• Journal of Microbiology and Biotechnology
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• v.20 no.6
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• pp.1042-1052
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• 2010

Forty-seven Salmonella Typhimurium (33 zoonotic, 14 clinical) strains were tested for antimicrobial resistance using the standard disk diffusion method. The presence of relevant resistance genes and class 1 integrons were investigated by using PCR. Pulsed-field gel electrophoresis (PFGE) and plasmid profiling were carried out to determine the genomic diversity of Salmonella Typhimurium. Approximately 57.4% of the S. Typhimurium strains were multidrug resistant (MDR) and showed high resistance rates to tetracycline (70.2%), sulfonamides (57.4%), streptomycin (53.1%), ampicillin (29.7%), nalidixic acid (27.6%), kanamycin (23.4%), chloramphenicol (21.2%), and trimethoprim (19.1%). Resistance towards cephalosporins was noted for cephalothin (27.6%), cephradine (21.2%), amoxicillin clavulanic acid (17.0%), and cephalexin (17.0%). Resistance genes, $bla_{TEM}$, strA, aadA, sul1, sul2, tetA, tetB, and tetC, were detected among the drug-resistant strains. Thirtythree strains (70.2%) carried class 1 integrons, which were grouped in 9 different profiles. DNA sequencing identified sat, aadA, pse-1, and dfrA genes in variable regions on class 1 integrons. Thirty-five strains (74.4%) were subtyped to 22 different plasmid profiles, each with 1-6 plasmids (2.0 to 95 kb). PFGE subtyped the 47 strains into 39 profiles. In conclusion, high rates of multidrug resistance were found among the Malaysian Salmonella Typhimurium strains. The emergence of multidrug-resistant Salmonella Typhimurium to cephalosporin antibiotics was also observed. The strains were very diverse and no persistent clone was observed. The emergence of MDR Salmonella Typhimurium is a worldwide problem, and this report provides information for the better understanding of the prevalence and epidemiology of MDR S. Typhimurium in Malaysia.

• Korean Journal of Clinical Pharmacy
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• v.5 no.2
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• pp.13-16
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• 1995

The Minimum Inhibitory Concentration (MIC) of a first-generation cephalosporin derivative, Cefazedone (CZD; $PAZERON^R$ inj.) was determined by the two-fold serial agar dilution method. The in-vitro antibacterial activity of CZD against a wide variety of clinical isolates was compared with those of other first generation cephalosporins such as Methylol Cephalexin (CEX), Cefazolin (CEZ), Cefadroxil (CDX), Cephradine (CED), Ceftezol (CTZ) and one of second generation cephalsporin antibiotics, Cefotaxime (CTX). CZD had the most potent inhibitory effect against Gram-positive strains, when compared to the first-generation cephalosporin antibiotics tested in this study and CTX. The geometric MIC mean of CZD for Gram-positive strains was calculated as 0.386 kg/m{\ell}$, and those of CEX, CEZ, CDX, CTZ, CED, and CTX were 6.073, 0.894, 3.399, 0.748, 7.884 and 1.502 $kg/m{\ell}$, respectively. In addition, the geometric mean of CZD for staphylococclJs aureus strains was obtained as 0.340 $kg/m{\ell}$ and those of CEX, CEZ, CDX, CTZ, CED, and CTX 6.145, 0.534, 4.126, 0.442, 10.51, and 2.500 $kg/m{\ell}$, respectively. Against Gram-negative strains, CZD showed better antibacterial activity than CEZ, CDX, CTZ, and CED.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.462-468
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• 2006

Antibiotics are manufactured and used for specific physiological functions, hence they may exert adverse ecological consequences when they are in contact with nontarget organisms. In the last decade, many reports have been made on the occurrences of various antibiotic compounds in surface water, and their potential impact to the environment has become an increasing concern. This study was conducted to prioritize antibiotic substances with potential environment risk in Korea. Human use antibiotics with an EIC (Expected Introduction Concentration) value greater than $1{\mu}g/l$, US FDA's action limit criteria, were selected. In order to calculate a worst-case EIC for each substance, annual production volume (in kg) of each antibiotic substance was derived using the Korea Pharmaceutical Manufacturers Association (KPMA)'s monetary database. Sixteen substances were preliminarily selected. The EICs of the 16 antibiotic substances were refined with the excretion rate of the parent substances. Ten antibiotic substances were identified to have EIC-corrected greater than $1{\mu}g/l$, which include Amoxicillin ($15.8{\mu}g/l$), Cefaclor ($10.1{\mu}/l$), Roxithromycin ($4.2{\mu}g/l$), Cephradine ($4.5{\mu}g/l$), Cefatrizine ($2.6{\mu}g/l$), Cefadroxil ($3.3{\mu}g/l$), Aztreonam ($2.3{\mu}g/l$), Ceftazidime ($2.8{\mu}g/l$), Ribostamycin ($1.3{\mu}g/l$), and Ceftezole ($1.3{\mu}g/l$). Additional risk assessments for these antibiotic substances are suggested.

• Analytical Science and Technology
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• v.23 no.6
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• pp.572-578
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• 2010

The extraction/clean-up and concentrating of pharmaceuticals from surface water were performed by HLB (Hydrophilic-Lipophilic Balanced) cartridge. The method allows for the simultaneous determination of six pharmaceuticals by HPLC/ESI(+)-MS/MS. Recoveries of the pharmaceutical were between 71.1 to 92.6% (except fenbendazole) and the overall variability of the method was below 11.2% (RSD). The calibration curves for the pharmaceuticals from blank surface water showed good linearities (above $r^2$ = 0.99) in the concentration range of 0.007~1.2 ng/mL. The limit of detection (LOD) and the limit of quantification (LOQ) were 7.2~128.7 pg/mL and 23.8~429.1 pg/mL, respectively. The present analytical method can be useful for monitoring residual pharmaceuticals in surface water and other aquatic samples. High concentrations of iopromide and fenbendazole were detected in a few samples of surface water.

• Analytical Science and Technology
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• v.29 no.4
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• pp.179-185
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• 2016

An effective analytical method has been developed for the determination of β-blockers(atenolol, metoprolol and propranolol) and 6 β-lactams(amoxicillin, penicillin G, cefaclor, cefadroxil, cephalexin and cephradine) in water samples using two different cartridges. The samples were extracted by solid-phase extraction (SPE) with the usage of polymeric hydrophile-lipophile balance(HLB cartridges) and strong cation-exchange mixed-mode polymeric sorbent (MCX cartridges). A XDB-C₁₈ column(1.8 μm; 3.0 mm × 100 mm) was used for the sufficient chromatographic resolution. The calibration curves showed good linearity with high correlation coefficients (>0.995). The method detection limits (MDL) and the limits of quantification(LOQ) were from 1.1 to 3.9 ng/L and from 5 to 13 ng/L, respectively. The method was applied for the determination of the target compounds in tributaries and raw water of the Han River and these were found at N.D. to 0.209 μg/L.