• Journal of Microbiology
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• 제45권1호
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• pp.29-33
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• 2007

Salmonella typhimurium, causing mouse typhoid, infects hosts such as macrophage cells, and proliferates in intracellular vacuoles causing infected cells to trigger numerous genes to respond against the infection. In this study, we tried to identify such genes in RAW264.7 cells by using the PCR screening method with degenerate primers. Fourteen genes were found to be differentially expressed after a 4 h infection in which the expression of 8 genes increased while expression of the others decreased. Most of the genes were involved in proinflammatory responses such as cytokines production and cell death. The mutation in msbB gene encoding the myristoyl transferase in lipid A of lipopolysaccharide (LPS) resulted in much lower toxicity to the inoculated animals. We compared the expression of the identified genes in wild-type and msbB-mutated S. typhimurium infections and found that Lyzs encoding lysozyme type M was differentially expressed. This gene is quite likely to be related to bacterial survival in the host cells.

• 대한미생물학회지
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• 제22권4호
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• pp.413-425
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• 1987

In the present experiments, isolated Vibrio species from marine and clinical specimens from July, 1985 to October, 1986, had the results as follows: 1. The 55 strains of Vibrio were isolated and identified; Vibrio parahaemolyticus was 35 strains, Vibrio vulnificus was 10 strains, Vibrio alginolyticus was 10 strains. 2. In the K-serotyping of Vibrio parahaemolyticus, fourteen serotypes identified but three were not strains typable by the availble K-antisera. 3. In the Kanagawa phenomenon experiment of Vibrio parahaemolyticus, it proved positive reaction, 14 of 15 strains(93%) isolated from the patient and 13 of 20 strains(65%) isolated from the nature. 4. In twelve antibiotic resistance experiments, Vibrio parahaemolyticus and Vibrio alginolyticus showed 100% resistance on ampicilline, but Vibrio vulnificus showed 100% sensitivity. But all of them proved 100% sensitivity on chloramphenicol, tetracycline, nalidixic acid. 5. In the antibiotic resistance patterns, Vibrio parahaemolyticus proved that 15 strains(43%) resisted on 4 antibiotics and 5 strains(14%) resisted on 7 antibiotisc and. Vibrio vulnificus proved that 1 strain(10%) resisted on 2 antibiotics and 6 strains(60%) without resistance, Vibrio alginolyticus proved that 7 strains(70%) resisted on 3 antibiotics and 2 strains(20%) resisted on 8 antibiotics.

• 한국환경보건학회지
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• 제46권5호
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• pp.525-531
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• 2020

Objectives: This study was performed to identify the epidemiological features of a food poisoning outbreak in a company cafeteria located in Chungcheongnam-do Province, Korea in June of 2020 and to suggest preventive measures for a similar incidence. Methods: A total of 84 patients with acute gastroenteritis were examined. Environmental samples were obtained from 16 food handlers, six food utensils, 135 preserved foods served over three days and nine menus, and six drinking water samples. These are analyzed to detect viruses and bacteria. Results: Ninety-four out of the 402 people who were served meals (23.4%) predominantly showed symptoms of diarrhea, and the number was over 3 times. Among the 84 patients under investigation, 17 cases (20.2%) were positive for Enteropathogenic E. coli (EPEC) and 18 cases were positive for Clostridium (C.) perfringens (21.4%). Based on the investigation, it was concluded that the main pathogens were EPEC and C. perfringens. For EPEC, it was detected in three of the food service employees and in the preserved food and curry rice. The results of pulsed field gel electrophoresis indicate that all EPEC cases are closely related except for one food service employee. Assuming that isolated EPEC originated from the preserved food, the incubation period is about 25 hours. The origin of the C. perfringens was not determined as it was not detected in the food service employees or environmental samples. Conclusions: This case suggests that food provided in group food service centers must be thoroughly managed. In addition, identifying the pathogens in preserved food is very important for tracing the causes of food poisoning, so food must be preserved in an appropriate condition. To prevent similar food poisoning cases, analyzing cases based on epidemiological investigation and sharing the results is needed.

