Comparative Epidemiology of Staphylococcus epidermidis Isolates from Patients with Catheter-Related Bacteremia and from Healthy Volunteers

Abstract

Staphylococcus epidermidis is a major cause of catheter-related bloodstream infections (CRBSIs). Recent studies suggested the existence of well-adapted, highly resistant, hospital-associated S. epidermidis clones. The molecular epidemiology of S. epidermidis in Belgian hospitals and the Belgian community has not been explored yet. We compared a set of 33 S. epidermidis isolates causing CRBSI in hospitalized patients with a set of 33 commensal S. epidermidis isolates. The factors analyzed included resistance to antibiotics and genetic diversity as determined by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and SCCmec typing. Additionally, the presence of virulence-associated mobile genetic elements, the ica operon and the arginine catabolic mobile element (ACME), was assessed and compared against clinical data. CRBSI S. epidermidis isolates were significantly resistant to more antibiotics than commensal S. epidermidis isolates. The two populations studied were very diverse and genetically distinct as only 23% of the 37 PFGE types observed were harbored by both CRBSI and commensal isolates. ACME was found in 76% of S. epidermidis strains, regardless of their origin, while the ica operon was significantly more prevalent in CRBSI isolates than in commensal isolates (P < 0.05). Nine patients presented a clinically severe CRBSI, eight cases of which were due to an ica-positive multiresistant isolate belonging to sequence type 2 (ST2) or ST54. S. epidermidis isolates causing CRBSI were more resistant and more often ica positive than commensal S. epidermidis isolates, which were genetically heterogeneous and susceptible to the majority of antibiotics tested. Clinically severe CRBSIs were due to isolates belonging to two closely related MLST types, ST2 and ST54.

Characterization of Ocular Methicillin-Resistant Staphylococcus epidermidis Isolates Belonging Predominantly to Clonal Complex 2 Subcluster II

“…However, since the number of isolates recovered from endophthalmitis in the present study was small, this conclusion could be true for keratitis-associated strains only. Corroborating our results, previous reports have also found a low occurrence of the ica locus and IS256 element among S. epidermidis comprising CC2-II (19,36).…”

“…Pulsed-field gel electrophoresis (PFGE) is the most discriminatory method for characterizing S. epidermidis and has been widely used for studying the dissemination of MRSE clones in hospitals and community (19)(20)(21)(22). However, its application has been more restricted to short-term epidemiology for characterization of hospital outbreaks (18,21).…”

Do Staphylococcus epidermidis Genetic Clusters Predict Isolation Sources?

“…Multilocus sequence typing (MLST) has identified clones such as sequence type 2 (ST2) that are common in hospitals (15,(17)(18)(19)(20)(21)(22)(23)(24). However, a robust classification of S. epidermidis STs into larger groups of related STs has been lacking (25).…”

Identification of Methicillin-Resistant Staphylococcus Epidermidis (MRSE) in Mild, Moderate and Severe Acne Patients

“…While S. epidermidis has long been considered nonpathogenic, it is now recognized as a relevant opportunistic pathogen [9].…”