Antimicrobial resistance in clinical isolates of Streptococcus pneumoniae in a tertiary hospital in Kuwait, 1997–2007: Implications for empiric therapy

Summary 

Objective

This study evaluated antibiotic resistance trends in Streptococcus pneumoniae isolated in a tertiary hospital in Kuwait and its implications for empiric therapy.

Materials and methods

Antimicrobial susceptibility of 1353 strains of S. pneumoniae isolated from clinical specimens during 1997–2007 was performed by disc diffusion method. MIC was determined by E test. The results were compared for 1997–2001, 2002–2005 and 2006–2007.

Results

The prevalence of resistance for the respective periods were as follows: penicillin, 51.3%, 61.3% and 54.5%; erythromycin, 31.2%, 36.7% and 37.7%; tetracycline, 30.8%, 45.3% and 41.3%; co-trimoxazole, 49.5%, 58.5% and 62.8%; clindamycin, 20.4%, 20.6% and 24.5% and chloramphenicol, 8.1%, 8.9% and 3.7%. All were susceptible to vancomycin and rifampicin. For oxacillin-resistant isolates, penicillin resistance was rare (0.8%) with the new non-meningeal breakpoint. However, using the meningeal breakpoints, resistance increased for penicillin from 0.6%, to 28.7%, for cefotaxime from none to 16.5%, and for ceftriaxone from none to 7%. Intermediate resistance to meropenem increased from 1.7% to 22.4%. Multiple drug resistance increased from 22.4% to 37.8%.

Conclusion

The study demonstrated that antimicrobial resistance of S. pneumoniae is increasing in Kuwait. However, the results of MIC determinations indicated that penicillin can still be used for therapy of non-meningeal infections. High prevalence of erythromycin resistance suggests that therapy of pneumonia with a macrolide alone may result in failure and should be based on results of susceptibility testing.

Keywords: Streptococcus pneumoniae, Antibiotic resistance, E test, Penicillin resistance, Cefotaxime resistance, Erythromycin resistance