[Postantibiotic effects (PAE's) of macrolide antibiotics evaluated using Bioscreen C method]

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Postantibiotic effect (PAE) is crucial for understanding antibiotic efficacy.
• Macrolide antibiotics are widely used against Gram-positive bacteria.
• Accurate PAE determination is essential for optimizing antibiotic therapy.

Purpose of the Study:

• To determine the postantibiotic effects (PAE) of macrolide antibiotics against Staphylococcus aureus and Enterococcus faecalis.
• To compare the viability counting method with the Bioscreen C method for PAE assessment.
• To evaluate the duration of PAE for specific macrolides.

Main Methods:

• Bacterial strains Staphylococcus aureus and Enterococcus faecalis were exposed to macrolide antibiotics (erythromycin, josamycin, rokitamycin) at twice the minimum inhibitory concentration (MIC) for 2 hours.
• Postantibiotic effects were measured using both traditional viable counting and the automated Bioscreen C method.
• PAE was quantified by comparing bacterial regrowth rates after antibiotic removal.

Main Results:

• No significant differences were observed between the viable counting and Bioscreen C methods for PAE determination.
• The Bioscreen C method proved to be less laborious than viable counting.
• Observed PAE durations for S. aureus ranged from 0.85 to 5.45 hours, and for E. faecalis, from 1.0 to 5.8 hours, depending on the macrolide antibiotic used.

Conclusions:

• Both viable counting and Bioscreen C are reliable methods for assessing macrolide antibiotic PAE.
• The Bioscreen C method offers a more efficient and less labor-intensive alternative for PAE studies.
• Macrolide antibiotics exhibit significant postantibiotic effects against S. aureus and E. faecalis, with varying durations.