title: Influence of biofilm formation in the susceptibility of Pseudomonas aeruginosa from Brazilian patients with cystic fibrosis.
abstract: Biofilms play a key role in the occurrence of lung infections by Pseudomonas aeruginosa in patients with cystic fibrosis (CF). In this study, we examined 40 isolates of P. aeruginosa from CF patients according to their capacity to form biofilm. We also compared their in vitro response to antimicrobials according to different modes of growth (planktonic vs biofilm) and performed molecular typing. All isolates proved capable of forming biofilm. However, there was no difference in biofilm development according to the mucoid and nonmucoid phenotypes and among isolates obtained at different periods of the chronic infection. All isolates tested for antimicrobial susceptibility in the biofilm state (BIC) were consistently more resistant to antibiotics than the same isolate tested in the planktonic state. The molecular typing indicates a considerable clonal diversity among isolates. We identified five patients harboring the same strain over different periods. These strains, however, displayed different levels of biofilm formation and BIC values for antibiotics tested. The results of the present study demonstrate that there is a marked difference in the susceptibility profile according to the mode of growth of CF P. aeruginosa, as cells tested in the biofilm state proved consistently more resistant to antibiotics.
authors.affiliation: Disciplina de Microbiologia e Imunologia, Faculdade de Ciências Médicas, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Alex Guerra
authors.initials: AG
authors.lastname: Ferreira
authors.forename: Robson Souza
authors.initials: RS
authors.lastname: Leão
authors.forename: Ana Paula D'Alincourt
authors.initials: AP
authors.lastname: Carvalho-Assef
authors.forename: Tania Wrobel
authors.initials: TW
authors.lastname: Folescu
authors.forename: Afonso Luís
authors.initials: AL
authors.lastname: Barth
authors.forename: Elizabeth Andrade
authors.initials: EA
authors.lastname: Marques
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D003550:Cystic Fibrosis / Q000150:complications / Q000382:microbiology*; D004198:Disease Susceptibility; D008826:Microbial Sensitivity Tests; D011552:Pseudomonas Infections / Q000188:drug therapy / Q000209:etiology*; D011550:Pseudomonas aeruginosa / Q000187:drug effects*