ERYTHROMYCIN CONCENTRATIONS IN MIDDLE EAR EXUDATES

Abstract

Children with acute otitis media were treated with oral esters of erythromycin in doses of 12.5 mg/kg at 6-hour intervals for 24 hours (50 mg/kg/day). Two hours after the last dose serum and middle ear exudates obtained by needle aspiration were assayed for erythromycin levels. Gram stained smears and cultures of the middle ear exudates were obtained and correlated with the levels of erythromycin found in the exudates. Concentrations of the drug were found in middle ear exudates sufficient to be effective against essentially all strains of D. pneumoniae and Lancefield Group A beta hemolytic streptococci. These results may explain why erythromycin is highly effective in the treatment of acute otitis media due to these organisms. Penetration of erythromycin into middle ear exudates may not be sufficient in some cases to eradicate all strains of H. inflenzae and therefore otitis media due to this organism may not respond as readily to therapy with this agent.