engleski

Composition of raw cow’s milk microbiota and identification of enterococci by MALDI-TOF MS – short communication

Raw milk consumption could present potential risk for public health due to the presence of foodborne pathogens and spoilage bacteria. In this research microbiota or raw cow milk was studied with particular reference to the presence of enterococcal opportunistic pathogens. Total viable count, psychrophilic bacteria, lactic acid bacteria, staphylococci, Escherichia coli, enterococci, enterobacteria, Listeria spp. and sulfite-reducing clostridia were evaluated using standard cultured methods. Milk samples originated from healthy (n=17) and antibiotic-treated cow udder (n=19). Presumptive enterococci (n=43) were randomly selected from chromogenic media and subjected to phenotypic identification by API 20 Strep, followed by Matrix-Assisted Laser Desorption Ionization – Time of Flight Mass Spectometry (MALDI-TOF MS). Statistically significant differences (P<0.05) considering the udder status were found in total viable count and lactic acid bacteria. MALDI-TOF MS determination showed the 100 % concordance with API 20 Strep in the identification of Enterococcus faecalis. Strains determined to the genus level only, or not determined strains by API 20 Strep have been successfully identified using MALDI-TOF MS to the strain level as E. faecalis, E. faecium and E. durans. Results showed that MALDI-TOF MS could be applied as reliable method in routine identification of enterococcal species from raw milk.

milk ; enterococci ; MALDI-TOF MS

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