• Environmental Engineering Research
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• v.12 no.4
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• pp.129-135
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• 2007

This study evaluated microbial risk that could develop within soil microbial communities after amended with organic fertilizers from stabilized swine manure waste. For this purpose, we assessed the occurrences and competitiveness of antibiotic resistance and pathogenicity in soil microbial communities that were amended with swine manure wastes stabilized by a traditional lagoon fermentation process and an autothermal thermophilic aerobic digestion process, respectively. According to laboratory cultivation detection analysis, soil applications of the stabilized organic fertilizers resulted in increases in absolute abundances of antibiotic resistant bacteria and of two tested pathogenic bacteria indicators. The increase in occurrences might be due to the overall growth of microbial communities by the supplement of nutrients from the fertilizers. Meanwhile, the soil applications were found to reduce competitiveness for various types of antibiotic resistant bacteria in the soil microbial communities, as indicated by the decrease in relative abundances (of total viable heterotrophic bacteria). However, competitiveness of pathogens in response to the fertilization was pathogens-specific, since the relative abundance of Staphylococcus was decreased by the soil applications, while the relative abundance of Salmonella was increased. Further testes revealed that no MAR (multiple antibiotic resistance) occurrence was detected among cultivated pathogen colonies. These findings suggest that microbial risk in the soil amended with the fertilizers may not be critical to public health. However, because of the increased occurrences of antibiotic resistance and pathogenicity resulted from the overall microbial growth by the nutrient supply from the fertilizers, potential microbial risk could not be completely ruled out in the organic-fertilized soil samples.

• Korean Journal of Environmental Agriculture
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• v.42 no.4
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• pp.269-278
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• 2023

Antibiotics either kill or inhibit the growth of bacteria. However, antibiotic-resistant bacteria are difficult to treat with antibiotics. Infections caused by such bacteria often lead to severe diseases. Antibiotic resistance genes (ARG) can be horizontally transmitted across different bacterial species, necessitating a comprehensive understanding of how ARGs spread across various environments. In this study, we analyzed the plasmid sequences of 33 extended-spectrum beta-lactamases (ESBL) producing Escherichia coli isolated from pigs, farms, and their owners. We conducted an antibiotic susceptibility test (AST) with aztreonam and seven other antibiotics, as well as whole genome sequencing (WGS) of the strains using MinION. Our results demonstrated that the plasmids that did not harbor ARGs were mostly non-conjugative, whereas the plasmids that harbored ARGs were conjugative. The arrangement of these ARGs exhibited a pattern of organization featuring a series of ARG cassettes, some of which were identical across the isolates collected from different sources. Therefore, this study suggests that the sets of ARG cassettes on plasmids were mostly shared between pigs and their owners. Hence, enhanced surveillance of ARG should be implemented in farm environments to proactively mitigate the risk of antibiotic-resistant bacterial infections.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.141-149
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• 2017

This study was to investigate the sanitary microbiological aspects of Cheonho Reservoir and its antibiotic resistance in the natural environment to contribute to the public healthcare improvement. Groups of coliforms, were counted at three sites of the Cheonho Reservoir in July and September 2013, and the isolates were identified according to the water pollution process test standards. Antibiotic resistance was evaluated using the Korea National Institute of Health's standard antibiotic susceptibility test. The average coliform counts in Cheonho Reservoir were $2.0{\times}10^3CFU/mL$, 41% of which were identified as Escherichia coli(E. coli). Antibiotic resistance rate in E. coli isolated from Cheonho reservoir was highest in Ampicillin 31.3%, Ticarcillin 25.0%, Cefaxolin and Cefoxitin 18.8% respectively. Convergence multiple resistance patterns, 38,5% presented resistance to 4 durgs, 6 drugs resistance were 7.7%. The more than 2 drugs resistance were 92.3%. Cheonho Reservoir is a public park that accessible to the citizens, further convergence studies are needed to develop sanitary microbiological management practices and study antibiotic resistance of the reservoir.

• Journal of Microbiology and Biotechnology
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• v.31 no.2
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• pp.250-258
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• 2021

Among various species of marine bacteria, those belonging to the genus Halomonas have several promising applications and have been studied well. However, not much information has been available on their antibiotic resistance. In our efforts to learn about the antibiotic resistance of strain Halomonas socia CKY01, which showed production of various hydrolases and growth promotion by osmolytes in previous study, we found that it exhibited resistance to multiple antibiotics including kanamycin, ampicillin, oxacillin, carbenicillin, gentamicin, apramycin, tetracycline, and spectinomycin. However, the H. socia CKY01 resistance pattern to kanamycin, gentamicin, apramycin, tetracycline, and spectinomycin differed in the presence of 10% NaCl and 1% NaCl in the culture medium. To determine the mechanism underlying this NaCl concentration-dependent antibiotic resistance, we compared four aminoglycoside resistance genes under different salt conditions while also performing time-dependent reverse transcription PCR. We found that the aph2 gene encoding aminoglycoside phosphotransferase showed increased expression under the 10% rather than 1% NaCl conditions. When these genes were overexpressed in an Escherichia coli strain, pETDuet-1::aph2 showed a smaller inhibition zone in the presence of kanamycin, gentamicin, and apramycin than the respective control, suggesting aph2 was involved in aminoglycoside resistance. Our results demonstrated a more direct link between NaCl and aminoglycoside resistance exhibited by the H. socia CKY01 strain.

• YAKHAK HOEJI
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• v.48 no.1
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• pp.27-29
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• 2004

The essential oil fractions from six plant parts including leaf of Zanthoxylum piperitum and flower of Lindera obtusiloba have revealed to possess resistance inhibitory activity on antibiotic resistant Staphylococcus aureus SA2 when combined with ohloramphenicol (Cm). The combination of Cm and essential oil mixtures showed potent resistance inhibition in the level of 10∼20 $\mu\textrm{g}$/ml.

