Ceftolozane-tazobactam activity against phylogenetically diverse Clostridium difficile strains

Area of Science:

• Microbiology
• Infectious Diseases
• Pharmacology

Background:

• Ceftolozane-tazobactam (C/T) is an antibiotic combination used for complicated intra-abdominal and urinary tract infections.
• Its activity against anaerobic bacteria is variable.
• Clostridium difficile is an important anaerobic pathogen causing healthcare-associated infections.

Purpose of the Study:

• To evaluate the in vitro activity of ceftolozane-tazobactam against a diverse collection of Clostridium difficile isolates.
• To determine the minimum inhibitory concentrations (MICs) of C/T for these isolates.

Main Methods:

• Antimicrobial susceptibility testing was performed.
• Minimum Inhibitory Concentrations (MICs) were determined for ceftolozane-tazobactam against multiple Clostridium difficile isolates.
• Isolates were selected to represent phylogenetic diversity.

Main Results:

• Ceftolozane-tazobactam demonstrated uniformly high minimum inhibitory concentrations (MICs) against all tested Clostridium difficile isolates.
• All MICs were ≥256 μg/ml, indicating high-level resistance.
• No significant variation in susceptibility was observed across the diverse collection.

Conclusions:

• Ceftolozane-tazobactam exhibits poor activity against Clostridium difficile in vitro.
• The high MICs suggest that C/T is unlikely to be effective for treating infections caused by Clostridium difficile.
• Further investigation into alternative treatment options for C. difficile infections is warranted.