• Journal of Food Hygiene and Safety
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• v.35 no.3
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• pp.219-224
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• 2020

The purpose of this study was to provide basic data necessary for the prevention of food poisoning and safe food management. We examined 872 food samples for B. cereus in accordance with the MFDS Food Code and investigated characteristics of their harboring toxin genes. We detected and isolated 113 strains of B. cereus from 78 food samples (8.9%), and the average detection level was 48 CFU/g. B. cereus isolates carried at least 1 toxin gene among the emetic toxins and 5 enterotoxin genes. The toxin gene profiles of B. cereus were classified into 18 different types of isolates showing genetic diversity. Among the strains, 34 (30.1%) had all 5 enterotoxin genes (Cytk-nheA-entFM-bceT-hblC), accounting for the highest percentage. The entFM and nheA genes were major enterotoxin genes, while the emetic toxin gene, CER, was the least detected in B. cereus isolated from food samples.

• Korean Journal of Veterinary Research
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• v.44 no.4
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• pp.551-559
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• 2004

Shiga toxin-producing Escherichia coli (STEC) causes various clinical signs in human and animals, and has been indicated as a global enteropathogen with zoonotic importance. In this study, the feces of healthy pigs were collected from the slaughtered pigs of Daejon abattoir during the period from December 2001 to October 2002. Of 326 specimens, 13 STEC were confirmed by culture, PCR and colony hybridization. The isolates were further studied for toxin types, pathogenic factors, plasmid profiles, and antimicrobial resistance to characterize the genetic and toxigenic properties. In PCR, all of 13 isolates were evident to have shiga toxin gene (stx). Of 13 isolates stx1 gene was detected in 4 and stx2 gene in 9. The genes of eaeA, hlyA and rfbE were not present in any isolates. In colony hybridization using shiga toxin common primer (STXc), 2 to 9 per 100 colonies subcultured from 13 isolates showed the positive reaction. In the examination for plasmid profiles of the isolates, one to eleven plasmids with varying sizes of 1.0 Kb to 100 Kb were detected, and the 13 STEC could be classified into four groups by the plasmid patterns. The antimicrobial resistance patterns of the isolates were comparably corresponded with the plasmid profile patterns.

• Journal of Food Hygiene and Safety
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• v.35 no.1
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• pp.6-12
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• 2020

Prevalence of toxin genes and profiles of antibiotic resistance in Vibrio vulnificus were investigated for prevention of Vibrio sepsis and selection of effective antibiotics. A total of 23 V. vulnificus strains were isolated from Vibrio sepsis patients, fish, and water samples collected from fish tanks in restaurants in Jeonnam province during 2015-2017 period. Prevalence of toxin genes including, RtxA, viuB and vvhA were assessed and susceptibilities to 15 different antibiotics were determined. As a result of the toxin gene profile, the RtxA toxin gene was detected in 19 (82.6%) out of 23 strains, and vvhA and viuB toxin genes were positive in all strains. These results showed that V. vulnificus tested in this study possessed at least one more toxin gene, and the toxin gene detection rate was higher than in previous reports. Therefore, there is always a risk of Vibrio sepsis through eating fish or having contact with aquarium water at seafood restaurants. Especially, it was deemed necessary to provide preventive education about Vibrio sepsis for workers in such restaurants. The results of antibiotic susceptibility tests presented 94.4% resistance to cepoxitin antibiotics but all strains showed susceptibility to 14 kinds of antibiotics including chloramphenicol and tetracycline. The currents antibiotic therapy using chloramphenicol and teteracycline against Vibrio sepsis was judged to be useful.

