• Korean Journal of Veterinary Research
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• v.35 no.3
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• pp.537-542
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• 1995

In this study, we aim to find the presence of virulence-related plasmid in Salmonella isolates from poultry, and the difference between S pullorum and S gallinarum on the plasmid profile and antibiotics resistance. We used seventeen isolates of Salmonella spp that were isolated from poultry. Thirteen isolates, S typhimurium(ST), S pullorum(SP) and S gallinarum(SG), contained virulence-related plasmids. These are 95Kd plasmid in ST and 85Kd plasmid in SP and SG. Three(1/4 of ST, 1/1 of SE, and 1/9 of SP) isolates have no detectable plasmids. The isolates of ST have relatively variable plasmid profile but the isolates of S pullorum except No 12(additional 3.0Kb plasmid) have common 85K6, 8.1Kb, 4.0Kb and 2.3Kb plasmid and two of three isolates of S gallinarum have common 85Kb, 4.0Kb and 2.3Kb plasmid but the rest has only 85Kb plasmid. Interestingly, all of the isolates of SP have 8.1Kb plasmid, and same size of plasmid is also found in one of ST isolates. All of the isolates have the resistance to penicillin, chloramphenicol, rifampicin, streptomycin, sulfamethazine and some isolates show the resistance to ampicillin and tetracycline. There is no relatedness between plasmid profile and antibiotics resistance and no differences between SP and SG in antibiotics resistance. Therefore further differentiation of each isolates by restriction enzyme assay and, if possible, charaterization of each plasmid, especially, 8.1Kb plasmid in SP and ST, may be necessary.

• Journal of Microbiology and Biotechnology
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• v.31 no.7
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• pp.949-955
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• 2021

Previously, our research group isolated Bifidobacterium breve IDCC4401 from infant feces as a potential probiotic. For this study, we evaluated the safety of B. breve IDCC4401 using genomic and phenotypic analyses. Whole genome sequencing was performed to identify genomic characteristics and investigate the potential presence of genes encoding virulence, antibiotic resistance, and mobile genetic elements. Phenotypic analyses including antibiotic susceptibility, enzyme activity, production of biogenic amines (BAs), and proportion of D-/L-lactate were evaluated using E-test, API ZYM test, high-performance liquid chromatography (HPLC), and D-/L-lactic acid assay respectively. The genome of B. breve IDCC4401 consists of 2,426,499 bp with a GC content of 58.70% and 2,016 coding regions. Confirmation of the genome as B. breve was provided by its 98.93% similarity with B. breve DSM20213. Furthermore, B. breve IDCC4401 genes encoding virulence and antibiotic resistance were not identified. Although B. breve IDCC4401 showed antibiotic resistance against vancomycin, we confirmed that this was an intrinsic feature since the antibiotic resistance gene was not present. B. breve IDCC4401 showed leucine arylamidase, cystine arylamidase, α-galactosidase, β-galactosidase, and α-glucosidase activities, whereas it did not show production of harmful enzymes such as β-glucosidase and β-glucuronidase. In addition, B. breve IDCC4401 did not produce any tyramine, histamine, putrescine, cadaverine, or 2-phenethylamine, which are frequently detected BAs during fermentation. B. breve IDCC4401 produced 95.08% of L-lactate and 4.92% of D-lactate. Therefore, our findings demonstrate the safety of B. breve IDCC 4401 as a potential probiotic for use in the food industry.

• Tuberculosis and Respiratory Diseases
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• v.85 no.1
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• pp.89-95
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• 2022

