Mycobacterium bovis and Mycobacterium caprae are zoonotic bacteria that cause tuberculosis with several clinical manifestations. We have evaluated the susceptibility to anti-tuberculosis drugs of a panel of Spanish isolates of animal origin. The analysis of the sequence of the main genes involved in resistance was performed in 41 M. bovis and five M. caprae. The katG, inhA, rpsL, embB and gyrA genes had single nucleotide polymorphisms, not previously described in other organisms of the complex. Thirty-two M. bovis and three M. caprae isolates were tested for susceptibility to isoniazid (INH), rifampin, streptomycin, ethambutol, and ofloxacin using the standard proportion method. The results revealed that the isolates were sensitive to the five drugs. However, interference caused by sodium pyruvate in the INH test was detected: 94.3% grew at 0.2 μg INH/ml and 68.6% grew at 1 μg INH/ml. In the medium without pyruvate, 34.3% of the isolates did not grow whereas growth of the others was poor and slow. Nine M. bovis isolates were also tested by ESP Culture System II test and were sensitive to INH. The susceptibility of M. bovis to INH cannot be reliably determined using the standard proportion method due to the M. bovis growth requirements and the interference of pyruvate with INH.
Bibliographical noteFunding Information:
Funding : This research was funded by project AGL2001-2029 and AGL2004-08092 of the Spanish Ministry of Science and Technology, and by the Spanish Ministry of Agriculture Fisheries and Food. B. Romero is recipient of a research contract funded by Comunidad de Madrid (IV regional framework programme of research and technological innovation 2005–2008). The group is a partner of the coordination action “Veterinary European Network on Mycobacteria (VENoMYC)” funded by the European Union.
- Mycobacterium bovis
- Mycobacterium caprae
- Susceptibility testing
- Target genes