• Asian Pacific Journal of Cancer Prevention
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• v.17 no.4
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• pp.2083-2087
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• 2016

A new compound namely (13-(3,3-dihydroxypropyl)-1,6-dihydroxy-3,4-dihydro-1H-isochromen-8(5H)-one (1) was isolated from an ethyl acetate extract of the borne fungi Screlotium rolfsii. Its chemical structure was elucidated by spectroscopic analysis. Screlotiumol 1 were evaluated for their effects on the reversion of multidrug resistant (MDR) mediated by P-glycoprotein (P-gp) of the soil borne fungi. The multidrug resistant P-glycoprotein is a target for chemotherapeutic drugs in cancer cells. In the present study rhodamine-123 exclusion screening test on human mdr1 gene transfected mouse gene transfected L5178 and L5178Y mouse T-cell lymphoma which showed excellent MDR reversing effect in a dose dependent manner against mouse T-lymphoma cell line. Moreover, molecular docking studies of compound-1 also showed better results as compared with the standard. Therefore the preliminary results obtained from this study suggest that screlotiumol 1 could be used as a potential agent for the treatment of cancer.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.24
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• pp.10597-10601
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• 2015

Up-regulation of multidrug resistance-associated protein 1 (MRP1) is regarded as one of the main causes for multidrug resistance (MDR) of tumor cells, leading to failure of chemotherapy-based treatment for a multitude of cancers. However, whether silencing the overexpressed MRP1 is sufficient to reverse MDR has yet to be validated. This study demonstrated that RNAi-based knockdown of MRP1 reversed the increased efflux ability and MDR efficiently. Two different short haipin RNAs (shRNAs) targeting MRP1 were designed and inserted into pSilence-2.1-neo. The shRNA recombinant plasmids were transfected into cis-dichlorodiamineplatinum-resistant A549 lung (A549/DDP) cells, and then shRNA expressing cell clones were collected and maintained. Real time PCR and immunofluorescence staining for MRP1 revealed a high silent efficiency of these two shRNAs. Functionally, shRNA-expressing cells showed increased rhodamine 123 retention in A549/DDP cells, indicating reduced efflux ability of tumor cells in the absence of MRP1. Consistently, MRP1-silent cells exhibited decreased resistance to 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and DDP, suggesting reversal of MDR in these tumor cells. Specifically, MRP1 knockdown increased the DDP-induced apoptosis of A549/DDP cells by increased trapping of their cell cycling in the G2 stage. Taken together, this study demonstrated that RNAi-based silencing of MRP1 is sufficient to reverse MDR in tumor cells, shedding light on possible novel clinical treatment of cancers.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.389-398
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• 2020

The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) is increasing globally, resulting in high mortality rates. Although CRE is a relatively recent problem in Korea (the first case was not diagnosed until 2010), it is responsible for serious morbidities at an alarming rate. In this study, we carried out a molecular genetic analysis to determine the incidence of CRE and carbapenemase-producing Enterobacteriaceae (CPE) at a general hospital in Korea between August 2017 and August 2019. Forty strains of CPE were isolated from various clinical specimens and analyzed via antimicrobial susceptibility testing, polymerase chain reaction to detect β-lactamase genes, deoxyribonucleic acid sequencing, multilocus sequence typing, curing testing, and conjugal transfer of plasmids. The results demonstrated that all 40 isolates were multidrug-resistant. The fluoroquinolone susceptibility test showed that 75% of the Enterobacteriaceae isolates were resistant to ciprofloxacin, whereas 72.5% were resistant to trimethoprim-sulfamethoxazole. Further, conjugation accounted for 57.5% of all resistant plasmid transfer events, which is 4.3-fold higher than that observed in 2010 by Frost et al. Finally, the high detection rate of transposon Tn4401 was associated with the rapid diffusion and evolution of CPE. Our results highlight the rapid emergence of extensively drugresistant strains in Korea and emphasize the need for employing urgent control measures and protocols at the national level.

• Korean Journal of Environmental Agriculture
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• v.42 no.3
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• pp.169-176
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• 2023

The emergence and spread of antibiotic-resistant bacteria have been increasing with anthropogenic contamination. Understanding the prevalence and distribution of these resistant bacteria in environments is crucial for effectively managing anthropogenic pollutants. Lake Gyeongpo in the Gangwon Province of South Korea is known for its diverse ecological features and human interactions. The lake is exposed to pollutants from nonpoint sources, including urban areas, agricultural practices, and recreational activities, which can introduce antibiotics and foster antibiotic resistance in bacteria. The present study investigates Lake Gyeongpo as a potential reservoir for antibiotic-resistant bacteria in a natural ecosystem. A total of 203 bacterial isolates were collected from six sampling locations in Lake Gyeongpo during May, July, and November 2022. Most isolates were taxonomically identified as Pseudoalteromonas, Bacillus, Shewanella, and Vibrio spp.; their abundance showed a spatiotemporal distribution. An antibiotic susceptibility test was conducted on 75 isolates using the disk diffusion method with six drugs according to the CLSI guideline; 42 isolates were resistant to one or more antibiotics. Among these, 15 isolates were identified as multidrug resistant bacteria. This finding suggests the potential anthropogenic impact on Lake Gyeongpo and provides valuable insights into the dissemination of antibiotic resistance caused by anthropogenic pollutants.

