title: Pneumonia outbreak associated with group a Streptococcus species at a military training facility.
abstract: BACKGROUND
  Although group A streptococci (GAS) infections are a major cause of morbidity and mortality, outbreaks of associated pneumonia are rare. We report an outbreak of GAS pneumonia that occurred at a US military training camp.
  
  
  METHODS
  Standard epidemiologic and laboratory procedures were used to characterize the outbreak and causative organism(s). A case-control study and determination of the prevalence of GAS infection among camp personnel were also performed.
  
  
  RESULTS
  A total of 162 of 4500 Marine Corps personnel were hospitalized for respiratory symptoms during the period of 1 November and 20 December 2002, and 127 (78%) had radiographically confirmed pneumonia. The attack rate was 1.6 cases per 100 person-months. Thirty-four (27%) of 127 patients with pneumonitis had definite or probable GAS pneumonia; an additional 22 (17.3%) were coinfected with GAS and another pathogen. Pathogens, in addition to GAS, included Chlamydia pneumoniae (27 patients), Mycoplasma pneumoniae (19), adenovirus (5), and Streptococcus pneumoniae (2). A survey revealed that the pharyngeal carriage rate of GAS among camp personnel was 16%. Molecular characterization of the GAS isolates found emm type 3, multilocus sequence type 15. The epidemic ended after administration of additional prophylaxis with a single dose of intramuscular benzathine penicillin (1.2 million U) or azithromycin (1 g orally). Because the number of days from the last penicillin injection was correlated with a positive throat culture result and the occurrence of pneumonia, the dosing interval of benzathine penicillin was shortened from every 28-35 days to every 21 days.
  
  
  CONCLUSIONS
  This is the largest outbreak of GAS pneumonia reported in >30 years. This outbreak emphasizes the potential for GAS to cause epidemics of severe infection and demonstrates the need for surveillance and consideration of appropriate antibiotic prophylaxis among particularly high-risk populations.
authors.affiliation: Infectious Diseases Division, Clinical Investigation Dept., Naval Medical Center San Diego, CA 92134-1005, USA. nfcrum@nmcsd.med.navy.mil
authors.forename: Nancy F
authors.initials: NF
authors.lastname: Crum
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Russell
authors.forename: Edward L
authors.initials: EL
authors.lastname: Kaplan
authors.forename: Mark R
authors.initials: MR
authors.lastname: Wallace
authors.forename: Jianguo
authors.initials: J
authors.lastname: Wu
authors.forename: Parvin
authors.initials: P
authors.lastname: Ashtari
authors.forename: Dana J
authors.initials: DJ
authors.lastname: Morris
authors.forename: Braden R
authors.initials: BR
authors.lastname: Hale
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D019072:Antibiotic Prophylaxis; D002353:Carrier State / Q000188:drug therapy / Q000382:microbiology; D016022:Case-Control Studies; D004196:Disease Outbreaks; D006801:Humans; D008889:Military Personnel; D010406:Penicillins / Q000627:therapeutic use; D010614:Pharynx / Q000382:microbiology; D018410:Pneumonia, Bacterial / Q000453:epidemiology* / Q000382:microbiology; D011024:Pneumonia, Viral / Q000453:epidemiology / Q000821:virology; D015995:Prevalence; D013290:Streptococcal Infections / Q000188:drug therapy / Q000453:epidemiology* / Q000517:prevention & control; D013297:Streptococcus pyogenes; D014481:United States / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents; D010406:Penicillins