Effects of subminimal inhibitory concentrations of antibiotics on the adherence of Pseudomonas aeruginosa to tracheobronchial mucin

Abstract

Bacterial adherence to mucins may be important in tracheobronchial infections in cystic fibrosis. Sublethal concentrations of antibiotics reduce bacterial adherence to epithelial cells and mucins. This reduction in adherence may be a component of antimicrobial effects in infections at anatomical sites where bactericidal concentrations of antibiotics are difficult to achieve. We therefore tested the effects of sublethal concentrations of an aminoglycoside, tobramycin, and a beta-lactam antibiotic, ceftazidime, on the adherence of Pseudomonas aeruginosa to tracheobronchial mucin, since mucus secretions are often colonized by P. aeruginosa in cystic fibrosis. Adherence of the mucoid strains tested was inhibited by ceftazidime, but not by tobramycin. This effect of ceftazidime may partially explain its efficacy in patients with cystic fibrosis despite variables achieved in sputum.

Effects of erythromycin onPseudomonas aeruginosaadherence to collagen and morphologyin vitro

“…The collagen had three major bands after sodium dodecyl-sulphate-polyacrylamide gel electropherisis under reducing conditions consistent with basement membrane collagen [16]. The lids of plastic Eppendorf tubes were carefully trimmed and removed from the body of the tubes and sterilised by autoclaving.…”

Bacterial adhesion: modulation by antibiotics which perturb protein synthesis

“…Different surface components of P. aeruginosa are involved in its attachment to host mucin or epithelial cells (73). Adhesion of nonmucoid strains is mediated by fimbriae, whereas alginate, a bacterial exopolysaccharide, mediates the attachment of mucoid strains (73).…”

“…Adhesion of nonmucoid strains is mediated by fimbriae, whereas alginate, a bacterial exopolysaccharide, mediates the attachment of mucoid strains (73). Net production of polymerized alginate by four mucoid strains of P. aeruginosa was inhibited by sub-MICs of tobramycin and gentamicin, resulting in reduced bacterial adhesion to tracheal explants (32).…”

“…The antibiotic treatment was proposed to promote the degradation of the adhesive exopolysaccharide by inducing the release of a depolymerase (32). The attachment of mucoid and nonmucoid strains of P. aeruginosa to tracheobronchial mucin was not affected by tobramycin, (73). In other sets of experiments, bacteria were allowed to grow to the stationary phase, and aminoglycosides were not added until the beginning of the adhesion assay.…”

Bacterial adhesion: modulation by antibiotics with primary targets other than protein synthesis

“…This effect correlated with reduced amounts of exopolysaccharides on the bacterial surfaces after growth with the antibiotic (62). Similarly, the adhesion of several slime-producing coagulase-negative staphylococci to plastic tissue culture plates was inhibited by P-lactam antibiotics (47).…”