Authors:Yasar Abbasi, Akbar Ali, Muhammad Khan, Muhammad Saeed, and Kashif Naeem
The extraction behavior of nalidixic acid (HNA) in CH2Cl2 has been studied for various di- and trivalent metal ions such as Cu(II), Fe(II), Ni(II), Mn(II), Sb(II), Co(II), Sc(III),
Y(III), Nd(III) and Eu(III) from aqueous buffer solutions of pH 1–7 with 0.1 mol dm−3 nalidixic acid in dichloromethane. Separation factors of Sc(III) from these metals has shown that its clean separation is
possible at pH 3.4–4. The parameters affecting the extraction of Sc(III) were optimized. The composition of the extracted
adduct was determined by slope analysis method that came out to be Sc(NA)3. Extraction of Sc(III) was studied in the presence of various cations and anions. Among the anions studied only fluoride,
citrate and oxalate have significant interference whereas, Fe(III) has reduced the extraction to 53% that can be removed by
using ascorbic acid as reducing agent. The proposed extraction system proved good stability up to six extraction-stripping
stages for the extraction of Sc(III).
A fast, simple, and sensitive sample preparation procedure based on dispersive liquid-liquid microextraction (DLLME) followed by high-performance liquid chromatography and ultraviolet (HPLC-UV) detection was developed for the determination of nalidixic acid in a human urine sample. A mixture of extraction solvent (35 μL carbon tetrachloride) and disperser solvent (1.0 mL acetonitrile) were rapidly injected into an aqueous sample (5.0 mL) for the formation of cloudy solution; the analyte in the sample was extracted into the fine droplets of carbon tetrachloride. After extraction, phase separation was performed by centrifugation and the enriched analyte in the sedimented phase was determined by HPLC-UV. The influence of several important parameters on extraction efficiency of nalidixic acid was evaluated. Under optimized experimental conditions, the calibration graph was linear in the concentration range of 1–800 μg L−1 with the coefficient of determination being 0.9994. The limits of detection and quantification were 0.2 and 0.7 μg L−1, respectively. The relative standard deviations (RSDs) and accuracies were in the range of 1.1–8.7% and 92.7–104.9%, respectively. This procedure was successfully applied to the determination of nalidixic acid in spiked urine samples with satisfactory results. The relative recoveries of urine samples ranged from 103.1% to 105.1%, with RSDs varying from 0.8% to 2.4%.
Authors:Oreva Ogbor, Abraham Ajayi, Andreas E. Zautner, and Stella I. Smith
), clarithromycin (10 μg), cotrimoxazole (25 μg), nalidixicacid (30 μg), chloramphenicol (10 μg), cloxacillin (5 μg), and streptomycin (10 μg).
The antibiotic-impregnated disks were placed on the inoculated blood agar plates using sterile forceps and
The influence of different solvents on Am3+·sold photoluminescen has been studied. A great increase of luminescence lifetime in deuterated DMSO compared with water was found. The sensitization of americium(III) photoluminescence by energy transfer from ligand (TTA or nalidixic acid) was realized for the first time. The photoluminescence of AmW10 O369– was discovered and some of its characteristics were measured. The use of photoluminescence for investigation of americium complex formation in solutions was demonstrated.
Authors:D. Oraić, Snježana Zrnčić, B. Šoštarić, and et al.
During the spring of 1996 and autumn of 1997 unusual mortality outbreaks among rainbow trout fry and yearlings occurred at two different trout farms, resulting in mortality of 20 and 10 per cent, respectively. Generally, the affected fish, swimming at the water surface, were reluctant to eat and were dark pigmented with visible haemorrhages around and within the oral cavity. Bacterial isolates from moribund fish from both cases were identified as Yersinia ruckeri by standard biochemical tests and API 20E. The isolated strains were found to be sensitive to tetracycline, chloramphenicol, co-trimoxazole, nalidixic acid, flumequine, enrofloxacin, carbenicillin and gentamicin. Microplate agglutination assay confirmed that both isolates belonged to serotype O1. The pathogenicity of the isolated bacteria was confirmed by challenge experiment. Titres of specific antibodies were determined in the sera of survivors. The titre was highest on the 21st day postchallenge and was detectable until the 81st day.
Authors:I. Biksi, Andrea Major, L. Fodor, and et al.
