[In vitro activity of pristinamycin on respiratory bacteria].

TWO-PHASE ACTION: Pristinamycin is composed of two active substances A and B. Pristinamycin A (SA) first binds to the ribosome subunit 50s. Pristinamycin B (SB) then locks onto SA causing irreversible inhibition of bacterial protein production. WELL-ADAPTED ACTIVITY SPECTRUM: A member of the streptogramin family of antibiotics, pristinamycin is active against the main bacteria causing respiratory tract infections (pneumococci, S. aureus, H. influenzae) as well as against mycoplasma and anaerobic pathogens. ANTI-PNEUMOCOCCI ACTIVITY: Minimal inhibitory concentrations measured over the last 5 years have confirmed that the antibacterial activity of pristinamycin against pneumococci remains unchanged even for strains which develop resistance to other antibiotics, particularly to penicillin or erythromycin. OTHER BACTERIA: The activity of pristinamycin against H. influenzae is a constant finding (unimodal distribution of MIC). The persistent of pristinamycin activity against S. aureus strains, excepting a few SA- resistant strains and SA + SB- resistant strains, is remarkable. MIC studies have also demonstrated the constant susceptibility of Moraxella catarrhalis, non-groupable streptococci, anaerobic bacteria, and Legionella pneumophila.