AIMTo learn the electrophysiological interference of levofloxacin (LVFX) to heart in guinea pig.

METHODSHigh, moderate and low doses of LVFX were given to the anesthetic guinea pig via i.p., and QT interval span and corrected QT-interval span in the II leading lines of ECG were recorded and analyzed from 5 min to 360 min after the drug administration. Single ventricular myocytes were obtained and impacted by LVFX solution of different concentrations. Then delayed rectifier potassium currents (I(K)) on single cells were recorded with whole-cell patch clamp technique, and compared with control group(without impact of LVFX).

RESULTS(1) After the administration of LVFX, at the dose of 200 mg/kg. QT-interval span was significantly elongated, and the increasing rate is 19.38% +/- 3.15% (P < 0.05). While at the relatively lower doses of 50 mg/kg and 100 mg/kg, the elongation is of low/no significance (P > 0.05). (2) LVFX inhibited I(K) dose-dependently and time-dependently.

CONCLUSIONLVFX might prolong the QT-interval span by the mechanism of inhibiting I(K), which implies a potential risk in clinical application.

Animals ; Guinea Pigs ; Levofloxacin ; Membrane Potentials ; Myocytes, Cardiac ; drug effects ; physiology ; Ofloxacin ; pharmacology ; Patch-Clamp Techniques

We determined the antimicrobial susceptibility of 90 clinical isolates of Stenotrophomonas maltophilia collected in 2009 at a tertiary care hospital in Korea. Trimethoprim-sulfamethoxazole, minocycline, and levofloxacin were active against most of the isolates tested. Moxifloxacin and tigecycline were also active and hold promise as therapeutic options for S. maltophilia infections.
Anti-Infective Agents/*pharmacology ; Hospitals ; Korea ; Microbial Sensitivity Tests ; Minocycline/pharmacology ; Ofloxacin/pharmacology ; Stenotrophomonas maltophilia/*drug effects ; Trimethoprim-Sulfamethoxazole Combination/pharmacology

Among 155 clinical respiratory isolates of Haemophilus influenzae in Korea, 6 (3.9%) isolates had reduced levofloxacin susceptibility (MICs > or = 0.5 microg/mL). These six isolates had no significant quinolone resistance-determining region (QRDR) mutations in gyrA, gyrB, parC, or parE. This phenomenon suggests that neither evolution nor spread of any significant QRDRs mutations in clinical isolates occurred in Korea. Therefore, continued surveillance is necessary to observe the evolution of antibiotic-resistance and take measures to avoid the spread of drug-resistant clones.
Anti-Bacterial Agents/*pharmacology ; DNA Gyrase/*genetics ; DNA Topoisomerases, Type II/*genetics ; Haemophilus influenzae/*drug effects/pathogenicity ; Korea ; Microbial Sensitivity Tests ; Mutation ; Ofloxacin/*pharmacology

Among 155 clinical respiratory isolates of Haemophilus influenzae in Korea, 6 (3.9%) isolates had reduced levofloxacin susceptibility (MICs > or = 0.5 microg/mL). These six isolates had no significant quinolone resistance-determining region (QRDR) mutations in gyrA, gyrB, parC, or parE. This phenomenon suggests that neither evolution nor spread of any significant QRDRs mutations in clinical isolates occurred in Korea. Therefore, continued surveillance is necessary to observe the evolution of antibiotic-resistance and take measures to avoid the spread of drug-resistant clones.
Anti-Bacterial Agents/*pharmacology ; DNA Gyrase/*genetics ; DNA Topoisomerases, Type II/*genetics ; Haemophilus influenzae/*drug effects/pathogenicity ; Korea ; Microbial Sensitivity Tests ; Mutation ; Ofloxacin/*pharmacology

OBJECTIVETo induce Mycobacterium tuberculosis (MTB) resistance with ofloxacin (Ofx) of stepwise increasing concentration in vitro, investigate stability to fluoroquinolone (FQs) antibiotic of MTB, and analyze the molecular mechanism and mutation specialty of drug resistance preliminarily.

METHODSMTB Standard strain H37RV and 24 clinical isolates susceptible to Ofx were selected and experimentally serially subcultured in liquid culture medium containing increasing concentration of Ofx and induced the drug resistance to Ofx. Variety of Minimal Inhibitory Concentrations (MICs) to FQs drugs were detected by microwell-MIC-test method. Mutations of quinolone resistance determining region (QRDR) of gyrA gene were sequenced and identified. Relationship of different mutation sites and drug resistant degree were analyzed. A total of 6 MTB clinical isolates resistant to Ofx and induced drug resistant isolates in vitro were serially subcultured in liquid culture medium without drug. Variety of drug resistant stability, including MIC and mutation of gyrA gene were detected.