Background: With the introduction of Xpert MTB/RIF assay (Xpert), its incorporation into tuberculosis (TB) diagnostic algorithm has become an important issue. The aim of this study was to evaluate the performance of the Xpert assay in comparison with a commercial polymerase chain reaction (PCR) assay. Methods: Medical records of patients having results of both Xpert and AdvanSure TB/NTM real-time PCR (AdvanSure) assays using the same bronchial washing specimens were retrospectively reviewed. Results: Of the 1,297 patients included in this study, 205 (15.8%) were diagnosed with pulmonary TB. Using mycobacterial culture as the reference method, sensitivity of the Xpert assay using smear-positive specimens was 97.5%, which was comparable to that of the AdvanSure assay (96.3%, p=0.193). However, the sensitivity of the Xpert assay using smear-negative specimens was 70.6%, which was significantly higher than that of the AdvanSure assay (52.9%, p=0.018). Usng phenotypic drug susceptibility testing as the reference method, sensitivity and specificity for detecting rifampicin resistance were 100% and 99.1%, respectively. Moreover, a median turnaround time of the Xpert assay was 1 day, which was significantly shorter than 3 days of the AdvanSure assay (p<0.001). Conclusion: In comparison with the AdvanSure assay, the Xpert assay had a higher sensitivity using smear-negative specimens, a shorter turnaround time, and could reliably predict rifampin resistance. Therefore, the Xpert assay might be preferentially recommended over TB-PCR in Korean TB diagnostic algorithm.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.49 no.4
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• pp.198-207
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• 2023

Objectives: This study investigated causative strains and their antibiotic sensitivity in patients who were hospitalized for maxillofacial odontogenic infections at a tertiary center in South Korea over the past 10 years with the aim of providing guidelines for the selection of appropriate empirical antibiotics. Materials and Methods: Patients with head and neck fascial space abscesses due to odontogenic infections who underwent incision and drainage surgery with pus culture tests between 2013 and 2022 at the Department of Oral and Maxillofacial Surgery, Dankook University Hospital were included. The bacterial isolates and antibiotic sensitivity of each strain were analyzed for 2013-2022, 2013-2017, and 2018-2022. The affected fascial spaces were classified into primary, secondary, and deep neck spaces. Results: In the 192 patients included in this study, 302 strains were detected. Viridans streptococcus had the highest frequency (51.7%), followed by Prevotella spp. (16.9%), Staphylococcus spp. (5.6%), and Klebsiella pneumoniae (4.6%). The identification rate of viridans streptococcus significantly increased from 41.8% in 2013-2017 to 60.9% in 2018-2022. Viridans streptococcus showed an antibiotic sensitivity of 80.5% to ampicillin; the sensitivity to penicillin antibiotics decreased over the study period. Antibiotic susceptibility was approximately 94% for third-generation cephalosporins. K. pneumoniae, which was identified at a high percentage in patients with deep neck space infection, showed increasing antibiotic resistance to most antibiotics over the study period. Conclusion: Viridans streptococcus was identified in head and neck fascial space abscesses with the highest frequency. Empirical antibiotics should be effective against this strain; penicillin antibiotics are considered inappropriate. For effective treatment of deep neck space abscesses, bacterial culture and antibiotic sensitivity tests performed as soon as possible are essential.

• Korean Journal of Veterinary Service
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• v.46 no.1
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• pp.29-34
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• 2023

Mycobacterium tuberculosis complex (M. tuberculosis complex) is a causative agent of contagious chronic disease in a wide range of mammalian hosts, mainly cattle, goat, pigs, wildlife, and humans. The definite diagnosis of tuberculosis is made based on culture of M. tuberculosis, but it takes a long time. In the present study, we analyzed whether the detection time of M. tuberculosis could be reduced when cultured in the medium containing the culture-promoting ingredients-107 (CPI-107) using the BacT/Alert 3D system, an automatic culture system. The time to detection (TTD) tended to decrease as the added concentration of CPI-107 increase. In the case of low numbers of M. tuberculosis, it decreased by 21.0% at 1.2 mg/mL of CPI-107 and by 15.9% in the case of high numbers of M. tuberculosis. In the culture using clinically isolated M. tuberculosis strains, the shortening of the culture time by CPI was more evident. In conclusion, the detection time of M. tuberculosis was shortened in the medium added with CPI-107, and this could be used for isolation, culture and drug susceptibility test of M. tuberculosis.

