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Year 2013 - Volume 33, Number 6
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Susceptibility profile of Brazilian Rhodococcus equi isolates to different antimicrobial classes and the presence of vapA gene, 33(6):735-740
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ABSTRACT.- Girardini L.K., Gressler L.T., Costa M.M., Botton S.A., Pellegrini D.C.P. & Vargas A.C. 2013. [Susceptibility profile of Brazilian Rhodococcus equi isolates to different antimicrobial classes and the presence of vapA gene.] Perfil de suscetibilidade antimicrobiana e presença do gene vapA em Rhodococcus equi de origem humana, ambiental e equina. Pesquisa Veterinária Brasileira 33(6):735-740. Departamento de Medicina Veterinária Preventiva, Centro de Ciências Rurais, Universidade Federal de Santa Maria, Camobi, Santa Maria, RS 97105-900, Brazil. E-mail: agueda@ccr.ufsm.br
Rhodococcus equi is a facultative intracellular bacterium and etiological agent of rodococosis, an important disease that affects specially foals under six months old and leading the death generally due to pulmonary lesions. R. equi also has zoonotic potential, and it has emerged as an opportunistic pathogen in the world, specially infecting solid organ transplant recipients and immunocompromised human patients, mainly those infected by human immunodeficiency virus (HIV). Additionally, R. equi infections by healthy hosts have been reported principally in children and elderly individuals. Studies have shown an increasing level of resistance of isolates of R. equi against antibiotics commonly used to treat affected animals and humans. The virulence of this agent is associated with a protein located on a plasmid, designated vapA, it is essential for survival and replication of R. equi within macrophages. The present study evaluated the susceptibility profile of R.equi isolates from different sources against the antimicrobials most commonly used to treat animals and humans, as well as the occurrence and association of vapA gene and the antimicrobial multiple resistance index (AMRI). Sixty-seven Brazilian isolates of R. equi from different sources were analyzed: 30 clinical samples of horses, seven of human and 30 of environmental (six from soil and 24 from horse feces). To evaluate the susceptibility profile of R. equi isolates, the Kirby Bauer method was performed by using 16 drugs of 11 distinct antimicrobials classes. Additionally, those samples were also resistant to macrolides (azithromycin 6.7%, erythromycin 6% and clarithromycin 3.3%) as well as rifamycin (13%). All human and environmental samples were sensitive to macrolides and rifamycin. However, environmental isolates demonstrated high levels of resistance to penicillin and chloramphenicol. Similarly, human isolates had high level of resistance to ceftiofur, lincomycin and sulfazotrim. AMRI in all R. equi isolates ranged 0 to 0.67, in clinical samples of horses the AMRI mean value obtained was 0.19, in environmental was 0.14 and in human isolates was 0.1. Despite of high sensitivity observed in most Brazilian R. equi isolates analyzed, it was verified in clinical samples of horses different levels of resistance against all antibiotics commonly used in the treatment of rodococosis. In contrast, environmental isolates not demonstrated any resistance against antimicrobials employed in equine rodococosis therapy. In addition, in human isolates it was not observed resistance against drugs for restricted use in human rodococosis therapy. Based on the AMRI achieved in clinical horse isolates, we highlight the importance of restrictive measures and more caution to use antimicrobial drugs in R. equi infections to avoid increasing of new multidrug-resistant strains. |
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