• Korean Journal of Clinical Laboratory Science
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• 제47권3호
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• pp.140-146
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• 2015

The increase in resistance by pathogenic bacteria to multiple antimicrobial agents has become a significant treat, as the effective antimicrobial agents available for the patients infected by such resistant bacteria are reduced, or even eliminated. Several natural plant extracts have exhibited antibacterial and synergistic activity against various resistant microorganisms. Houttuynia cordata is frequently used by many traditional medicine practicioners for its antimicrobial, antiviral, and anti-inflammatory properties. This study investigated the antibacterial effects of H. cordata extract against clinical multi-resistant bacteria, and compared the two methods used for the antimicrobial susceptibility testing. Thirty isolates of Methicillin-resistant Staphylococcus aureus (MRSA, 10), Vancomycin-resistant Enterococcus faecium (VRE, 10), Carbapenem-resistant Acinetobacter baumannii (CRAB, 10) were included in this study. The antibacterial effect of H. cordata was tested by disk diffusion and microbroth dilution methods as per CLSI guidelines. In disk diffusion, all isolates (30) showed no inhibition to 30,000 ug/mL of H. cordata. But in the microbroth dilution method, $MIC_{90}$ of H. cordata was 4,096 ug/mL, 8,192 ug/mL and 4,096 ug/mL in MRSA, VRE and CRAB, respectively. These results demonstrate that H. cordata exhibits antibacterial activity against MRSA, VRE and CRAB. Moreover, the microbroth dilution method is a more effective method than disk diffusion to evaluate the antibacterial activity of natural products. The Disk diffusion method used to evaluate the antibacterial activity of natural products required new standard guidelines including inoculum concentration of bacteria.

• Biomedical Science Letters
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• 제16권2호
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• pp.75-82
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• 2010

The molecular epidemiological characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolates have demonstrated their genetic diversity and evolution. A total of 137 strains of MRSA clinical isolates was collected from Korean healthcare facility in 2007. The MRSA clinical isolates were analyzed by molecular typings (SCCmec element and agr locus typing), virule nce factor gene detections {(Panton-Valentine leukocidin (PVL), enterotoxin, exfoliative toxin and toxic shock syndrome toxin-1), and amplified fragment length polymorphism (AFLP)}. The MRSA clinical isolates were classified as SCCmec type II-agr type 1 (2 strains), type II-agr type 2 (79 strains), type III-agr type 1 (24 strains), type III-agr type 2 (2 strains), type IV-agr type 1 (27 strains), type IV-agr type 2 (2 strains), and non-typable (1 strain, agr type 3). Based on SCCmec types, SCCmec type II (95.1%) and III (88.5%) indicated higher multidrug resistance rate than SCCmec type IV (10.3%) (P<0.001). The most common enterotoxin genes were seg (83.8%), sei (83.1%), and sec (80.2%). The tst gene was present in 86 out of 137 (62.8%) MRSA isolates. All MRSA isolates were negative for PVL and exfoliative toxin genes. The combinations of toxin genes were observed in particular SCCmec types; 97.6% of SCCmec type II strains carried sec, seg, sei and tst genes, 73.0% of SCCmec type III strains carried sea gene, and 89.7% of SCCmec type IV strains carried sec, seg and sei genes. Each of the SCCmec types of MRSA isolates had distinct AFLP profile. In conclusion, SCCmec type II, agr type 1 and 2 have demonstrated to be the most common types in Korea, and the results indicated that the virulence factors are closely associated with their molecular types (SCCmec and agr types).

