Background: The benefit of antibiotic prophylaxis for intracranial pressure (ICP) monitors remains
controversial, and clinical practice varies widely. Whether any antibiotic coverage, particularly
broad-spectrum coverage, reduces monitor-related infections remains unproved, and
exposure to antibiotics may affect the susceptibility patterns of pathogens producing subsequent
infectious complications. Despite the lack of data supporting its use, our level I trauma
center had a long-standing ICP monitor prophylaxis protocol that provided broad-spectrum
coverage that included ceftriaxone. In April 2002, a protocol change was instituted that substituted
cefazolin for ceftriaxone as single-agent prophylaxis for ICP monitors.
Hypothesis: Broader-spectrum antibiotic prophylaxis does not reduce ICP monitor-related
infections but is associated with acquisition of more drug-resistant infections than narrowspectrum
prophylaxis.
Methods: To evaluate the influence of broad- versus narrow-spectrum prophylaxis, a threeyear
period encompassing each practice was selected. All injured patients with ICP monitors
placed between January 1, 2001, and December 31, 2003 (n = 279), were identified using the Vanderbilt
trauma database. Antibiotic prophylaxis for ICP monitors was determined using the hospital
financial database to identify all antibiotics given to individual patients and subsequent
chart review to identify those antibiotics given solely for ICP prophylaxis. A total of 119 patients
received narrow-spectrum (either cefazolin or vancomycin; n = 100) or no (n = 19) prophylaxis,
whereas 160 received broad-spectrum prophylaxis (ceftriaxone or ciprofloxacin). The two groups
did not differ with respect to baseline demographics, type of ICP monitor, or duration of monitor
placement. Infectious complications were determined by continuous infection surveillance
utilizing standard U.S. Centers for Disease Control and Prevention National Nosocomial Infection
Surveillance System (CDC-NNIS) definitions and maintained in a contemporary database.
The influence of broad-spectrum antibiotic prophylaxis on both ICP monitor infections and subsequent
infections outside the central nervous system (CNS) was determined.
Results: Nine patients (3.2%) developed CNS infections; two of 119 patients (1.7%) who received
narrow-spectrum or no prophylaxis versus seven of 160 patients (4.4%) who received protobroad-
spectrum prophylaxis (p = NS). Only the duration of monitor placement and Injury
Severity Score were associated with the infection rate. In the total population, 185 infections
occurred in 93 patients (33%). Infection rates did not differ between patients who received
narrow-spectrum or no prophylaxis (32%) and those who received broad-spectrum prophylaxis
(34%). However, patients who received broad-spectrum prophylaxis acquired gram-negative
infections with significantly greater antibiotic resistance.
Conclusions: Broad-spectrum antibiotic prophylaxis of ICP monitors does not reduce CNS
infections, but is associated with a shift to resistant gram-negative pathogens in subsequent
infectious complications. Thus, broad-spectrum antibiotic prophylaxis of ICP monitors should
be eliminated or minimized unless data from randomized trials prove its utility.
