|RIVERA, FERNANDO - UNIVERSITY OF VENEZUELA
|HURD, SCOTT - IOWA STATE UNIVERSITY
|SIMOES, DAVID - UNIVERSITY OF VENEZUELA
|SOSA, ALIX - LARNACA LAB,VENEZUELA
|RIVERA, SERGIO - UNIVERSITY OF VENEZUELA
Submitted to: Revista Cientifica-Universidad Del Zulia Faculatad De Ciencia Veterinarias Division De Investigacion
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2006
Publication Date: 3/15/2006
Citation: Rivera, F.H., Wesley, I.V., Hurd, S.S., Simoes, D., Sosa, A., Rivera, S. 2006. Microbiological and molecular detection of Listeria spp. and Listeria monocytogenes in a cull sows process plant in USA. Revista Cientifica-Universidad Del Zulia Faculatad De Ciencia Veterinarias Division De Investigacion. 26(3):297-307.
Interpretive Summary: Listeria monocytogenes is a human pathogen with the highest mortality rate of all bacterial foodborne agents. Presence of Listeria in a food processing plant indicates potential co-contamination with monocytogenes. We screened 160 cull sows (sub-iliac and ileocecal lymph nodes, cecal contents, carcass swabs and pork) for both Listeria and L. monocytogenes using traditional and a multiplex PCR formats. By conventional methods, Listeria (5.2%) and L. monocytogenes (0.14%) were detected at levels comparable to those obtained with the multiplex PCR format. However, the PCR multiplex technique yielded results within 8 hours after the secondary enrichment whereas traditional microbiology required 8 days. The incorporation of molecular methods into a plant’s verification system may improve the effectiveness of HACCP strategies.
Technical Abstract: Listeria spp. and Listeria monocytogenes present in a cull sow processing plant in the USA was evaluated by a PCR multiplex method. 160 cull sows were surveyed after slaughter. Samples were collected from sub-iliac node, ileocecal node, cecal contents and carcass swabs. Additionally, samples were taken from the environment of the plant and from raw meat ready to be processed. A total of 708 samples were processed. Using traditional microbiological methods, 5.2% of the samples were positive for Listeria spp. and 0.14% were positive for L. monocytogenes. With a PCR multiplex, 4.1% of samples were positive for Listeria spp. and 0.85% were positive for L. monocytogenes. There was no significant difference in the results obtained with a PCR multiplex and traditional microbiological procedures. In relation to the raw material that leaves the slaughter area to be processed inside the same plant, Listeria spp. was observed in 1.9% of carcass swabs and 5% of raw sow meat samples. Listeria was identified in 6.3% and L. monocytogenes in 1.3% of subiliac nodes. None of the subiliac nodes were positive for Listeria. For samples related to the contamination source in the processing plant, cecal contents were 19% positive for Listeria spp. and 2.5% positive for L. monocytogenes. Environmental samples were 4.2% positive for Listeria spp. There were no differences between conventional microbiology and PCR multiplex technique for this pathogen when carcass swabs and ileocecal nodes were evaluated. Differences were observed between samples from cecal contents and sub-iliac node . With the PCR multiplex technique, result were obtained in 8 hours after the second enrichment culture of each sample. With traditional microbiology it took 8 days. The incorporation of molecular methodology in the verification process for microbiological controls in the food industry would allow an important improvement of the effectiveness and dynamics in the food safety systems implanted at the food industries.