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Infections caused by erythromycin-resistant Streptococcus pneumoniae: incidence, risk factors, and response to
S Moreno1, M E García-Leoni, E Cercenado
1Department of Clinical Microbiology and Infectious Diseases, Hospital General Gregorio Marañón, Madrid, Spain.
Abstract:
To evaluate the incidence and the significance of resistance to erythromycin among clinical isolates of Streptococcus pneumoniae, we identified and prospectively followed all hospitalized patients in a 27-month period who had the organism isolated from any clinical sample. Patients who had an infection caused by pneumococci resistant to erythromycin (minimum inhibitory concentration, > 1 microgram/mL) were compared to those with infections caused by erythromycin-susceptible organisms. The incidence of erythromycin resistance among pneumococci doubled over the study period (from 7.6% in 1988 to 15.2% in 1992). Most strains (94%) showed resistance to multiple antibiotics, including other macrolides. By multivariate analysis, an age of < 5 years and nosocomial acquisition of the infection were independent risk factors for erythromycin resistance. Among patients with pneumococcal pneumonia caused by erythromycin-resistant organisms, 9 patients treated with third-generation cephalosporins were cured, while therapy with erythromycin failed for 2 of the 6 patients to whom it was administered. The rapid and significant increase of erythromycin resistance among clinical isolates of S. pneumoniae points to the need for routine surveillance of pneumococcal resistance.
Insights
Erythromycin resistance in Streptococcus pneumoniae doubled between 1988 and 1992. Young children and hospital-acquired infections were key risk factors, highlighting the need for resistance surveillance.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Erythromycin resistance in Streptococcus pneumoniae is a growing concern.
- Macrolide resistance poses a significant threat to treating bacterial infections.
Purpose of the Study:
- To determine the incidence and clinical significance of erythromycin resistance in Streptococcus pneumoniae.
- To identify risk factors associated with erythromycin-resistant pneumococcal infections.
Main Methods:
- Prospective study of hospitalized patients over 27 months.
- Comparison of patients with erythromycin-resistant versus susceptible pneumococcal isolates.
- Multivariate analysis to identify independent risk factors.
Main Results:
- Incidence of erythromycin resistance in S. pneumoniae doubled from 7.6% to 15.2% (1988-1992).
- 94% of resistant strains showed multi-drug resistance, including other macrolides.
- Younger age (<5 years) and nosocomial infection were independent risk factors for resistance.
Conclusions:
- The rapid increase in erythromycin resistance necessitates routine surveillance of pneumococcal resistance.
- Third-generation cephalosporins were effective in treating resistant pneumococcal pneumonia, unlike erythromycin.