• Journal of Pharmaceutical Investigation
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• v.39 no.6
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• pp.431-435
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• 2009

The comparative superior in vitro activity of DW-224a was supported by the downward MIC distribution due to the weakened influence of alterations within target enzymes in ciprofloxacin-resistant Staphylococcus aureus. The MI$C_{50}$ for DW-224a was 4 $\mu$g/mL, similar to that of gemifloxacin, 8-fold less than that of sparfloxacin and 16-over-fold less than that of ciprofloxacin. We constructed combinations of amino acid changes, located at codon 80, 83 or 84 within GrlA and 84, 85 or 88 within GyrA, which were associated with MIC increase. The amino acid changes were less influential to the MIC of DW-224a compared to those of other fluoroquinolones, and it was verified from the requirement of a total of two GrlA- and two GyrA-alterations to reach the MIC of DW-224a over 32 $\mu$g/mL.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.6
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• pp.440-445
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• 2008

Ciprofloxacin is the most commonly used fluoroquinolones for treating bacterial disease in olive flounder (Paralichthys olivaceus) farming, but its withdrawal time for industrial-scale farming has not been established. The depletion of ciprofloxacin was investigated in the olive flounder under field conditions. Fish were kept in an inland fish farm and fed a commercial diet containing 5 mg/kg of ciprofloxacin for 13 days. Seven fishes per sampling time were examined during and after the treatment. Ciprofloxacin and its major metabolite, enrofloxacin, were analyzed using HPLC with a fluorescence detector. The concentrations of ciprofloxacin and enrofloxacin in muscle increased during the medication period, and then decreased rapidly. The ciprofloxacin and enrofloxacin concentration in the olive flounder peaked on days 11 and 13, respectively, with maximum concentrations in muscle of 0.58 and 0.73 mg/kg. Residual ciprofloxacin and enrofloxacin were eliminated rapidly; 6 days after treatment, the respective levels in muscle were 0.04 and 0.10 mg/kg and neither was detected 15 days post treatment. The level of ciprofloxacin accumulation at the beginning of oral administration was variable according to the farming conditions, but the overall exhaustion time was similar. In conclusion, an adequate withdrawal period for enrofloxacin is 15 days in the case of oral ciprofloxacin administration.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3275-3279
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• 2014

A mass balance method for purity assessment of thermolabile organic reference materials was established by combining several techniques, including liquid chromatography with UV/VIS detector (LC-UV), Karl-Fischer (K-F) Coulometry, and thermal gravimetric analysis (TGA). This method was applied to three fluoroquinolones like enrofloxacin, norfloxacin and ciprofloxacin. LC-UV was used to analyze structurally related organic impurities based on UV/VIS absorbance spectra obtained in combination with LC separation. For all three organic reference materials, the UV/VIS spectra of the separated impurities were similar to that of the major component of the corresponding materials. This indicates that the impurities are structurally related to the respective reference material sharing common chromophores. Impurities could be quantified by comparing their absorbances at the wavelength of maximum absorbance (${\lambda}_{max}$). The water contents of the reference materials were measured by K-F Coulometry by an oven-drying method. The total inorganic impurities contents were assayed from ash residues in TGA analysis with using air as a reagent gas. The final purities estimated from results of those analytical techniques were assigned as ($99.91{\pm}0.06$), ($97.09{\pm}0.17$) and ($91.85{\pm}0.17$)% (kg/kg) for enrofloxacin, norfloxacin and ciprofloxacin, respectively. The assigned final purities would be applied to the reference materials which will be used as calibrators for the certification of those compounds in matrix CRMs as starting points for the traceability of their certified values to SI units.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.2
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• pp.72-77
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• 2006

Enrofloxacin (ENRO) is one of the most commonly used fluoroquinolones for treating bacterial disease in olive flounder (Paralichthys olivaceus) farming, but its withdrawal time for industrial-scale farming has not been well established. Withdrawal times of ENRO following oral administration were evaluated in olive flounder under field conditions. Fish were held in an inland fish tank and fed a commercial mediated diet containing 5 mg/kg of ENRO for 9 days. Seven fish per sampling point were examined during and after treatment. ENRO and its major metabolite, ciprofloxacin (CIP), were analyzed using high-performance liquid chromatography with a fluorescence detector. The concentration of ENRO and CIP in muscle increased during the medication period, and then decreased rapidly The sum of ENRO and CIP concentration in olive flounder peaked on day 6, with a maximal concentration in muscle of 4.30 mg/kg. ENRO residues were eliminated rapidly; at 10 days post treatment, the level in muscle was 0.10 mg/kg, but it took about 50 days to be reduced to below 0.1 mg/kg. After 60 days, the residual concentration was below 0.1 mg/kg in all samples. The level of ENRO accumulation at the beginning of oral administration was variable, according to the farming conditions, but the overall exhaustion time was almost the same. We concluded that an adequate withdrawal period of enrofloxacin is 60 days in the case of oral administration.

