In vitro activity of Ro 24-6392, a novel ester-linked co-drug combining ciprofloxacin and desacetylcefotaxime.

In preliminary in vitro susceptibility tests Ro 24-6392 (desacetylcefotaxime with a 3'-ciprofloxacin substitution) demonstrated activity against a wide spectrum of aerobic bacteria, 98.6% of strains being inhibited by less than or equal to 8 mg/l. Of the commonly isolated species tested, only enterococcal strains were resistant (MICs greater than or equal to 32 mg/l). The potency of Ro 24-6392 was generally between that observed for the two hydrolysis components, except in the case of Providencia stuartii and penicillin-resistant pneumococci isolates which were more susceptible to Ro 24-6392. This new dual-action compound appears to be slightly more active than the previously studied peer drug Ro 23-9424, principally because of the superior activity of the fluoroquinolone component, ciprofloxacin.