Postoperative central nervous system infection: incidence and associated factors in 2111 neurosurgical procedures.

BACKGROUND Postoperative central nervous system infection (PCNSI) in patients undergoing neurosurgical procedures represents a serious problem that requires immediate attention. PCNSI most commonly manifests as meningitis, subdural empyema, and/or brain abscess. Recent studies (which have included a minimum of 1000 operations) have reported that the incidence of PCNSI after neurosurgical procedures is 5%-7%, and many physicians believe that the true incidence is even higher. To address this issue, we examined the incidence of PCNSI in a sizeable patient population. METHODS The medical records and postoperative courses for patients involved in 2111 neurosurgical procedures at our institution during 1991-2005 were reviewed retrospectively to determine the incidence of PCNSI, the identity of offending organisms, and the factors associated with infection. RESULTS The median age of patients at the time of surgery was 45 years. Of the 1587 cranial operations, 14 (0.8%) were complicated by PCNSI, whereas none of the 32 peripheral nerve operations resulted in PCNSI. The remaining 492 operative cases involved spinal surgery, of which 2 (0.4%) were complicated by PCNSI. The overall incidence of PCNSI was 0.8% (occurring after 16 of 2111 operations); the incidence of bacterial meningitis was 0.3% (occurring after 4 of 1587 operations), and the incidence of brain abscess was 0.2% (occurring after 3 of 1587 operations). The most common offending organism was Staphylococcus aureus (8 cases; 50% of infections), followed by Propionibacterium acnes (4 cases; 25% of infections). Cerebrospinal fluid leakage, diabetes mellitus, and male sex were not associated with PCNSI (P>.05). CONCLUSIONS In one of the largest neurosurgical studies to have investigated PCNSI, the incidence of infection after neurosurgical procedures was <1%--more than 6 times lower than that reported in recent series of comparable numerical size. Cerebrospinal fluid leak, diabetes mellitus, and male sex were not associated with an increased incidence of PCNSI. The results from this study indicate that the true incidence of PCNSI after neurosurgical procedures may be greatly overestimated in the literature and that, in surgical procedures associated with a high risk of infection, prophylaxis for S. aureus and/or P. acnes infection should be of primary concern.