• YAKHAK HOEJI
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• v.40 no.3
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• pp.343-346
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• 1996

The influence of LB20304a, a new fluoroquinolone antibiotic agent, on microflora of caecum in mice was compared with those of ciprofloxacin and piperacillin after administration of drugs for 5 days. Selective medium (CCFMA) was used for the isolation of Clostridium difficile from the specimens of mouse caecum. The emergence of C. difficile in mouse caecum induced by LB20304a was lower than that by ciprofloxacin or piperacillin at day 1 and day 7 after completing administration of drugs.

• The Journal of the Korean Society for Microbiology
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• v.35 no.5_6
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• pp.337-339
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• 2000

MRSA, erythromycin-resistant S. pyogenes, penicillin non-susceptible pneumococci, PPNG, ESBL-producing E. coli and K. pneumoniae, class C ${\beta}$-lactamase-producing E. coli, fluoroquinolone-resistant E. coli, aminoglycoside-resistant A. baumannii and P. aeruginosa are all prevalent in Korea, which suggest the presence of high levels of antimicrobial selective pressure and nosocomial spread of resistant bacteria. Rapid increase of VRE and emergence of fluoroquinolone-resistant gonococci and VIM-2 metallo-${\beta}$-lactamase-producing P. aeruginosa are recently observed new threats in Korea.

• YAKHAK HOEJI
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• v.31 no.2
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• pp.98-104
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• 1987

The compounds synthesized by authors were evaluated for their antimicrobial activities against. Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris and Pseudomonas aeraginosa New compounds[1, 10] possess striking potency against a wide range of microorganisms, especially the Gram negative aerobes and has spectacular activity against Enterobacteriaces, S. aureus and Ps. aeruginosa. Most of new compounds are very active in vitro against most strains of Enter- bacteriaceae and Gram positive aerobes, but moderately active against Ps. aeruginosa.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.131-133
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• 1999

The bactericidal activities of DW-116, a new fluoroquinolone was estimated by comparing the minimal bactericidal concentrations (MBCs) of it against some Gram-positive and -negative bacterial strains with the minimal inhibitory concentrations (MICs). The MBCs against the test organisms were equal to or two times higher than MICs. The results support that the antibacterial activity of DW-116 is bactericidal.

• Archives of Pharmacal Research
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• v.20 no.4
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• pp.358-362
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• 1997

Metabolite identification and urinary and biliary excretion of the new fluoroquinolone antibacterial agent DW116 [1-(5-fluoro-2-pyridyl)-6-fluoro-7-(4-methyl-1 -piperazinyl)-1, 4-dihydro-4-oxoquinoline-3-carboxylic acid, hydrochloride] after oral administration have been studied in Sprague-Dawley rats. The excretion kinetics were monoexponential. Most of the drug was eliminated via the hepatic and renal routes. Mean renal clearance of DW116 was 73.4 ml/hr/kg and mean biliary clearance was 83.8 ml/hr/kg. The major metabolite excreted in the bile was identified as the glucuronide ester of the parent drug using base-hydrolysis of the conjugate metabolite followed by co-HPLC with standard compound, $^{19}$ F-NMR and LC-MS methods. The glucuronide conjugate was also found in urine. The mean urinary recoveries of free and total (free plus glucuronide ester) DW116 were $28.6{\pm}2.7% $and $36.4{\pm}1.8%$ of the administered dose and the corresponding biliary recoveries were $14.4{\pm} 5.5%$ and $37.0{\pm}7.6%$, respectively.

• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.93-99
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• 2008

Fluoroquinolones have been widely used since the development of nalidixic acid because of the excellent spectrum of activity, superior tissue penetration, and convenient route of administration. Despite such advantages, the usage in children is limited by concerns of toxicity to cartilage, damage to joints in animal studies, and an increase in antibiotic resistance. However, pediatric use has been increasing under certain circumstances with no report of such adverse effects. Further study is required prior to recommendation for general use of fluoroquinolones in children. The careful administration of fluoroquinolones is recommended only in limited circumstances, such as failure of primary antibiotics and lack of alternative antibiotics.

• YAKHAK HOEJI
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• v.55 no.1
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• pp.11-15
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• 2011

Zabofloxacin is a novel broad spectrum fluoroquinolone with excellent anti-pneumococcal activity. We investigated the in vitro activity of zabofloxacin against clinical isolates of gram-positive bacteria and the in vivo activity against systemic infection in mice. Zabofloxacin was very active against gram-positive bacteria except QRSA (Quinolone-resistant S. aureus) and VRE(Vancomycin-resistant Enterococci). Especially, zabofloxacin was extremely potent against clinical isolates of Streptococci. Zabofloxacin was as active as gemifloxacin against systemic infection in mice. In view of its improved antibacterial activities against gram-positive bacteria and good pharmacokinetic profiles in animals, the clinical usefulness of zabofloxacin should be established by further studies.

