Drug-resistance in Streptococcus pneumoniae isolates among Spanish middle aged and older adults with community-acquired pneumonia.

BACKGROUND: Pneumococcal diseases remain a major cause of morbidity and mortality worldwide. Updated data on drug-resistance from different populations may be important to recognize changes in disease patterns. This study assessed current levels of penicillin resistance among Streptococcus Pneumoniae causing pneumonia in Spanish middle age and older adults.

METHODS: Antimicrobial susceptibility was tested for 104 consecutive isolates of Streptococcus pneumoniae recovered from patients 50 years or older with radiographically confirmed pneumonia in the region of Tarragona (Spain) between 2002 and 2007. According to the minimum inhibitory concentration of tested antimicrobials (penicillin, erythromycin, cefotaxime and levofloxacin) strains were classified as susceptible or resistant. Antimicrobial resistance was determined for early cases (2002-2004) and contemporary cases (2005-2007).

RESULTS: Twenty-seven (25.9%) were penicillin-resistant strains (19 strains with intermediate resistance and 8 strains with high resistance). Penicillin-resistance was higher in 2002-2004 than in 2005-2007 (39.5% vs 18.2%, p = 0.017).Of 27 penicillin-resistant strains, 10 (37%) were resistant to erythromycin, 8 (29.6%) to cefotaxime, 2 (7.4%) to levofloxacin, and 4 (14.8%) were identified as multidrug resistant. Case-fatality rate was higher among those patients who had an infection caused by any penicillin susceptible strain (16.9%) than in those with infections due to penicillin-resistant strains.

CONCLUSION: Resistance to penicillin among Streptococcus pneumoniae remains high, but such resistance does not result in increased mortality in patients with pneumococcal pneumonia.