In vitro Activities of Various Antimicrobials against <i>Brucella melitensis</i> Strains in the Aegean Region in Turkey

Abstract

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.

Identification and In Vitro Antimicrobial Susceptibility ofBrucellaSpecies Isolated from Human Brucellosis

“…This is in concordance with the previous reports [11, 22, 29]. Our MIC 50 and MIC 90 values were lower than previously being reported [21, 30]. Therefore this drug is still a potent agent for the treatment of brucellosis.…”

Identification and Determination of Antibiotic Susceptibilities of Brucella Strains Isolated from Patients in Van, Turkey by Conventional and Molecular Methods

“…In many studies, azithromycin was found to be an effective antibiotic against Brucella strains 27,31. In the present study, however, azithromycin's MIC values were high.…”

<i>In Vitro</i> Antimicrobial Susceptibility of <i>Brucella melitensis</i> Isolates from Sheep in an Area Endemic for Human Brucellosis in Turkey

“…It was concluded that DOXY was the most active antibiotic and CPFX, and LVX had similar activities. AZ and CL were the most active macrolides followed by EM and DRM [38]. In another study in the same region of Turkey, 34 B. melitensis isolates from humans were tested against RIF, SM, CPFX, TC, DOXY, ceftriaxone (CFX) and LVX.…”

“…One (2.4%) isolate was resistant to CPFX, 14 (34.1%) isolates to TMP/SMZ, one (2.4%) isolate to TMP/SMZ and GM, three (7.3%) isolates to RIF and TMP/SMZ, one (2.4%) isolate to SM, CPFX and TMP/SMZ and one (2.4%) isolate to RIF, CPFX and TMP/SMZ. A lot of different antibiotics were evaluated in these studies [2,7,9,19,35,38], and different results were obtained. These findings support the combinations of the various antibiotics recommendation for the treatment of human brucellosis [6,37].…”