Serial surveillance cultures of skin and catheter hub specimens from critically ill patients with central venous catheters: molecular epidemiology of infection and implications for clinical management and research

Abstract

A prospective study of 45 central venous catheters was conducted to assess, by strain delineation, the turnover of skin and catheter hub (superficial) colonization and the relative contributions of catheter hub and skin colonization to catheter tip colonization. Serial quantitative cultures of skin and catheter hub were performed. Catheter tip, blood, and specimens for culture from targeted superficial sites (TSSs) were also collected at the time of catheter removal. Strains from 17 tip-positive catheters were delineated by pulsed-field gel electrophoresis. Only 12 (28.6%) of 42 skin strains and 14 (31.1%) of 45 catheter hub strains were found to be present at the time of catheter removal. In addition, only 9 (29.0%) of the 31 tip-colonizing strains were present on TSSs. Moreover, 15 (48.4%) of the 31 tip-colonizing strains had a superficial origin, and the other 16 (51.6%) were of unknown origin. In catheters suspected of infection, cultures of TSSs had a negative predictive value for catheter-related bacteremia of 94.4% but a positive predictive value of 44.4%. When the causative agent was identified (to the strain level) these values dropped to 80.9 and 18.7%, respectively. The study shows that skin and catheter hub colonization is a common, dynamic phenomenon. Strains recovered from TSSs showed a low level of correlation with strains from previous cultures of specimens from superficial sites and catheter tip isolates. Consequently, TSSs cannot be recommended for use in determining the therapy. However, catheter-related bacteremia is uncommon when cultures of TSSs are negative.

Evidence for Nasal Carriage of Methicillin-Resistant Staphylococci Colonizing Intravascular Devices

“…However, of the 54 patients at risk of methicillin-resistant coagulase-negative staphylococcal catheter-related sepsis, only 20 (37%) were nasally colonized with the same strain, which suggests that nasal surveillance is not a sensitive indicator of patients at risk of sepsis. Similarly, other investigators found less than 30% of the strains were colonizing catheters in the skin and catheter hub cultured after catheter withdrawal (3). Two drawbacks may explain the lack of sensitivity of the methicillin-resistant coagulase-negative staphylococcus detection reported in our study.…”

“…In adults, coagulase-negative staphylococcus colonization remains stable over many years (14), and coagulase-negative staphylococci causing postoperative infections have the same resistance profiles as colonizing strains (1). However, other studies showed evidence for the changing nature of microbial skin colonization in neonates (3,6,26), concluding that surveillance cultures of superficial sites (3) or the catheter hub (26) are a poor reflection of catheter tip colonization and thus cannot be used to predict the development of catheter-related sepsis.…”

Microbial Profile of Various Catheter Tips among Hospitalized Patients

“…In previous study on growth positive tip culture was found 37.8% (Atela et al 1997) This study showed a highest growth in tracheostomytip followed by Urinary catheter, Et-tips, Suction tip, CVP and the least growth was in Drain tips. 70.9% urinary catheters were found to have signifi cant growth in our setting which was comparable with the result of a study done in India in which 69.6% catheters were found to have microbiological growth (Deep et al 2004).…”

Why Is It That Internists Do Not Follow Guidelines for Preventing Intravascular Catheter Infections?

“…Skin contamination at the insertion site of a short-term (indwelling time, 1 to 10 days), non-tunneled CVC with subsequent migration of pathogens along the extraluminal surface of the catheter has a major role in the development of a catheter-related BSI. [36][37][38][39][40] Greater numbers of organisms at the skin insertion site increase the likelihood of catheter-related BSI. Use of maximal barrier precautions is believed to reduce skin contamination by the CVC inserter, whereas chlorhexidine gluconate likely reduces the impact of colonizing organisms.…”