Risk Factors for Meningitis Following Cerebral Angiography: A Case-Control Study

BACKGROUND/OBJECTIVES: During May-August 2004, an increased rate of meningitis was noted among patients admitted to Shands Hospital (SH) with intracranial hemorrhage or cerebral aneurysms, and who underwent angiography and embolization of the cerebral vasculature. Infection control initiated an investigation to (i) determine the cause of the outbreak; (ii) identify associated risk factors; and (iii) implement appropriate control measures. METHODS: An epidemic curve was constructed for January-October 2004 (study period) followed by a retrospective case-control study. Also, observational studies were conducted to assess practices and procedures. A case was defined as any adult patient who acquired meningitis after undergoing cerebral angiography during the study period. Cases were ascertained through review of patient medical charts and microbiology records. Data were recorded in a standardized questionnaire and included age, sex, severity of illness scores, prior hospitalization, medical device usage, duration of hospitalization, co-morbidities, administration of pre-angiography antimicrobial prophylaxis, surgeon, and outcome (death or survived). Odds ratios (OR) and 95% confidence intervals (CI) were calculated. Fisherʹs exact test was used, where appropriate. RESULTS: Post-operative meningitis rates in pre-epidemic and epidemic periods were 3.1% and 18.5%, respectively (p < 0.05). Eight patients met the case definition; 19 controls were randomly selected. Case characteristics: median age 55 (range 40-71) years; 5 (63%) female; all Caucasian. Case and controls were similar for intensive care unit stay, coiling procedure, surgeon, co-morbidities, serum biochemistry, receipt of antimicrobials, and survival. In contrast, cases were significantly more likely to be obese (i.e. body mass index >32, p < 0.001); have an arterial line (p < 0.005), central venous line (p < 0.0001), nasogastric tube (p < 0.007), ventriculostomy (p < 0.001), or ventilator (p < 0.05); transfer from another hospital (p < 0.05); to have undergone emergency angiography (p < 0.0001); or to have higher severity of illness scores (p < 0.05). CONCLUSIONS: Patients who acquired meningitis following angiography at SH during the study period appeared to have intrinsic risk factors associated with severity of the intracranial hemorrhage. Neither coiling procedures nor the surgeons who performed the angiography were found to be associated risk factors as was presumed. Moreover, receipt of pre-angiography antimicrobials appeared not to be protective against the acquisition of meningitis. Obese patients with severe intracranial hemorrhage transferred from an outside hospital were at increased risk of meningitis post angiography. Lennox K. Archibald, MD, FRCP, Rengeration Technologies Inc, Employee. Also please note: A version of this abstract was also submitted to SHEA 2006.