POSTANTIBIOTIC EFFECTS AND POSTANTIBIOTIC SUB-MIC EFFECTS OF CIPROFLOXACIN, PEFLOXACIN AND AMIKACIN ON THE BIOLOGICAL PROPERTIES OF SALMONELLA STRAINS

The postantibiotic effect (PAE) and the postantibiotic sub-MIG effect (PASME) of ciprofloxacin, pefloxacin and amikacin were studied for Sal monella typhimurium and S. enteritidis strains. PAE was induced by 2x and 4xMIC of antibiotics studied for 0.5 h. After PAE and PASME their effect on prophage induction of a lysogenic S. typhimurium strain and on Congo red binding for both strains as a marker of their surface hyd rophobicity was examined. The longest PAE was found after treatment wi th ciprofloxacin, higher values being observed with S. typhimurium. PA Es of pefloxacin and amikacin were much lower, except for the suprainh ibitory concentration 4xMIC of amikacin with S. enteritidis (6.9 h). P ASMEs of ciprofloxacin did not allow any regrowth of either strain. Fo r other antibiotics the PASMEs were different while concentrations of 2xMIC + 0.2xMIC and 0.3xMIC, and of 4xMIC + 0.1xMIC, 0.2xMIC and 0.3xM IC of amikacin did not allow any regrowth of S. enteritidis. PAEs of t he antibiotics tested did not affect the Congo red binding by both Sal monella strains, but the PAEs of ciprofloxacin and pefloxacin expressi vely induced a prophage of lysogenic S. typhimurium strain. We noted t he influence of Congo red binding after applying 4xMIC + 0.1xMIC, 0.2x MIC and 0.3xMIC of amikacin for S. typhimurium and 2xMIC + 0.1xMIC for S. enteritidis.