Central Nervous System Infections Caused by Acinetobacter baumannii.
Methods: We conducted a retrospective cohort study at Jackson Memorial Hospital, Miami, from January 2004 to December 2011. The cohort group consisted of cases with A. baumannii CNS infections; whereas the comparison group consisted of patients with CNS infections due to other Gram-negative bacilli. SAS software was used to perform statistical analysis.
Results: The A. baumannii group consisted of 26 patients, and the Gram-negative group included 39 patients. The A. baumannii patients were more likely to be in the Intensive Care Unit (ICU)(p=0.005), intubated (p=0.005) and have carbapenem resistance(p=0.001) than the comparison group. Groups were otherwise similar in terms of age, renal function, nosocomial acquisition of infection, prior neurosurgical procedures, appropriate antibiotic initiation within 24 hours of cerebrospinal fluid collection, and mean number of days to appropriate therapy. Crude mortality for the A. baumannii group and the comparison group was 38% and 25 % respectively, with relative risk(RR) of 1.5(95% CI, 0.73 --3.09). Clinical resolution was 77 % in the A. baumannii group, and 84% in the comparison group, with RR 1.5 (95% CI: 0.1-22.9). In univariate analysis, carbapenem resistance was associated with increased crude mortality (p=0.037). However, when controlling for the group, carbapenem resistance was associated with increased mortality in the Gram-negative group only but not in the A.baumannii group( p =0.013 vs p=1.000 respectively).
Conclusion: The Abaumannii patients were more likely to be intubated, in the ICU, and have carbapenem resistance. However, this did not result in difference in outcomes between the two groups. Carbapenem resistance was associated with increased mortality only in the Gram-negative bacilli group. This could possibly be related to difference in the organisms' degree of virulence, with A. baumannii being generally a low grade pathogen.
T. Cleary, None
N. Namias, None