Cerebrospinal Fluid Infection Associated with Silver-Impregnated External Ventricular Drain Catheters

Abstract

Silver-impregnated external ventricular drains (EVDs) have reduced the number of cases of ventriculitis. Risk factors for developing ventriculitis associated with plain EVD catheters have been well documented and incorporated into clinical practice, but risk factors in association with silver EVDs are unknown. Therefore, we sought to determine the risk factors for developing ventriculitis in patients with a silver EVD. Prospectively collected data on consecutive patients undergoing insertion of a silver-impregnated EVD between October 2011 and September 2013 were analyzed. Cerebrospinal fluid (CSF) infection was defined as positive CSF microbiologic culture. Univariate and multivariate regression was performed to identify independent risk factors for CSF infection. There were 362 EVDs placed in 263 patients (142 women; median age 52 years; interquartile range, 40-62 years). There were 15 infections (6.4 per 1000 days of EVD drainage) recorded. Gram-negative organisms (8 of 15) were most commonly observed, although Staphylococcus was the most common genus (7 of 15; 46%) identified. Univariate analysis indicated that patients requiring EVD replacement (P < 0.0001), patients requiring bilateral EVDs (P < 0.0001), and patients with a CSF leak (P < 0.0001) were at increased risk of infection. Only need for EVD replacement remained significant on multivariate analysis (P <0.0001, odds ratio= 15.9, confidence interval= 4.5-55.9). We identified an infection rate of 5.2% in this large contemporary series of patients undergoing silver EVD insertion according to a set protocol. These data suggest that targeting strategies to reduce Staphylococcus species is important, and increased vigilance for an increased incidence of gram-negative organisms is needed. Decreasing the need for EVD replacement is important in reducing infection rates further.