• The Journal of the Korean Society for Microbiology
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• v.22 no.2
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• pp.155-162
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• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.163-171
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• 2020

This study examined the prevalence of adherence factors, toxin genes, antimicrobial resistance phenotypes, and resistance genes in Escherichia coli (E. coli) isolated from piglets with diarrhea before and after the ban on antibiotic growth promoters (AGPs) in Korea from 2007 to 2018. In this period, pathogenic 474 E. coli isolates were obtained from diarrheic piglets. The virulence factors and antimicrobial resistance genes were assayed using a polymerase chain reaction, and the susceptibility to antibiotics was tested according to the Clinical and Laboratory Standards Institute guidelines. After the ban on AGPs, the frequency of F4 (12.5% to 32.7%) increased significantly, and LT (31.9% to 20.3%) and EAST-I (46.5% to 35.2%) decreased significantly. In addition, the resistance to streptomycin (45.8% to 67.9%), cephalothin (34.0% to 59.4%), and cefazlin (10.4% to 28.8%) increased significantly. Colistin resistance plasmid-mediated genes, mcr-1 and mcr-3, were detected after the ban on AGPs. The results of this study can provide useful data for analyzing the impact of the ban on AGPs on the virulence profiles and antimicrobial resistance of E. coli isolated from piglets with diarrhea in Korea.

• Korean Journal of Clinical Pharmacy
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• v.33 no.4
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• pp.261-269
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• 2023

Background: Acute rhinosinusitis (ARS) is a common condition encountered in ambulatory practice and is one of the most common reasons for antibiotic prescriptions. This study aimed to evaluate the potentially inappropriate antibiotic prescribing for ARS in South Korea and identify influencing factors. Methods: We analyzed Health Insurance Review and Assessment Service-National Patient Samples data. We selected outpatients aged 20 to 64 with ARS, prescribed antibiotics between February and November 2020. Potentially inappropriate antibiotic prescribing was categorized as: 1) inappropriate antibiotic selection and 2) inappropriate antibiotic dosage or duration. Multiple logistic regression was conducted to estimate the impact of various factors on inappropriate antibiotic prescribing. Results: Of 1,210 patients, 80.83% received potentially inappropriate ARS antibiotic prescriptions. Inappropriate antibiotic selection accounted for 43.55%, and inappropriate antibiotic dosage and duration contributed to 37.28%. Otolaryngologists had higher odds ratio (OR) of potentially inappropriate antibiotic prescribing compared to internal medicine practitioners, while dentists had lower OR. Patients aged 20 to 29 years had a higher OR than other age groups, and those who visited primary care clinics had a higher OR than those who visited hospitals. Conclusion: Potentially inappropriate antibiotic prescribing for ARS is prevalent in South Korea. This study identified physician specialty, patient age group, and the level of healthcare facility as factors influencing potentially inappropriate antibiotic prescriptions. Addressing this issue through targeted interventions, such as improved guidelines adherence and patient education, is imperative to mitigate the risks associated with antibiotic misuse and antibiotic resistance.

• BMB Reports
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• v.33 no.4
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• pp.332-336
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• 2000

Phenazine 1-carboxylic acid (PCA) is an antifungal antibiotic isolated from a culture filtrate of Bacillus sp. B-6 producing an acyl CoA synthetase inhibitor. This antibiotic is reported as an inhibitor of an acyl CoA synthetase from Pseudomonas sp.. Bacillus sp. B-6 was resistant to PCA up to 350 ${\mu}g/ml$. We investigated the mechanism of the resistance of Bacillus sp. B-6 to PCA. The rate of growth in a medium containing up to 100 ${\mu}g/ml$ was as rapid as the PCA-free medium. At a PCA concentration of 300 ${\mu}g/ml$, the growth rate was more than half that of the control. In this work, we purified acyl CoA synthetase from Bacillus sp. B-6 and found that this acyl CoA synthetase was much less sensitive to PCA than the acyl CoA synthetase from other source. These findings suggested that the insensitivity of Bacillus sp. B-6 acyl CoA synthetase plays an important role in the PCA resistance of this bacterium.

• Journal of Food Hygiene and Safety
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• v.35 no.2
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• pp.189-194
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• 2020

In this study, we investigated the efficacy of Salmonella phage P22 combined with antibiotics to inhibit antibiotic-resistant S. Typhimurium CCARM 8009. The synergistic effect of phage P22 and antibiotics was evaluated by using disk diffusion and broth dilution assays. The development of Antimicrobial resistance was determined after time-kill assay. The antibiotic susceptibility assay showed the inhibition zone sizes around the antibiotic disks were increased up to 78.8% in the presence of phage (cefotaxime; 13.6%, chloramphenicol; 19.3%, ciprofloxacin; 12.7% and erythromycin; 78.8%). The minimum inhibitory concentration values of the combination treatment significantly decreased from 256 to 64 mg/mL for tetracycline, 8 to 4 mg/mL for chloramphenicol, 0.0156 to 0.0078 mg/mL for ciprofloxacin, 128 to 64 mg/mL for erythromycin and 512 to 256 mg/mL for streptomycin. The number of S. Typhimurium CCARM 8009 was approximately 4-log lower than that of the control throughout the combination treatment with phage P22 and ciprofloxacin delete at 37℃ for 20 h. The results indicate that the development of antimicrobial resistance in S. Typhimurium could be reduced in the presence of phage treatment. This study provides promising evidence for the phage-antibiotic combination as an effective treatment to control antibiotic-resistant bacteria.