JAC Advance Access originally published online on March 21, 2006
Journal of Antimicrobial Chemotherapy 2006 57(5):855-864; doi:10.1093/jac/dkl071
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Commensal isolates of methicillin-resistant Staphylococcus epidermidis are also well equipped to produce biofilm on polystyrene surfaces
1 Faculdade de Farmácia, Universidade Federal Fluminense, Niterói, 24241002 RJ, Brazil; 2 Departamento de Microbiologia Médica, Instituto de Microbiologia Prof Paulo de Góes, Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Bloco I, Cidade Universitária, Rio de Janeiro, RJ, 21941590, Brazil; 3 Hospital Samaritano, Rio de Janeiro, 22041010 RJ, Brazil
Received 20 December 2005; returned 25 January 2006; revised 9 February 2006; accepted 14 February 2006
* Corresponding author. Tel: +55-21-22604193; Fax: +55-21-25608528; E-mail: agnes{at}micro.ufrj.br
Objectives: To study biofilm production and to detect icaAD, atlE and aap genes in 137 isolates of methicillin-resistant Staphylococcus epidermidis (MRSE) obtained from healthy individuals from the community (35 isolates), from hospitalized patients at the Antônio Pedro University Hospital (25 isolates) and from individuals from a home-care system (HCS; 77 isolates).
Methods: Biofilm production was determined in vitro using polystyrene inert surfaces. icaAD, atlE and aap genes were detected using PCR. Hybridization experiments were also carried out to confirm some PCR results. Antimicrobial susceptibility testing was carried out using the NCCLS methods.
Results: Although many of the commensal MRSE isolates produced biofilms, the percentage of biofilm producers was significantly higher (P = 0.0107) among hospital isolates (76%) than among isolates from the community (60%) and from the HCS (57%). An association was observed between multiresistance and biofilm production for isolates obtained from healthy individuals from the community and from household contacts from the HCS (P < 0.0001). The concomitant presence of the ica operon and atlE and aap genes was associated with the strong biofilm-producer phenotype (P < 0.0001).
Conclusion: Because many of the commensal MRSE isolates obtained from nares produced biofilms and carried icaAD, aap and atlE genes, biofilms or such genetic elements should not be used as markers for clinical significance. The biofilm environment seems to increase genetic exchanges and hence may contribute to multiresistance phenotypes.
Keywords: MRSE , biofilm , ica , aap , atlE