[The postantibiotic effect of azithromycin on respiratory pathogens]

We assessed the post-antibiotic effect (PAE) of azithromycin against 3 strains of Streptococcus pneumoniae 2 strains of Haemophilus influenzae and 2 strains of Moraxella catarrhalis. The strains were exposed for 2 hours to a concentration of 0.5 mg/l. A stationary phase inoculum of 1 x 10(6)-5 x 10(6) CFU/ml in IsoSensitest Broth with 5% lysed horse blood and 20 mg/l NAD was used and shaken for the duration of the experiment. Antibiotic was neutralised by dilution 1:1000 into pre-warmed medium. [table: see text] In conclusion, even at such low concentration as achieved in serum, azithromycin has a PAE against the respiratory pathogens studied. In our opinion this could allow the use of azithromycin, in the usual regimen even in bacteremic respiratory infections.