RESULTSMIC values of 21 Ofx susceptible isolates after induction were eight times higher than before, which were induced to drug resistant strains successfully and also resistant to Lfx and Mfx. Hot mutations of QRDR of gyrA gene were detected by sequencing, except one strain. Mutation of codon 94 occurred in 60% (12/20) of the strains with mutations and corresponding value of 50% Minimal Inhibitory Concentrations(MIC50) was ≥ 8 µg/ml. In all, 4 of 6 MTB clinical isolates resistant to Ofx harbored mutation of codon 90 (67%) , but the corresponding value of MIC50 was 2 µg/ml. After 21 serially subcultured in liquid culture medium without drug, MIC values of 6 clinical isolates resistant to Ofx were not changed obviously and mutations were also not changed. After 11 times serially subcultured in culture medium without drug, MIC values of induced drug resistant strains were also not changed obviously, but new mutations were detected in QRDR of 3 isolates.

CONCLUSIONMTB strains resistant to three kinds of FQs antibiotic were obtained by induction in vitro with Ofx. Codons 88, 94 mutations of QRDR of gyrA gene were related to the high level FQs drug resistance of MTB. Drug resistant stability of MTB to FQs was strong, and it is difficult for MTB to resume susceptibility.

Antitubercular Agents ; pharmacology ; DNA Gyrase ; genetics ; Drug Resistance, Bacterial ; genetics ; Microbial Sensitivity Tests ; Mycobacterium tuberculosis ; drug effects ; genetics ; isolation & purification ; Ofloxacin ; pharmacology

OBJECTIVETo investigate the resistance of Helicobacter pylori (H. pylori) to antimicrobial agents in adolescents.

METHODSOne hundred and eight adolescents (6-18 years old) underwent a gastroscopy examination. H. pylori strains were isolated from gastric mucosa. Antimicrobial susceptibility testing was performed by means of Kirby-Baner.

RESULTSThirty-six H. pylori strains were identified. The resistant rate of H. pylori strains to clarithromycin, fruranzolidone and amoxicillin was 8.3%, 16.7% and 33.3%, respectively. H. pylori strains showed a high resistance to metronidazole (94.4%), while no strain was resistant to gentamicin and levofloxacin.

CONCLUSIONSThe H. pylori strains from the adolescents in Zhejiang showed a high resistance to metronidazole and amoxicillin but a low resistance to clarithromycin and fruranzolidone. All of H. pylori strains were susceptive to gentamicin and levofloxacin.

Adolescent ; Amoxicillin ; pharmacology ; Anti-Infective Agents ; pharmacology ; Child ; Clarithromycin ; pharmacology ; Drug Resistance, Bacterial ; Female ; Gastroscopy ; Helicobacter pylori ; drug effects ; Humans ; Levofloxacin ; Male ; Metronidazole ; pharmacology ; Microbial Sensitivity Tests ; Ofloxacin ; pharmacology

Antitubercular Agents/therapeutic use* ; China/epidemiology* ; Drug Resistance, Multiple, Bacterial ; Extensively Drug-Resistant Tuberculosis ; Humans ; Kanamycin Resistance ; Microbial Sensitivity Tests ; Mycobacterium tuberculosis ; Ofloxacin/pharmacology* ; Tuberculosis, Multidrug-Resistant/epidemiology*

The aim of this study was to determine antimicrobial susceptibility of recent clinical Stenotrophomonas maltophilia isolates from Korea, and to compare the activity levels of several combinations of antimicrobials. A total of 206 non-duplicate clinical isolates of S. maltophilia was collected in 2010 from 11 university hospitals. Antimicrobial susceptibility testing was performed using the Clinical Laboratory Standards Institute agar dilution method. In vitro activity of antimicrobial combinations was tested using the checkerboard method. The susceptibility rates to trimethoprim-sulfamethoxazole and minocycline were 96% and 99%, respectively. The susceptibility rate to levofloxacin was 64%. All of four antimicrobial combinations showed synergy against many S. maltophilia isolates. A combination of trimethoprim-sulfamethoxazole plus ticarcillin-clavulanate was most synergistic among the combinations. None of the combinations showed antagonistic activity. Therefore, some of the combinations may be more useful than individual drugs in the treatment of S. maltophilia infection. Further clinical studies are warranted to validate our in vitro test results.
Anti-Infective Agents/*pharmacology ; Gram-Negative Bacterial Infections/microbiology ; Hospitals, University ; Humans ; Microbial Sensitivity Tests ; Minocycline/pharmacology ; Ofloxacin/pharmacology ; Republic of Korea ; Stenotrophomonas maltophilia/*drug effects/isolation & purification ; Trimethoprim-Sulfamethoxazole Combination/pharmacology

