Influence of subinhibitory concentrations of antibiotics on surface hydrophobicity of Salmonella enteritidis.
The effects of subinhibitory concentrations (sub-MICs) of quinolones ciprofloxacin (CAS 85721-33-1), enoxacin (CAS 74011-58-8), norfloxacin (CAS 70458-96-7), ofloxacin (CAS 82419-36-1), pefloxacin (CAS 70458-92-3), aminoglycosides amikacin (CAS 37517-28-5), gentamicin (CAS 1403-66-3), netilmicin (CAS 563911-56-1), tobramycin (CAS 32986-56-4), and beta-lactam antibiotics imipenem (CAS 64221-86-9) and meropenem (CAS 96036-02-2) on the surface hydrophobicity of a clinical isolate of Salmonella enteritidis were studied. Cell hydrophobicity on the tested strain was determined by the method of bacterial adherence to hydrocarbone-xylene (BATH) and on the basis of salt aggregation test of ammonium sulphate (SAT). From the quinolones tested, the highest inhibition of adherence was shown by ciprofloxacin (40%) and enoxacin (38%) at 1/4 of MIC. Aminoglycoside antibiotics stimulated the adherence, having no appreciable effect on the SAT values. The only significant effect on the adhesion was that of gentamicin, 1/4 of MIC of which lowered its value to 2.5%. The decrease of adherence also was accompanied by a drop of hydrophobicity of the bacterial strain in the SAT test. The results obtained in both tests show that sub-MICs of beta-lactams cause a significant inhibition of the hydrophobicity of the studied strain and that the effect of imipenem is more pronounced than that of meropenem. The levels of the inhibition of adherence induced by 1/8 and 1/16 of MIC were 22% and 20%, respectively, as compared to the control value. The influence exerted by the sub-MICs of antibiotics on the cell surface hydrophobicity might be seen as an interference with the pathogenic potential of Salmonella enteritidis.
Institute of Preventive and Clinical Medicine, Bratislava, Slovak Republic.
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D042462:4-Quinolones; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000494:pharmacology; D001422:Bacterial Adhesion / Q000187:drug effects; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D007769:Lactams; D008826:Microbial Sensitivity Tests; D012477:Salmonella enteritidis / Q000737:chemistry* / Q000187:drug effects*
D042462:4-Quinolones; D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D007769:Lactams