Microbiological aspects of erythromycin.

Almost 35 years after its discovery, erythromycin remains highly active against most strains of a broad array of clinically important organisms. Many strains of Gram-positive and Gram-negative aerobic, facultative and anaerobic bacteria, as well as Mycoplasma, treponemes and Chlamydia, are susceptible to this agent. Erythromycin acts by binding to the ribosomes of the target organisms, thereby inhibiting protein synthesis. Although a pharmacokinetically superior erythromycin estolate has been shown to be a less potent antibiotic prior to hydrolysis, it appears to contribute significantly to the therapeutic response following administration of erythromycin estolate. Clinical laboratory susceptibility testing or erythromycin may be done using standardized methods, but the laboratorian is cautioned to remember the adverse effect of acidic test conditions on the apparent activity of this antibiotic.