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Streptococcus pneumoniae resistant to penicillin: incidence and potential therapeutic options
W J Rodriguez1, R H Schwartz, S Akram
1Department of Infectious Diseases, Children's National Medical Center, Washington, D.C. 20010-2970.
Abstract:
Streptococcus pneumoniae was recovered from 12 (50%) samples of middle ear fluid of 24 consecutive patients with AOME and in mixed culture of middle ear pathogens from one (4%) additional specimen. Two (15.3%) isolates had intermediate resistance to penicillin (minimal inhibitory concentration (MIC) 0.125 and 1.0 micrograms/mL). The antimicrobial susceptibility to various antimicrobials of 30 S pneumoniae strains recovered from patients seen in the last 12 months was also determined. One of the patients with AOME developed bacteremia that resolved uneventfully, whereas the other developed meningitis. MIC90 was determined from penicillin (2 micrograms/mL), erythromycin (> 32 micrograms/mL), cefaclor (32 micrograms/mL), loracarbef (> or = 64 micrograms/mL), cefixime (16 micrograms/mL), ceftibuten (> 64 micrograms/mL), chloramphenicol (16 micrograms/mL), cefpodoxime (4 micrograms/mL), ciprofloxacin (2 micrograms/mL), cephalexin (> or = micrograms/mL), augmentin (2 micrograms/mL), cefprozil (8 micrograms/mL), clindamycin (64 micrograms/mL), TMP-SXT (> 64 micrograms/mL), clarithromycin (32 micrograms/mL), rifampin (0.06 micrograms/mL), cefuroxime (2 micrograms/mL), cefotaxime (0.25 micrograms/mL), vancomycin (0.25 micrograms/mL), and imipenem (0.5 micrograms/mL). Cefprozil, vancomycin, and rifampin inhibited all strains, whereas cefpodoxime, cefuroxime, clindamycin, and clarithromycin exhibited very good activity.
Insights
Streptococcus pneumoniae, a common cause of acute otitis media (AOME), showed intermediate resistance to penicillin in some isolates. Cefprozil, vancomycin, and rifampin effectively inhibited all tested S. pneumoniae strains.
Area of Science:
- Microbiology
- Infectious Diseases
- Clinical Medicine
Background:
- Acute otitis media (AOME) is frequently caused by Streptococcus pneumoniae.
- Understanding antimicrobial resistance patterns is crucial for effective AOME treatment.
Purpose of the Study:
- To investigate the prevalence of Streptococcus pneumoniae in AOME cases.
- To determine the antimicrobial susceptibility of S. pneumoniae isolates from AOME patients.
Main Methods:
- Middle ear fluid samples from 24 AOME patients were cultured.
- Antimicrobial susceptibility testing (MIC) was performed on 30 S. pneumoniae strains.
- MIC90 values were determined for various antibiotics.
Main Results:
- Streptococcus pneumoniae was isolated from 50% of middle ear fluid samples.
- Two isolates (15.3%) exhibited intermediate resistance to penicillin.
- Cefprozil, vancomycin, and rifampin demonstrated complete inhibition of all tested strains.
Conclusions:
- Streptococcus pneumoniae is a significant pathogen in AOME.
- While some penicillin resistance exists, several antibiotics like cefprozil, vancomycin, and rifampin remain effective against S. pneumoniae causing AOME.