Biofilm formation by persistent and non-persistent isolates of Staphylococcus epidermidis from a neonatal intensive care unit

Correlation of biofilm formation and presence of the icaADBC genes was studied in 161 clinical isolates of S. epidermidis from persistent and non-persistent neonatal infections. Biofilm formation was compared in trypticase soy broth with or without added glucose (0.5-9.23%), and total parenteral nutrition (TPN) containing 9.23% glucose. Detection of icaADBC genes was carried out using polymerase chain reaction and ica-specific primers. Quantitative biofilm formation for all isolates was highest in the presence of 1% glucose, followed by trypticase soy broth and TPN. There was no significant difference between the amount of biofilm formed by persistent and non-persistent isolates under different test conditions. In contrast, 70% of the persistent isolates produced biofilm in TPN compared to the 56.3% of the non-persistent group. Neither the persistent bacterial phenotype nor presence of the icaADBC operon was correlated with biofilm formation. (c) 2008 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.