• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1059-1064
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• 2014

Staphylococcus aureus is a major human pathogen, implicated in both community and hospital acquired infections. The therapy for methicillin-resistant Staphylococcus aureus (MRSA) infections is becoming more difficult because of multidrug resistance and strong biofilm-forming properties. Schiff bases have attracted attention as promising antibacterial agents. In this study, we investigated the in vitro activity of taurine-5-bromosalicylaldehyde Schiff base (TBSSB) against MRSA. The minimum inhibitory concentrations (MIC) and minimum bactericidal concentration (MBC) were determined using a microtiter broth dilution method. TBSSB effectively inhibited planktonic MRSA, with an MIC of $32{\mu}g/ml$. The time-kill curve confirmed that TBSSB exhibited bactericidal activity against MRSA. TBSSB was also found to significantly inhibit MRSA biofilm formation at 24 h, especially at $1{\times}MIC$ and sub-MIC levels. Furthermore, scanning electron microscopy and transmission electron microscopy showed remarkable morphological and ultrastructural changes on the MRSA cell surface, due to exposure to TBSSB. This study indicated that TBSSB may be an effective bactericidal agent against MRSA.

• 한국응용과학기술학회지
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• 제37권6호
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• pp.1635-1645
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• 2020

In this study would like to find extending or increasing the efficacy of the antibiotic substance for the strains with resistance to antibiotics or persister cells by inhibition of the resistance. This study was used different species of 'legal high' plants leaves from Leonotis leonurus, Mitragyna speciosa, and seeds from Ipomoea murucoides with antibiotics which are Amoxicillin, Chloramphenicol, Ciprofloxacin, Kanamycin, Oxacillin, and Vancomycin. Legal highs were extracted with methanol. Minimum inhibitory concentration(MIC) testing for a range of antibiotics with extracts of plant was fulfilled by broth dilution methods. In this essay, it was determined in a microdilution assay utilizing suspended in ISB up to a final concentration of 512㎍/ml in 96 wells microtitre plates, threefold and serial dilutions. After that, the microplates were kept in incubator between 35℃ and 37℃ for overnight. Leonotis leonurus, Mitragyna speciosa, and Ipomoea murucoides of Legal highs (512㎍/ml) investigated small activity to inhibit against pathogens which are susceptible Staphylococcus aureus, resistant Staphylococcus aureus, susceptible Enterococcus faecalis, resistant Escherichia coli.

• Parasites, Hosts and Diseases
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• 제61권1호
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• pp.78-83
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• 2023

The use of an effective antimalarial drug is the cornerstone of malaria control. However, the development and spread of resistant Plasmodium falciparum strains have placed the global eradication of malaria in serious jeopardy. Molecular marker analysis constitutes the hallmark of the monitoring of Plasmodium drug-resistance. This study included 96 P. falciparum PCR-positive samples from southern Somalia. The P. falciparum chloroquine resistance transporter gene had high frequencies of K76T, A220S, Q271E, N326S, and R371I point mutations. The N86Y and Y184F mutant alleles of the P. falciparum multidrug resistance 1 gene were present in 84.7 and 62.4% of the isolates, respectively. No mutation was found in the P. falciparum Kelch-13 gene. This study revealed that chloroquine resistance markers are present at high frequencies, while the parasite remains sensitive to artemisinin (ART). The continuous monitoring of ART-resistant markers and in vitro susceptibility testing are strongly recommended to track resistant strains in real time.

• 대한수의학회지
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• 제51권2호
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• pp.123-128
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• 2011

Salmonella spp. is an important pathogen to both public and swine industry. The aim of this study was to investigate the distribution of Salmonella serovar and antibiotics susceptibility of the isolates from Korean swine producing systems. A total of 63 (5.28%) Salmonella spp. was isolated from 1,194 samples (977 fecal materials and 67 organ samples). The predominant Salmonella (S.) enterica serotype and serovar was group B (69.8%) and S. Typhimurium (47.6%), S. Derby (20.6%) and S. Heidelberg (1.6%). But S. Cholerasuis which is characterized host specific by septicemia and enteritis to pigs was not isolated. Antimicrobial susceptibility of the isolates varies as follows: Norfloxacine (75%), Ciprofloxacin (67.5%), Amikacin (60%), Colistin (60%), Enrofloxacin (55%). All of isolates were resistant to Erythromycin, Penicillin, Tetracycline and Lincomycin. The results of this study provided useful information regarding antimicrobial susceptibility and resistance patterns to treat salmonellosis and to prevent emergence of multidrug resistance Salmonella.