• Food Science of Animal Resources
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• v.31 no.1
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• pp.40-46
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• 2011

The growth profile of Bacillus cereus in ready-to-eat (RTE) food products of animal origin was examined under different temperature and incubation conditions. In sandwiches and Kimbab, B. cereus did not grow or exhibited only minimal growth at 4 and $10^{\circ}C$, but it grew rapidly at ambient temperature. In sandwiches, B. cereus did not grow efficiently at $25^{\circ}C$, however, in ham, the main ingredient of sandwiches, B. cereus growth was observed at the same temperature, with bacterial levels reaching 7.94 Log CFU/g after incubation for 24 h at $25^{\circ}C$. Toxigenicity of B. cereus was observed only at temperatures above $25^{\circ}C$. In Kimbab, B. cereus produced toxin after 9 h at $30^{\circ}C$ and after 12 h at $25^{\circ}C$. Ingredients of sandwiches and Kimbab were collected from 3 different Korean food-processing companies to investigate the source of contamination by B. cereus. Among the 13 tested food items, 6 items including ham were found to be contaminated with B. cereus. Of these ingredients, B. cereus isolates from 3 items produced enterotoxins. None of these isolates harbored the emetic toxin-producing gene. The findings of the present study can be used for risk assessments of food products, including ham and cheese, contaminated with B. cereus.

• Biomedical Science Letters
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• v.16 no.2
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• pp.75-82
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• 2010

The molecular epidemiological characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolates have demonstrated their genetic diversity and evolution. A total of 137 strains of MRSA clinical isolates was collected from Korean healthcare facility in 2007. The MRSA clinical isolates were analyzed by molecular typings (SCCmec element and agr locus typing), virule nce factor gene detections {(Panton-Valentine leukocidin (PVL), enterotoxin, exfoliative toxin and toxic shock syndrome toxin-1), and amplified fragment length polymorphism (AFLP)}. The MRSA clinical isolates were classified as SCCmec type II-agr type 1 (2 strains), type II-agr type 2 (79 strains), type III-agr type 1 (24 strains), type III-agr type 2 (2 strains), type IV-agr type 1 (27 strains), type IV-agr type 2 (2 strains), and non-typable (1 strain, agr type 3). Based on SCCmec types, SCCmec type II (95.1%) and III (88.5%) indicated higher multidrug resistance rate than SCCmec type IV (10.3%) (P<0.001). The most common enterotoxin genes were seg (83.8%), sei (83.1%), and sec (80.2%). The tst gene was present in 86 out of 137 (62.8%) MRSA isolates. All MRSA isolates were negative for PVL and exfoliative toxin genes. The combinations of toxin genes were observed in particular SCCmec types; 97.6% of SCCmec type II strains carried sec, seg, sei and tst genes, 73.0% of SCCmec type III strains carried sea gene, and 89.7% of SCCmec type IV strains carried sec, seg and sei genes. Each of the SCCmec types of MRSA isolates had distinct AFLP profile. In conclusion, SCCmec type II, agr type 1 and 2 have demonstrated to be the most common types in Korea, and the results indicated that the virulence factors are closely associated with their molecular types (SCCmec and agr types).

• Journal of Microbiology and Biotechnology
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• v.17 no.9
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• pp.1498-1503
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• 2007

To identify novel crystal proteins, Bacillus thuringiensis 2385-1 was isolated from Korean soil samples and characterized. The H-serotype of 2385-1 was identical to that of subsp. kenyae (H4a4c), and its crystal toxin was bipyramidal-shaped. However, 2385-1 showed a much higher toxicity towards Plutella xylostella and Spodoptera exigua larvae than subsp. kenyae. In addition, the crystal protein profile and plasmid DNA pattern of 2385-1 differed from those of subsp. kenyae. To verify the crystal protein gene types of 2385-1, a PCR-RFLP analysis was performed, and the results revealed that 2385-1 contained two novel cry1-type crystal protein genes, cryl-5 and cry1-12, in addition to the crylJal gene. The deduced amino acid sequences of cryl-5 and cry1-12 showed a 97.9% and 75.7% sequence similarity with the CrylAb and CrylJa crystal proteins, respectively. Among the novel crystal proteins, Cry1-5 showed a high toxicity towards P. xylostella and S. exigua larvae. In conclusion, B. thuringiensis 2385-1 is a new isolate in terms of its gene types, and should be a promising source for an insecticide to control lepidopteran larvae.

