Outbreak of Pneumonia in the Setting of Fatal Pneumococcal Meningitis among US Army Trainees: Potential Role of Chlamydia pneumoniae Infection

We reviewed surveillance data on pneumonia and febrile respiratory illness at the training facility; conducted chart reviews for cases of radiologically-confirmed pneumonia; and administered surveys and collected nasopharyngeal swabs from trainees in the outbreak battalion (Alpha and Hotel Companies), associated training staff, and trainees newly joining the battalion.Among Alpha and Hotel Company trainees, the average weekly attack rates of radiologically-confirmed pneumonia were 1.4% and 1.2% (most other companies at FLW: 0-0.4%). The pneumococcal carriage rate among all Alpha Company trainees was 15% with a predominance of serotypes 7F and 3. Chlamydia pneumoniae was identified from 31% of specimens collected from Alpha Company trainees with respiratory symptoms.Although the etiology of the outbreak remains unclear, the identification of both S. pneumoniae and C. pneumoniae among trainees suggests that both pathogens may have contributed either independently or as cofactors to the observed increased incidence of pneumonia in the outbreak battalion and should be considered as possible etiologies in outbreaks of pneumonia in the military population.Military trainees are at increased risk for respiratory infections compared to the general civilian population[1]. Crowded living conditions and intense physical stress may contribute to an increased risk for infections with Streptococcus pneumoniae, Streptococcus pyogenes, Mycoplasma pneumoniae, Chlamydia pneumoniae, Bordetella pertussis, adenoviruses, and influenza viruses[1-3]. Outbreaks of pneumococcal disease are relatively rare in the general civilian population, but sporadic outbreaks of pneumococcal pneumonia have been reported among military trainees in the past[4-8]. We describe the investigation of an outbreak of radiologically-confirmed pneumonia in the setting of two fatal cases of pneumococcal meningitis that occurred in February, 2009, at a Fort Leonard Wood, MO military training facility. The findings of