[An experimental study on erythromycin in combination with beta-lactam and aminoglycoside antibiotics (author's...

Combinations of erythromycin with penicillins (ampicillin, azlocillin, carbenicillin and mezlocillin) and with aminoglycosides (amikacin, gentamicin and sisomicin) were tested for their efficacy against Escherichia coli and Staphylococcus aureus using the checkerboard technique. No antagonistic effect could be ascertained. Synergistic effects (inhibition with 25% of the effective antibiotic concentration after mono-application) were seen only in rare instances using the penicillin/erythromycin combinations. In over 30% of the tests the aminoglycoside/erythromycin combinations were synergistically effective against E. coli.