Mycoplasma pneumoniae: A Frequent Cause of Pneumonia among U.S. Marines in Southern California

From August 1993 through April 1994, U.S. Marines (98% male, median age 20 years) who were hospitalized with radiographically confirmed pneumonia were prospectively studied for evidence of acute Mycoplasma pneumoniae infection. Overall, 32 (36.4%) of the 88 patients with paired sera had evidence of acute infection by an elevated immunoglobulin M titer (22.7%), a 4-fold rise in immunoglobulin G titer (9.1%), a positive polymerase chain reaction result (11.1%), and/or a positive culture (5.8%). No specific symptoms or clinical findings were strong predictors of M. pneumoniae infection. Among patients with evidence of acute M. pneumoniae infection, admitting clinicians chose other pathogens as more likely etiologic agents 46.4% of the time, and over the course of the hospitalization, 10% of patients failed to receive appropriate antibiotics. These data indicate that M. pneumoniae may cause a high proportion of pneumonias among military personnel and should be considered in empiric treatment and prophylaxis.