Postantibiotic effects of subinhibitory concentrations of some antibiotics and their influence onPseudomonas aeruginosa enzymic activity |
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Authors: | A Ho?tacká |
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Institution: | (1) Institute of Preventive and Clinical Medicine, 833 01 Bratislava, Slovak Republic |
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Abstract: | The postantibiotic effects of subinhibitory concentrations (PA SMEs) and virulence factor alterations induced by ciprofloxacin,
tobramycin and netilmicin inPseudomonas aeruginosa were studied. After induction of the postantibiotic phase (PA) (2x or 4x MIC) the cultures were exposed to subinhibitory
concentrations (0.1, 0.2 and 0.3x MIC) of the same antibiotic PA SME). The regrowth of treated as well as control cultures
was followed for 24 or 45 h. In the sterile culture filtrates obtained from these bacterial cultures, elastase and proteinase
were determined. Ciprofloxacin and aminoglycosides exhibited PA SMEs of 3.5–35 h for certain combinations of supra-subinhibitory
antibiotic concentrations. Longer PA SMEs were observed after treatment with higher sub-MICs. Tobramycin at 0.2 and 0.3x MIC
(postantibiotic phase induced by 2x MIC) and at all sub-MICs added to the bacteria previously exposed to 4x MIC do not allow
any regrowth of bacterial culture. PA SMEs of tested antibiotics affected virulence factors ofP. aeruginosa. Elastase compared to proteinase was suppressed more effectively. Ciprofloxacin at 0.3x MIC reduced elastase and proteinase
activity most significantly (to 14.2 and 60 % of the control values). |
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