Species-specific PCR for the diagnosis and determination of antibiotic susceptibilities of brucella strains Isolated from Tehran, Iran

Background: Brucellosis is an endemic zoonotic disease in the Middle East. This study intended to design a uniplex PCR assay for the detection and differentiation of Brucella at the species level and determining the antibiotic susceptibility pattern of Brucella in Iran. Methods: Sixty-eight Brucella specimens (38 animal and 30 human specimens) were analyzed using PCR (using one pair of primers). Antibiotic susceptibility patterns were evaluated and compared using the E-Test and disk diffusion susceptibility test. Tigecycline susceptibility pattern was compared with other antibiotics. Results: Thirty six isolates of B. melitensis, 2 isolates of B. abortus and 1 isolate of B. suis from the 38 animal specimens, 24 isolates of B. melitensis and 6 isolates of B. abortus from the 30 human specimens were differentiated. The MIC50 values of doxycycline for human and animal specimens were 125 and 10 μg/ml, respectively, tigecycline 0.064 μg/ml for human specimens and 0.125μg/ml for animal specimens, and trimethoprim/ sulfamethoxazole and ciprofloxacin 0.065 and 0.125μg/ml, respectively, for both human and animal specimens. The highest MIC50 value of streptomycin in the human specimens was 0.5μg/ml and 1μg/ml for the animal specimens. The greatest resistance shown was to tetracycline and gentamicin, respectively. Conclusion: Uniplex PCR for the detection and differentiation of Brucella at the strain level is faster and less expensive than multiplex PCR, and the antibiotics doxycycline, rifampin, trimethoprim-sulfamethoxazole, ciprofloxacin, and ofloxacin are the most effective antibiotics for treating brucellosis. Resistance to tigecycline is increasing, and we recommend that it be used in a combination regimen. © 2016, Iran J Pathol. All rights reserved