Pathogenic Bacteria in Finnish Bulk Tank Milk

Abstract

While the quality of raw cow milk in Finland is known for its high hygienic standard, with the national average total bacterial count being below 10(4) CFU/mL annually, the prevalence of pathogenic bacteria in Finnish raw milk is underreported. The aim of this study was to determine the occurrence of Listeria monocytogenes, thermophilic Campylobacter spp., Salmonella spp., stx-positive Escherichia coli (STEC), coagulase-positive staphylococci, Yersinia spp., and Bacillus cereus group in raw cow milk samples collected from bulk tanks at 183 Finnish farms. Additionally, the hygienic quality of the milk was studied by determining the total bacterial and E. coli counts. L. monocytogenes was detected in 5.5% of the milk samples, with concentrations varying from <1 to 30 CFU/mL. Thermophilic Campylobacter spp. or Salmonella spp. were not detected in any of the samples. STEC with Shiga toxin-encoding stx2 was detected in 2.7% of the samples. Yersinia enterocolitica was detected in 7.7% of the samples; however, all isolates were negative for ail, suggesting that they were non-pathogenic. Coagulase-positive staphylococci were detected in 34.4% of the samples, with an average concentration of 25 CFU/mL in the positive samples. Members of the B. cereus group were detected in 20.8% of the samples, with an average concentration of 1 CFU/mL in the positive samples. No relationship was detected between E. coli or the total bacterial count and the presence of pathogenic bacteria, which suggests that pathogens can be present also in farms with excellent production hygiene. Although the concentration of pathogenic bacteria in fresh raw milk was mainly relatively low, it should be borne in mind that some of the pathogenic bacteria can survive and multiply at refrigeration temperatures and may cause a disease with a very low infectious dose. Thus, consumption of raw milk and related products poses a potential risk for food poisoning.

Genotypic and phenotypic virulence characteristics and antimicrobial resistance of Yersinia spp. isolated from meat and milk products

“…was observed to be 36.6% and 45.2% in raw milk samples reported by Hamama and others () and Tassinari and others (), respectively. In our study, the contamination rate with Y. enterocolitica is relatively low in comparison with several reports ranging from 7% to 30% (Hamama and others ; Tassinari and others ; Ruusunen and others ). Meanwhile, the incidence rates of Y. enterocolitica as low as 1.3% and 1.6% were reported by Güven and others () and Soltan‐Dallal and others (), respectively.…”

Prevalence and risk factors for Bacillus cereus in raw milk in Inner Mongolia, Northern China

“…Next, 0.1 mL of each dilution was plated onto mannitol‐egg‐yolk‐polymyxin agar (Beijing Land Bridge Technology Co., LTD.) and incubated for 48 h at 30 °C (Ruusunen et al . ). A minimum of five typical colonies per samples were streaked on nutrient agar (Beijing Land Bridge Technology Co., LTD.) and incubated for 24 h at 30 °C (GB 4789.14 ).…”

Arcobacter Species and Their Pulsed-Field Gel Electrophoresis Genotypes in Finnish Raw Milk during Summer 2011

“…A total of 177 raw milk samples were collected from Finnish dairy farms from June to August 2011 (12). Samples were stored refrigerated and were analyzed up to 48 h after collection.…”