Three types of antiseptic or antibiotic impregnated central venous catheters (CVCs) are commercially available. Only one study has examined the durability of these catheters (chlorhexidine/silver sulfadiazine vs minocycline/rifampin (MR)). We hypothesized that CVCs coated with MR have a longer antimicrobial activity as a function of duration of catherization compared to silver/carbon/platinum (SPC) CVCs.
The UMMS Human Subjects Committee approved this study. Insertion of antiseptic CVCs was rotated on a monthly basis in the surgical intensive care unit. When CVCs were removed, the catheters were flushed and cut in 1 cm segments to be used for modified Kirby-Bauer testing. Bacteria isolates (S. aureus, S. epidermidis, E. coli, enterococcus and P. aeruginosa) were obtained from the hospital microbiology laboratory, grown to 1.5 MacFarland standard and plated onto blood agar plates. The CVC segments were imbedded at right angles into the agar. The plates were incubated at 37°C for 24 hours. The zone of inhibition (ZOI) of bacterial growth was measured with a caliper. Data were analyzed using a general linear model (Statistica, Tulsa, OK). The null hypothesis was rejected for p<0.05.
Forty-two SPC and 47 MR catheters were recovered from patients. Baseline activity against the test organisms was significantly higher with the MR CVCs than the SPC CVCs. Inhibition of bacterial growth persisted for a much longer duration of time with the MR CVCs than with the SPC CVCs with the exception of P. aeruginosa (Figure, organism: S. epidermidis).
Antimicrobial activity of MR CVCs against the common organisms causing catheter-related bloodstream infections (CRBSI) persisted for a longer period of time as a function of duration of catheterization compared to SPC CVCs.
These data predict better clinical efficacy of MR CVCs compared to SPC CVCs in the prevention of CRBSI.
Theofilus Matheos, Other Unused catheters were gifts from Cook Critical Care and Edwards Life Sciences.