• Korean Journal of Veterinary Research
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• v.63 no.2
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• pp.17.1-17.12
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• 2023

Antimicrobial (AM) resistance is a growing threat in human and veterinary medicine, spreading across species and perceived as One-Health issue. Prudent use of AM products is essential in mitigating this risk in both human and veterinary medicine. Farm veterinarians, responsible for prescribing appropriate AM and offering advice to farmers on their proper usage, are regarded as key players in the livestock industry. An online survey of farm veterinarians (n = 1,531) was conducted to assess their educational experience, beliefs, current status of prescription, practical behavior, and self-efficacy regarding the prudent use of antimicrobials (PUA). The data from 170 respondents were analyzed using descriptive statistics, regression and mediation analysis. Participants chose AM based on their experiences, academic resources, and peer veterinarians. Approximately 77% did not routinely conduct antibiotic-susceptibility-test. Most participants believed in the importance of PUA and the role of veterinarians to reduce AM resistance, but they reported a lack of awareness among farmers and insufficient national support interfere with their practical behavior with regard to PUA. Half of the participants had PUA-education, and 78.6% reported that education had a positive impact on their behavior with PUA. Self-efficacy partly mediates the relationship between belief and behavior for PUA, which accounted for 23.77% of the total effect that beliefs have on behavior for PUA. The findings of the study show that enhancing veterinarians' abilities to practice and their self-efficacy through education tailored to the current status of farms can contribute to the reduction of AMs in the livestock sector.

• Tuberculosis and Respiratory Diseases
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• v.62 no.6
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• pp.492-498
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• 2007

Background: Several lines of evidence suggest that a host's genetic factors influence the outcome of exposure to Mycobacterium tuberculosis. The aim of this study was to determine whether polymorphism in NRAMP1 (natural resistance associated macrophage protein 1) gene is associated with the susceptibility or resistance to tuberculosis infection for patients with drug-sensitive pulmonary tuberculosis (DS-TB) and multi-drug resistant pulmonary tuberculosis (MDR-TB). Methods: Eight genetic polymorphisms of the NRAMP1 gene were investigated in patients suffering with DS-TB (n=100) or MDR-TB (n=102), and in healthy normal controls (NC, n=96). The genetic polymorphisms of NRAMP1 were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: The frequency of D543N A/G heterogygotes was significantly higher in the DS-TB subjects than the NCs (OR=2.10, 95% CI: 1.00 to 4.41, p=0.049). The frequency of 823C/T T/C heterozygotes was significantly higher in the DS-TB subjects (OR=2.79, 95% CI: 1.11 to 7.04, p=0.029) and the MDR-TB subject (OR=3.30, 95% CI 1.33 to 8.18, p=0.010) than in the NCs. However, the frequency of these genotypes was not different between the DS-TB and MDR-TB subjects. Conclusion: A significant association was found between NRAMP1 823 C/T polymorphism and pulmonary tuberculosis. This result suggests that NRAMP1 polymorphism may be involved in the development of pulmonary tuberculosis in Koreans.

• Neonatal Medicine
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• v.16 no.2
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• pp.172-181
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• 2009

Purpose: To identify trends in causative bacterial organisms for neonatal sepsis and antimicrobial susceptibilities over 10 years in one neonatal intensive care unit. Methods: We retrospectively reviewed the cases of culture-proven neonatal sepsis between January 1998 and December 2007. The 10-year period was divided into two phases (phase I, 1998-2002; phase II, 2003-2007) to distinguish the differences during the entire period. Results: Total 350 episodes of neonatal sepsis were identified in 315 neonates. The common pathogens of early-onset sepsis were S. epidermidis, S. aureus, P. aeruginosa, and E. cloacae in phase I, and S. epidermidis and E. cloacae in phase II. In cases of late-onset sepsis, coagulase negative Staphylococcus, S. aureus, and K. pneumoniae were isolated frequently in both phases. The incidence of sepsis caused by multi-drug resistant organisms decreased with strict infection control. Gram positive organisms showed 0-20% susceptibility to penicillin, ampicillin, and cefotaxime in both phases. Sensitivity to amikacin for Enterobacter spp. increased, whereas P. aeruginosa showed decreased sensitivity in phase II. Between 50% and 60% of other gram negative bacteria, except P. aeruginosa, were susceptible to cefotaxime in phase II in contrast to phase I. Greater than 80% of gram negative bacteria were sensitive to imipenem except P. aeruginosa and ciprofloxacin in both phases. Conclusion: The trend in causative microorganisms and antimicrobial susceptibilities can be used as a guideline for selection of appropriate antibiotics. A particular attention should be paid to infection control, especially to reduce sepsis caused by multi-drug resistant organisms.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.714-722
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• 1998

