Mixed Bacterial Meningitis

1\vo recent cases of mixed bacterial meningitis at the Kansas City Veterans Administra-tion Medical Center were studied. A reviewof the literature suggests that IOJo of all cases of meningitis are caused by more than one bacterial species. Before 1950such cases oc-curredpredominantly in children and werecaused by combinations of bacteria commonly associated with meningitis. Since 1950 a largely adult population has been affected by mixed bacterial meningitis, with a higher incidence of gram-negative bacillary organisms cultured from the cerebrospinal fluid. Common predisposing factors in this older group of patients include infection at contiguous foci, tumors in close proximity to the central nervous system, or fistulous communications with the central nervous system. Mortality was 26OJo for cases occurring before 1950and 63OJo for those occuring after 1950. Failure to recognize one of the organisms present in the cerebrospinal fluid may result in the initi-tation of inadequate therapy in as many as 67OJo of cases. Empiric broad-spectrum an-timicrobial therapy is indicated in symptomatic patients predisposed to mixed bacterial meningitis until culture results become available. Bacterial meningitis is a significant cause of mor-bidityand mortalityin the UnitedStates.In general, the infectionresultsfrom invasion of the meninges bya singlespecies of bacterium, but casereports of mixed bacterialmeningitis (MBM)haveappearedin the literature since the early 1900s. Few literature compilations havedealt withMBM, especially in re-cent years. 1\vo cases of MBM at our institution prompted a review. of the literature to determine whichpatients are at riskof developing this condi-tion and whetherthesepatientscan be distinguished from patientsinfectedwitha single organismon the basisof associatedand underlyingillnesses, clinical presentation, or disease course. Case Report