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Minimum inhibitory concentrations of cephalosporin compounds and their active metabolites for selected mastitis

Cristina S Cortinhas1, Leane Oliveira, Carol A Hulland

  • 1Department of Animal Nutrition and Production, School of Veterinary Medicine, University of São Paulo, Pirassununga, SP-17 13635-900, Brazil.

American Journal of Veterinary Research
|May 1, 2013
PubMed
Abstract

Insights

This study compared cephapirin and ceftiofur minimum inhibitory concentrations (MICs) against mastitis pathogens. Differences between parent drugs and their active metabolites may explain varied clinical outcomes and in vitro susceptibility results.

Area of Science:

  • Veterinary Microbiology
  • Antimicrobial Resistance
  • Bovine Mastitis Pathogenesis

Background:

  • Bovine mastitis remains a significant challenge in dairy herds, impacting animal welfare and economic viability.
  • Accurate antimicrobial susceptibility testing is crucial for effective treatment strategies.
  • Cephapirin and ceftiofur are commonly used cephalosporins for mastitis treatment.

Purpose of the Study:

  • To compare the in vitro activity of cephapirin and ceftiofur against key mastitis pathogens.
  • To evaluate the minimum inhibitory concentrations (MICs) of their active metabolites, desacetylcephapirin and desfuroylceftiofur.
  • To investigate potential discrepancies between parent compound and metabolite activity.

Main Methods:

  • Agar dilution method was employed to determine MICs.
  • 488 isolates of mastitis pathogens were tested, including Staphylococcus aureus, coagulase-negative staphylococci, Streptococcus dysgalactiae, Streptococcus uberis, and Escherichia coli.
  • Susceptibility testing was performed for parent compounds and their active metabolites.

Main Results:

  • All Staphylococcus aureus isolates were susceptible to cephapirin and ceftiofur.
  • Escherichia coli showed variable susceptibility to parent compounds, with limited inhibition by desacetylcephapirin.
  • Significant proportions of Staphylococcus aureus and coagulase-negative staphylococci susceptible to ceftiofur were intermediate or resistant to its metabolite, desfuroylceftiofur.

Conclusions:

  • The activity of active metabolites differs from parent cephalosporin compounds.
  • These differences in antimicrobial activity may contribute to variations observed between in vitro susceptibility testing and clinical treatment outcomes.
  • Further research is warranted to elucidate the clinical implications of metabolite activity in bovine mastitis therapy.

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