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Eur J Clin Microbiol Infect Dis (2008) 27:311314 DOI 10.1007/s10096-007-0433-y
CONCISE ARTICLE
Strong slime production is a marker of clinical significance in Staphylococcus epidermidis isolated from intravascular catheters
M. Mateo & J. R. Maestre & L. Aguilar & M. J. Gimnez &
J. J. Granizo & J. Prieto
Received: 1 September 2007 /Accepted: 10 November 2007 /Published online: 18 December 2007 # Springer-Verlag 2007
Abstract Biofilm production was assessed in 52 Staphylococcus epidermidis isolates from the catheters of 52 patients with catheter-related bloodstream infections (CR-BSI) and compared with 14 isolates from the skin of healthy volunteers by spectrophotometry. The isolates were classified as non- (G1), weak- (G2) or strong- (G3) slime producers based on optical density, and as producers and non-producers based on the results of the Congo red agar test. Differences (p=0.012) in the proportion of G1, G2 and G3 among the isolates were found between catheter and healthy skin strains: there was a higher percentage of G1 types among the healthy skin strains (35.7 vs. 11.5%; p=0.046) and a higher percentage of G3 types among the catheter isolates (44.2 vs. 0%; p=0.001). No significant differences were found with the Congo red agar test. G3 is a phenotypic marker for CR-BSI.
Introduction
Slime production and biofilm formation in coagulase-negative staphylococci (CNS) play a key role in the colonization of foreign bodies. The ica locus that encodes the production of polysaccharide intercellular adhesins is required for biofilm formation [1], but there is no strict association between the presence of the icaADBC operon (which comprises four intercellular adhesion genes icaA, icaB, icaC, icaD and one regulator gene, icaR) and in vitro biofilm formation [2]. The presence of the entire cluster does not always correlate with biofilm production and, conversely, isolates lacking the ica operon have been found to be able to grow as a biofilm [3, 4]. Consequently, the applicability of these markers for distinguishing commensal or infective strains varies [5], and some studies have refuted the usefulness of these molecular markers (icaADBC operon, aap and atlE genes) for assessing biofilm-associated infectivity in catheter-related bloodstream infections (CR-BSI) [2, 5, 6].
Catheter-related bloodstream infections can be caused by various commensal bacterial microflora, with Staphylococcus epidermidis being the main species and the microorganism responsible for 5070% of all...