Objective: Treatment of respiratory tract infections due to Streptococcus pneumoniae is mostly empirical and depends on the local resistance rates in the relevant community to available drugs. Resistance manifests more frequently in certain serotypes. As serotypes isolated from clinical samples and antibiotic resistance frequencies may vary according to the vaccine used in the population, it is important to monitor the antibiotic resistance in clinical isplates of S. pneumoniae. The aim of this study was to determine the serotypes and resistance patterns to antibiotics of S. pneumoniae strains isolated from respiratory specimens of adult patients at the Adult Hospital of Hacettepe University in 2017.

Material and Methods: Streptococcus pneumoniae (n=52) strains were isolated from bronchoalveolar lavage fluids (n=4), tracheal aspirates (n=9) and sputum (n=39). Serogroups were determined by Pneumotest-Latex Kit (Statens Serum Institut, Denmark) with 14 antisera and, serotypes using factor antisera. Susceptibilities to penicillin, cefuroxime, ceftriaxone, vancomycin, moxifloxacin, levofloxacin, meropenem, erythromycin, clindamycin were determined by gradient test (Liofilchem® (Italia)) according to the EUCAST criteria.

Results: Rates of resistance against penicillin, cefuroxime, erythromycin and clindamycin in S. pneumoniae isolates were 61,5%, 23,1%, 53,8% and 30,8%, respectively. There was no resistance against ceftriaxone, meropenem, moxifloxacin, levofloxacin and vancomycin. The most common serotypes were 3 (n=15), 19F (n=6) and 8 (n=5). All isolates of S. pneumoniae serotypes 8 and 19F and eight isolates of serotype 3 were penicillin resistant. The rate of resistance to macrolides in serotypes 19F, 8 and 3 among S. pneumoniae isolates were 83,3%, 100% and 40%, respectively.

Conclusion: According to the results of this study, resistance to penicillin and macrolide antibiotics is high in respiratory tract isolates of S. pneumoniae. All serotypes resistant to macrolides and penicillins are in the coverage of 23- valent vaccine.