• BMB Reports
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• v.31 no.3
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• pp.269-273
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• 1998

The objective of this study was to evaluate the reversal of multi drug resistance of human cell lines by specific inhibitors of ${\alpha}-glycosidase$ and mannosidases that had been reported to be involved in N-linked oligosaccharide processing of glycoproteins. N-methyldeoxynojirimycin, I-deoxynojirimycin, and castanospermine, which were known to be potent inhibitors of both ${\alpha}-glycosidase$ I and II, showed no activity against the multidrug resistant phenotype of the cell lines of SNU1DOX, KB-V1, and MCF-7/ADR. In contrast, I-deoxymannojirimycin, an inhibitor of mannosidase I, resulted in a slight reversal for the vinblastine resistance of the KB-V1 cell line, but did not show any activity toward the other cell lines. Parallel experiments with tunicamycin, an inhibitor of N-linked glycosylation, also resulted in no significant changes in multidrug resistant (MDR) phenotype of the cell lines tested in this work. These observations suggest that the unglycosylation of P-glycoprotein associated with the inhibitor treatments might not be correlated with the reversal of multidrug resistance of the cell lines tested in this study.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.2
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• pp.68-74
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• 2011

Pseudomonas aeruginosa is an aerobic, Gram-negative, glucose-nonfermenting bacterium, which has emerged as a serious opportunistic pathogen. Recently, outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. The genes of metallo-${\beta}$-lactamase (MBL), a powerful carbapenemase, are carried as a part of the mobile gene cassettes inserted into integrons playing an important role in rapid dissemination of antibiotic resistance genes among bacterial isolates. In this study, we investigated the prevalence of integron in imipenem resistant P. aeruginosa isolates. A total of 61 consecutive, non-duplicate, and imipenem resistant P. aeruginosa strains were isolated from a university hospital in the Chungcheong province of Korea. We employed repetitive extragenic palindromic sequence-based PCR (rep-PCR) method for the selection of clonally different P. aerusinosa strains. PCR and DNA sequencing were conducted for the detection of integrons. Twenty-one clonally different P. aeruginosa strains were isolated. Only one (P28) of the strains harbored $bla_{VIM-2}$ that was found as gene cassettes in class 1 integrons. Four of 21 carbapenem resistant P. aeruginosa strains harbored class 1 integron containing aminoglycoside resistance determinant. All of the integrons detected in the study contained more than one resistance gene cassette, which can mediate resistance to multiple antibiotics. To prevent further spreading of the multi-drug resistant P. aeruginosa, conseguent monitoring and clinical polices are required.

• Food Science of Animal Resources
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• v.38 no.2
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• pp.391-402
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• 2018

The aim of the present work was to provide information about Enterococcus strains isolated from pre-packaged chicken samples in Ankara (Turkey), focusing on their prevalence, phenotypic and genotypic characteristics, and antibiotic resistance. We report the first study on the occurrence of antibiotic resistant enterococci in pre-packaged chicken samples in Ankara. A total of 97 suspicious enterococcal isolates were identified from 122 chicken samples. All isolates were identified to species level by phenotypic and molecular methods. In the 16S rDNA sequence analysis, Enterococcus faecium (61.85%) and Enterococcus faecalis (38.15%) were found to be the most frequently detected Enterococcus spp. Of the 97 isolates tested for hemolytic activity, 12.37% enterococcal strains were ${\beta}$-hemolytic. ${\beta}$-Hemolysin was most prevalent among E. faecium (58.33%) compared to E. faecalis (41.66%). Disk diffusion method was used for determining of antibiotic resistance. The analysis of the antimicrobial resistance of the 97 Enterococcus isolates revealed that the resistance to kanamycin (98.96%), rifampicin (80.41%) and ampicillin (60.82%) was most frequent. Furthermore, resistance to erythromycin (38.14%) and ciprofloxacin (34.02%) was also observed. The frequencies of resistance to tetracycline (9.27%), penicillin G (8.24%), and chloramphenicol (3.09%), gentamicin (2.06%) and streptomycin (1.03%) were low. None of the isolates was resistant to vancomycin. Multi-drug resistance was found in 97.93% of Enterococcus strains. E. faecium strains showed a more resistant phenotype than E. faecalis strains according to the antibiotic resistance levels. The results of this study indicated that chicken meat is a potential reservoir for the transmission of antibiotic resistance from animals to humans.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.653-659
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• 2016

The purpose of the study is to investigate the correlation between the amount of antimicrobial agent (Defined Daily Dose, DDD) and antimicrobial resistance rate (%). The treatment of infectious diseases is becoming increasingly difficult, due to the increase in the number of multi-drug resistant bacteria, making it a clinically significant problem. Among the various factors, antimicrobial abuse is a major cause of antimicrobial resistance. The study was conducted on inpatients in a secondary university hospital in the central region utilizing the hospital's computerized statistical data and microbiological program of laboratory medicine from January 2010 to December 2014 pertaining to the dose of antimicrobial drugs for Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli strains isolated from blood culture. We analyzed the antimicrobial resistance rate per dose with the Pearson correlation coefficient. A significant (positive?) correlation was detected between the cefepime dose and the resistance of E. coli (P<0.033; r=0.907), while a significant negative correlation was found between the tobramycin dose and the resistance of E.coli. (P<0.028; r=-0.917). The aminoglycoside resistance of A. baumannii showed a significant negative correlation (P<0.048; r=-0.881), and the aminoglycoside resistance of E. coli showed a significant negative correlation as well (P<0.001; r=-0.992). In conclusion, the amount of antimicrobial agent (Defined Daily Dose, DDD) (is partly related to) the bacterial strain and its antimicrobial resistance rate (%).

