Use of quantitative 16S ribosomal DNA detection for diagnosis of central vascular catheter-associated bacterial infection

Abstract

Many central vascular catheters (CVCs) are removed unnecessarily because current diagnostic methods for CVC-associated infection are unreliable. A quantitative PCR assay using primers and probe targeted to bacterial 16S ribosomal DNA was used to measure the levels of bacterial DNA in blood samples drawn through the CVC in a population of patients receiving intravenous nutrition. Bacterial DNA concentrations were raised in 16 of 16 blood samples taken during episodes of probable bacterial CVC-associated infection. Bacterial DNA concentrations were raised in 4 of 29 episodes in which bacterial CVC-associated infection was unlikely. The use of this technique has the potential to substantially reduce the unnecessary removal of CVCs.

FIG. 1.

Relationship between the apparent amounts of S. epidermidis and E. coli DNAs and the median C_t with three different sets of 16S rDNA primers and probes. The lowest C_t values indicate the highest concentrations of bacterial DNA.

FIG. 2.

C_t values in patients with probable CVC-associated bacterial infection and patients in whom CVC-associated infection was unlikely. C_t results are medians of three results.

FIG. 3.

Differences in median C_t values between CVC and peripheral blood sample. (C_t value for CVC blood − C_t value for peripheral blood).

FIG. 4.

Receiver-operating curve plotting true-positive rate (sensitivity) against false-positive rate (1 − specificity), showing the actual data (dashed line) and the modeled receiver-operating curve (solid line).