Microbial composition, including the incidence of pathogens, of goat milk from the Bergamo region of Italy during a lactation year

Sixty samples of raw goat milk intended for Caprino cheese-making were collected from ten farms in the Bergamo area over a 6-month period. Analyses of main microbial groups. somatic cell count (SCC) and pH Were performed to determine the effect of origin (farm) and lactation period (April - September) on microbial composition and the incidence of pathogens in milk. Overall mean values were: standard plate count (SPC), 5.0 x 10(4) cfu/ml: yeasts. 2.5 x 10(2) cfu/ml coliforms 9.1 x 10(2) cfu/ml; Escherichia coli. 2.9 cells/ml enterococci. 1.1 x 10(2) cfu/ml; lactococci, 3.4 x 10(3) cfu/ml: lactobacilli, 3.0 x 10(3) cfu/ml -, halotolerant bacteria, 8.2 x 10(3) cfu/ml; spores of mesophilic aerobic bacteria, 11 cfu/ml SSC. 9.9 x 10(5) cells/ml; pH. 6.63, Moulds and spores of sulphite-reducing clostridia Were found intermittently. Neither Salmonella spp. nor Listeria monocytogenes was detected, while Esch. coli O157: H7 was isolated from one milk sample (an incidence of 1.7%). Staphylococcus aureus was discovered at a level > 10(2) cfu/ml in 26 samples (43%) with an overall mean of 1.2 x 10(3) cfu/ml. whereas coagulase-negative staphylococci were found in 54 samples (90%) with an overall mean of 1.3 x 10(3) cfu/ml. Of Staph. aureus strains, 23% proved to be enterotoxinogenic with a prevalence of enterotoxin C producers. Staph. caprae was the coagulase-negative species most frequently isolated none of the coagulase-negative staphylococci strains synthesized any of the enterotoxins tested for. Sample source was the major factor affecting the microbial composition of goat milk: significant differences (P < 0.01) were observed among samples from different farms for SPC. coliforms. lactococci, lactobacilli and halotolerant bacteria. Period of lactation had a significant effect (P < 0.025) on SCC and pH. SPC correlated well with coliforms. lactococci and lactobacilli: SSC did not reveal positive interactions with any microbial groups or pH.