Comparison of Antibiogram, Staphylococcal Enterotoxin Productivity, and Coagulase Genotypes among Staphylococcus aureus Isolated from Animal and Vegetable Sources in Korea

Abstract

Staphylococcal food poisoning is caused by enterotoxin-producing Staphylococcus aureus. We investigated the prevalence of such organisms in samples of bovine mastitic milk (n = 714), raw meat (n = 139), and vegetables (n = 616). We determined the degrees of relatedness of isolates as indicated by antibiogram, staphylococcal enterotoxin (SE) productivity, and coagulase gene restriction fragment length polymorphism analysis. We examined 297 S. aureus isolates and found SE production in 57 (31.8%), 4 (7.8%), and 49 (73.1%) isolates from raw milk, raw meat, and vegetables, respectively. A high proportion of the isolates obtained from milk produced more than two types of toxins (mainly SEA, SEB, and/or SEC), whereas isolates from raw meat and vegetables primarily produced SEA alone. Most isolates were sensitive to cephalothin (97.6%), gentamicin (80.8%), erythromycin (79.5%), and tetracycline (72.7%), but were resistant to penicillin (90.2%) and ampicillin (88.9%). The proportion of antibiotic-resistant isolates differed according the source of the bacteria; the milk and vegetable isolates were more resistant to penicillin and ampicillin than were the meat isolates (P < 0.05), whereas tetracycline resistance was limited to the milk and vegetables isolates. The coagulase genotypes (I to XII) varied with the source of the organism, and only a few genotypes prevailed in each source: II (42.4%) and IV (24%) types in isolates from milk, IX (35.3%) and XI (45%) from raw meat, and III (40.3%) and XII (32.8%) from vegetables. These findings suggest that remarkable differences exist in antibiogram, SE productivity, and coagulase genotypes, resulting in limited clonal transmission of S. aureus into various food sources. As enterotoxin production only occurs when S. aureus grows to high numbers, staphylococcal food poisoning can be prevented by proper refrigeration.

Staphylococcus aureus Enterotoxin A Gene Isolated From Raw Red Meat And Poultry in Tehran, Iran

“…The results of two studies also showed that the prevalence of SEA encoding gene in isolated strains were 15.4% and 18.8% (27). A study by Moon et al on three groups of food revealed that the contamination of meat products with S. aureus was the highest 36% (28). The above results are almost similar to those of the current study.…”

Toxigenicity and genetic diversity of Staphylococcus aureus isolated from Vietnamese ready-to-eat foods

“…The likelihood of microbial disease emergence and spread is becoming higher with the enhancement of world globalization interconnectedness; the spread of antibiotic resistant bacteria with food products is a major concern. Many S. aureus population have developed resistance to commonly used antibiotics, e.g., penicillin, ampicillin due to the wide use of the ß-lactams, particularly for treatment of bovine mastitis (Moon et al, 2007;Peles et al, 2007). It is apparent from the present study that in Vietnam appropriate public health and food hygiene practices during production, transportation, storage and retailing should be implemented to reduce the risk of S. aureus related food poisoning.…”

“…Thus, our limited number of sample analysis indicates a high prevalence of enterotoxin producing S. aureus strains in the ready-to-eat foods in Vietnam. Moon et al (2007) reported that mastitic milk and raw meat samples in Korea contained 31.8% and 7.8% SE positive S. aureus, respectively. A higher abundance (47%) of SE positive strains among total S. aureus isolates has also been reported in a recent survey from ready-toeat foods in Korea (Oh et al, 2007).…”

Asymptomatic colonization of Staphylococcus aureus with intermediate resistance to vancomycin harboring vanB resistance gene

“…Swabs were transferred to the TSB containing 7% NaCl. The isolates were subcultured on MSA and incubated at 37°C for 24 hrs [22].…”