Streptococcus pneumoniae serotype 4 outbreak in a home for the aged: report and review of recent outbreaks.
OBJECTIVE
To describe a pneumonia outbreak caused by Streptococcus pneumoniae among residents of a home for the aged and to review contemporary pneumococcal outbreaks.


METHODS
Epidemiological investigation.


METHODS
S pneumoniae isolates were serotyped and analyzed by pulsed-field gel electrophoresis. Paired sera were tested for antibodies to pneumococcal surface adhesin A protein (PsaA, a 37-kDa cell-wall protein). Pneumococcal outbreaks reported in the last decade in English were reviewed.


RESULTS
Pneumonia developed in 18 of 200 residents. In 11 (61%), a pneumococcal etiology was demonstrated. S pneumoniae, serotype 4, was isolated from the blood cultures of 3 patients; all isolates were indistinguishable by pulsed-field gel electrophoresis. Pneumococcal involvement was established in 2 by sputum culture and latex agglutination of parapneumonic fluid and in 6 others by a twofold rise in optical density of serum antibody reactive to PsaA. Pneumococcal immunization had not previously been received by any patient; mortality was 22%. No additional cases were noted following administration of pneumococcal vaccine and antibiotic prophylaxis with penicillin or erythromycin. Twenty-six outbreaks of invasive pneumococcal disease since 1990 were reviewed. Twelve occurred in the United States, and serotypes 23F, 14, and 4 accounted for 8 (67%) of 12 outbreaks. All confirmed serotypes in US outbreaks are included in the 23-valent vaccine. More than one half of pneumococcal outbreaks worldwide involved elderly persons in hospitals or long-term-care facilities.


CONCLUSIONS
A pneumococcal pneumonia outbreak occurred among unvaccinated residents of a residential facility for the aged. Institutionalized elderly persons are at risk of outbreaks of pneumococcal disease and should be vaccinated.
Gleich
S
S
Division of Infectious Diseases, St John's Episcopal Hospital, Far Rockaway, New York 11691, USA.
Morad
Y
Y
Echague
R
R
Miller
J R
JR
Kornblum
J
J
Sampson
J S
JS
Butler
J C
JC
D000368:Aged; D000369:Aged, 80 and over; D004196:Disease Outbreaks; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006304:Health Status; D006707:Homes for the Aged; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D009519:New York City / Q000453:epidemiology; D018410:Pneumonia, Bacterial / Q000453:epidemiology*; D012703:Serotyping; D013290:Streptococcal Infections / Q000453:epidemiology*; D013296:Streptococcus pneumoniae / Q000145:classification / Q000302:isolation & purification*