiotic residues in milk due to its impact on public health to ensure consumer safety.