Background: Rifampicin (RFP) is a key component of the antituberculous short-course chemotherapy and the RFP resistance is a marker of multi-drug resistant (MDR) tuberculosis. RPoB gene encodes the $\beta$-subunit of RNA polymerase of M. tuberculosis which is the target of RFP. And the mutations of rpoB gene have been found in about 96% of rifampicin resistant clinical isolates of M. tuberculosis. So in order to find a rapid and clinically useful diagnostic method in identifying the RFP resistance, we compared the PCR -line probe method with PCR-SSCP for the detection of the rpoB gene mutation in cultured M. tuberculosis. Methods: 45 clinical isolates were collected from patients who visited Sung Kyun Kwan University Hospital. The RFP susceptibility test was referred to the referral laboratory of the Korean Tuberculosis Institute. 33 were rifampicin resistant and 12 were rifampicin susceptible. The susceptibility results were compared with the results of the PCR-BSCP and PCR-line probe method. Results: We could find rpoB mutations in 27/33(81.8%) RFP-resistant strains by PCR-line probe method, and in 23/33 (69.7%) by PCR-SSCP and there was no significant difference between two methods. There was no mutation in rifampicinn susceptible strains by both methods. Conclusion: PCR-line probe method would be a rapid, sensitive and specific method for the detection of rifampicin resistant Mycobacterium tuberculosis.

• Journal of Food Hygiene and Safety
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• v.17 no.2
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• pp.61-70
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• 2002

In order to investigate the classification and antibiotic resistance of Salmonella species,718 isolates were isolated from patient in Seoul from 1996 to 2001. The two hundred and ninety eight isolates (41.5%) were identified as Sal. Enteritidis, followed by Sal. Typhi 218 isolates (30.4%), and Sal. Typhimurium 87 isolates (12.1%). The identified Salmonella species were most resistant to tetracycline (32.7%), followed by streptomycin (28.0%), ticarcillin (18.1%) and ampicillin (12.4%). Among isolates,34.7% of Sal. Enteritidis were resistant to tetracycline, 32.3% to streptomycin,23.2% to ticarcillin,13.5% to ampicillin, respectively. 13.8% of Sal. Typhi were resistant to streptomycin,10.6% to tetracycline, respectively.66.7% of Sal. Typhimurium were resistant to tetracycline, 42.5% to streptomycin, 28.7% to ticarcillin, 26.4% to ampicillin and 17.2% to chloramphenicol, respectively. Of 718 isolates, 324 isolates (45.1%) were resistant to 1 or more drugs and 64 isolates (19.8%) were resistant to 1 drug, 132 isolates (40.7%) were resistant to 2 drugs,50 isolates (15.4%) were resistant to 3 drugs, 27 isolates (8.3%) to 4 drugs,27 isolates (8.3%) to 5 drugs,22 Isolates (6.8%) to 6 drugs. The most prevalent multiple resistant pattern was tetracycline-kanamycin (35.5%), followed by tetracycline-kanamycin-ticarcillin (8.3%), and tetracycline-kanamycin-ticarcillin-ampicillin (7.4%) . Antibiotic resistant rate of Sal. Typhimurium was 73.6%,1311owe4 by Sal. Enteritidis 53.7% and Sal. Typhi 19.3%. Most Sal. Enteritidis was resistant to 1 drug o.2 drugs, whereas Sal. Typhi. and Sal.. Typhunurium were more .resistant to 5 (16.7%) or 6 drugs (26.6%). The old generation antibiotics such as ampicillin, tetracycline, and streptomycin were annually more resistant than the new generation antibiotics such as ceftriaxone, ciprofloxacin or cefoxitin.