Rapp NS, Gilroy J, Lerner AM : Role of bacterial infection in exacerbation of multiple sclerosis.Am J Phys Med Rehabil1995;74 :415—418.One hundred consecutive patients admitted to the hospital with a diagnosis of exacerbation of multiple sclerosis were evaluated for an infectious process. All patients received a complete blood count, urinalysis, urine culture with susceptibility studies, blood cultures, and a chest x-ray at the time of admission. A control group of 55 patients carrying the diagnosis of multiple sclerosis but without symptoms of neurologic decline were also studied. Thirty-five percent of patients experiencing exacerbation of their disease were identified as having a significant bacterial infection compared with 11 % in the control group with quiescent disease. These results were significant with aPvalue of <0.001. When presumptive viral and bacterial infections diagnosed before admission were included, almost 50% of patients could have had an exacerbation of their disease in response to an infectious process. Bacterial infection might well play a role in precipitating relapse in multiple sclerosis as well as influencing treatment.