• Proceedings of the Korean Society of Sericultural Science Conference
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• 2003.04a
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• pp.73-73
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• 2003

Bacillus thuringiensis 2385-1, which showed toxicity to lepidopteran but not to dipteran was isolated from Korean soil sample and characterized. The H-serotype of 2385-1 was identical to that of serovar kenyae (H4a4c), and its crystal toxin was bipyramidal-shaped with a molecular weight of 130 kDa. However, the plasmid profile of 2385-1 was different from that of serovar kenyae. (omitted)

• Korean Journal of Food Science and Technology
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• v.46 no.3
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• pp.334-340
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• 2014

Toxin-producing Bacillus cereus is the causative agent of two different types of food poisoning: the emetic and the diarrheal types. This study was conducted to investigate the presence of enterotoxin and emetic toxin genes in 263 B. cereus isolated from 619 different ready-to-eat food items. Hemolytic enterotoxins hblA, hblC, and hblD were detected in 85.6, 41.1, and 76.8%, respectively, of the B. cereus isolates. About 67.0% (175/263) of the isolates presented all of three genes. Non-hemolytic enterotoxins nheA, nheB, and nheC were detected in 100, 97.0, and 68.4% of the isolates, respectively. Approximately 90.0% (236/263) of the isolates presented all of these three non-hemolytic enterotoxin genes. Emetic toxin gene, CER, was detected in 132 of 263 (50.2%) isolates. Computer-assisted cluster analysis of Rep-PCR profiles showed a high genetic diversity among the isolates. All B. cereus isolates from food samples tested in this study carried at least 6 of 10 toxin genes.

• Korean Journal of Microbiology
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• v.41 no.4
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• pp.262-268
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• 2005

Intoxication of murine macrophages (RAW 264.7) with the anthrax lethal toxin (LeTx 100 ng/ml) results in profound alterations in the host cell gene expression. The role of LeTx in mediating these effects is unknown, largely due to the difficulty in identifying and assigning function to individual proteins. In this study, we have used two-dimensional polyacrylamide gel electrophoresis to analyze the protein profile of murine macrophages treated with the LeTx, and have coupled this to protein identification using MALDI-TOF mass spectrometry. Interpretation of the peptide mass fingerprint data has relied primarily on the ProFound database. Among the differentially expressed spots, cleaved mitogen-activated protein kinase kinase (Mek1) and glucose-6-phosphate dehydrogenase were increased in the LeTx treated macrophages. Mek1 acts as a negative element in the signal transduction pathway, and G6PD plays the role for the protection of the cells from the hyper-production of active oxygen. Our results suggest that this proteomic approach is a useful tool to study protein expression in intoxicated macrophages and will contribute to the identification of a putative substrate for LeTx.

• Journal of Veterinary Clinics
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• v.28 no.2
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• pp.196-203
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• 2011

Staphylococcus spp. is one of the most common bacteria isolated from the lesions of atopic dermatitis (AD) in humans, and their colonization is known to be a possible trigger factor of clinical signs. The aim of this study was to determine the prevalence of Staphylococcus spp. in canine AD (CAD), the types of exotoxins present, and their relation with the clinical severity of CAD. From 79 dogs with AD, 72 samples of Staphylococcus spp. were isolated (91.1%), and 65 (90.3%) were confirmed as Staphylococcus pseudintermedius. Concerning the profile of the exotoxin gene, 50 isolates (69.4%) contained at least one exotoxin gene, and 28 isolates (56%) were found to contain more than 2 different exotoxins. There was a significant difference in clinical severity with the presence of staphylococcal exotoxins (P=0.028), whereas no correlation was found with the presence of Staphylococcus spp. (P=0.598). The clinical severity of CAD increased only in relation to staphylococcal enterotoxin D (SED) and exfoliative toxins (P<0.05). Some clinical evaluation criteria (erythema, papule/pustule) were correlated with the presence of the exotoxin gene (P<0.05). This study showed that the high prevalence of Staphylococcus spp. and staphylococcal exotoxins in lesions from dogs with AD may be regarded as an important trigger factor for exacerbation of the clinical signs of CAD.