• 한국축산식품학회지
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• 제42권2호
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• pp.252-265
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• 2022

Kocuria salsicia can survive in extreme environments and cause infections, including catheter-related bacteremia, in humans. Here, we investigated and evaluated the characteristics of nine K. salsicia strains (KS1-KS9) isolated from cheese brine from a farmstead cheese-manufacturing plant in Korea from June to December, 2020. Staphylococcus aureus American Type Culture Collection (ATCC) 29213 was used as a positive control in the growth curve analysis and biofilm-formation assays. All K. salsicia isolates showed growth at 15% salt concentration and temperatures of 15℃, 25℃, 30℃, 37℃, and 42℃. KS6 and KS8 showed growth at 5℃, suggesting that they are potential psychrotrophs. In the biofilm-formation analysis via crystal violet staining, KS6 exhibited the highest biofilm-forming ability at various temperatures and media [phosphate buffered saline, nutrient broth (NB), and NB containing 15% sodium chloride]. At 25℃ and 30℃, KS3, KS6, and KS8 showed higher biofilm-forming ability than S. aureus ATCC 29213. The antimicrobial resistance of the isolates was evaluated using the VITEK^® 2 system; most isolates were resistant to marbofloxacin and nitrofurantoin (both 9/9, 100%), followed by enrofloxacin (7/9, 77.8%). Five of the nine isolates (5/9, 55.6%) showed multidrug resistance. Our study reports the abilities of K. salsicia to grow in the presence of high salt concentrations and at relatively low temperatures, along with its multidrug resistance and tendency to form biofilms.

• Archives of Plastic Surgery
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• 제34권6호
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• pp.691-696
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• 2007

Purpose: The emergency of multi-drug resistant stains of bacteria represents a challenge in the field of plastic surgery. Especially, MRSA(methycillin-resistant Staphylococcus aureus) and Pseudomonas aeruginosa have strong pathogenicity as well as multi-drug resistance so that they have become a lot more problematic strains. This study has been planned to reduce the bacterial burden by applying $Acticoat^{(R)}$(Smith & Nephew Healthcare, Hull, England)dressing into the chronic wounds infected by multi-drug resistant strains and to facilitate their healing. Methods: Nanocrystalline silver dressings($Acticoat^{(R)}$) were applied to chronic wound infected by MRSA or Pseudomonas aeruginosa. Multi-drug resistant bacteria were smeared over a slide glass using sterilized cotton swabs and gram stains were performed directly before and after applying $Acticoat^{(R)}$ dressings at 1, 24, 48 and 72 hours. The gram-stained slides were observed using an optical microscope magnified 1000 times(${\times}1000$). The bacterial counts of the control group(0 hour) were compared to those of the experimental groups(1, 24, 48, and 72 hour). Paired T-test was used to assess a statistical significance. MRSA was cultured in two BAPs(blood agar plate) and two MacConkey plates with streak plate method. None were interventions on one culture plate, while on the other culture plate, $Acticoat^{(R)}$ was placed in a square shape and cultured for 72 hours at $37^{\circ}C$, then plates were examined. Pseudomonas aeruginosa was cultured in the same manner as MRSA. Results: There are the large amount of declination of bacterial counts with statistical significance after $Acticoat^{(R)}$ dressing. The bacteria grew in culture plate without specific intervention, but no bacteria grew in culture plate with applying of $Acticoat^{(R)}$ dressing. Conclusion: We believe that $Acticoat^{(R)}$ dressing could be used as an effective method of treating chronic wounds which are infected by multi-drug resistant organisms.

• 대한의생명과학회지
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• 제20권2호
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• pp.77-84
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• 2014

Periodic analysis of local epidemiologic data of prevalent pathogens of blood culture can provide clinicians with relevant information to guide empirical antibiotic therapy. In this study, we analyzed a pattern of change of causative microorganisms and antimicrobial resistance at a tertiary medical center in Chungcheong province from 2003 to 2012, retrospectively. Of 70,258 blood specimens cultured, 6,063 (8.6%) were positive. Among the positive isolates, 95.9% were aerobic or facultative anaerobic bacteria, 0.1% were anaerobes, and 3.9% were fungi. Coagulase-negative Staphylococci (CoNS) (32.9%), Escherichia coli (16.7%), Staphylococcus aureus (9.1%), Klebsiella pneumoniae (6.4%), and ${\alpha}$-hemolytic Streptococcus (5.9%) were commonly isolated bacteria, and Candida albicans (1.4%) was the most commonly isolated fungi. Enterococcus faecium progressively increased but Streptococcus pneumoniae, Acinetobacter baumannii and Proteus species gradually decreased over a period of 10 years. The multidrug-resistant microorganisms such as methicillin-resistant S. aureus (MRSA), vancomycin-resistant enterococci (VRE), cefotaxime-resistant E. coli, imipenem-resistant Pseudomonas aeruginosa (IRPA) and imipenem-resistant A. baumannii (IRAB), were significantly increased. Therefore, there is a need for a more strict control of antibiotics and a more updated guideline for the treatment of bloodstream infection.

