• Korean Journal of Food Science and Technology
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• v.37 no.1
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• pp.134-141
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• 2005

To characterize genotypic and phenotypic traits of Staphylococcus aureus isolates (n = 86) from lettuces and raw milk, major virulence-associated genes and antibiotic susceptibility were detected using PCR-based methods and disk diffusion method, respectively. All isolates possessed coagulase gene and showed five polymorphism types [500 bp (2.4%), 580 bp (17.4%), 660 bp (61.6%), 740 bp (17.4%), and 820 bp (1.2%)] due to variable numbers of tandem repeats present within the gene. Two or three different loci of hemolysin gene family were dominant in isolates, 47 of which (55%) possessed combination of hla/hld/hlg-2 genes as the most prevalent types. Among enterotoxin-encoding genes, sea was detected from 32 isolates (37%), sed from 1 isolate (1%), and sea and sed genes were co-detected from 4 isolates (5%), whereas seb, sec, and tsst-1 genes were not detected. All isolates were susceptible to ciprofloxacin, trimethoprim/sulfamethoxazole, oxacillin, and vancomycin, 85 isolates (99%) to penicillin G, 54 isolates (63%) to chloramphenicol, 51 isolates (59%) to erythromycin, and 7 isolates (8%) to clindamycin. Among resistant isolates, seven displayed multiantibiotic-resistance against two different antibiotics.

• Tuberculosis and Respiratory Diseases
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• v.65 no.2
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• pp.91-98
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• 2008

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is the most common organism associated with nosocomial infections. MRSA infections are becoming increasing important because they have emerged no only as healthcare-associated (HA) infections but also as community-associated (CA) ones. This study examined the moleculo-epidemiology of MRSA, which was isolated from nasal swabs in the intensive care unit (ICU) at Konyang University Hospital. MRSA are classified into HA-MRSA and CA-MRSA. Methods: From June to September 2006, 353 patients who were admitted to the ICU in Konyang University Hospital were enrolled in this study. Single nasal swabs were obtained for culture in the ICU on the 1st day. Pulsed-field gel electrophoresis and the antimicrobial resistant patterns were analyzed between HA- and CA-MRSA. An antimicrobial sensitivity test was also performed. Results: Forty two strains of MRSA were isolated from 353 patients (11.9%). Among the 42 isolates, HA-MRSA and CA-MRSA were found in 33 (78.6%), and 9 (21.4%), respectively. Eleven different PFGE types (type A to K) were identified. Types A (n=9) and B (n=7) were the most common for HA-MRSA, and types A (n=2) and B (n=2) were identified in CA-MRSA. The proportion of types A and B in CA-MRSA (44.4%) was similar to that in HA-MRSA (48.5%). The rates of resistance rates to erythromycin and ciprofloxacin were higher in HA-MRSA than in CA-MRSA. Conclusion: The rate of isolation of MRSA in an ICU setting was 11.9%. HA-MRSA was isolated more frequently than CA-MRSA. The rate of resistance of HA-MRSA to erythromycin and ciprofloxacin was higher than that of CA-MRSA. Despite the small number of subjects, the main isolates (type A and B) of CA-MRSA were similar to those of HA-MRSA.

• Journal of Microbiology and Biotechnology
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• v.33 no.2
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• pp.211-218
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• 2023

