In vitro evaluation of Ro 13-9904

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Emerging antibiotic resistance necessitates the development of novel antimicrobial agents.
• Cephalosporins represent a critical class of antibiotics used to treat bacterial infections.

Purpose of the Study:

• To evaluate the in vitro antimicrobial activity of the novel cephalosporin Ro 13-9904.
• To compare Ro 13-9904's efficacy against a panel of reference antibiotics.

Main Methods:

• In vitro susceptibility testing was performed on clinical bacterial isolates.
• Ro 13-9904 activity was assessed against Enterobacteriaceae, Pseudomonas aeruginosa, and enterococci.
• Comparative analysis included cephalothin, cefamandole, cefoxitin, moxalactam, several semisynthetic penicillins, and tobramycin.

Main Results:

• Ro 13-9904 demonstrated potent activity against 75% of Enterobacteriaceae isolates at 6.25 µg/ml, including Enterobacter spp., Serratia marcescens, and indole-positive Proteus spp.
• Minimal activity was observed against Pseudomonas aeruginosa and enterococci.
• Drug activity remained stable across various pH and media conditions, but a significant inoculum effect was noted at higher bacterial concentrations.

Conclusions:

• Ro 13-9904 exhibits promising in vitro activity against a broad spectrum of Enterobacteriaceae.
• Its limited efficacy against Pseudomonas aeruginosa and enterococci warrants further investigation.
• The observed inoculum effect requires consideration in clinical application and further study.