Biofilm characteristics of Staphylococcus epidermidis isolates associated with device-related meningitis

Abstract

Staphylococcus epidermidis biofilm causes device-related meningitis in neurosurgical patients. This study assessed the contribution of polysaccharide and protein to the development of a strong biofilm-positive phenotype in four S. epidermidis isolates associated with probable device-related meningitis, under varying environmental conditions. RT-PCR analysis of the intercellular adhesion operon (icaADBC) and assessment of polysaccharide intercellular adhesin (PIA) production indicated a correlation between increased icaA transcription and PIA production in ica + isolates grown in medium with 4 % ethanol and 4 % NaCl. Treatment of biofilm with sodium metaperiodate caused dispersion of adhered cells (P ,0.0001), indicating involvement of PIA. Transcriptional levels of protein factors revealed that atlE transcription levels were similar in all isolates, whilst aap levels were variable, with induction being seen in two isolates following growth in the presence of alcohol or salt. Transcription of agr did not influence protein expression and RNAIII transcription varied among the strains. Although aap transcription was induced, the treatment of biofilm with proteinase K did not always disperse the biofilm. Our data suggest that, among the three ica + S. epidermidis isolates clinically associated with meningitis that were studied, PIA contributed to the strong biofilm-positive phenotype, whereas protein factors appeared to have a secondary role. INTRODUCTIONSuccessful treatment and prevention of hydrocephalus, a common neurosurgical condition, often involves the insertion of an external ventricular drain (EVD) or a shunt. However, this can be complicated by infections such as meningitis, often caused by coagulase-negative staphylococci (CoNS), with Staphylococcus epidermidis being isolated most frequently (Diaz-Mitoma et al., 1987). Mounting evidence suggests that such infections are a result of biofilm formation on the device (Diaz-Mitoma et al., 1987;Tojo et al., 1988;Kockro et al., 2000).Staphylococcal biofilm formation involves both host and bacterial factors. Early investigations have shown that production of polysaccharide is a primary mechanism employed by S. epidermidis (Peters et al., 1987;Tojo et al., 1988; Christensen et al., 1990;Mack et al., 1992). The polysaccharide is a polymeric homoglycan consisting of repeating units of b-1,6-N-acetylglucosamine (Mack et al., 1996; McKenney et al., 1998;Maira-Litran et al., 2002;Sadovskaya et al., 2005), termed polysaccharide intercellular adhesin (PIA). Synthesis of PIA is linked to the biosynthetic enzyme-coding genes located in the intercellular adhesion operon (icaADBC) (Heilmann et al., 1996), and biofilm production involving PIA is known to be ica-dependent and is considered the primary mechanism employed by staphylococci (Stevens et al., 2008).Other ica-independent mechanisms of biofilm development in staphylococci have been identified and protein factors such as the major cell-wall autolysin (AtlE) have been found to promote the initial adhesion of S. epiderm...

Staphylococcus epidermidis biofilms induce lower complement activation in neonates as compared with adults

“…Biofilms are adherent multicellular bacterial aggregates embedded in a self-produced extracellular matrix. The best-described matrix compound in SE biofilms is a β-(1,6)-linked N-acetylglucosamine named polysaccharide intercellular adhesin (PIA) (5,6).…”

Evidence of the presence of nucleic acids and β-glucan in the matrix of non-typeable Haemophilus influenzae in vitro biofilms

“…However, no exopolysaccharide has been identified that clearly contributes to NTHi biofilms23. Sodium metaperiodate has been extensively used to test for the presence of carbohydrates in EPS46. This compound induced disaggregation of NT Hi biofilms strongly suggesting that they contain a glycan.…”

Prevalence of biofilm controlling ica genes of Staphylococcus epidermidis detected in healthy skin, blood samples from septicaemia patients and chronic wounds

“…32,36 Stevens et al studied various protein components including PIA of biofilm in S. epidermidis and have suggested that PIA has a primary role in biofilm positivity while protein components contribute significantly towards the maturation of the biofilm. 37,38 PIA synthesis requires the presence of the ica operon because the enzymes which are involved in its synthesis are controlled by the intercellular adhesion operon (ica ADBC). 37,38 Biofilm studies have used oral biofilm as research models for some time and its characteristics and pathogenesis have been studied.…”

“…37,38 PIA synthesis requires the presence of the ica operon because the enzymes which are involved in its synthesis are controlled by the intercellular adhesion operon (ica ADBC). 37,38 Biofilm studies have used oral biofilm as research models for some time and its characteristics and pathogenesis have been studied. On the other hand, recent studies have indicated the role of biofilm in chronic wound development and persistence.…”