A cryptic plasmid (pTH32) was characterized from Tetragenococcus halophilus 32, an isolate from jeotgal, Korean traditional fermented seafood. pTH32 is 3,198 bp in size with G+C content of 35.84%, and contains 4 open reading frames (ORFs). orf1 and orf2 are 456 bp and 273 bp in size, respectively, and their translation products showed 65.16% and 69.35% similarities with RepB family plasmid replication initiators, respectively, suggesting the rolling-circle replication (RCR) mode of pTH32. orf3 and orf4 encodes putative hypothetical protein of 186 and 76 amino acids, respectively. A novel Tetragenococcus-Escherichia coli shuttle vector, pMJ32E (7.3 kb, Em^r), was constructed by ligation of pTH32 with pBluescript II KS(+) and an erythromycin resistance gene (ErmC). pMJ32E successfully replicated in Enterococcus faecalis 29212 and T. halophilus 31 but not in other LAB species. A pepA gene, encoding aminopeptidase A (PepA) from T. halophilus CY54, was successfully expressed in T. halophilus 31 using pMJ32E. The transformant (TF) showed higher PepA activity (49.8 U/mg protein) than T. halophilus 31 cell (control). When T. halophilus 31 TF was subculturd in MRS broth without antibiotic at 48 h intervals, 53.8% of cells retained pMJ32E after 96 h, and only 2.4% of cells retained pMJ32E after 14 days, supporting the RCR mode of pTH32. pMJ32E could be useful for the genetic engineering of Tetragenococcus and Enterococcus species.

• Journal of the korean academy of Pediatric Dentistry
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• v.38 no.2
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• pp.170-178
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• 2011

The purpose of this study was to assess the prevalence of periodontopathic bacteria and resistance determinants from oral biofilm of children. Subgingival dental plaque was isolated from 87 healthy children, and PCR was performed to determine the presence of 5 periodontal pathogens including P. gingivalis, T. forsythia, T. denticola, F. nucleatum, A. actinomycetemcomitans, and nine resistance genes including tet(Q), tet(M), ermF, aacA-aphD, cfxA, $bla_{SHV}$, $bla_{TEM}$, vanA, mecA. 1. The prevalence of F. nucleatum, T. forsythia. and P. gingivalis was 95.4%, 55.2%, and 40.2%, respectively. In addition. the prevalence of A. actinomycetemc omitans was 5.7%, while T. denticola was 3.4%. 2. In analysis of antibiotic resistance determinants. cfxA, $bla_{TEM}$ and tet(M) were detected in all the samples tested. It was also found that the prevalence of tet(Q) showing tetracycline resistance. $bla_{SHV}$ associated with resistance to ${\beta}$-lactams, ermF exhibiting erythromycin resistance, and, vanA resulting vancomycin resistance was 88.5%, 29.9% 87.4%, and 48.5%, respectively. The aacA-aphD gene showing resistance to aminoglycosides and mecA gene harboring methicillin resistance exhibited the lowest prevalence with 9.2%. 3. In a correlation analysis between periodontopathic pathogens and antibiotic resistance determinants, it was found that there was a significant correlation between T. forsythia and $bla_{SHV}$. Also, P. gingivalis and vanA showed a correlation. Finally, tet(Q) and ermF showed a significant correlation (phi: 0.514) while mecA and vanA also showed a correlation(phi: 0.25).

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.352-364
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• 2016

In this study, we examined in vitro the potential probiotic properties of lactic acid bacteria (LAB) obtained from the fish intestine and their ability to degrade histamine through the production of diamine oxidase (DAO) enzymes and bacteriocin. Among 97 LAB strains isolated from the intestine of croaker, flatfish, pollack, and rockfish, CIL08, CIL16, FIL20, FIL31, PIL45, PIL49, PIL52, and RIL60 isolates exhibited excellent survival rates under simulated gastrointestinal tract conditions, high adhesion ability to HT-29 epithelial cells, and resistance to the antibiotics such as amoxicillin, ampicillin, erythromycin, penicillin G, streptomycin, tetracycline, or vancomycin. In addition, these strains did not produce histamine in decarboxylating broth containing histidine. In particular, 4 strains (CIL08, FIL20, PIL52, and RIL60) that may produce DAO were significantly able to degrade histamine. The bacteriocins produced by FIL20, FIL31, and PIL52 LAB inhibited the growth and histamine production of Enterococcus aerogenes CIH05, Serratia marcescens CIH09, Enterococcus faecalis FIH11, Pediococcus halophilus FIH15, Lactobacillus sakei PIH16, Enterococcus faecium PIH19, Leuconostoc mesenteroides RIH25, or Aeromonas hydrophilia RIH28. Histamine-producing strains isolated from fish intestine were found to reduce histamine accumulation during co-culture with CIL08, FIL20, PIL52, and RIL60 LAB showing histamine degradation or bacteriocin production ability. The probiotic strains preventing histamine formation were identified as Pediococcus pentosaceus CIL08, Lactobacillus plantarum FIL20, Lactobacillus paracasei FIL31, Lactobacillus sakei PIL52, and Leuconostoc mesenteroides RIL60 with high similarity based on 16S rRNA gene sequencing.