• Pediatric Infection and Vaccine
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• v.18 no.1
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• pp.23-30
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• 2011

Purpose : Acinetobacter baumannii is an aerobic, gram negative coccobacillus. Due to its pathogenicity and ability to accumulate diverse mechanisms of resistance, the importance of this organism is increasing. Many reports have targeted adults, and studies of pediatric patients are limited. This study aims to investigate the current status of A. baumannii infection in children. Methods : From January 2001 to December 2008, 505 patients hospitalized with A. baumannii infection were enrolled. Admission records for underlying disease, duration of hospitalization, previous antibiotic use, location of admission, presence of ventilator care, and resistance to antibiotics were retrospectively reviewed and analyzed. Results : Hemato-oncological disease and neurological disease were 30.6% and 24.3% of all cases; therefore, these were the most common underlying diseases of patients with A. baumannii infection. Prevalence of A. baumannii infection was 78.1% in patients with previous antibiotic use, which was higher than that of the group not using previous antibiotic. And prevalence of multi-drug resistant and pan-drug resistant A. baumannii infection was 76.4% and 38.3% in patients with ICU care, 76.8% and 38.9% with ventilator care, and these were higher than the others. Rate of resistance to all groups of antibiotics showed a gradual increase to over 50% in 2008. Multi-drug resistant A. baumannii was 63.5% and pan-drug resistant A. baumannii was 48.2% of all cases. Conclusion : Prevalence of A. baumannii infection and resistance to antibacterial agents of A. baumannii is increasing. Adequate use of antibiotics and infection control should be emphasized in pediatric patients.

• Tuberculosis and Respiratory Diseases
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• v.55 no.1
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• pp.41-58
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• 2003

Background : The resurgence of tuberculosis and the widespread emergence of multidrug-resistant M. tuberculosis have emphasized the importance of rapid and accurate diagnostic procedures. Recently, the oligonucleotide chip has proven to be a useful tool in the rapid diagnosis of infectious diseases. The purpose of this study was to rapidly and accurately detect specific mutations in the rpoB, katG and rpsL genes associated with rifampin, isoniazid and streptomycin resistance in M. tuberculosis, respectively, using a single oligonucleotide chip. Method : For detection of drug-resistance, 7 wild-type and 13 mutant-type probes for rifampin, 2 wild-type and 3 mutant-type probes for isoniazid, and 2 wild-type and 2 mutant-type probes for streptomycin were designed and spotted onto glass slides. Fifty-five cultured samples of M. tuberculosis were amplified by PCR, and then underwent hybridization and scanning. Direct sequencing was done to verify the results from the oligonucleotide chip and to analyze the types of mutations. Result : Thirty-five cases out of 40 rifampin-resistant strains(~88%) had mutations in the rpoB gene. One case had a new mutation(D516F, GAC R TTC) and another known mutation together. Twenty cases out of 42 isoniazid-resistant strains(~50%) had mutations in the katG gene, while 7 cases out of 9 streptomycin-resistant strains(~78%) had mutations in the rpsL gene. From these results, the oligonucleotide chip was confirmed to be able to detect the most frequent mutations from the genes associated with rifampin, isoniazid and streptomycin resistance. The results proved that the drug-resistance detection probes were specific. When the results from the oligonucleotide chip and DNA sequencing were compared, the types of mutations were exactly matched. Conclusion : The diagnostic oligonucleotide chip with mutation specific probes for drug resistance is a very reliable and useful tool for the rapid and accurate diagnosis of drug resistance against rifampin, isoniazid and streptomycin in M. tuberculosis infections.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.171-180
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• 2013

This study was carried out to investigate the antimicrobial resistance pattern and distribution of resistance gene in 44 Enterobacteriaceae and 21 Pseudomonas (P) aeruginosa isolated from hospitalized dogs and cats in animal hospital from 2010 to 2011 in Daegu. Among Enterobacteriaceae, Escherichia (E) coli was highly resistant to ampicillin (56.7%), followed by tetracycline (53.3%), cephalothin, streptomycine, sulfamethoxazole/trimethoprim, gentamicin and norfloxacin (40.0~43.3%). The remaining isolates of Enterobacteriaceae had high resistance to ampicillin (64.3%) and streptomycin (42.9%). Whereas, P. aeruginosa was low resistant to all antimicrobials tested (less than 15%). int I 1 gene was detected in 20 (57.1%) of 35 antimicrobial resistant Enterobacteriaceae and 2 (9.5%) of 21 P. aeruginosa., but int I 2 gene was not detected in all isolates. The eight resistance genes were found either alone or combination with other gene (s): $bla_{TEM}$, aadA, strA-strB, clmA, tetA, tetB, sul I and sul II. About 78% of integron-positive isolates were resistance to more than four antimicrobial agents. The findings suggest that class I integrons are widely distributed in E. coli among Enterobacteriaceae from dogs and cats and multi-drug resistance related to the presence of class I integrons. The prudent use of antimicrobials and continuous monitoring for companion animals are required.

