Penicillin-Resistant Streptococcus pneumoniae in Iran

Objective: To determine the prevalence of penicillin-resistant Streptococcus pneumoniae isolated from patients with community-acquired pneumococcal infections. Materials and Methods: A broth dilution method was used to determine the minimum inhibitory concentration (MIC) of penicillin and other commonly used antibiotics. 115 heavy growth or pure culture of S. pneumoniae strains were isolated from: blood 10, cerebrospinal fluid (CSF) 15, ear 5, eye 12, purulent rhinosinusitis 48, sputum 22, and pleural fluid 3. Results: Of the 115 pneumococcoal isolates, 76 (66.1%) were sensitive to penicillin while the remaining 39 (33.9%) were nonsusceptible (15.6% resistant and 18.3% intermediately resistant). Among the 25 pneumococcal isolates from sterile sites (blood 15, CSF 10), 15 (60%) were penicillin-resistant whereas among the 90 isolates from nonsterile sites, 24 (26.7%) were resistant to penicillin ( 0.004). The MIC values of antibiotics tested for S. pneumoniae were: penicillin 0.008–4 μg/ml, chloramphenicol 0.25–32 μg/ml, erythromycin 0.008–128 μg/ml, tetracycline 0.06–64 μg/ml, vancomycin 0.03–0.5 μg/ml, azithromycin 0.016–128 μg/ml, ciprofloxacin 0.006–8 μg/ml, cefotaxime 0.007–2 μg/ml, and ceftriaxone 0.016–12 μg/ml. Conclusion: Approximately one third of S. pneumoniae isolated from the clinical specimens were nonsusceptible to penicillin in this region.