To characterize risk factors associated with pneumococcal disease and asymptomatic colonization during an outbreak of multidrug-resistant Streptococcus pneumoniae (MDRSP) among AIDS patients in a long-term–care facility (LTCF), evaluate the efficacy of antimicrobial prophylaxis in eliminating MDRSP colonization, and describe the emergence of fluoroquinolone resistance in the MDRSP outbreak strain.

Epidemiologic investigation based on chart review and characterization of SP strains by antimicrobial susceptibility testing and PFGE and prospective MDRSP surveillance.

An 80-bed AIDS-care unit in an LTCF.

Staff and residents on the unit.

From April 1995 through January 1996, 7 cases of MDRSP occurred. A nasopharyngeal (NP) swab survey of all residents (n = 65) and staff (n = 70) detected asymptomatic colonization among 6 residents (9%), but no staff. Isolates were sensitive only to rifampin, ofloxacin, and vancomycin. A 7-day course of rifampin and ofloxacin was given to eliminate colonization among residents: NP swab surveys at 1, 4, and 10 weeks after prophylaxis identified 1 or more colonized residents at each follow-up with isolates showing resistance to one or both treatment drugs. Between 1996 and 1999, an additional 6 patients were diagnosed with fluoroquinolone-resistant (FQ-R) MDRSP infection, with PFGE results demonstrating that the outbreak strain had persisted 3 years after the initial outbreak was recognized.

Chemoprophylaxis likely contributed to the development of a FQ-R outbreak strain that continued to be transmitted in the facility through 1999. Long-term control of future MDRSP outbreaks should rely primarily on vaccination and strict infection control measures.

We describe an effort to reduce transmission of a multidrug-resistant Streptococcus pneumoniae (MDRSP) in a long-term-care facility (LTCF).

Longitudinal cross-sectional study.

An LTCF in New York City with ongoing disease due to an MDRSP strain among residents with AIDS since a 1995 outbreak. The MDRSP outbreak strain was susceptible to vancomycin but not to other antimicrobials tested, including fluoroquinolones.

Residents and staff members of the LTCF during 1999 through 2001.

Implementing standard infection control measures, and developing and implementing "enhanced standard" infection control measures, modified respiratory droplet prevention measures to reduce inter-resident transmission.

Before the intervention, nasopharyngeal carriage of the MDRSP outbreak strain was detected in residents with AIDS and residents with tracheostomies who were not dependent on mechanical ventilation. The prevalence of nasopharyngeal carriage of the MDRSP outbreak strain was 7.8% among residents who had AIDS and 14.6% among residents with tracheostomies. After training sessions on standard and enhanced standard infection control measures, the staff appeared to have good knowledge and practice of the infection control measures. After the intervention, new transmission among residents with tracheostomies was prevented; however, these residents were prone to persistent tracheal carriage and needed ongoing enhanced standard infection control measures. Ongoing transmission among residents with AIDS, a socially active group, was documented, although fewer cases of disease due to the outbreak strain occurred.

Infection control contributed to less transmission of MDRSP in the LTCF. Additional strategies are needed to reduce transmission and carriage among certain resident populations.

To describe a pneumonia outbreak caused by Streptococcus pneumoniae among residents of a home for the aged and to review contemporary pneumococcal outbreaks.

Epidemiological investigation.

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.

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.

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.