• Journal of Veterinary Science
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• 제23권6호
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• pp.12.01-12.10
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• 2022

Background: Staphylococcus aureus and Streptococcus agalactiae are the main cause of clinical mastitis in dairy cattle in Argentina, whereas coagulase-negative staphylococci (CNS) and environmental streptococci are the main cause of subclinical mastitis. Bacteria isolated from infected animals show increasing antimicrobial resistance. Objectives: This study aims to determine the antimicrobial resistance of staphylococci and streptococci isolated from milk with mastitis, and to genotypically characterize the methicillin-resistant (MR) staphylococci. Methods: Isolation was performed on blood agar and identification was based on biochemical reactions. Antimicrobial susceptibility was according to the Clinical and Laboratory Standards Institute guidelines. The antimicrobial resistance genes, SCCmec type and spa type were detected by the polymerase chain reaction method. Results: We isolated a total of 185 staphylococci and 28 streptococci from 148 milk samples. Among the staphylococcal isolates, 154 were identified as CNS and 31 as S. aureus. Among the 154 CNS, 24.6% (n = 38) were resistant to penicillin, 14.9% (n = 23) to erythromycin, 17.5% (n = 27) to clindamycin, 6.5% (n = 10) to cefoxitin and oxacillin. Among the S. aureus isolates, 16.1% (n = 5) were resistant to penicillin, 3.2% (n = 1) to cefoxitin and oxacillin (MRSA). Six MR isolates (5 CNS and 1 MRSA) were positive to the mecA gene, and presented the SCCmec IVa. The MRSA strain presented the sequence type 83 and the spa type 002. Among the 28 streptococcal isolates, 14.3% (n = 4) were resistant to penicillin, 10.7% (n = 3) to erythromycin and 14.3% (n = 4) to clindamycin. Conclusions: The present findings of this study indicate a development of antimicrobial resistance in main bacteria isolated from cows with mastitis in Argentina.

• Journal of Microbiology and Biotechnology
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• 제8권2호
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• pp.111-118
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• 1998

A bacterium producing unique antistaphylococcal substance (ASS) was isolated from soil samples. The isolated strain KUH-001 was identified to belong to Pseudomonas species from the characteristic properties of its fluorescence and cellular 3-hydroxy fatty acid composition, etc. The ASS component was purified by procedures employing activated carbon adsorption, column chromatography with silica gel, preparative TLC and HPLC. This compound could also be purified mainly by repeating of trituration and precipitation with chilled ether. Purified ASS with a m.p. value of $140~142^{\circ}C$ showed marked stability at high temperature (at $121^{\circ}C$ for 10 min) and extreme pHs (in 1N HC1 and 1N NaOH for 1 day) without significant loss of antibiotic activity. From spectral data of UV, IR, NMR, and FAB-MS, the compound was elucidated as 2-heptyl-4-hydroxyquinoline N-oxide (HHQO). Under the conditions employed, HHQO exhibited a narrow antimicrobial spectrum. active particularly against Staphylococcus aureus including the methicillin resistant strain. Moreover, it did not induce resistance, and besides, interacted synergistically with certain antibiotics such as vancomycin or erythromycin.

• Journal of Korean Academy of Nursing
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• 제43권2호
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• pp.287-295
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• 2013

Purpose: The purpose of this study was to identify vancomycin-resistant enterococcus (VRE) colonization rate in patients admitted to the intensive care unit (ICU), associated risk factors and clinical outcomes for VRE colonization. Methods: Of the 7,703 patients admitted to the ICUs between January, 2008 and December, 2010, medical records of 554 VRE colonized and 503 uncolonized patients were reviewed retrospectively. To analyzed the impact of colonization on patients' clinical outcomes, 199 VRE colonized patients were matched with 199 uncolonized patients using a propensity score matching method. Results: During the study period, 567 (7.2%) of the 7,703 patients were colonized with VRE. Multivariate analysis identified the following independent risk factors for VRE colonization: use of antibiotics (odds ratio [OR]=3.33), having bedsores (OR=2.92), having invasive devices (OR=2.29), methicillin-resistant Staphylococcus aureus co-colonization (OR=1.84), and previous hospitalization (OR=1.74). VRE colonized patients were more likely to have infectious diseases than uncolonized patients. VRE colonization was associated with prolonged hospitalization and higher mortality. Conclusion: Strict infection control program including preemptive isolation for high-risk group may be helpful. Further research needs to be done to investigate the effects of active surveillance program on the incidence of colonization or infection with VRE in the ICU.

