Author(s):
Cerca, Nuno 
; Martins, Silvia ; Pier, Gerald B. ; Oliveira, Rosário ; Azeredo, Joana
Date: 2005
Persistent ID: http://hdl.handle.net/1822/2621
Origin: RepositóriUM - Universidade do Minho
Subject(s): Adhesion; Antibiotics sub-MIC; Biofilm; CoNS; Inhibition
Description
Many studies have demonstrated that subminimal inhibitory concentrations (sub-MICs) of antibiotics can inhibit initial microbial adherence
to medical device surfaces. It has been suggested that, by inhibiting initial adhesion, biofilm formation might be prevented. However,
since initial adherence and subsequent biofilm formation may be two distinct phenomena, conclusions regarding the effects of sub-MIC antibiotics
on initial adhesion cannot be extrapolated to biofilm formation. In this study, we evaluated the adherence of several clinical isolates
of coagulase-negative staphylococci (CoNS) to acrylic and the effect of sub-MICs of vancomycin, cefazolin, dicloxacillin and combinations
of these antibiotics on adherence and biofilm formation. Most of the antibiotics used resulted in effective reduction of bacterial adherence
to acrylic, in some cases reaching over 70% inhibition of adherence. When strains with a high biofilm-forming capacity were grown in
sub-MICs of those antibiotics, there existed combinations of the drugs that significantly inhibited biofilm formation. However, most of the
antibiotic combinations that inhibited adherence did not have a profound effect on biofilm formation. When comparing the results of the
effect of sub-MIC amounts of antibiotics in inhibiting adherence with their effect on the inhibition of biofilm formation, significant differences
were found, mainly when using combinations of antibiotics. In general, the effect on the inhibition of adherence was greater than the
effect on inhibiting biofilm formation. These results demonstrate that assays evaluating the inhibition of initial adherence to medical surfaces
cannot fully predict the effect on inhibition of biofilm formation.
