61C-35 |
Survivability of Burkholderia cepacia in pasteurized and unpasteurized bovine milk stored at 4ºC and 8ºC |
M. K. MOHAN NAIR, P. Vasudevan, T. Hoagland, and K. Venkitanarayanan. Animal Science, University of Connecticut, 3636 Horse barn hill road, G. White building, Storrs, CT 06480 Burkholderia cepacia is an environmental saprophyte associated with soil, water and root rhizosphere of plants. It has been implicated in life threatening opportunistic infections in cystic fibrosis and immunocompromised patients. A recently published survey indicated the presence of B. cepacia in more than 50% of 26 raw milk samples analyzed. Further, B. cepacia has been implicated in cases of subclinical mastitis in sheep. The objective of this study was to determine the survival of B. cepacia in bovine milk. A two-strain mixture of B. cepacia was inoculated into 100 ml of fresh, pasteurized and unpasteurized milk (pH 6.8 and fat 3.65%) in triplicates at two inoculum levels of 103 and 105 CFU/ml, and stored at 4ºC and 8ºC. B. cepacia count and total bacterial count in milk were enumerated on B. cepacia selective agar and Nutrient agar, respectively on days 0, 1, 3, 5, 7, 14, 21, 28, 35 and 42. At both temperatures, B. cepacia did not grow but survived throughout the study. At 8ºC and 4ºC, B. cepacia count at 103CFU/ml inoculation level decreased to <1 log CFU/ml levels by second and fourth week, respectively in pasteurized milk, and by third and sixth week, respectively in unpasteurized milk. At 105 CFU/ml inoculation level, a reduction in B. cepacia count by approximately 1 log CFU/ml at 8ºC and by 3 log CFU/ml at 4ºC was observed in the pasteurized milk. In unpasteurized milk, B. cepacia declined by 2 log CFU/ml at 4ºC, and to <1 log CFU/ml levels at 8ºC at the end of the sampling period. The survival of B. cepacia in pasteurized and unpasteurized milk was not significantly different (P > 0.05). Data indicate that B. cepacia can survive in milk for a long time and contaminated milk can serve as a potential source of infection.
Session 61C, Food Microbiology: General I
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