• Journal of Microbiology and Biotechnology
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• v.22 no.4
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• pp.567-570
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• 2012

In vitro activities of 13 antibiotics were assessed against 85 Brucella abortus isolates from naturally infected cattle in the Republic of Korea during 1998-2006, using broth microdilution test. Tetracyclines showed the most excellent activity against B. abortus, displaying MIC values of 0.5 ${\mu}g/ml$ or below. In particular, minocycline showed the lowest $MIC_{50/90}$ values (0.125/0.125 ${\mu}g/ml$) in this study. Among four fluoroquinolones tested, ciprofloxacin ($MIC_{50/90}$, 0.5/1 ${\mu}g/ml$) and norfloxacin ($MIC_{50/90}$, 8/8 ${\mu}g/ml$) had the most and the least activities, respectively. Gentamicin ($MIC_{50/90}$, 1/1 ${\mu}g/ml$) was more effective than streptomycin, erythromycin, rifampin, and chloramphenicol ($MIC_{50/90}$, 2/2 ${\mu}g/ml$).

• Korean Journal of Veterinary Research
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• v.60 no.3
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• pp.173-177
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• 2020

Edible offal is easily contaminated by Escherichia coli (E. coli) and fluoroquinolone (FQ)-resistant E. coli is considered a serious public health problem, thus, this study investigated the genetic characteristics of FQ-resistant E. coli from edible offal. A total of 22 FQ-resistant E. coli isolates were tested. A double mutation in each gyrA and parC led the highest MIC. Four (18.2%) isolates carried plasmid-mediated quinolone resistance genes. The fimH, eaeA, escV, astA, and iucC genes were confirmed. Seventeen isolates (77.3%) were positive for plasmid replicons. The isolates showed high genetic heterogeneity based on pulsed-field gel electrophoresis patterns.

• Bulletin of the Korean Chemical Society
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• v.25 no.3
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• pp.365-372
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• 2004

Two simple, rapid and sensitive spectrophotometric methods for the determination of three fluoroquinolones, namely levofloxacin, norfloxacin and ciprofloxacin have been performed either in pure form or in their tablets. In the first method, levofloxacin and norfloxacin are directly treated with bromocresol green (BCG) in dichloromethane while ciprofloxacin is allowed to react with the same dye in aqueous acidic buffer. Highly yellow colored complex species were formed instantaneously in case of levofloxacin and norfloxacin or after extraction into dichloromethane for ciprofloxacin. The formed complexes are quantified spectrophotometrically at their absorption maxima at 411 nm for levofloxacin and 412 nm for norfloxacin and ciprofloxacin. The second method involves the reaction of levofloxacin with ${\rho}$-chloranilic acid ( ${\rho}$-CA) and norfloxacin with tetracyanoethylene (TCNE) in acetonitrile to give complexes with maximum absorbance at 521 and 333 nm for the two drugs, respectively. Adopting the first procedure, calibration graphs were linear over the range 1- 20 ${\mu}g\;mL^{-1}$ with mean percentage recoveries of 100.41 ${\pm}$ 0.72, 99.99 ${\pm}$ 0.54 and 100.23 ${\pm}$ 0.91 for the theree drugs, respectively. For the second procedure, the concentration ranges were 15-250 ${\mu}g\;mL^{-1}$ for levofloxacin using ${\rho}$-CA and 0.8-16 ${\mu}g\;mL^{-1}$ for norfloxacin using TCNE with mean percentage recoveries of 99.88 ${\pm}$ 0.45 and 100.26 ${\pm}$ 0.68 for the two drugs, respectively. The proposed methods were successfully applied to determine these drugs in their tablet formulations and the results compared favorably to that of reference methods. The proposed methods are recommended for quality control and routine analysis.

