Penicillin-resistant Streptococcus pneumoniae in Iran

ABSTRACT

To determine the prevalence of penicillin-resistant Streptococcus pneumoniae isolated from patients with community-acquired pneumococcal infections. 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. 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 micro g/ml, chloramphenicol 0.25-32 micro g/ml, erythromycin 0.008-128 micro g/ml, tetracycline 0.06-64 micro g/ml, vancomycin 0.03-0.5 micro g/ml, azithromycin 0.016-128 micro g/ml, ciprofloxacin 0.006-8 micro g/ml, cefotaxime 0.007-2 micro g/ml, and ceftriaxone 0.016-12 micro g/ml. Approximately one third of S. pneumoniae isolated from the clinical specimens were nonsusceptible to penicillin in this region