• Korean Journal of Microbiology
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• v.51 no.1
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• pp.39-47
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• 2015

Secondary metabolism in actinomycetes has been known to be controlled by a small molecule, ${\gamma}$-butyrolactone autoregulator, the binding of which to each corresponding receptor leads to the regulation of the transcriptional expression of the secondary metabolites. We expected that expression of an autoregulator receptor or a pleiotropic regulator in a non-host was to be gained insight of effective production of new metabolic materials. In order to study the function of the receptor protein (seaR), which is isolated from Saccharopolyspora erythraea, we introduced the seaR gene to Streptomyces coelicolor A3(2) as host strains. An effective transformation procedure for S. coelicolor A3(2) was established based on transconjugation by Escherichia coli ET12567/pUZ8002 with a ${\varphi}C31$-derived integration vector, pSET152, which contained int, oriT, attP and $ermEp^*$ (erythromycin promotor). Therefore, the pEV615 was introduced into S. coelicolor A3(2) by conjugation and integrated at the attB locus in the chromosome of the recipients by the ${\varphi}C31$ integrase (int) function. Exconjugant of S. coelicolor A3(2) containing the seaR gene was confirmed by PCR and transcriptional expression of the seaR gene in the transformant was analyzed by RT-PCR. In case of S. coelicolor A3(2), a phenotype microarray was used to analyze the phenotype of transformant compared with wild type by seaR expression. After that, in order to confirm the accuracy of the results obtained from the phenotype microarray, an antimicrobial susceptibility test was carried out. This test indicated that sensitivity of the transformant was higher than wild type in tetracycline case. These results indicated that some biosynthesis genes or resistance genes for tetracycline biosynthesis in transformant might be repressed by seaR expression. Therefore, subsequent experiments, analysis of transcriptional pattern of genes for tetracycline production or resistance, are needed to confirm whether biosynthesis genes or resistance genes for tetracycline are repressed or not.

• Journal of Food Hygiene and Safety
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• v.16 no.3
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• pp.159-167
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• 2001

Staphylocorccus aureus is gram positive, facultatively anaerobic, non-sporulative coccus, and positive for coagulase and DNase. The food-poisoning outbreak of Staphylococcus aureus increases in the world, and third occurrence happened in our country. Of 105 isolates (25.4%) obtained 413 focal samples of food-poisoning suspicious patients. In those cases, the enterotoxins were detected from a total of 45 isolates (42.9%), 9 isolates(20.0%) were A type, 33 isolates (73.3%) were H types, 2 isolates (4.4%) were G type and 1 isolate was a I type enterotoxin. Among the isolates possessing staphylococcal enterotoxins, 29 isolates had H type only(64.4%), 5 isolates had A type only and 4 isolates had both A and H type. Two isolates had G type only and 1 isolate had I type only. In the antibiotic susceptibility, 48 isolates (46%) had at least one antibiotic resistance among 105 isolates, 34 isolates (70.8%) were resistant to penicillin. 1 isolate (2.1%) to ampicillin, 3 isolates (6.3%) to erythromycin and kanamycin. Seven were resistant to more than two antibiotics and especially 1 isolate was resistant to penicillin-ampicillin-nitrofurantoin.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.296-302
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• 2020

