Bactericidal activity of erythromycin in the respiratory system

In vivo and in vitro studies were carried out to assess tha levels in bronchial mucus of ampicillin, amoxycillin, bacampicillin, cefotaxime and erythromycin, and to compare their minimum bactericidal concentrations and killing rate against hospital strains of Staphylococcus aureus, Streptococcus pyogenes and Haemophilus influenzae. Both the percentage ratios of serum/mucus concentration peaks and of serum/mucus area under the concentration time curve values were higher for erythromycin than for the other antibiotics. Determination of the minimum bactericidal concentrations showed that the bacterial strains were sensitive to small quantities of erythromycin, and the time necessary to sterilize inocula varied from 4 to 16 hours.