Activity of quinolones against viridans group streptococci isolated from blood cultures of patients with haematological malignancy

Use of fluoroquinolones for antimicrobial prophylaxis during neutropenia is often cited as a significant predisposing factor for viridans group streptococcus (VGS) bacteraemia. Newer compounds in this class are reputed to have enhanced activity against Gram-positive bacteria, and we determined the minimal inhibitory concentrations (MICs) for ciprofloxacin and three of the newer compounds: trovafloxacin, fleroxacin and clinafloxacin, against 44 isolates of VGS. On a gravimetric basis, clinafloxacin was most active (MIC90 0.19 mg/l), whereas ciprofloxacin and fleroxacin were the least active (both MIC90 16 mg/l). Clinafloxacin warrants further study as an agent of prophylaxis against bacterial infection in neutropenic patients.