JAC Advance Access originally published online on July 18, 2006
Journal of Antimicrobial Chemotherapy 2006 58(3):622-626; doi:10.1093/jac/dkl289
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Efficacy of several antibiotic combinations against Brucella melitensis Rev 1 experimental infection in BALB/c mice
1 Unidad de Sanidad Animal, Centro de Investigación y Tecnología Agroalimentaria (CITA) de Aragón 50.080 Zaragoza, Spain 2 Departamento de Enfermedades Infecciosas, Hospital Universitario de Bellvitge Universidad de Barcelona, Spain
Received 28 March 2006; returned 3 May 2006; revised 12 June 2006; accepted 23 June 2006
*Corresponding author: Tel: +34-976-716455; Fax: +34-976-716335; E-mail: mjgrillo{at}aragon.es
Objectives: The objective of the present study was to compare the efficacy of gentamicin given alone or combined with doxycycline with that of standard combination therapies in BALB/c mice experimentally infected with the Brucella melitensis vaccine strain Rev 1.
Methods: A standard broth microdilution method was applied to determine the susceptibility of strain Rev 1 to the clinically most relevant aminoglycosides. Eight groups of BALB/c mice were inoculated intraperitoneally (ip) with 1 x 106 cfu/mouse of strain Rev 1. While one group remained untreated, the other seven groups were treated 10 days later once a day for 14 days with (i) doxycycline given orally at 2 mg/day; (ii) streptomycin given ip at 0.4 mg/day; (iii) gentamicin given ip at 0.4 mg/day; (iv) rifampicin given orally at 0.5 mg/day; (v) doxycycline plus streptomycin; (vi) doxycycline plus gentamicin; and (vii) doxycycline plus rifampicin. The number of cfu per spleen and clearance of Rev 1 were assessed 34 days after inoculation.
Results: With the exception of streptomycin, strain Rev 1 was susceptible to all aminoglycosides tested. As expected, the combination doxycycline/streptomycin was ineffective against Rev 1 infection. In contrast, the combinations doxycycline/gentamicin and doxycycline/rifampicin were effective in the clearance of Rev 1 infection, but only the former improved significantly the therapeutic efficacy as compared with that of the antibiotics given alone.
Conclusions: Gentamicin may be used along with doxycycline when the classical combination is considered the first choice in the treatment of patients with brucellosis due to B. melitensis vaccine strain Rev 1.
Keywords: Human brucellosis , B. melitensis Rev 1 vaccine strain , antimicrobial therapy