• Parasites, Hosts and Diseases
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• 제48권2호
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• pp.113-120
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• 2010

To understand protozoan, viral, and bacterial infections in diarrheal patients, we analyzed positivity and mixedinfection status with 3 protozoans, 4 viruses, and 10 bacteria in hospitalized diarrheal patients during 2004-2006 in the Republic of Korea. A total of 76,652 stool samples were collected from 96 hospitals across the nation. The positivity for protozoa, viruses, and bacteria was 129, 1,759, and 1,797 per 10,000 persons, respectively. Especially, Cryptosporidium parvum was highly mixed-infected with rotavirus among pediatric diarrheal patients (29.5 per 100 C. parvum positive cases), and Entamoeba histolytica was mixed-infected with Clostridium perfringens (10.3 per 100 E. histolytica positive cases) in protozoan-diarrheal patients. Those infected with rotavirus and C. perfringens constituted relatively high proportions among mixed infection cases from January to April. The positivity for rotavirus among viral infection for those aged $\leq$ 5 years was significantly higher, while C. perfringens among bacterial infection was higher for $\geq$ 50 years. The information for association of viral and bacterial infections with enteropathogenic protozoa in diarrheal patients may contribute to improvement of care for diarrhea as well as development of control strategies for diarrheal diseases in Korea.

• Asian-Australasian Journal of Animal Sciences
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• 제30권4호
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• pp.576-584
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• 2017

Objective: To generate recombinant Bacillus subtilis (B. subtilis) engineered for expression of porcine ${\beta}-defensin-2$ (pBD-2) and cecropin P1 (CP1) fusion antimicrobial peptide and investigate their anti-bacterial activity in vitro and their growth-promoting and disease resisting activity in vivo. Methods: The pBD-2 and CP1 fused gene was synthesized using the main codons of B. subtilis and inserted into plasmid pMK4 vector to construct their expression vector. The fusion peptide-expressing B. subtilis was constructed by transformation with the vector. The expressed fusion peptide was detected with Western blot. The antimicrobial activity of the expressed fusion peptide and the recovered pBD-2 and CP1 by enterokinase digestion in vitro was analyzed by the bacterial growth-inhibitory activity assay. To analyze the engineered B. subtilis on growth promotion and disease resistance, the weaned piglets were fed with basic diet supplemented with the recombinant B. subtilis. Then the piglets were challenged by enteropathogenic Escherichia coli (E. coli). The weight gain and diarrhea incidence of piglets were measured after challenge. Results: The recombinant B. subtilis engineered for expression of pBD-2/CP1 fusion peptide was successfully constructed using the main codons of the B. subtilis. Both expressed pBD-2/CP1 fusion peptide and their individual peptides recovered from parental fusion peptide by enterokinase digestion possessed the antimicrobial activities to a variety of the bacteria, including gram-negative bacteria (E. coli, Salmonella typhimurium, and Haemophilus parasuis) and grampositive bacteria (Staphylococcus aureus). Supplementing the engineered B. subtilis to the pig feed could significantly promote the piglet growth and reduced diarrhea incidence of the piglets. Conclusion: The generated B. subtilis strain can efficiently express pBD-2/CP1 fusion antimicrobial peptide, the recovered pBD-2 and CP1 peptides possess potent antimicrobial activities to a variety of bacterial species in vitro. Supplementation of the engineered B. subtilis in pig feed obviously promote piglet growth and resistance to the colibacillosis.

• 대한의생명과학회지
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• 제13권1호
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• pp.47-53
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• 2007

Due to wide abuse of antibiotics both in human and livestock use, the advent and spread of multidrug resistant (MDR) pathogens becomes a serious health problem all over the world. Since the development of new antibiotics is at a standstill in pharmaceutical industry, the choice of therapeutic antibiotics is getting narrower. In this study, in an effort to search new antibiotics, the antimicrobial activity of Paenibacillus DY1 isolated from Korean soil was characterized on its growth inhibition spectrum against various health threatening MDR strains, with its stability and chemical structure. Extracellular culture filtrate of Paenibacillus DY1 effectively inhibits the growth of all the tested MDR enteropathogenic Eshcherichia coli, enterohemolytic E. coli, and enterotoxigenic E. coli strains, at a similar level to that on the nonresistant control E. coli strains. It showed significant growth inhibition effect against the causative agents of class one legal communicable disease, MDR Salmonella typhi, MDR Salmonella paratyphi A, food poisoning bacteria, MDR Salmonella typhimurium, and other MDR Salmonella spp. The growth of all of 10 different MDR Shigella spp. strains and 6 different Vibrio spp. strains tested was also inhibited. The antimicrobial activity of Paenibacillus DY1 was well preserved after heat treatment, and was also stable in both alkaline and acidic environment. The antimicrobial activity was partially purified with Diaion HP20 column and TLC. By NMR study, the putative structure of the activity was postulated as an alkane having hydroxyl groups.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제20권2호
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• pp.107-113
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• 2017

