Comparative antimicrobial susceptibilities of Streptococcus pneumoniae and Haemophilus influenzae in a university hospital in Turkey

Sağıroğlu P. , İlki Z. A.

16th European Congress of Clinical Microbiology and Infectious Diseases , Nice, Fransa, 1 - 04 Nisan 2006, cilt.12, no.4, ss.384-480


P1308 Comparative antimicrobial susceptibilities of Streptococcus pneumoniaeand Haemophilus influenzae in a university hospital in Turkey

A. Ilki, P. Sagiroglu, N. Elgormus, U. Over-Hasdemir, G. Soyletir (Istanbul, TR)

Objective: Increasing rates of resistance in both Streptococcus pneumoniae and Haemophilus influenzae to clinically useful antimicrobials are major concern worldwide. In this study we aimed to investigate the comparative susceptibility patterns of these pathogens to antimicrobials (Table 1.).

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.

Table 1. Comparative resistance rates to larious antimicrobials in isolates S. pneumoniae and H. influenzae isolates

S. pneumoniae (n: 150)H. influenzae (n:387)
AntimicrobialsAll isolates (n:150)PR* (n:54)All isokites (n.387)BL** positives (n:11)
Penicillin54 (36.0)54 (100)
Erythromycin23 (15.4)19 (35.2)
Tetracycline21 (14.0)17 (31.5)
Tnmethoprim-sulfimetlioxaiole57 (38.0)35 (64.8)90 (23.3)7 (63.6)
Chlorampenicol8 (5.3)6 (11.1)7 (1.8)4 (36.4)
Ampicillin12 (3.1)11 (100)
Cefcclor3 (0.8)1 (9.1)

Penicillin resistant isolate


Beta lactamases

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. influenzae is still in its initiative levels and seems to be totally due to beta-lactamase production.