Şöhret Aydemir

In vitro activities of various antimicrobials against Brucella melitensis strains in the Aegean region in Turkey.

Objective: To study in vitro activities of three quinolones (ciprofloxacin, levofloxacin, moxifloxacin), four macrolides (erythromycin, dirithromycin, azithromycin, clarithromycin) and doxycycline against 44 clinical isolates of Brucella melitensis. Materials and Methods: Forty-four B. melitensis strains were isolated from blood cultures of adult patients with acute brucellosis who were hospitalized in the clinical ward of the Department of Clinical Microbiology and Infectious Diseases. The minimum inhibitory concentrations (MICs) of the tested antimicrobials were measured by the agar dilution method. MIC90 and MIC50 values were defined as the lowest concentration of the antibiotic at which 90 and 50% of the isolates were inhibited, respectively. Results: Doxycycline (MIC50: 0.25 µg/ml, MIC90: 0.50 µg/ml) had the lowest MIC in vitro against the B. melitensis strains. Among the quinolones, ciprofloxacin and levofloxacin had similar activities (MIC50: 0.5 µg/ml, MIC90: 2 µg/ml), whereas MIC of moxifloxacin (MIC50: 1 µg/ml, MIC90: 8 µg/ml) was higher than both antibiotics in this group. Clarithromycin and azithromycin were the most active macrolides (MIC50: 8 µg/ml and MIC90: 32 µg/ml), followed by erythromycin (MIC50: 16 µg/ml, MIC90: 32 µg/ml) and dirithromycin (MIC50: 64 µg/ml and MIC90: 64 µg/ml). Conclusion: The results indicate that the conventional agent doxycycline is more active than quinolones and macrolides against the B. melitensis in vitro.

Plasmid-mediated quinolone resistance mechanisms in ESBL positive Escherichia coli and Klebsiella pneumoniae strains at a Tertiary-Care Hospital in Turkey.

Abstract Plasmid-mediated quinolone resistance mechanisms in extended spectrum beta-lactamase positive and quinolone resistant Escherichia coli and Klebsiella pneumoniae strains isolated from Ege University Hospital were investigated. The presence of qnrA, qnrB, qnrS, aac(6’)-Ib and qepA genes were detected by PCR and the products were sequenced. Clonal relationship of isolates was determined by REP-PCR and mutations in gyrA and parC genes were investigated in representative strains. aac(6’)-Ib-cr, qnrB and qnrS genes were detected in both E. coli and K. pneumoniae strains, but qnrA detected only in K. pneumoniae strains. qepA determinant is detected in an E. coli strain first time in Turkey. Mutations were observed in both gyrA and parC genes of all representative nalidixic acid and ciprofloxacin resistant E. coli isolates but no mutation was found in parC genes of E. coli and K. pneumoniae strains that were resistant to only nalidixic acid.