In vitro antimicrobial sensitivity of 12 Hungarian isolates and the type strain ATCC 33144 of Actinobaculum suis to different antimicrobial compounds was determined both by the agar dilution and by the disc diffusion method. By agar dilution, MIC50 values in the range of 0.05-3.125µg/ml were determined for penicillin, ampicillin, ceftiofur, doxycycline, tylosin, pleuromutilins, chloramphenicol, florfenicol, enrofloxacin and lincomycin. The MIC50 value of oxytetracycline and spectinomycin was 6.25 and 12.5µg/ml, respectively. For ofloxacin, flumequine, neomycin, streptomycin, gentamicin, nalidixic acid, nitrofurantoin and sulphamethoxazole + trimethoprim MIC50 values were in the range of 25-100µg/ml. With the disc diffusion method, all strains were sensitive to penicillin, cephalosporins examined, chloramphenicol and florfenicol, tetracyclines examined, pleuromutilins, lincomycin and tylosin. Variable sensitivity was observed for fluoroquinolones (flumequine, enrofloxacin, ofloxacin), most of the strains were susceptible to marbofloxacin. Almost all strains were resistant to aminoglycosides but most of them were sensitive to spectinomycin. A strong correlation was determined for disc diffusion and MIC results (Spearman's rho 0.789, p<0001). MIC values of the type strain and MIC50 values of other tested strains did not differ significantly. Few strains showed a partially distinct resistance pattern for erythromycin, lincomycin and ampicillin in both methods.
The occurrence of tetracycline resistance determinants in 203 Escherichia coli isolates recovered from clinical samples at three different hospitals in Nigeria between June 2009 and May 2010 was investigated. The isolates were subjected to standard procedures. Antibiotic susceptibility to a panel of eight antibiotics was also performed, and resistance genes were detected with the polymerase chain reaction (PCR) technique. One hundred and six E. coli isolates (52.2%) were obtained at LAUTECH Teaching Hospital Osogbo, 85 (41.9%) from OAUTHC Ile Ife and 12 (5.9%) from Osun State Hospital Asubiaro Osogbo. Result of the disk diffusion antibiotic susceptibility test showed 96.1% isolates to be resistant to ampicillin, 77.8% to tetracycline, 37.9% to cotrimoxazole, 38.4% to nalidixic acid, 20.7% to ofloxacin, 17.7% to ceftriaxone, 11.8% to gentamycin, and 2% to nitrofurantoin. One hundred and sixty two (79.9%) isolates had minimum inhibitory concentration (MIC) of tetracycline ≥ 128 μg/ml. The polymerase chain reaction (PCR) detected tetA gene in 89 (43.8%) isolates, tetB gene in 65 (32.0%), and both tetA and tetB genes in 9 (4.4%) isolates. The study demonstrated a relatively high level of gene mediated antibiotic resistance to tetracycline and other antibiotics in E. coli clinical isolates in Southwest region of Nigeria.
Authors:Réka Szabó, Enikő Wehmann, and Tibor Magyar
The antimicrobial susceptibility of 19 Bordetella avium and 36 Ornithobacterium rhinotracheale strains was tested by the Kirby-Bauer disk diffusion method, and the minimal inhibitory concentrations (MIC) of amoxicillin, doxycycline and erythromycin were also determined. Most O. rhinotracheale strains were resistant to nalidixic acid, sulphamethoxazole–trimethoprim and gentamicin, and were susceptible to ampicillin, chloramphenicol, spectinomycin and tilmicosin. All B. avium strains were resistant to ceftiofur and lincomycin and susceptible to doxycycline, gentamicin, polymyxin B, spectinomycin and sulphonamides. The MICs ranged widely for all three antibiotics tested against O. rhinotracheale strains, from 0.12 μg/ml to 32 μg/ml for amoxicillin and erythromycin, and from 0.6 μg/ml to 32 μg/ml for doxycycline. For B. avium isolates, the MIC values ranged from ≤ 0.03 μg/ml to 1 μg/ml for amoxicillin, from ≤ 0.03 μg/ml to 0.12 μg/ml for doxycycline and from 8 μg/ml to 16 μg/ml for erythromycin. These findings support the idea that the use of antibiotics in a region or a farm may affect antimicrobial resistance and underline the need for prudent application of antibiotic therapy based on proper antimicrobial susceptibility testing.