• Journal of Microbiology and Biotechnology
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• v.18 no.11
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• pp.1853-1857
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• 2008

Salmonella contamination in chicken meat was studied with 100 chicken meat samples purchased from 55 shops located in various regions. A total of 21 isolates of Salmonella enterica were isolated from 21 chicken meat samples from four shops located at open markets, whereas there were none from supermarkets with well-equipped cold systems. Among these, 18 isolates were identified as Salmonella enterica serotype Haardt (S. Haardt) and three isolates were S. enterica serotype Muenchen. When the minimal inhibitory concentrations of the S. Haardt isolates were assayed with the agar dilution method to determine susceptibility to ampicillin, chloramphenicol, sulfisoxazole, tetracycline, and nalidixic acid, all 18 isolates were resistant to tetracycline and nalidixic acid and nine of these were resistant to ampicillin. These isolates showed reduced susceptibility to eight fluoroquinolones including ciprofloxacin, enrofloxacin, levofloxacin, gatifloxacin, gemifloxacin, moxifloxacin, norfloxacin, and ofloxacin. When quinolone resistance determining regions of gyrA and gyrB were sequenced, every isolate had the same missense mutation Ser83$\rightarrow$Tyr (TCC$\rightarrow$+TAC) in gyrA, whereas no mutation was found in gyrB. Pulsed-field gel electrophoresis with XbaI revealed a close relationship among these isolates, suggesting a contamination of raw chicken meat with clonal spread of nalidixic acid-resistant and quinolone-reduced susceptibility S. Haardt in chickens. Results in this study show the importance of a well-equipped cold system and the prudent use of fluoroquinolone in chickens to prevent the occurrence of quinolone-resistant isolates.

• Tuberculosis and Respiratory Diseases
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• v.69 no.6
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• pp.474-479
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• 2010

Torsades de pointes associated with a prolonged QT interval is a life-threatening arrhythmia, which may be induced by any of the following: drugs, electrolyte imbalances, severe bradycardia and intracranial hemorrhage. Torsades de pointes is characterized by beat-to-beat variations in the QRS complexes in any ECG leads with rates of 200~250 per minute. Fluoroquinolones are widely used and well tolerated antibacterial agents. However, prolongation of the QT interval leads rarely to Torsades de pointes as a significant adverse effect. So, it should be used with caution in high-risk patients for developing Torsades de pointes. We report one case of 67-year old man with contact burns who experienced Torsades de pointes, which probably resulted from the use of levofloxacin, and no further episode occurred after its withdrawal.

• Korean Journal of Clinical Pharmacy
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• v.20 no.1
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• pp.78-84
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• 2010

Background: Clostridium difficile is the primary reason of the nosocomial diarrhea. The antimicrobial therapy plays a central role in the pathogenesis of Clostridium difficile associated diarrhea (CDAD). Although nearly all classes of antimicrobial agents have been associated with CDAD, clindamycin and the third-generation cephalosporins have traditionally been considered to the greatest risk factor. Recent studies have also implicated fluoroquinolones as high-risk agents due to increasing use of the agents. This study was to determine the incidence and the risk factors of CDAD related to the administered antibiotics and to assess the therapeutic regimen of metronidazole or vancomycin based on the C. difficile toxin assay Methods: A retrospective study was performed in patients with Clostridium difficile toxin assay at I Hospital (Incheon, South Korea) during the period from January 2007 through December 2007. Administrative, laboratory, and pharmacy data were collected from Electronic Medical Databases. Results: The analysis included 129 reported C.difficile toxin assay results, with 42 positive cases and 87 negative cases. Significant antibiotic risk factors for CDAD included the use of the fourth-generation cephalosporinse (OR=5.97, 95% CI 1.37-25.98, P=0.017). Administration of metronidazole was protective against CDAD (OR=0.30, 95% CI 0.12-0.74, P=0.009). Prolonged antimicrobial therapy has been associated with an increased risk of CDAD. The third-generation cephalosporins (OR=3.81, 95% CI 1.08-13.41, P=0.037) and aminoglycoside (OR=5.50, 95% CI 1.43-21.10, P=0.013) demonstrated greater risk for CDAD over 15 days than 8days or less days of treatment duration. Conclusions: The fourth and third generation cephalosporin, aminglycoside were the significant risk factors compared with other antibiotics, whereas metronidazole appears to be protective. The longer duration of antiobiotic use increased CDAD.