Comparative Bactericidal Activity of three Fluoroquinolones against Streptococcus pneumoniae and Hemophilus influenzae isolated from Acute Bacterial Rhinosinusitis

Background: Recently, the most common bacteriae in acute bacterial rhinosinusitis (ABRS), Streptococcus pneumoniae and Hemophilus influenzae, have acquired various degrees of resistance to many traditional antibiotics.

Methods: We evaluated the bactericidal activity of three new fluoroquinolones, levofloxacin (LVFX), garenoxacin (GRNX), and sitafloxacin (STFX), against current isolates of S. pneumoniae (50 strains) and H. influenzae (50 strains) from patients with ABRS in Japan.

Results: No fluoroquinolone-resistant penicillin-susceptible S. pneumoniae (PSSP) strains were detected. The MIC of PSSP for both GRNX and STFX were . 0,06 ƒÊg/ml, whereas that for LVFX was significantly elevated as compared with those of GRNX and STFX. One strain of penicillin-intermediate S. pneumoniae (PISP) was an LVFX-resistant strain. A significant elevation of MIC of PISP was observed in LVFX as compared with GRNX and STFX. There were no strains of S. pneumonia with resistance to the three fluoroquinolones. All of the H. influenzae strains showed excellent sensitivity to all three fluoroquinolones.

Conclusions: Although LVFX-resistant S. pneumoniae was found in this study, the strong potency of GRNX and STFX against S. pneumoniae and H. influenzae suggests the use of antibiotics is appropriate in severe cases of ABRS.