October - December 2011: 
Volume 24, Issue 4

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Pneumon 2011, 24(4):379-391
The clinical significance of Streptococcus pneumoniae resistance in community-acquired pneumonia
SUMMARY. As resistance to Streptococcus pneumoniae has escalated dramatically over the past decades, the efficacy of the three major classes of antibiotics most commonly used for the empirical treatment of community-acquired pneumonia (CAP), (i.e., β-lactams, macrolides and respiratory quinolones) is under investigation. According to recently published international data 21.8% of strains of S. pneumoniae are penicillin non-susceptible and 36.3% are resistant to azithromycin. Rates of quinolone resistance remain low, but clonal spread of resistant strains has been reported in closed communities. The precise clinical impact of antimicrobial resistance is difficult to assess, but treatment failures due to antibiotic-resistant S. pneumoniae have been documented. Comparison of the relatively small number of failures with the magnitude of confirmed resistance reveals a paradox that has not been clarified and possibly involves both pharmacokinetic and pharmacodynamic parameters. It is evident that the final outcome of CAP depends not only on the therapeutic regime but also on a variety of factors including the genetic characteristics of the bacterial strain and the background of the patient. Knowledge of the mechanisms of the emergence and spread of resistance is necessary for the rational selection of appropriate antibiotics. Current data suggest that the possibility of penicillin resistance should not be a leading factor for the choice of the therapeutic regime in CAP. In Greece, monotherapy of CAP with a macrolide poses clinical risks, while quinolones should be used with caution. In the setting of increasing resistance the administration of the appropriate antimicrobial therapy is essential for the prevention of emerging infections due to resistant S. pneumoniae strains, which apart from the increased cost of treatment may lead to an unfavourable outcome. Pneumon 2011, 24(4):379-391.