title: An outbreak of multidrug-resistant pneumococcal pneumonia and bacteremia among unvaccinated nursing home residents.
abstract: BACKGROUND
  Outbreaks of pneumococcal disease are uncommon and have occurred mainly in institutional settings. Epidemic, invasive, drug-resistant pneumococcal disease has not been seen among adults in the United States. In February 1996, there was an outbreak of multidrug-resistant pneumococcal pneumonia among the residents of a nursing home in rural Oklahoma.
  
  
  METHODS
  We obtained nasopharyngeal swabs for culture from residents and employees. Streptococcus pneumoniae isolates were serotyped and compared by pulsed-field gel electrophoresis. A retrospective cohort study was conducted to identify factors associated with colonization and disease.
  
  
  RESULTS
  Pneumonia developed in 11 of 84 residents (13 percent), 3 of whom died. Multidrug-resistant S. pneumoniae, serotype 23F, was isolated from blood and sputum from 7 of the 11 residents with pneumonia (64 percent) and from nasopharygeal specimens from 17 of the 74 residents tested (23 percent) and 2 of the 69 employees tested (3 percent). All the serotype 23F isolates were identical according to pulsed-field gel electrophoresis. Recent use of antibiotics was associated with both colonization (relative risk, 2.3; 95 percent confidence interval, 1.3 to 4.2) and disease (relative risk, 3.6; 95 percent confidence interval, 1.2 to 10.8). Only three residents (4 percent) had undergone pneumococcal vaccination. After residents received pneumococcal vaccine and prophylactic antibiotics, there were no additional cases of pneumonia, and the rates of carriage decreased substantially.
  
  
  CONCLUSIONS
  In this outbreak a single pneumococcal strain was disseminated among the residents and employees of a nursing home. The high prevalence of colonization with a virulent organism in an unvaccinated population contributed to the high attack rate. Clusters of pneumococcal disease may be underrecognized in nursing homes, and wider use of pneumococcal vaccine is important to prevent institutional outbreaks of drug-resistant S. pneumoniae infection.
authors.affiliation: Epidemiology Program Office, Respiratory Diseases Branch, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Nuorti
authors.forename: J C
authors.initials: JC
authors.lastname: Butler
authors.forename: J M
authors.initials: JM
authors.lastname: Crutcher
authors.forename: R
authors.initials: R
authors.lastname: Guevara
authors.forename: D
authors.initials: D
authors.lastname: Welch
authors.forename: P
authors.initials: P
authors.lastname: Holder
authors.forename: J A
authors.initials: JA
authors.lastname: Elliott
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016470:Bacteremia / Q000453:epidemiology* / Q000382:microbiology; D001428:Bacterial Vaccines; D015331:Cohort Studies; D004196:Disease Outbreaks; D018432:Drug Resistance, Multiple; D005260:Female; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D009735:Nursing Homes; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology* / Q000382:microbiology; D012189:Retrospective Studies; D012307:Risk Factors; D013296:Streptococcus pneumoniae / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification*
chemical_list: D001428:Bacterial Vaccines