Synergistic effect of subinhibitory concentrations of erythromycin, minocycline and norfloxacin on commonly used antibiotics

ABSTRACT

Subinhibitory concentration of erythromycin, minocycline and norfloxacin were individually incorporated into inoculated agar plates and 12 antibiotic discs were aseptically placed onto the surface. The diameters of the developed inhibition zones were compared with those obtained with similar discs on antibiotic-free plates. The increase in zone diameters on the base-antibiotic plate indicated synergy. The present study showed that traditional antibiotics can still be used more effectively in the presence of subinhibitory concentrations of erythromycin, minocycline and norfloxacin