• The Korean Journal of Physiology and Pharmacology
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• v.24 no.3
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• pp.233-240
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• 2020

Autophagy regulators are often effective as potential cancer therapeutic agents. Here, we investigated paclitaxel sensitivity in cells with knockout (KO) of ATG5 gene. The ATG5 KO in multidrug resistant v-Ha-ras-transformed NIH 3T3 cells (Ras-NIH 3T3/Mdr) was generated using the CRISPR/Cas9 technology. The qPCR and LC3 immunoblot confirmed knockout of the gene and protein of ATG5, respectively. The ATG5 KO restored the sensitivity of Ras-NIH 3T3/Mdr cells to paclitaxel. Interestingly, ATG5 overexpression restored autophagy function in ATG5 KO cells, but failed to rescue paclitaxel resistance. These results raise the possibility that low level of resistance to paclitaxel in ATG5 KO cells may be related to other roles of ATG5 independent of its function in autophagy. The ATG5 KO significantly induced a G₂/M arrest in cell cycle progression. Additionally, ATG5 KO caused necrosis of a high proportion of cells after paclitaxel treatment. These data suggest that the difference in sensitivity to paclitaxel between ATG5 KO and their parental MDR cells may result from the disparity in the proportions of necrotic cells in both populations. Thus, our results demonstrate that the ATG5 KO in paclitaxel resistant cells leads to a marked G₂/M arrest and sensitizes cells to paclitaxel-induced necrosis.

• Korean Journal of Microbiology
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• v.54 no.1
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• pp.53-59
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• 2018

The objective of this study was to investigate the plasmid profiling of multi-drug resistant (MDR) Vibrio in influent (inflow) and effluent (discharged) water samples of fish farms in Jeju, South Korea. MDR isolates identified through disc diffusion susceptibility tests, were subjected to plasmid profiling. One hundred fifty Vibrio isolates were obtained from each influent and effluent water sample. All MDR isolates were subjected to plasmid profiling. Greater number of bacteria were enumerated from effluents (61%) comparing to influents (39%). High incidence of neomycin, sulfamethoxazole, amoxicillin and oxytetracycline resistance was observed among the isolates, which was higher in effluent samples. In contrast, Vibrio isolates were more susceptible to florfenicol, chloramphenicol, ciprofloxacin, and nalidixic acid. Among 99 (influent 39 and effluent 60) MDR isolates, a total of 58 (influent 38 and effluent 20) were found to bear plasmids ranging from 1.7 kb to >10 kb and showed 19 different antibiograms according to the size of plasmids. MDR isolates showed six and four distinct plasmid profiles in influent and effluent, respectively. Effluent samples contained more plasmid-carrying MDR Vibrio isolates with more diverse plasmid profiles and antibiograms, suggesting that fish farm tanks may serve as a reservoir of antibiotic resistance genes. The presence of plasmid-carrying MDR Vibrio isolates in fish farm effluent water may contribute to the dissemination of antibiotic resistance genes to the environments, which ultimately poses threat to human health.

• Korean Journal of Veterinary Service
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• v.26 no.1
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• pp.39-50
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• 2003

Non-typhoidal Salmonella serovars remain a potential threat to human health and many animals including beef cattle, broiler chickens, and pigs which possible sources of non-typhoidal salmonellosis in human. In this study, the cecal contents of slaughtered pigs were examined for Salmonella serovar prevalence. The characteristics of the isolates, including antimicrobial resistance patterns and virulence genes, were studied along with the reference strain S typhimurium ATCC 13311. Out of 640 sample, 137 Salmonella(21.4%) were isolated and their serovar were identified S typhimurium 83 strains(60.6%), S agona 10 strains(7.3%), S schwarzengrund 4 strains(2.9%), S derby 4 strains(2.9%), S ayinde 1 strains(0.7%), and untypable 35 strains(25.5%). All 83 S typhimurium strains(100%) were multi-drug resistance to at least 7 antibiotics, and 20 strains(24.1%) of 83 isolates were R-type ACSSuT. Examination of virulent gene by PCR revealed that 73 S typimurium field isolates(88%) have a invA gene and 24 strains(28.9%) have a spvC gene. Consequently, S typhimurium infection in slaughtered pigs was relatively to appear high prevalence in their herds which suggested that it should be necessary for herd health monitoring and surveillance.