Microbiological Examination of Bulk Tank Goat's Milk in the Castilla y León Region in Northern Spain

Abstract

The purpose of the study was to evaluate the microbiological status (mesophilic aerobic microorganism counts) of 68 samples of bulk tank goat's milk and determine the risk associated with the foodborne pathogens Staphylococcus aureus, enteropathogenic and Shiga toxin–producing Escherichia coli, and Cronobacter sakazakii. Most samples (83.8%) complied with the limits of mesophilic aerobe counts set in the European Union for milk of species other than cows. A total of 144 isolates of coagulase-positive staphylococci were characterized, and 11 (7.6%) of them carried staphylococcal enterotoxin (SE) genes of the classical types (encoding SEA to SEE), distributed as follows: 4 carried the SEA gene, 1 the SEB gene, and 6 the SED gene. C. sakazakii was not detected in any sample. Regarding detection of E. coli virulence-related genes in enriched milk samples, 12 milk samples were positive only for the presence of stx genes, 4 were positive for both stx and eae genes, and 20 were negative for stx amplification and positive for eae amplification. Seven enteropathogenic E. coli and 9 Shiga toxin–producing E. coli isolates (one of them of serogroup O157) were recovered. In conclusion, goat's milk produced on farms in Castilla y León is generally in accordance with European Union standards, but the presence of pathogenic E. coli isolates indicates that the consumption of raw goat's milk may pose a risk to public health.