Purpose: This study clarified the bacterial pathogens currently causing acute infectious enterocolitis (AIE) in children and evaluated the clinical characteristics and ultrasonographic findings according to the different pathogens. Methods: Medical records regarding age, sex, clinical symptoms, laboratory data, identified enteropathogens, ultrasonographic findings, treatment, and outcome of 34 patients who were diagnosed with AIE via stool examination using multiplex polymerase chain reaction (PCR) or culture, were retrospectively reviewed. Results: Twenty-four patients (70.6%) were male. The mean age of the patients was $8.5{\pm}6.2$ (range, 1.1-17.1) years. Six bacterial pathogens were isolated: Salmonella species (spp.) (32.4%), Campylobacter spp. (20.6%), verotoxin-producing Escherichia coli (14.7%), Staphylococcus aureus (11.8%), Clostridium difficile (8.8%), and Shigella spp. (2.9%). Abdominal pain occurred in all patients regardless of pathogen. The patients infected with Salmonella were older than those infected with verotoxin-producing E. coli (p<0.05). C-reactive protein levels were higher in patients with Salmonella and Campylobacter infections than in those with verotoxin-producing E. coli infection (p< 0.05), the other clinical and laboratory data were indistinguishable between pathogens. Ultrasonography demonstrated diverse involvement of bowel segments according to pathogen. Wall thickening of both the ileum and the entire colon was the most common lesion site regardless of pathogen. Conclusion: Various bacterial agents cause AIE and the symptoms are diverse symptoms, however, all most children recovered spontaneously. Use of multiplex PCR on stool samples warrants improvement of its sensitivity for diagnosis of enteropathogenic bacteria. Ultrasonographic examination is useful for diagnosis of AIE; it can also detect the disease extent and severity.

• Molecules and Cells
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• 제28권4호
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• pp.389-395
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• 2009

We previously observed that the transcription of some flagellar genes decreased in Salmonella Typhimurium tdcA mutant, which is a gene encoding the transcriptional activator of the tdc operon. Since flagella-mediated bacterial motility accelerates the invasion of Salmonella, we have examined the effect of tdcA mutation on the invasive ability as well as the flagellar biosynthesis in S. Typhimurium. A tdcA mutation caused defects in motility and formation of flagellin protein, FliC in S. Typhimurium. Invasion assays in the presence of a centrifugal force confirmed that the defect of flagellum synthesis decreases the ability of Salmonella to invade into cultured epithelial cells. In addition, we also found that the expression of Salmonella pathogenicity island 1 (SPI1) genes required for Salmonella invasion was down-regulated in the tdcA mutant because of the decreased expression of fliZ, a positive regulator of SPI1 transcriptional activator, hilA. Finally, the virulence of a S. Typhimurium tdcA mutant was attenuated compared to a wild type when administered orally. This study implies the role of tdcA in the invasion process of S. Typhimurium.

• 한국동물위생학회지
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• 제21권4호
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• pp.413-429
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• 1998

Escherichia coli is recovered from a wide variety of infections in many animals species. It may be a primary or secondary agent. Nursing and young animals are particularly susceptible, and urinary tract infections are frequent. The various serotypes of E coli are intestinal inhabitants of animals including humans and probably infect most mammals and birds : therefore, they have a cosmopolitan distribution. Colibacillosis refers to any totalized or systemic infection caused entirely or partly by E coli. Collibacillosis in mammals is most often a primary enteric disease, whereas collibacillosis in poultry is typically a secondary located or systemic disease occurring when host defenses have been impaired or overwhelmed. Other opportunistic bacteria, which can be identified by culture, may play a similar role to that of I coli in secondary infections. Collectively, infections caused by E coli are responsible for significant economic losses to the animal performance. From the standpoint of pathogenic mechanisms and diseases, four major categories of E coli are recognized : enterotoxigenic(ETEC), enteropathogenic (EPEC), enteroinvasive(EIEC), and enterohemorrhagic(EHEC). In addition, two less-well-defined E coli categories are recognized in animals and humans : enteroaggregative and cytotoxin necrotizing factor-positive. The aforementioned categories are represented by different serotypes. Certain serotypes show a host preference and are encountered more frequently in some disease syndromes. Of the four major categories, ETEC is the most common cause of diarrhea in calves, lambs, and pigs. Strains in the other categories cause the less-common diarrhea and other disease syndromes. Enterotoxins and pilus antigens are the two most prominent virulence factors thus far identified for ETEC. Two enterotoxins, one heat-stable(ST) and one heat-labile(LT), are produced by enterotoxigenic strains of E coli : not all culture produce both of these plasmid-based enterotoxins.

• 한국수산과학회지
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• 제49권6호
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• pp.800-806
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• 2016

In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.