• Microbiology and Biotechnology Letters
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• v.39 no.1
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• pp.37-42
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• 2011

I isolated the actinomycete strain KH223 from soil samples collected from the Kye Ryong mountain area. This strain is antagonistic to the multidrug-resistant Acinetobacter baumannii. KH223 was confirmed as belonging to the genus Streptomyces based on the scanning electronmicroscopy(SEM) observations of the diaminopimelicacid(DAP) type and morphological and physiological characteristics. Comparison of the 16S rDNA nucleotide sequences revealed that KH223 has a relationship with Streptomyces galbus. Production of antibiotics by KH223 was most favorable when cultured on a glucose, polypeptone, and yeast extract(PY) medium for 6 days at 27$^{\circ}C$. The supernatant was found to exhibit an antimicrobial effect on various kinds of bacteria and fungi. Particularly, butanol and ethylacetate extracts of KH223 and cyclo(trp-trp) exhibited significant activity against A. baumannii at concentration ranges of 0.8-12.5 ${\mu}g$/mL, 5.0-25 ${\mu}g$/mL and 12.5${\rightarrow}$100 ${\mu}g$/mL, respectively. Moreover, in contrast to cyclo(trp-trp) had shown to activity against Micrococcus luteus JCM 1464 at the concentration of 12.5 ${\mu}g$/mL, the butanol extract of KH223 showed significant activity against Bacillus subtilis IAM 1069 and Micrococcus luteus JCM 1464 at the concentration of 0.4 and 0.8 ${\mu}g$/mL, respectively. These results suggest that KH223 may have a great potential in the production of new antibiotics to combat multidrug-resistant pathogens and further studies may be warranted for the same.

• Tuberculosis and Respiratory Diseases
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• v.60 no.2
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• pp.180-186
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• 2006

Background : Para-aminosalicylic acid(PAS) is a 2nd-line drug that can cause severe adverse reactions leading to poor patient compliance. This study evaluated the relapse rate according to the discontinuance of PAS at a certain point after bacteriological conversion during the course of chemotherapy for multidrug-resistant tuberculosis(MDR-TB). Methods : 42 out of 452 MDR-TB patients were enrolled in this study. All subjects were receiving chemotherapy including PAS at National Masan TB Hospital between Jan. 1, 2000 and Dec. 31, 2001. The relapse rate was evaluated after the discontinuance of PAS from their initial regimen as a result of the severe adverse reactions at a certain point after the bacteriological conversion during the course of chemotherapy for MDR-TB. Results : The male to female ratio was 2.5:1, and the mean age was 47.2 years old. The average number of past histories, used drugs and resistant drugs was 1.2, 3.9 and 4.3. The mean number of sensitive drugs included in the inirial regimen was 3.9. The mean time for bacteriological conversion and discontinuance of the PAS was 2.3 months after initiating treatment and 6 months after bacteriological conversion, respectively. There was no relapse after discontinuing PAS during a mean follow up period of 31.6 months. Conclusion : PAS may be discontinued in the cases of serious gastrointestinal problems approximately 6 months after bacteriological conversion without concern about relapse.

• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.146-151
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• 2008

Purpose : Multidrug-resistant Acinetobacter baumannii (A. baumannii) is recognized to be the most difficult pathogen to control and treat in pediatric burn centers. We analyzed the antibiotic susceptibility pattern of A. baumannii in our pediatric burn intensive care unit during the past 7 years. Methods : We retrospectively evaluated 56 patients (105 samples) under the age 15 years and who were infected with A. baumannii between January 1999 and December 2005. Results : Fot the 56 patients, the ratio of males to females was 1.15:1 and the median age was 48.3 months. The sites of 105 isolates were wounds (65%), sputum (20%), blood (6 %), cutdown tips (5%), endo-tip tubes (2%) and urine (2%). A. baumannii presented yearround. The annual antimicrobial resistance rate increased and the multidrug resistant rate for two or more antibiotics was 93.33%. For 3 patients in whom resistance emerged, the interval period between the susceptible and resistant strains after antibiotic use was a mean of 10 days. The A. baumannii isolated from blood were all multi-drug resistant pathogens. Conclusion : Multidrug resistance of A. baumannii is increasing. Strict infection control guidelines and active surveillance are needed for the prevention and treatment of A. baumannii in hospitals.

