Assessment of ica operon carriage and biofilm production in Staphylococcus epidermidis isolates causing bacteraemia in bone marrow transplant recipients

Abstract

The clinical significance of coagulase-negative staphylococci isolated from blood culture is typically assessed on the basis of a combination of clinical and microbiological criteria. However, these criteria are difficult to apply to haematology patients who are highly immunosuppressed and from whom blood cultures are obtained most frequently through a central venous catheter. This study analysed 112 episodes of Staphylococcus epidermidis bacteraemia that occurred in 79 bone marrow transplant recipients. In 73 (65%) episodes, only one blood culture set was positive for S. epidermidis, while 39 (35%) episodes grew S. epidermidis from multiple blood cultures. Nine patients had two or more episodes of bacteraemia with the same strain, as determined by pulsed-field gel electrophoresis (PFGE). The PFGE method also showed that 34 (31%) isolates belonged to seven clusters, indicating the persistence of certain clones in the environment. Of the 109 isolates analysed, 59 (54%) produced biofilm and 91 (83.5%) carried the ica operon. Isolates that produced biofilm were observed to colonise central venous catheters faster than non-biofilm-producing isolates (18 vs. 37 days; p 0.03). No clinical features were associated with carriage of the ica operon, but the ica operon was carried more frequently by the isolates that formed clusters.

Partial atlE Sequencing of Staphylococcus epidermidis Strains from Prosthetic Joint Infections

“…Partial sequencing of atlE confirm the existence of two major lineages among S. epidermidis strains (30), as previously found by pulsed-field gel electrophoresis analysis of isolates from Brazil (21), Italy (5), Sweden (23), and France (20). During preliminary comparisons of PJI and control strains, we felt that allele 1 (i.e., the type strain sequence) was a potential marker of infectious strains.…”

Staphylococcus epidermidis device-related infections: pathogenesis and clinical management

“…The ica locus and biofilm formation are important parameters for staphylococcal colonisation and survival on IMDs (Fluckiger et al 2005); however, recent publications have revealed the emergence of biofilm-positive and ica-negative staphylococcal clinical isolates (Qin et al 2007). Recently, Ninin et al (2006) observed an increase in the subpopulation of biofilm-positive, intercellular adhesin (ica)-negative S. epidermidis isolates to 9.17% of the total 109 clinical isolates that caused bacteraemia in bone-marrow transplant recipients. Chokr et al (2006) also noted that PIA synthesis alone is not sufficient to produce a biofilm and that staphylococci can form a biofilm independent of PIA production, which was consistent with the findings that the presence of the ica locus alone is not sufficient for biofilm formation (Fitzpatrick et al 2002).…”

Genetic Evidence for an Alternative Citrate-Dependent Biofilm Formation Pathway in Staphylococcus aureus That Is Dependent on Fibronectin Binding Proteins and the GraRS Two-Component Regulatory System

“…In contrast, S. aureus strains lacking the ica locus appear to colonize to the same extent as the wild type (WT) in animal models of implant infections (16,21,23,36), although Fluckiger et al did show a defect in growth for the ica mutant in an implant infection model when competed against the WT (21). Also, several recent studies have shown that the presence of icaA was not predictive of pathogenicity among staphylococci (4,24,42,52,59). In contrast, a clear role for the ica locus has been demonstrated in biofilm formation and infection models for Staphylococcus epidermidis (6,42,53,70).…”