• Clinical and Experimental Pediatrics
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• v.64 no.9
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• pp.459-467
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• 2021

Mycoplasma pneumoniae (MP) is the most common cause of childhood bacterial pneumonia. Although macrolide is known to be effective as a first-line therapy, the proportion of macrolide resistance in MP pneumonia has strikingly increased during recent 2 decades in East Asia. This is challenging to physicians since they have to decide more often whether to use secondary treatment. Diagnostic methods to detect macrolide-resistance of MP are currently not available in Korean hospitals. Even in the diagnosis of MP infection, both serologic and molecular test have limitation: inability to differentiate current illness from carriage or asymptomatic infection. Combining these 2 diagnostic methods and excluding infection caused by other respiratory pathogens allow a more reliable diagnosis. This effort is even more demanding in recent years to keep children from unnecessary exposure to secondary antibiotics. Although several observational studies have reported that tetracycline and fluoroquinolone, which are considered in the treatment of refractory MP pneumonia, have efficacy of shortening the duration of fever and respiratory symptoms, those findings need to be proven by well-designed prospective studies. The use of tetracycline and fluoroquinolone in children is generally tolerable, as supported by many observational data. However, since concerns about side effects still remain, careful consideration about benefits and risks is needed to decide their use.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.285-287
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• 2016

Background: The efficacy of standard treatment of Helicobacter pylori (H. pylori) is declining because of antibiotic resistance. Clarithromycin resistance is also increasing in many Asian countries. The aim of this study was to determine the antibiotic susceptibility patterns of H. pylori infection and clinical association in Laos. Materials and Methods: A total of 329 Lao dyspeptic patients who underwent gastroscopy at Mahosot Hospital, Vientiane, Laos during December 2010-March 2012 were enrolled in this study. During gastroscopy, 4 biopsies were collected (2 each from the antrum and body) for CLO-test and histopathology. Only the positive CLO-test gastric tissues was stored at $-80^{\circ}C$ in a freezer until DNA was extracted and a GenoType$^{(R)}$HelicoDR test was conducted for detecting mutations in the rrl gene encoding 23S rRNA (clarithromycin resistance) and mutations in gyrA gene (fluoroquinolone resistance). Results: Of the total, 119 Lao patients (36.2%) were infected with H. pylori including 59 males (49.6%) and 60 females (50.4%) with a mean age of 46 years. Clarithromycin and fluoroquinolone resistance of H. pylori infection was demonstrated in 15 (12.6%) and 16 strains (13.4%) respectively. In clarithromycin resistance, the number of patients who had education above primary school and $BMI{\geq}25kg/m^2$ were significantly higher than those who had education below primary school and BMI<$25kg/m^2$ (23.1% vs 7.5%, P-value= 0.036 and 20.5% vs 8%, P-value= 0.048, respectively). In fluoroquinolone resistance, the number of lowland Lao was significantly higher than those of non-lowland (highland and midland) Lao ethnic groups (16.7% vs 0%, P-value= 0.039). Conclusions: H. pylori infections remain common in Laos. Clarithromycin and fluoroquinolone resistance with H. pylori infection are growing problems. Education above primary school and $BMI{\geq}25kg/m^2$ might be predictors for clarithromycin resistance and lowland Lao ethnicity might be predictors for fluoroquinolone resistance with H. pylori infection in Laos.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.3
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• pp.217-224
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• 2021

Fluoroquinolone (FQ) resistant gram-negative pathogens have emerged worldwide, and the recent increase in FQ resistant Escherichia coli is of great concern in Korea. This study investigated FQ resistance determinants and the epidemiological relationship of 56 ciprofloxacin-resistant E. coli isolated from a tertiary hospital in Daejeon, South Korea from June to December 2018. Molecular epidemiology was investigated by multilocus sequence typing (MLST). Polymerase chain reaction (PCR) and sequence analysis were performed to identify chromosomal mutations in the quinolone resistance determining regions (QRDR) of gyrA, gyrB, parC, and parE and to describe the occurrence of the following plasmid-mediated quinolone resistance (PMQR) genes: aac(6)-Ib-cr, qepA, qnrA, qnrB, qnrC, qnrD, and qnrS. MLST analysis showed 12 sequence types (STs) and the most prevalent ST was ST131 (31/56, 55.4%), followed by ST1193 (13/56, 23.2%), and ST405 (3/56, 5.4%). In 56 ciprofloxacin-resistant E. coli isolates, Ser83→Leu and Asp87→Asn in gyrA and Ser80→Ile and Glu84→Val in parC (51.8%, 29/56) were the most frequent amino acid substitutions and aac(6)-Ib-cr (33.9%, 19/56) was the most common PMQR gene. These results of FQ resistance determinants were more frequently observed in ST131 compared with other clones. Continuous monitoring of the epidemiological characteristics of ciprofloxacin-resistant E. coli isolates and further investigation of FQ resistance determinants are necessary.