Prevalence and Characterization of Pathogenic Bacteria in Bulk Tank Raw Milk, Thailand

Abstract

Although there are a number of raw milk collection centers in Nakhon Ratchasima, there is a lack of information with regard to the process of isolation and characterization of foodborne pathogens in raw milk. Therefore, the purpose of this research was to investigate the prevalence and characterization of foodborne pathogens, including Bacillus cereus, Escherichia coli, Listeria monocytogenes, Salmonella spp. and Staphylococcus aureus from 33 raw milk samples from 9 different raw milk collection centers located in 8 districts in Nakhon Ratchasima, Thailand. This study was conducted from January to March 2016. Results revealed that the contaminations of L. monocytogenes and Salmonella spp. were not detected in any of the raw milk samples tested. The prevalence of B. cereus, E. coli, and S. aureus in raw milk samples was found to be 9 % (10 - 2.0 ×104 CFU/ml), 42.4 and 54 % (85 - 2.7 ×104 CFU/ml), respectively. The distribution of virulence genes was tested in B. cereus and S. aureus using gene specific primers by polymerase chain reaction. Out of the 29 analyzed coagulase-positive S. aureus isolates, 27 isolates (93 %) were positive for eap gene amplification and 14 isolates (48 %) showed amplicon of eap gene and all 5 enterotoxin genes, including seG, seGV, seI, seIV, and seM genes. All 8 B. cereus isolates tested showed positive PCR result with enterotoxin FM (entFM) gene but they showed negative with hemolysin gene (hblA and hblD genes) amplifications. It was inferred from these findings that bulk tank milk is a potential source of S. aureus and B. cereus in milk.

Listeria Contamination in Milk-Processing Chain and Proficiency in Listeria monocytogenes Decontamination of Small-Scale Milk Retailers

“…in raw milk was reported in a wide range such as 3-7% in North America, 0-50% in Europe, and about 5% in Iran [9][10][11]. In Tailand, there was not the report of Listeria contamination in raw milk [12]. Unpasteurized or improper processed milk caused three out of 36 outbreaks of listeriosis.…”

The first study on antimicrobial resistance of Staphylococcus aureus isolated from raw goat milk associated with subclinical mastitis in Siliragung Subdistrict, East Java, Indonesia

“…To date, awareness of antimicrobial-resistant Staphylococcus spp. has become the primary concern in public health because it affects not only animals but also milk products routinely consumed by humans [ 9 ]. In the dairy cattle industry, subclinical mastitis is caused by Staphylococcus spp.…”

Prevalence and antibiotic resistance of Staphylococcus aureus and Escherichia coli isolated from raw milk in East Java, Indonesia

“…In dairy farming in East Java, the lack of production quantity is also offset by the potential for low quality, where the feeding system, milking management, high temperature, and humidity contribute significantly to the contamination of pathogenic bacteria, such as Staphylococcus aureus and Escherichia coli [6,7]. In line with this, Kupradit et al [8] reported that in milking management, the teats of cows or the Milker's hands have a significant effect on bacterial milk contamination. Such contamination can also occur with the movement through the intermediaries of workers, water, and production equipment [9,10].…”

“…It does affect not only human health but also the economic sector [11]. Cases of the food-borne disease have been found due to raw milk consumption [8], contamination with S. aureus, and E. coli bacteria that can come from raw milk. Thus, this study aimed to estimate the prevalence of S. aureus and E. coli from raw milk and the presence of crucial antimicrobial-resistant gene encodings such as the mecA gene in S. aureus and the blaTEM gene in E. coli are expected to provide a clear picture of the findings of the distribution of antimicrobial resistance (AMR) isolated from raw milk in East Java Province, Indonesia.…”