[In vitro activity of moxifloxacin (8-methoxyquinolone) alone or in combination with cefotaxime against group B...

Our objective is to determine in vitro efficiency of moxifloxacin (MXF) alone or in combination with cefotaxime (CTX) on Group B streptococcus (GBS).

For 21 strains of GBS isolated from newborn invasive infections (6 meningitis and 15 bacteraemia), the bacterial growth in Mueller Hinton broth with MXF and/or CTX leaded to the determination of MIC and MBC, the determination of tolerance for CTX and the evaluation of the bacteriostatic action of these antibiotics combination by calculating the FIC index. Time-kill studies were conducted for MXF and CTX alone or in combination for the first four hours, with concentrations likely reached in CSF.

Study of GBS growth with crossed concentrations of MXF and CTX showed no resistant strains, no tolerant strains, and no antagonism between MXF and CTX. Killing curves demonstrated that MXF is ten-fold more active than CTX in the first four hours.

MXF is an interesting antibiotic for its good activity on the GBS, suggesting that MXF is a good candidate for further evaluation in GBS meningitis in animal model.