• Archives of Pharmacal Research
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• 제28권7호
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• pp.823-828
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• 2005

Multidrug resistance (MDR) is one of the most significant obstacles in cancer chemotherapy. One of the mechanisms involved in the development of MDR is the over-expression of P-glycoprotein (P-gp). It is widely known that natural compounds found in vegetables, fruits, plant-derived beverages and herbal dietary supplements not only have anticancer properties, but may also modulate P-gp activity. Therefore, the purpose of this investigation was to examine the effects of naturally occurring products on P-gp function in human breast cancer cell lines, MCF-7 (sensitive) and MCF-7/ADR (resistant). The accumulation of daunomycin (DNM), a P-gp substrate, was greater in the sensitive cells compared to the resistant cells, while the efflux of DNM was higher in the resistant cells compared to the sensitive cells over a period of 2h. The $IC_{50}$ value of DNM in the resistant cells was about 22 times higher than that in the sensitive cells, indicating an over-expression of P-gp in the resistant cells, MCF-7/ADR. All of the compounds tested, with the exception of fisetin, significantly decreased the $IC_{50}$ value of DNM. Biochanin A showed the greatest increase in $[^3H]-DNM$ accumulation, increasing by $454.3{\pm}19.5%$ in the resistant cells, whereas verapamil, the positive control, increased the accumulation by $229.4{\pm}17.6%$. Also, the accumulation of $[^3H]-DNM$ was increased substantially by quercetin and silymarin while it was reduced by fisetin. Moreover, biochanin A, silymarin, and naringenin significantly decreased DNM efflux from MCF-7/ADR cells compared with the control. These results suggest that some flavonoids such as biochanin A and silymarin may reverse MDR by inhibiting the P-gp function.

• Tuberculosis and Respiratory Diseases
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• 제69권2호
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• pp.95-102
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• 2010

Background: The increasing rate of drug-resistant tuberculosis (TB) is a threat to the public health and TB control. In Korea, about 75~80% of TB patients are treated in private hospitals and the rate has been continuously increasing since 2000. Methods: On a retrospective basis, we enrolled 170 newly diagnosed with or retreated for multidrug-resistant TB (MDR-TB) in 2004 from 21 private hospitals. We extracted the following demographics and treatment history from patient medical records: initial treatment outcomes, cumulative survival rates, treatment outcomes, and prognostic factors. Results: Of the 170 patients, the majority were male (64.1%), the mean age was 44.5 years old, and mean body-mass-index was $20.2kg/m^2$. None of the patients tested positive for HIV. Eleven (6.5%) were confirmed to have extensively drug-resistant TB (XDR-TB) at treatment initiation. Treatment success rates were not different between XDR-TB (36.4%, 4/11) and non-XDR MDR-TB (51.6%, 82/159). Default rate was high, 21.8% (37/170). Far advanced disease on X-ray was a significant negative predictor of treatment success; advanced disease and low BMI were risk factors for all-cause mortality. Conclusion: In private hospitals in Korea, the proportion of XDR-TB in MDR-TB was comparable to previous data. The treatment success rate of MDR-/XDR-TB remains poor and the failure rate was quite high. Adequate TB control policies should be strengthened to prevent the further development and spread of MDR-/XDR-TB in Korea.

• 약학회지
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• 제49권1호
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• pp.38-43
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• 2005

The occurrence of resistance to chemotherapeutic drugs is a major problem for successful cancer treatment. This resistant phenotype of cancer cell frequently reveals a broad spectrum to structurally and/or functionally unrelated anticancer drugs, termed multidrug resistance (MDR). Overexpression of P-glycoprotein (P-gp), a transmembrane drug efflux pump, is a major mechanism of MDR. Accordingly, considerable effort has been directed towards to development of compounds that inhibit P-gp, reverse the MDR phenotype and sensitize cancer cells to conventional chemotherapy without undesired toxicological effects. In an effort to search for novel MDR reversal agent, we tested the cytotoxicity of paclitaxel, a well-known substrate of P-gp, against P-gp-expressing HCT15 and HCT15/CL02 human colorectal cancer cells in the presence or absence of benzotriazepin analogues, as well as against P-gp-negative A549 human non-small cell lung and SK-OV-3 human ovarian cancer cells in vitro. Among the compounds tested, the agents that have phenyl amide moiety at 3 position remarkably increased the cytotoxicity of paclitaxel against P-gp-expressing cancer cells, but not against P-gp-negative cancer cells. BTZ-15 and BTZ-16 at $4\;{\mu}M$ revealed similar MDR reversal activity to $10\;{\mu}M$ verapamil, a well-known MDR reversal agent.