Prevalence, Detection Methods and Antimicrobial Susceptibility of Listeria monocytogens Isolated from Milk and Soft Cheeses and its Zoonotic Importance
The present study was carried out to detect Listeria monocytogenes prevalence by conventional isolation, colony PCR and enrichment PCR methods in 200 dairy product samples (50 each of market raw milk, bulk tank milk, Damietta cheese and kareish cheese), as well as 120 human specimens. While conventional biochemical tests revealed that 36% (72/200) of the dairy products were positive for L. monocytogenes, only 14% (28/200) of these products were positive for L. monocytogenes using colony PCR method. Enrichment PCR method, however, indicated that 23% (46/200) of samples tested were confirmed as L. monocytogenes. Only 5% (2/40) of stool specimens from apparently healthy dairy handlers were positive for L. monocytogene by enrichment PCR method which is proven to be more precise and fast. The fifty four L. monocytogenes strains detected by colony PCR method were multidrug resistant. Pasteurization should be applied to milk and milk used for cheeses manufacture. There is a need of continuous surveillance and more prudent use of antibiotics in human and dairy farms.
Mayada M. Gwida
Maha A.M. AL-Ashmawy and Khaled H. Abdelgalil
World Applied Sciences Journal,29 (7): 869-878, 2014