[Flouroquinolone activity in clinical isolates of Streptococcus pneumoniae with different susceptibility to penicilline: an epidemiological study in five cities of Mexico].

Objective: Determine the susceptibility to five fluoroquinolones and cross-resistance of pneumococcusclinical isolates with different penicillin susceptibilities gathered in a community-based study.
Design: Cross-sectional survey.
Materials: Two hundred and thirty one (231) isolates were obtained from respiratory secretions or blood specimens from 231 patients with acquired acute respiratory infection or bacteremia.
Outcome Measures: In vitro susceptibility to penicillin (PEN), ciprofloxacin (CIP), levofloxacin (LEV), gatifioxacin (GAT), moxifloxacin (MOX) and gemifioxacin (GEM) was determined with minimal inhibitory concentration (MIC) using the E test.
Results: 42% of the isolates showed decreased susceptibility to PEN. The lowest antibiotic concentration that inhibited 90% of the isolates was 3 microg/ml (for CIP), 1 microg/ml (for LEV), 0.25 microg/ml (for GAT), 0.125 microg/ml (for MOX) and 0.032 microg/ml (for GEM). Median MIC for LEV, GAT, MOX and GEM increased with decreasing susceptibility to CIP. Susceptibility to CIP was similar between penicillin-susceptible and penicillin-resistant pneumococci.
Conclusion: Third and fourth generation fluoroquinolones showed very high inhibitory activity, higher than that for CIP, for both penicillin-susceptible and penicillin-resistant pneumococci. We noted cross-resistance among fluoroquinolones.