Prevalence and classification of toxigenic Staphylococcus aureus isolated from refrigerated ready-to-eat foods (sushi, kimbab and California rolls) in Korea

Various ready-to-eat (RTE) foods are becoming increasingly popular in the world and could be easily contaminated with various microorganisms including certain pathogens. A total of 342 RTE food samples, including 32 cooked meats, 123 vegetable salads, 26 boiled peanuts, 109 cold noodles, and 52 dried tofu samples, were collected in Shaanxi Province, People's Republic of China, during the period of July to October 2012 and screened for Staphylococcus aureus. All S. aureus isolates were characterized by antimicrobial susceptibility and PCR for detecting nine enterotoxin genes (sea to sej). Overall, 25.4% of samples were positive for S. aureus, including 10 (31.3%) cooked meats, 34 (27.6%) salad vegetables, 6 (23.1%) boiled peanuts, 20 (18.3%) cold noodles, and 17 (32.7%) dried tofu samples. Of the isolated S. aureus organisms, 98.4% were resistant to at least one antimicrobial agent and 58.6% to three or more antimicrobials. Resistance to erythromycin (78.1%) and tetracycline (40.6%) was most frequently detected, while all isolates were sensitive to vancomycin and amikacin. Moreover, 55.5% of isolates were positive for one or more enterotoxin genes. The genes sed (25.8%) and sea (19.5%) were commonly detected among the isolates; seg, sei, and sej were not found. Our findings indicate that RTE foods in Shaanxi were contaminated with S. aureus isolates that harbored multiple toxin genes and exhibited multiple-drug resistance. Appropriated hygienic measures should be taken by producers, retailers, and consumers to reduce the risk posed by S. aureus in RTE foods.

Section: Discussioncontrasting

confidence: 57%

mentioning

confidence: 95%

Prevalence, Antimicrobial Susceptibility, and Enterotoxin Gene Detection of Staphylococcus aureus Isolates in Ready-to-Eat Foods in Shaanxi, People's Republic of China

Xing¹,

Li²,

Zhang³

et al. 2014

“…Food operation environments have major effects on the microbial contam ination of final food products (7,36), but most previous studies have been concerned with commercially manufac tured and prepacked products sold in retail markets or with RTE foods from street vendors (11,14,17,27,28,39). The present study was conducted to evaluate the microbiological quality of sandwiches prepared on site and served in bakeries, cafes, and sandwich bars.…”

Section: Discussionmentioning

confidence: 99%

“…One chicken-based sandwich had a very high level of contamination with both B. cereus (5.0 log CFU/g) and S. aureus (3.2 log CFU/g); however, these contaminations probably did not occur simultaneously because their sources are generally very different (B. cereus is associated with bread or raw materials from soils and sediments; S. aureus is associated with unsanitary food handlers) (25,26,28,42). Two samples with Salmonella at > 4 log CFU/g also had a high potential for causing salmonellosis (infective dose is 5 to 10 log CFU/g) (32).…”

Section: Discussionmentioning

confidence: 99%

Microbiological Quality and Risk Factors Related to Sandwiches Served in Bakeries, Cafés, and Sandwich Bars in South Korea

Jang

Kim

Choi

et al. 2013

The objective of this study was to investigate the microbiological quality of sandwiches produced on site and served in bakeries, cafés, and sandwich bars in South Korea and to determine the major risk factors affecting the sanitation level in each store (n = 1,120). The microbiological quality of the sandwiches was analyzed, and the sanitation level of each store was evaluated as satisfactory or unsatisfactory based on sanitation guidelines. Total coliforms were detected in 906 samples (80.9%), but only 3 samples (0.3%) contained confirmed Escherichia coli contamination. The detection rate was highest for Bacillus cereus (10.0%), followed by Staphylococcus aureus (1.3%) and Salmonella (0.2%). Vibrio parahaemolyticus was not detected in any samples. The microbial contamination level was significantly lower in winter (P < 0.05) and in stores with a higher sanitation grade. Factors related to the microbiological quality of sandwiches were evaluated as the relative risk (RR) of coliform contamination, and the higher risk factors for sandwich contamination were improper holding temperature (RR = 8.75), cross-contamination (RR = 6.30), lack of proper ventilation systems (RR = 6.16), and the absence of clean and/or suitable outer garments (RR = 5.73). Most factors were related to the failure of food handlers to adhere to sanitation guidelines rather than to unsanitary environments. This study provides a comprehensive analysis of the relationship between the microbiological quality of sandwiches served on-site and various risk factors. These results will help researchers establish guidelines for the sanitary management of sandwich shops.

“…Laver has a high potential for contamination with microorganisms because of its cultivation environment (8,10). Some researchers have reported that dried laver is a major source of bacterial contamination in the well-known ready-to-eat food kimbab and in rolled sushi (1,11,12). However, to the best of our knowledge, there have been no previous investigations of the potential microbiological hazards present in processed laver products from real processing lines.…”

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confidence: 99%

Microbiological Quality of Seasoned Roasted Laver and Potential Hazard Control in a Real Processing Line

Choi

Kim²,

Kim³

et al. 2014

Microbiological quality of laver, one of the edible seaweeds, has not been reported in a real processing line. Laver or supplements were collected from six manufacturers (A to F) to assess potential microbiological hazards and the critical control points in commercial processing lines. Aerobic plate counts (APC), coliform counts, Bacillus cereus, Staphylococcus aureus, and Vibrio parahaemolyticus were enumerated, and the presence of B. cereus, Listeria monocytogenes, Salmonella, S. aureus, and V. parahaemolyticus were confirmed during processing. The raw material, i.e., dried laver, had a high initial APC level (4.4 to 7.8 log CFU/g), which decreased gradually during processing (final products, 1.3 to 5.9 log CFU/g). Coliforms and B. cereus were not detected in any of the final products, but they were present in some raw materials and semiprocessed products in quantitative analysis. After enrichment for recovery of stress-injured cells, E. coli and foodborne pathogens were not detected in any samples, with the exception of B. cereus. Heat-injured and spore-forming B. cereus isolates were occasionally obtained from some of the raw materials and products after enrichment, thus B. cereus may be a potential microbiological hazard that should be controlled using strategic intervention measures. Secondary roasting (260 to 400°C, 2 to 10 s) significantly reduced the APC (maximum log reduction, 4.7 log CFU/g), and this could be a key intervention step for controlling microbiological hazards during processing (critical control point). When this step was performed appropriately, according to the processing guide for each plant, the microorganisms were inactivated more successfully in the products. This study provides scientific evidence that may facilitate the development of strategies for microbiological hazard control and hygienic management guidelines for real manufacturing plants.