Use of pulsed field gel electrophoresis to determine the source of microbial contamination of central venous catheters

Abstract

Microorganisms detected in situ on the distal tip of central venous catheters (CVC) within 90 min of insertion were investigated using pulsed-field gel electrophoresis to analyse genomic fragments obtained with the SmaI restriction enzyme. Thirty patients received a triple lumen CVC, which was inserted directly through the skin using the Seldinger technique. In a further 30 patients a triple lumen CVC was inserted through a Swan sheath, thereby avoiding direct contact of the CVC with the skin. Staphylococci were isolated from the distal tips of the catheters in 6 patients (5 who had the CVC inserted directly through the skin and 1 who had the CVC inserted via a Swan sheath.) Twenty-three staphylococcal isolates were also isolated from the insertion equipment and the skin swabs surrounding the insertion site of these six patients. All the isolates were genotyped. In one of the patients the organisms isolated from the skin were identical to those on the CVC tip. In two further patients similar organisms were isolated from the insertion equipment and the patients' skin. These results, in addition to the reduced colonisation rates observed when catheters were introduced through a Swan sheath, support the hypothesis that microorganisms from the skin are impacted onto the CVC tip and the CVC insertion equipment at catheter insertion.

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

“…These ST2 and ST54 CRBSI-specific PFGE types were observed causing CRBSI in patients otherwise epidemiologically unrelated (different units, different years), suggesting the persistence of these clones over time in our institution, as observed by others (34). Identification more precisely of the reservoir and the routes of colonization of venous catheters by these S. epidermidis clones would be useful to develop efficient prevention strategies, as several methods are possible and are commonly described: via the flora of the patient, who would have been progressively colonized with these hospitaladapted S. epidermidis isolates (autoinfection) or via the hands of colonized health care workers (cross-infection) (35)(36)(37). Some authors even evoke the role of ambient air in nosocomial MRSE transmission (38).…”

Central venous catheter-related bloodstream infection caused by Staphylococcus aureus: microbiology and risk factors

“…In the pathogenesis of CR-BSIs caused by S. aureus, the importance of nasal contamination by this microorganism is well established [49,50]. Sesso et al [51] showed that nasal decolonization reduces the risk of pericatheter colonization eight-fold and CR-BSI four-fold.…”

DNA fingerprinting analysis of coagulase negative staphylococci implicated in catheter related bloodstream infections

“…Because many species of staphylococci are resident in the skin at varying depths, skin swab cultures may not yield bacteria that are representative of all areas and depths of the skin. 13 Furthermore, sampling errors when choosing colonies from culture plates may affect results. In our study, in only six cases were the same coagulase negative staphylococci isolated from the central venous catheter and the skin entry site.…”