BACKGROUND/AIMS: This study was performed to compare the prevalence rates of primary antibiotic resistance in Helicobacter pylori (H. pylori) isolates among different regions of Korea. METHODS: H. pylori were isolated from gastric mucosal biopsy specimens of 99 Koreans who lived in Gyeonggi (n=40), Kangwon province (n=40) and Busan (n=19) from April to August in 2008. All the patients had no history of H. pylori eradication therapy. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, ciprofloxacin, levofloxacin, and moxifloxacin were tested according to the agar dilution method. RESULTS: There was a difference in resistance to clarithromycin in three institutes located among Gyeonggi (32.5%), Kangwon province (12.5%) and Busan (42.1%) by One way ANOVA test (p=0.027) and nonparametric Kruskal Wallis test (p=0.027). However, by post-hoc analysis, there was no statistically significant difference among three regions. Similarly, the other 7 antibiotics (amoxicillin, metronidazole, tetracycline, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin) did not show any significant difference. CONCLUSIONS: There was no significant regional difference of the primary antibiotic resistance of H. pylori. However, the included patient number might not be enough for this conclusion demanding further evaluations.
Amoxicillin/pharmacology ; Anti-Bacterial Agents/pharmacology/therapeutic use ; Aza Compounds/pharmacology ; Azithromycin/pharmacology ; Ciprofloxacin/pharmacology ; Clarithromycin/pharmacology ; *Drug Resistance, Bacterial ; Female ; Helicobacter Infections/*epidemiology/microbiology ; Helicobacter pylori/*drug effects/isolation & purification ; Humans ; Male ; Metronidazole/pharmacology ; Microbial Sensitivity Tests ; Middle Aged ; Ofloxacin/pharmacology ; Quinolines/pharmacology ; Republic of Korea/epidemiology ; Tetracycline/pharmacology

BACKGROUND/AIMS: This study was performed to compare the prevalence rates of primary antibiotic resistance in Helicobacter pylori (H. pylori) isolates among different regions of Korea. METHODS: H. pylori were isolated from gastric mucosal biopsy specimens of 99 Koreans who lived in Gyeonggi (n=40), Kangwon province (n=40) and Busan (n=19) from April to August in 2008. All the patients had no history of H. pylori eradication therapy. The susceptibilities of the H. pylori isolates to amoxicillin, clarithromycin, metronidazole, tetracycline, azithromycin, ciprofloxacin, levofloxacin, and moxifloxacin were tested according to the agar dilution method. RESULTS: There was a difference in resistance to clarithromycin in three institutes located among Gyeonggi (32.5%), Kangwon province (12.5%) and Busan (42.1%) by One way ANOVA test (p=0.027) and nonparametric Kruskal Wallis test (p=0.027). However, by post-hoc analysis, there was no statistically significant difference among three regions. Similarly, the other 7 antibiotics (amoxicillin, metronidazole, tetracycline, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin) did not show any significant difference. CONCLUSIONS: There was no significant regional difference of the primary antibiotic resistance of H. pylori. However, the included patient number might not be enough for this conclusion demanding further evaluations.
Amoxicillin/pharmacology ; Anti-Bacterial Agents/pharmacology/therapeutic use ; Aza Compounds/pharmacology ; Azithromycin/pharmacology ; Ciprofloxacin/pharmacology ; Clarithromycin/pharmacology ; *Drug Resistance, Bacterial ; Female ; Helicobacter Infections/*epidemiology/microbiology ; Helicobacter pylori/*drug effects/isolation & purification ; Humans ; Male ; Metronidazole/pharmacology ; Microbial Sensitivity Tests ; Middle Aged ; Ofloxacin/pharmacology ; Quinolines/pharmacology ; Republic of Korea/epidemiology ; Tetracycline/pharmacology