• Tuberculosis and Respiratory Diseases
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• v.64 no.3
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• pp.187-193
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• 2008

Background: Multidrug-resistant tuberculosis (MDR-TB) and extensively drug resistant tuberculosis (XDR-TB) are serious threats to worldwide tuberculosis control, but the national burden and the trends of infectious spread are largely unknown. Methods: We retrospectively reviewed the results of drug sensitivity tests and medical records of patients that were diagnosed with culture-confirmed pulmonary tuberculosis and were admitted to the National Masan Tuberculosis Hospital between 2001 and 2005. Results: From 2001 to 2005, the proportion of MDR-TB among new cases was 9.2%, 13.8%, 16.9%, 23% and 27.0% in 2001, 2002, 2003, 2004 and 2005, respectively, and the proportion of MDR-TB among previously treated cases was 58.5%, 60.2%, 62.7%, 61.7% and 71.3% in 2001, 2002, 2003, 2004 and 2005, respectively. A significant increasing trend could be discerned for MDR-TB among both new and previously treated cases (p<0.001, p=0.002 for trend, respectively). The proportion of XDR-TB among new cases was 0%, 2.3%, 3.1%, 2.5% and 6.3% in 2001, 2002, 2003, 2004 and 2005, respectively, and the proportion of XDR-TB among previously treated cases was 9.1%, 15.7%, 17.3%, 19.9% and 19.1% in 2001, 2002, 2003, 2004 and 2005, respectively. A significant increasing trend could be discerned for XDR-TB among both new and previously treated cases (p=0.005, p<0.001 for trend, respectively). Conclusion: Both MDR-B and XDR-TB were gradually increased among both new and previously treated cases. Integrated national surveillance, including the public and private sectors, will be needed to estimate the exact status of antituberculous drug resistance.

• Korean Journal of Food Science and Technology
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• v.54 no.2
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• pp.209-217
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• 2022

In this study, Enterococcus faecalis BMSE-HMP005 isolated from human breast milk demonstrated antimicrobial effects against multidrug-resistant (MDR) bacterial strains. The bacteriocin produced by E. faecalis BMSE-HMP005 was fractionated using reverse-phase high-performance liquid chromatography. This fraction showed antimicrobial effects against both gram-positive and gram-negative MDR bacteria. No hemolytic reactions were observed. E. faecalis BMSEHMP005 was resistant to vancomycin; however, kanamycin, ampicillin, and erythromycin showed minimum inhibitory concentrations that were lower than the acceptable range provided by the European Food Safety Authority. For artificial gastric juice and bile acid, the survival rates were 98.67% and 95.70%, respectively. These results show the potential utility of E. faecalis BMSE-HMP005 as a probiotic with remarkable antimicrobial effects against MDR bacteria.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.975-991
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• 1997

Background : Many patients with isoniazid and rifampin-resistant pulmonary tuberculosis have organisms that are also resistant to other first-line drugs. Despite of aggressive retreatment chemotherapy, the results are often unsuccessful, with a failure rate approaching 40%. Recently, there has been a revival of resectional surgery for the treatment of multidrug-resistant pulmonary tuberculosis. Methods : A retrospective analyses of the case records and radiographic findings were done. Between January 1991 and December 1995, 14 human immunodeficiency virus (HIV)-seronegative patients with multidrug-resistant pulmonary tuberculosis were selected for resection to supplement chemotherapy. All patients had organisms resistant to many of the first-line drugs, including both isoniazid and rifampin. Results : Despite of aggressive therapy for median duration of 9.5 months, 12 of the 14 patients (86%) were still sputum smear and/or culture positive at the time of surgery. The disease was generally extensive. Although main lesions of the disease including thick-walled cavities were localized in one lung, lesser amounts of contralateral disease were demonstrated in 10 of 14 (71%). Types of surgery performed were pneumonectomy including extrapleural pneumonectomy in six patients, lobectomy or lobectomy plus in six patients, and segmentectomy in two patients. The resected lung appeared to have poor function ; preoperative perfusion lung scan showed only 4.8% of the total perfusion to the resected portion of the lung. There were no operative deaths. Two patients had major postoperative complications including empyema with bronchopleural fistula and prolonged air leak, respectively. Of the 14 patients, 13 (93%) remained sputum-culture-negative for M. tuberculosis for a median duration of 23 months and one remained continuously sputum smear and culture positive for M. tuberculosis. Conclusion : On the basis of comparison with historical controls, adjunctive resectional surgery appears to play a significant beneficial role in the management of patients with multidrug-resistant pulmonary tuberculosis if the disease is localized and there are adequate reserve in pulmonary function.