Bacteremic pneumococcal pneumonia in one American City: a 20-year longitudinal study, 1978-1997

Area of Science:

• Infectious Diseases
• Epidemiology
• Public Health Surveillance

Background:

• Pneumococcal pneumonia remains a significant cause of morbidity and mortality worldwide.
• Understanding trends in incidence, serotypes, and outcomes is crucial for effective public health interventions.
• Antibiotic resistance patterns and treatment efficacy necessitate ongoing surveillance.

Purpose of the Study:

• To conduct a long-term surveillance of bacteremic pneumococcal pneumonia in Huntington, West Virginia (1978-1997).
• To analyze changes in case-fatality rates, disease incidence, prevalent capsular types, and antibiotic usage over time.
• To identify risk factors for mortality and evaluate the effectiveness of different treatment regimens.

Main Methods:

• Retrospective analysis of consecutive inpatient cases of bacteremic pneumococcal pneumonia.
• Serotyping of blood isolates using capsular swelling procedures.
• Abstraction of clinical data, treatment, and outcomes from hospital charts.

Main Results:

• Overall case-fatality rate was 20.3%, with higher rates in older adults (≥80 years: 37.7%).
• Case-fatality rates decreased significantly from 30.2% (1978-1982) to 15.6% (1993-1997).
• Incidence increased notably in young children (<4 years) and the elderly (≥70 years).
• Serotypes 1, 4, 9, 14, 3, 6, 12, 5, 23, and 19 were most common.
• Macrolide-based antibiotic regimens showed the lowest case-fatality rate (6%) in adults >50 years during 1993-1997.

Conclusions:

• Bacteremic pneumococcal pneumonia demonstrated evolving epidemiological patterns, including decreased fatality and increased incidence over the study period.
• Specific capsular types predominated, and their prevalence may have shifted.
• Combination antibiotic therapy including macrolides proved most effective in reducing mortality among older adults.