Macrolide antibiotic inhibition of translation and 50S ribosomal subunit assembly in methicillin-resistant Staphylococcus aureus cells

Methicillin-resistant Staphylococcus aureus cells were treated with three macrolide antibiotics to examine the inhibitory effect of the drugs on the growth rate and cell viability. Inhibition of protein synthesis and 50S ribosomal subunit assembly were also examined. The growth rate and cell viability were reduced by each antibiotic in both erythromycin-susceptible and erythromycin-resistant MRSA organisms. Translation and the formation of the 50S ribosomal subunit were inhibited to an equal extent in the erythromycin-susceptible cells, but protein synthesis was affected to a greater extent by each macrolide in the erythromycin-resistant organisms. Clarithromycin was the most inhibitory of the three compounds, followed by erythromycin and azithromycin in relative effectiveness. The use of these compounds against MRSA organisms is discussed.