A. Ilki, P. Sagiroglu, N. Elgormus, U. Over-Hasdemir, G. Soyletir (Istanbul, TR)
Materials and Methods: Clinical strains of S. pneumoniae and H. influenzae isolated between 2002 and 2005 were included. In pneumococci, E-test was used for determination of MIC of penicillin, and susceptibility to other antimicrobials were performed by disk diffusion test (CLSI, M2-A8). Nevertheless, ampicillin MIC determinations were also studied in H. influenzae strains showing resistance to ampicillin in disk diffusion test. Nitrocefin was used for detection of beta-lactamase activity in H. influenzae.
Results: S. pneumoniae; Overall resistance to penicillin was 36.0%. Intermediate and full resistance to penicillin were 25.3% and 10.7%, respectively. Percentages of fully penicillin resistant pneumococci gradually decreased by year: 14.3% in 2003; 10.7% in 2004; 6.3% in 2005. There were no marked changes in MIC50 and MIC90 values over 3 years. Penicillin resistant pneumococci were also highly resistant to erythromycin, tetracycline and trimethoprim-sulfamethoxazole. No resistance was detected against ofloxacin and vancomycin (Table 1.). H. influenzae; Overall incidence of beta lactamase production was 2.8%. Ampicillin resistance was only determined in beta lactamase producers; except one beta lactamase negative isolate presenting increased MIC (2.0 µg/ml) of ampicillin. There was considerable resistance to chloramphenicol and trimethoprim-sulfamethoxazole in ampicillin resistant strains. None of the strains was found resistant to ampicillin sulbactam, azithromycin, and cefotaxime.
Conclusion: When compared with older studies in our hospital, full penicillin resistance in pneumococci reached to alarming levels with cross resistance to erythromycin, a commonly used alternative drug in respiratory tract pneumococcal infections. It is pleasant to observe no resistance to other alternative drugs including ofloxacin and vancomycin in pneumococci. Fortunately, ampicillin resistance in H.