Rapamycin, derived from Streptomyces rapamycinicus, is an important bioactive compound having a therapeutic value in managing Parkinson's disease, rheumatoid arthritis, cancer, and AIDS. Because of its pharmaceutical activity, studies over the past decade have focused on the biosynthesis of rapamycin to enhance its yield. In this study, the effect of rapG on rapamycin production was investigated. The rapG expression vector was constructed by utilizing the integration vector pSET152 under the control of the erythromycin resistance gene (ermE^⁎), a strong constitutive promoter. The rapamycin yield of wild type (WT) and WT/rapG overexpression mutant strains, under fermentation conditions, was analyzed by high-performance liquid chromatography (HPLC). Our results revealed that overexpression of rapG increased rapamycin production by approximately 4.9-fold (211.4 mg/l) in MD1 containing 15 g/l of glycerol, compared to that of the WT strain. It was also found that Illicium verum powder (10 g/l), containing shikimic acid, enhanced rapamycin production in both WT and WT/rapG strains. Moreover, the amount of rapamycin produced by the WT/rapG strain was statistically higher than that produced by the WT strain. In conclusion, the addition 15 g/l glycerol and 15 g/l I. verum powder produced the optimal conditions for rapamycin production by WT and WT/rapG strains.

• Korean Journal of Microbiology
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• v.49 no.3
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• pp.228-236
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• 2013

Campylobacter jejuni is one of important food-borne pathogens causing human gastroenteritis. We isolated 42 strains of C. jejuni from diarrhea patients and 4 food-poisoning outbreaks in 2010, Gyeonggi-do. In this study, 42 strains were tested for genetic characteristics, the serotype distribution and antimicrobial resistant rate. The presence of hipO (100%), cdtB (100%), and mutated gyrA (95.2%) genes was detected in C. jejuni by polymerase chain reaction (PCR). Detection of mutated gyrA gene correlated with ciprofloxacin resistance. Forty isolates had mutated gyrA gene and were actually resistant to ciprofloxacin. Furthermore, comparing the gyrA DNA sequence data, ciprofloxacin-resistant isolates had a mutation of the DNA sequence from ACA (threonine) to ATA (isoleucine). But 41 strains (97.6%) of patient isolates were susceptible to erythromycin and azithromycin. A total of 35.7% among 42 C. jejuni isolates were identified into 4 different serotypes. The serotype distribution of C. jejuni strains were shown to be HS2(B), HS3(C), HS4(D), HS19(O). To investigate the genotypes of C. jejuni isolated in Gyeonggi province, repetitive sequence polymerase chain reaction (rep-PCR) analysis and SmaI-digested pulsed-filed gel electrophoresis (PFGE) profile analysis were performed. From the PFGE analysis of 42 C. jejuni strains, 12 clusters of PFGE profile were obtained. On the other hand, 11 clusters of rep-PCR profile were obtained from 42 strains of C. jejuni.

• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.420-426
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• 2017

Methicillin-resistant Staphylococcus (MRS) can be colonized in various body sites and is more frequently isolated in healthcare associated persons. This study aimed to evaluate the contamination rate of MRS in a high school environment, those living with closed life style. Staphylococcus aureus was isolated from only the hands of 2 students among a sample of 28 students, and S. aureus were susceptible to methicillin antibiotics. Coagulase negative Staphylococci (CoNS) were isolated from the hands of 26 students (26/28, 92.9%), and among them, 14 (53.8%) isolates were methicillin-resistant CoNS (MRCoNS). Among the 14 MRCoNS, S. warneri was the most common (8/14, 57%) and susceptible to most $non-{\beta}-lactam$ antibiotics, such as clindamycin, erythromycin, ciprofloxacin, tetracycline, gentamicin, and vancomycin. In a culture of 31 desks, S. aureus was not isolated but CoNS were isolated from 26 desks (26/31, 83.6%), which did not harbor the mecA gene. The other bacteria isolated from the hands and desks were Micrococcus and Bacillus spp. In conclusion, methicillin-resistant S. aureus was not isolated from the hands and desks of high school students. However, the frequency of MRCoNS harboring mecA gene were high in the hands of high school students. Therefore, to prevent and to control the transfer of infection, intensifying preventive education, such as hand washing, and active surveillance systems, such as an investigation of contamination or carrier rate of resistant bacteria are necessary.