In vitro evaluation of cefoperazone.

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Broad-spectrum cephalosporins are crucial in combating bacterial infections.
• Emerging bacterial resistance necessitates the development of novel antimicrobial agents.
• Pseudomonas aeruginosa and Enterobacteriaceae pose significant therapeutic challenges due to resistance patterns.

Purpose of the Study:

• To evaluate the in vitro antimicrobial activity of cefoperazone against a diverse range of clinical bacterial isolates.
• To compare the efficacy of cefoperazone with existing cephalosporins and other investigational antibiotics.
• To assess the impact of environmental factors and inoculum size on cefoperazone's activity.

Main Methods:

• In vitro susceptibility testing of cefoperazone against 670 clinical isolates (Gram-negative bacilli and Gram-positive cocci).
• Determination of minimal inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs).
• Comparative analysis against other antibiotics and evaluation under varying medium, pH, and inoculum conditions.

Main Results:

• Cefoperazone inhibited most tested organisms at 6.25 µg/ml, except Enterobacter spp.
• Demonstrated significant activity against Pseudomonas aeruginosa, a common challenge for cephalosporins.
• Outperformed existing cephalosporins against Enterobacteriaceae; comparable to investigational drugs, but less active than moxalactam against non-Pseudomonas strains.
• Activity remained stable across medium and pH variations but decreased significantly with increased inoculum size (10^5 to 10^7 cells/ml).
• MBCs were close to MICs for most isolates, excluding Staphylococcus aureus.

Conclusions:

• Cefoperazone exhibits broad-spectrum in vitro activity, notably against Pseudomonas aeruginosa.
• Its performance is promising compared to current cephalosporins, though generally less potent than moxalactam.
• Inoculum size is a critical factor influencing cefoperazone's bactericidal efficacy.