• Journal of Korean Academy of Fundamentals of Nursing
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• 제22권3호
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• pp.268-276
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• 2015

Purpose: The purpose of this study was to identify factors which influence the management of MultiDrug -Resistant Organisms (MDROs) by nurses in Intensive Care Units (ICUs). Methods: Data were collected from December 8 to 20, 2013 and participants were 163 ICU nurses working in one general hospital. The Health Belief Model tool and knowledge and management of MDROs infection tools were used in the study. Descriptive statistics, t-test, analysis of variances, Pearson correlation coefficients and multiple regression were used to analyze the data. Results: Knowledge, perceived susceptibility, and perceived benefits had a significant influence on MRSA (Methicillin Resistant Staphylococcus Aureus,) and MDRAB (Multidrug Resistant Acinetobacter Baumannii) infection management when all the other variables were considered. Significant variable which had influence on VRE (Vancomycin Resistant Eenterococci) infection management were perceived susceptibility and perceived benefits. Conclusion: Perceived susceptibility and perceived benefits had significant influence on MDROs infection management. Emphasis needs to be on the perceived susceptibility and perceived benefits of MDROs infection management when providing an educational program for ICU nurses.

• Korean Journal of Veterinary Research
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• 제23권2호
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• pp.205-209
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• 1983

Some investigations on chronic mastitis in dairy cattle in Kyungnam Province during the year 1982 were conducted with the special reference to the causative agents and their drug resistance. Milk samples from 46 isolated cases of chronic mastitis cattle were investigated bacteriologically and the organisms recovered were examined for their drug susceptibility against the major antibiotics used in this country by the use of disk diffusion susceptibility test. Four major causative agents involved in chronic mastitis were in order of prevalence Staphylococcus aureus (32.6%), Escherichia coli (28.3%), Streptococcus agalactiae (8.7%) and Candida albicans (8.7%). Staph. epidermidis, Streptococcus uberis, Klebsiella pneumoniae and Candida subtropicalis were found to be one of the minor agents. The majority of staphylococcal isolates were highly resistant to the most of antibiotics employed while 8% of them were resistant to gentamicin and 32% to chloramphenicol. The percentages of staphylococcal cultures resistant to penicillin, lincomycin. streptomycin, methicillin, oleandomycin, tetracycline, cephalothin, ampicillin and erythromycin were 100%, 96%, 96%, 92%, 84%, 84%, 80%, 76%, and 64% respectively. Streptococcal isolates were also highly resistant to the majority of the drugs used although 85.7% of them were susceptible to gentamicin. All Escherichia coli isolates were found to be resistant to erythromycin, lincomycin and penicillin while the majority of them were resistant to ampicillin (92.9%), carbenicillin (85.7%), oleandomycin (85.7%), streptomycin(85.7%), kanamycin (78.6%), methicillin (78.6%) and tetracycline (71.4%). The percentages of E. coli cultures resistant to gentamicin, nitrofurantoin, cephalothin and chloramphenicol were 21.4%, 21.4%, 35.7% and 50.0% respectively.

• Journal of Microbiology
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• 제45권5호
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• pp.447-452
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• 2007

In this study, we compared the phenotypic and genotypic characteristics of 138 MRSA isolates obtained from adult and pediatric patients (adult, 50; children, 88). The resistance rates against gentamicin, clindamycin, and ciprofloxacin were much higher in the adult MRSA isolates than in the pediatric MRSA isolates. The ermC gene, which is responsible for inducible clindamycin resistance, was detected in 52(59.1%) of the 88 pediatric MRSA isolates but in only 5(10.0%) of the 50 adult MRSA isolates. MRSA isolates of clonal type ST5 with an integration of SCCmec type II/II variants was the most predominant clone among the adult isolates, while clonal type ST72 with an integration of SCCmec IV/IVA was the most predominant clone among the pediatric MRSA isolates. Staphylococcal enterotoxin A and toxic shock syndrome toxin-1 were prevalent among the adult MRSA isolates but not among the pediatric MRSA isolates. The results of this study demonstrated remarkable differences between adult and pediatric MRSA isolates in terms of their antimicrobial susceptibility profiles, SCCmec type, multilocus sequence type, staphylococcal toxin genes, and erythromycin resistance genes.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1265-1270
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• 2009

