• Korean Journal of Food Science and Technology
• /
• v.52 no.6
• /
• pp.661-669
• /
• 2020

Samgak-Kimbap is a popular ready-to-eat (RTE) food at convenience stores, in Korea. Although Samgak-Kimbap is distributed through the cold chain supply system, inappropriate temperature storage conditions prior to consumption are a cause of concern. The objective of this study was to evaluate the risk of Staphylococcus aureus growth in Samgak-Kimbap in the retail market. The prevalence and contamination levels of S. aureus in Samgak-Kimbap (n=170) were monitored, and the predictive growth model of a five-strain cocktail of enterotoxin-producing S. aureus (SEA, SEB, SEC, SED, and SEE) was developed in Samgak-Kimbap as a function of temperature (4, 10, 11, 20, 25, and 37℃). We could not observe the growth of S. aureus and enterotoxin-producing S. aureus in Samgak-Kimbap at temperatures below 10℃. The probability of illness with S. aureus per serving of Samgak-Kimbap was 1.44×10-10 per day. The most influential factor in increasing the risk of foodborne illnesses was the contamination level of S. aureus in Samgak-Kimbap.

• Journal of Food Hygiene and Safety
• /
• v.3 no.2
• /
• pp.75-81
• /
• 1988

Various methods such as lel-mtration on Sephadex G-SO, 75, 100 Sephacry, and Ultro gel, and lon-exchanle chromatoaraphy on Amberilte and carboxymethyl (CM)-cellulose, and Fast Protein liquid Chromatolraphy (FPLC) were applied for the purification of enterotoxin B from Staphylococcus aureus ATCC 14458 and compared one another. lon-exchanle chromatography on Amberllte resin was good enough to remove non-entrotoxln materials in culture, convlnient to use and fast although tbe purity was less tban 70%. However, CM-cellulose showed to be better purity and yield tban those of Amberilte resin. The yields of these two resins for ion-exchange cbromatograpby were about 70% and 75%, respectively. When the gel-filtration methods on Sepbadex G-50, 75, 100, Sepbacryl, and Ultro lei were applied, the purities were about 90%. FPLC was found to be tbe most efficient metbod in terms of purity (96%) and speed. For the purification of sample with large volume, particularly, tbe combined metbod, gel-mtration after Amberlite can be also used efficiently. Tbe purified toxin was found to be identical to type B enterotoxin used for reference standard by Oucbterlony immunodiffusion test.

• Korean Journal of Food Science and Technology
• /
• v.43 no.5
• /
• pp.648-654
• /
• 2011

Staphylococcus aureus, a major human pathogen, produces a wide array of toxins, which causes various types of disease symptoms. Prevalence of S. aureus in various foods collected during 2006-2008 in Korea was investigated. S. aureus was isolated from 275 of 5,186 (5.3%) food samples collected from hyper-markets in Korea. Seasonal temperature affected the prevalence of S. aureus in various foods with high isolation rate during the summer. Most of the enterotoxigenic strains produced enterotoxin A only or enterotoxin A in combination with another toxin. A total of 54.5% of the tested strains contained either one or more enterotoxin genes and 3.6% possessed a tst gene. This study offers basic information for securing the stability of food during storage and circulation, and provides an epidemiological tool to study the cause, origin and temporal spread of S. aureus food poisoning.

• Korean Journal of Food Science and Technology
• /
• v.35 no.1
• /
• pp.97-102
• /
• 2003

Raw and washed spinaches were tested to evaluate the incidences of Aeromonas hydrophila, Escherichia coli O157:H7, Plesiomonas shigelloides, Pseudomonas aeruginosa, Salmonella spp., Shigella spp., Yersinia enterocolitica, Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Listeria monocytogenes, and Staphylococcus aureus. Four pathogenic bacteria were isolated from spinach samples, and identified by morphological and biochemical methods, including API and ATB identification systems. Isolates from MacConkey, Cereus Selective, Clostridium Perfringens, and Baird-Parker agar media were in 99.9, 99.8, 99.9, and 97.8% agreements with A. hydrophila, B. cereus, C. perfringens, and S. aureus at the species level, respectively. SET-RPLA revealed, among the five strains of S. aureus isolates, two produced type A enterotoxin. All five strains of B. cereus isolates produced enterotoxin as revealed with CRET-RPLA.

