Related Experiment Video
Updated: Dec 21, 2025
Improved Enzyme Protection Assay to Study Staphylococcus aureus Internalization and Intracellular Efficacy of Antimicrobial Compounds
Published on: September 8, 2021
In vitro efficacy and pharmacodynamic profiles of four polyether ionophores against methicillin-resistant
Elizabeth E Hickey1, Stephen W Page2, Darren J Trott1
1Australian Centre for Antimicrobial Resistance Ecology, School of Animal and Veterinary Sciences, The University of Adelaide, SA, Australia.
Abstract:
The objective of this study was to determine the minimum inhibitory concentrations (MICs) and pharmacodynamic profiles of four ionophores (lasalocid, monensin, narasin and salinomycin) against staphylococcal isolates from clinical cases of human and veterinary staphylococcal infections, and to determine the effect of methicillin resistance on the antimicrobial activity of ionophores. Broth microdilution MIC testing was used to determine antimicrobial activity against 156 staphylococcal isolates of human and veterinary origin. Pharmacodynamic profiles were examined using time-kill kinetics profiles against an ATCC type strain of Staphylococcus aureus and a clinical isolate of methicillin-resistant Staphylococcus pseudintermedius. All tests were performed in accordance with CLSI guidelines. All four ionophores demonstrated antimicrobial activity against methicillin-resistant staphylococci at concentrations similar to those observed for methicillin-susceptible isolates of the same species. Testing of human and veterinary MRSA isolates also showed that MIC values were not influenced by the host origin of the isolates. Pharmacodynamic profiles were similar for both isolates tested across all four ionophores, with similar reductions in viable cell counts being observed over an 18- to 24-hr period. Lasalocid, monensin, narasin and salinomycin all demonstrated antimicrobial activity against staphylococcal isolates of human and veterinary origins, with activity being unaffected by methicillin resistance status, although some Staphylococcus species-specific effects were observed that require further investigation.
Insights
Four ionophores showed antimicrobial activity against staphylococcal infections in humans and animals. Methicillin resistance did not affect ionophore effectiveness, indicating broad applicability for these antimicrobials.
Area of Science:
- Veterinary Medicine
- Microbiology
- Infectious Diseases
Background:
- Staphylococcal infections pose significant threats to both human and animal health.
- Ionophores are a class of compounds with known antimicrobial properties.
- The impact of methicillin resistance on ionophore efficacy against staphylococci requires further elucidation.
Purpose of the Study:
- To determine the minimum inhibitory concentrations (MICs) and pharmacodynamic profiles of four ionophores (lasalocid, monensin, narasin, salinomycin).
- To evaluate the antimicrobial activity of these ionophores against staphylococcal isolates from human and veterinary clinical cases.
- To assess the influence of methicillin resistance on the antimicrobial activity of ionophores against staphylococci.
Main Methods:
- Broth microdilution MIC testing was performed on 156 staphylococcal isolates of human and veterinary origin.
- Time-kill kinetics profiles were used to examine pharmacodynamic properties against Staphylococcus aureus and methicillin-resistant Staphylococcus pseudintermedius.
- All procedures adhered to Clinical and Laboratory Standards Institute (CLSI) guidelines.
Main Results:
- All four ionophores exhibited antimicrobial activity against methicillin-resistant staphylococci at concentrations comparable to methicillin-susceptible isolates.
- The host origin (human or veterinary) did not influence MIC values for methicillin-resistant Staphylococcus aureus (MRSA) isolates.
- Pharmacodynamic profiles were consistent across ionophores and isolates, showing similar reductions in viable cell counts over 18–24 hours.
Conclusions:
- Lasalocid, monensin, narasin, and salinomycin are effective against staphylococcal isolates from both human and veterinary sources.
- Antimicrobial activity of these ionophores is not diminished by methicillin resistance.
- Further research is warranted to investigate observed Staphylococcus species-specific effects.
More Related Videos
09:26Antibiotic Efficacy Testing in an Ex vivo Model of Pseudomonas aeruginosa and Staphylococcus aureus Biofilms in the Cystic Fibrosis Lung
Published on: January 22, 2021
12:03Antimicrobial Synergy Testing by the Inkjet Printer-assisted Automated Checkerboard Array and the Manual Time-kill Method
Published on: April 18, 2019
