[In vitro antibacterial activity of pristinamycin against penicillin resistant Streptococcus pneumoniae]

Pristinamycin, a member of streptogramin family, is the association of two groups (components I and pristinamycin II A) which have a high synergistic activity. Given the increasing rates of penicillin resistance in Streptococcus pneumoniae in many countries, and in particular of strains exhibiting multiple resistance to commonly used antibiotics, it was interesting to study the in vitro activity of pristinamycin against penicillin resistant S. pneumoniae (47 strains) and compare it with that of erythromycin. All strains were isolated from otitis media. Minimal inhibitory concentrations (MICs) were determined by an agar dilution technique using Mueller-Hinton medium supplemented with 5% horse blood. An inoculum of 10(4)-10(5) CFU per spot was delivered by a Steers replicator. This study showed that, among the 47 penicillin resistant strains, 29 (61.7%) were resistant to erythromycin but none of them were resistant to pristinamycin. The good in vitro activity of pristinamycin against S. pneumoniae could be of particular interest in cases of infections with multiresistant strains.