• Journal of Life Science
• /
• v.21 no.2
• /
• pp.257-264
• /
• 2011

Seventy five methicillin- resistant Staphylococcus aureus (MRSA) strains and 24 methicillin- susceptible S. aureus (MSSA) were isolated from clinical specimens obtained from a hospital in Suncheon, Jeonnam province, Korea, from July to December, 2009. Antibiotic resistance was determined using the disc diffusion method. Genes encoding enterotoxin (SE), toxic shock syndrome toxin-1 (TSST-1), exfoliative toxin (ET) and Panton-Valentine leukocidin (PVL) were detected by multiplex PCR-mediated amplification using specific primers. Sixty (80%) MRSA isolates possessed either one or more toxin genes and the most common pattern that coexisted in MRSA was seb, sec, seg, sei and tst (22.7%) followed by coexistence of sec, seg, sei and tst genes (18.7%). Gene pvl encoding leukocidin was not found. Significant correlation between the production of sec, seg, sei and tst genes was found. MRSAs were resistant to erythromycin (89% of the isolates), gentamicin (70.7%), ciprofloxacin (69.3%), clindamycin (61.3%) and tetracycline (58.7%), while MSSAs were susceptible to the antibiotics with the exception of erythromycin. Toxin genes seb, sec and tst were related to the tetracycline resistance of MRSA.

• Journal of Environmental Health Sciences
• /
• v.38 no.6
• /
• pp.510-519
• /
• 2012

Objectives: This study was conducted in order to evaluate the microbiological contamination of the indoor air of the lunchrooms at child care centers and investigate the toxin genes and toxin production ability of food-borne pathogens. Methods: A total of 64 child care centers were sampled to test total aerobic bacteria, coliform bacteria, fungi, Staphylococcus aureus, Bacillus cereus and Salmonella spp. according to the Korea Food Code. All toxin genes of pathogens were detected using the Polymerase Chain Reaction method. The Sthaph. aureus enterotoxin was detected by a Staphylococcus aureus enterotoxin-reversed passive latex agglutination kit. The heamolysin BL (HBL) and non-heamolytic enterotoxin (NHE) produced by B. cereus were detected using a B. cereus enterotoxin-reversed passive latex agglutination kit and Bacillus diarrheal enterotoxin visual immunoassay kit, respectively. Results: The means of total aerobic bacteria and coliform bacteria were $1.91{\pm}1.84$ log CFU/plate and $0.47{\pm}0.62$ log CFU/plate, respectively. The mean of fungi also showed $0.59{\pm}0.71$ log CFU/plate. Among the pathogenic bacteria tested in this study, Staphy. aureus and B. cereus were detected in four (6.3%) and 21 (32.8%) out of 64 indoor air samples from lunchrooms in child care centers, respectively. All Staphy. aureus tested in this study possessed no toxin genes and did not produce enterotoxin. The detection rate of nheABC, hblCDA, entFM and ces toxin gene in B. cereus was 100, 57.1, 76.2 and 0%, respectively. B. cereus isolates were classified into four groups according to the presence or absence of toxin genes. The nheABC gene was the major toxin gene among B. cereus tested in this study. The HBL was detected in 11 out of 21 B. cereus isolates (52.4%) and three B. cereus isolates produced NHE (14.3%). Conclusion: The results indicated that the contamination by microorganisms in the indoor air of lunchrooms was unqualified to supply safe catering in child care centers. The ongoing control of indoor air quality is required.

• Journal of Dairy Science and Biotechnology
• /
• v.32 no.2
• /
• pp.105-109
• /
• 2014

Food borne pathogens are a growing concern for human health and food safety throughout the world. Milk and dairy products are commonly associated with spoilage or contamination from a wide variety of physical, microbial, and chemical hazards. Milk was inoculated with Staphylococcus aureus and stored at 5, 10, 15, 25, and $35^{\circ}C$ for 7 days, and we monitored the growth change and the variance of toxin production. The growth rate of S. aureus was suppressed in low temperature. We confirmed that growth rate and toxin production were accelerated when the storage temperature was increased. S. aureus began to produce toxins when the number of bacteria was higher than $10^5CFU/mL$. Therefore, managing the storage temperature of milk is important to inhibit the growth and the toxin production of S. aureus.

