Incidence of pathogenic bacteria in raw milk in Ireland.
Raw milk from 70 farms was sampled over 13 months for salmonellas, listerias, Escherichia coli, Staphylococcus aureus and mastitic streptococci; total bacterial counts (TBC), coliforms and somatic cells were also counted. TBC < or = 30,000/ml were obtained in 63% of samples. High count milks were found mainly during the winter months: 13% of samples had > 10(4) mastitis pathogens/ml of milk. The mean somatic cell count varied from 4.0 x 10(5) to 8.0 x 10(5)/ml throughout the year with highest counts during the late lactation period. Coliforms were present in all samples, but 65-71% of samples had < 100 coliforms/ml. Up to 60% of supplies had < or = 10 E. coli/ml. One of the 589 samples tested (0.1%) was positive for salmonellas. Yersinia enterocolitica and Y. enterocolitica-like organisms were isolated from 39% of samples with up to 68% of samples positive at some sampling periods. A total of 222 strains of yersinias were isolated; Y. enterocolitica (59%) was the most common strain followed by Y. fredriksenii (35%), Y. kristensenii (1.0%), Y. intermedia (4.5%) and Y. aldovae (0.5%). Listerias were isolated from 8.3% of samples tested; 4.9% were Listeria monocytogenes and 3.4% were L. innocua. There was a significant rise in the isolation rate between December and April from a base line of 0-5% during the spring and summer to 35-37% during the winter months while the cows were indoors. Of 66 silage samples tested from the farms involved in the survey 9% of samples were positive for listerias; 3% of these were L. monocytogenes and 6% were L. innocua.(ABSTRACT TRUNCATED AT 250 WORDS)
Rea
M C
MC
National Dairy Products Research Centre, Fermoy, County Cork, Ireland.
Cogan
T M
TM
Tobin
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D000818:Animals; D001419:Bacteria / Q000302:isolation & purification / Q000472:pathogenicity*; D002452:Cell Count; D004926:Escherichia coli / Q000302:isolation & purification; D005516:Food Microbiology; D007494:Ireland; D008087:Listeria / Q000302:isolation & purification; D008413:Mastitis / Q000382:microbiology; D008892:Milk / Q000166:cytology / Q000382:microbiology*; D012475:Salmonella / Q000302:isolation & purification; D013210:Staphylococcus / Q000302:isolation & purification; D013291:Streptococcus / Q000302:isolation & purification; D014774:Virulence; D015007:Yersinia / Q000302:isolation & purification