The objectives of this study were to determine the antibiotypes, SCCmec subtypes, PVL carriage, and genetic diversity of MRSA strains from a tertiary hospital. Sixty-six MRSA strains were selected randomly (2003, 2004, and 2007) and tested for the Panton-Valentine leukocidin gene, mecA gene, and SCCmec type via a PCR. The antibiograms were determined using a standard disc diffusion method, and the genetic diversity of the isolates was determined by PFGE. Thirty-four antibiograms were obtained, with 55% of the 66 strains exhibiting resistance to more than 4 antimicrobials. All the isolates remained susceptible to vancomycin, and low resistance rates were noted for fusidic acid (11%), rifampicin (11%), and clindamycin acid (19%). The MRSA isolates that were multisensitive (n=12) were SCCmec type IV, whereas the rest (multiresistant) were SCCmec type III. Only two isolates (SCCmec type IV) tested positive for PVL, whereas all the isolates were mecA-positive. The PFGE was very discriminative and subtyped the 66 isolates into 55 pulsotypes (F=0.31-1.0). The multisensitive isolates were distinctly different from the multidrug-resistant MRSA. In conclusion, no vancomycin-resistant isolate was observed. The Malaysian MDR MRSA isolates were mostly SCCmec type III and negative for PVL. These strains were genetically distinct from the SCCmec type IV strains, which were sensitive to SXT, tetracycline, and erythromycin. Only two strains were SCCmec IV and PVL-positive. The infections in the hospital concerned were probably caused by multiple subtypes of MRSA.

• The Journal of the Korean Society for Microbiology
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• 제22권3호
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• pp.283-294
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• 1987

One hundred and fifty-seven strains of staphylococci isolated from various clinical specimens and 80 of Gram-negative bacilli from urine of patients with urological diseases were tested for resistance to antimicrobial drugs by microdilution broth method. Among staphylococci, 50 to 89% of the strains were resistant to gentamicin(Gm), kanamycin(Km), erythromycin(Em), nalidixic acid(Na), and tetracycline. Ninety per cent MIC was lowest in ciprofloxacin(Cp), followed by vancomycin(Vc), trimethoprim(Tp), enoxacin(Ex), and norfloxacin(Nf) with the values of two ${\mu}g/ml$ or lower. Twenty-seven strains were resistant to methicillin(MR), with 24 strains of Staphylococcus aureus and 3 of S. epidermidis. All strains of MR S. aureus were resistant to oxacillin, rifampin(Rf), Gm, Km, Em, Na, and Tc, and no strain was resistant to Vc and Tp. Almost all staphylococci isolated from urine were S. epidermidis and sensitive to most drugs tested without MR strain. Among Gram-negative bacilli from urine, Escherichia coli(43 strains) was most frequently isolated, and followed by Klebsiella spp.(11), Proteus spp.(10), Serratia spp.(10), and Pseudomonas aeruginosa(6) in the decreasing order. The majority of E. coli and Serratia spp. were resistant to chloramphenicol(Cm), Tc, streptomycin, sulfisomidine(Su), ampicillin(Ap), Km, and carbenicillin(Cb), and 50 and 90% MICs of these drugs were also high. In Klebsiella spp., 54% or more were resistant to Cm, Su, Ap, cephalothin, and Cb. Proteus spp. were susceptible to most drugs tested, but Pseudomonas were resistant to nearly all drugs tested except Rf, amikacin, and moxalactam(Mx). All Gram-negative bacilli tested were found to be susceptible to Mx. New quinolone carboxylic acid compounds, such as Nf, Ex, and Cp showed very high antimicrobial activities against the majority of organisms tested except Pseudomonas, and 50 and 90% MICs of Nf and Ex were always equal or 2 to 4 times higher than Cp. Organisms multiply resistant to drugs were noted in almost all isolates tested. Twenty-seven strains of staphylococci were multiply resistant to 11 or more drugs, and 6 of Klebsiella spp. to 8 to 11 drugs. The most frequent multiplicity of durg resistance were 7 and 8, 12, and 13 in E. coli, Serratia spp., and Pseudomonas, respectively. No strain was resistant to more than 5 drugs in Proteus spp..