Occurrence of Salmonella, Listeria monocytogenes, and enterotoxigenic Staphylococcus in goat milk from small and medium-sized farms located in Minas Gerais State, Brazil

Abstract

Consumption of goat milk has been increasing due to its nutritional characteristics and health benefits. Therefore, assessment of the presence of foodborne pathogens in this product is critical to ensure its safety to consumers. The present study aimed to identify common foodborne pathogens in raw goat milk. Fifty-three samples of raw goat milk from 11 farms were collected and cultured for the presence of Salmonella spp. and Listeria monocytogenes, as well as for enumeration and isolation of coagulase-positive and coagulase-negative Staphylococcus (CPS and CNS, respectively). All samples tested negative for Salmonella spp. and L. monocytogenes. The CPS counts in raw goat milk samples were predominantly less than 2 log cfu/mL (n=39), and CNS counts were predominantly higher than 3 log cfu/mL (n=42). Based on Staphylococcus counts, 51 isolates were selected (CPS=26; CNS=25) and tested by PCR for the presence of classic enterotoxin-encoding genes (sea, seb, sec, sed, and see). Only 3 isolates (CPS=2, CNS=1) were negative for all enterotoxin-encoding genes tested, and the genotype sec and see was the most frequent (n=16), followed by sea, sec, and see (n=13) and sec (n=13); sed was not detected in any isolate. The frequencies of enterotoxin-encoding genes for CPS and CNS were similar, demonstrating the equivalence of both groups in harboring these virulent markers. These results suggest that Salmonella and L. monocytogenes are not frequent contaminants of raw goat milk, but that Staphylococcus spp. that are capable of producing enterotoxins are prevalent; therefore, consumers of raw goat milk and products made from raw milk are at risk.

Prevalence, antimicrobial susceptibility, and molecular characterization of Staphylococcus aureus isolated from dairy herds in northern China

“…aureus infections is virulence. Once enterotoxins are produced, they generally retain their biological activity even after heat treatment (Cavicchioli et al, 2015). In the present study, 19 staphylococcal enterotoxin genes were tested, and 60.3% of Staph.…”

“…The most frequently reported virulence gene in Staph. aureus from goat milk is the sec gene (Cavicchioli et al, 2015); tst and sec are usually detected together from goat and ovine milk (Xing et al, 2016); and pvl is usually detected in Staph. aureus from raw milk.…”

“…Staphylococcus aureus is one of the main pathogens involved in dairy cow and goat mastitis worldwide, and it is an important opportunistic pathogen in raw milk (Cavicchioli et al, 2015;Wang et al, 2016). Staphylococcus aureus IMI results in significant economic losses due to reduced milk production and poor milk quality (Stapels et al, 2014), and Staph.…”

“…Studies of antimicrobial resistance and virulence traits in Staph. aureus have been performed in milk of bovines with mastitis in several countries, including Turkey, Brazil, Iran, and India, as well as the mideast of China (Gundogan and Avci, 2014;Cavicchioli et al, 2015;Jamali et al, 2015;Mistry et al, 2016;Zhang et al, 2016). However, reports on the incidence of antimicrobial resistance of Staph.…”

Fat substitution by inulin in goat milk ice cream produced with cajá (Spondias mombin) pulp and probiotic cultures: influence on composition, texture, and acceptability among consumers of two Brazilian regions

“…In Brazil, goat milk production has increased in recent years and most of the goat herd is concentrated in the north-eastern Brazilian states. Particularly in the Brazilian Northeast region, this growth was most a result of government programs designed to encourage this activity (Cavicchioli et al, 2015;SIDRA-IBGE, 2017).…”