Abstract: Aim The postantibiotic effects (PAE)of 20 ant imicrobial agents against S.aureus collected from patients with nosocomial infections were studied.Methods PAE was determined by the spectrophotometric method and calculated by the difference of time in regrow th phase of bacte ria between tested and controlled groups.Results The PAE of β-lactams against S.aureus was short, but PAEs of macrolides, fluroquinolones and amino glycosides and fosfomycin were marked, especially PAEs of macrolides were up to 2 h in sub-MIC.PAEs of penicillins and carbenpenem were longer than that of cephalospories, PAEs of macrolides, aminoglycosides and fluroquino lones were obviously longer than PAEs of β-lactams in four times of MIC of the drugs. Conclusion PAEs of the antimicrobial agent s, which inhibite synthesis or proteins of DNA, and fosfomycin are significant longer than that of β-lactams(it may be associated with different action mechanisms).

Key words: S.aureus, postantibiotic effects