Genetic and phenotypic analysis of biofilm phenotypic variation in multiple Staphylococcus epidermidis isolates

Abstract

Production of biofilm in Staphylococcus epidermidis is mediated through enzymes produced by the four-gene operon ica and is subject to phenotypic variation. The purpose of these experiments was to investigate the regulation of ica and icaR transcription in phenotypic variants produced by multiple unrelated isolates of S. epidermidis. Ten isolates were chosen for the study, four of which contained IS256. IS256 mediates a reversible inactivation of ica in approximately 30 % of phenotypic variants. All ten strains produced at least two types of phenotypic variant (intermediate and smooth) in which biofilm formation was significantly impaired. Reversion studies indicated that all phenotypic variants were stable after overnight growth, but began to revert to other phenotypic forms after 5 days of incubation at 37 8C. ica transcriptional analysis was performed on phenotypic variants from three IS256-negative isolates; 1457, SE5 and 14765. This analysis demonstrated that ica transcription was significantly reduced in the majority of phenotypic variants, although two variants from SE5 and 1457 produced wild-type quantities of ica transcript. Analysis of seven additional phenotypic variants from SE5 revealed that ica expression was only reduced in three. Expression of icaR transcript was unaffected in all smooth phenotypic variants. Mutations within ica were identified in two SE5 variants with wild-type levels of ica transcription. It is concluded that mutation and transcriptional regulation of ica are the primary mechanisms that govern phenotypic variation of biofilm formation within IS256-negative S. epidermidis.

Clonal Analysis of Staphylococcus epidermidis Isolates Carrying or Lacking Biofilm-Mediating Genes by Multilocus Sequence Typing

“…IS256 is an insertion sequence element which is part of the aminoglycoside resistancemediating transposon Tn4001 but also occurs independently in multiple copies in the genomes of staphylococci and enterococci. IS256 has the capacity to influence expression of the ica operon and subsequent biofilm formation by reversible insertion into the ica operon and its regulatory genes as well as by chromosomal rearrangements (2,14,35,37). To investigate whether SCCmec cassettes and IS256 occur in specific STs, all isolates were tested for the presence of these genes.…”

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

“…Congo red agar was used to examine indirectly the potential of S. epidermidis isolates to produce polysaccharide or slime (Ziebuhr et al, 1997;Arciola et al, 2003;Stevens et al, 2008). Colony phenotypes were identified according to criteria described previously (Handke et al, 2004).…”

Staphylococcus epidermidis device-related infections: pathogenesis and clinical management

“…This is attributable to a number of factors observed in biofilm populations (Table 1), including restricted penetration, decreased growth rate, a distinct genetic phenotype (Handke et al 2004;Harrison et al 2004;Fitzpatrick et al 2005;O'Gara 2007), the expression of resistance genes (Maira-Litrán et al 2000) and the presence of biofilm persister cells (Lewis 2001(Lewis , 2005Spoering & Lewis 2001;.…”