• Journal of Food Hygiene and Safety
• /
• v.30 no.1
• /
• pp.51-58
• /
• 2015

Thirty one of Staphylococcus aureus isolated from perilla leaf cultivation areas in Miryang were investigated on the characteristics, such as enterotoxin genes and antibiotic susceptibility. Five toxin genes (sea, seb, sec, sed, and see) were examined by PCR method. Disc diffusion method was used to examine the antibiotic susceptibility of S. aureus by using 18 types of antibiotic discs with different concentrations. Among enterotoxin-encoding genes, sea and sed genes were co-detected from 4 isolates (12.9%), sed gene was founded in 9 isolates (29.0%), and see gene was founded in 1 isolate (3.2%). However seb and sec and tsst were not detected in any isolates. As a result of antibiotic susceptibility test, 7 isolates (22.6%) were resistant to 12 antibiotics (penicillin, ampicillin, oxacillin, amoxicillin-clavulanic acid, cefazolin, cephalothin, imipenem, gentamicin, tetracycline, ofloxacin, norfloxacin, and erythromycin). 2 isolates (6.5%) were resistant to 5 antibiotics (penicillin, ampicillin, amoxicillin-clavulanic acid, gentamycin, and telithromycin). MRSA (Methicilline Resistant Staphylococcus aureus) was founded in packing vinyl, hands, and perilla leaves.

• Journal of Food Hygiene and Safety
• /
• v.19 no.1
• /
• pp.49-54
• /
• 2004

The prevention of infectious disease from contaminated foods is very important in public health. Quantitative microbial risk assessment has been used in advance countries to achieve the safety of public health against hazardous microbial causing contaminated foods. This study was conducted to estimate maximum edible time without producing enterotoxin from Staphylococcus aureus in Kimbap selling at different domestic store using Food MicroModel and monitoring data and to compute maximum edible time by temperature with 99th percentile safety probability based on only restaurant data. For estimating maximum edible time, model operation conditions like reaching time at 2 ${\times}$ 10$^{7}$ , which enterotoxin was known as producing point from S. aureus, temperature of 28∼3$0^{\circ}C$, pH 5.2, NaCl 0.22%, aw(water activity) 0.99, and intaking one serving size of 171g in Kimbap were considered. Estimated maximum edible times by regarding outdoor temperature in summer were 3.9∼4.6 hrs in restaurant, 6.7∼7.9 hrs in department store and 7.4∼8.7 hrs in convenient store. Based on restaurant data, estimated maximum edible times with 99th percentile safety probability by temperature were 1.9 hrs in 3$0^{\circ}C$ and 17.7 hrs in 15$^{\circ}C$.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.36 no.7
• /
• pp.938-943
• /
• 2007

This study investigated the hazard analysis of ready-to-eat sandwiches sold in various establishments. Sandwich samples were collected from convenience stores, discount stores, sandwich chain stores, bakery shops, fast-food chain stores, and food service operations located in Daegu and Gyeongbuk. Out of 174 samples, 18 (10.3%) contained coagulase positive staphylococci with counts ranging from 0.30 to 4.08 log CFU/g. There was significant seasonal difference in Staphylococcus aureus isolation; the average count in summer (3.24 log CFU/g) was 3 times higher than that of winter (1.10 log CFU/g) (P<0.001). According to the microbiological guidelines of PHLS for ready-to-eat foods, 95.4% of the samples were acceptable. As a result of enterotoxin producing experimental data ($35^{\circ}C$, pH 5.8, NaCl 0.5%), enterotoxin was not produced in a sandwich until Staphylococcus aureus increased to a level greater than 4.95 log CFU/g. This microbiological hazard analysis data could be applied to future studies on quantitative risk assessment of ready-to-eat foods.