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Correlation between linezolid zone diameter and minimum inhibitory concentration values determined by regression
G Dimitriu1, Antonia Poiata, Cristina Tuchiluş
1School of Pharmacy, "Gr. T. Popa" University of Medicine and Pharmacy, Iaşi.
Linezolid exhibits excellent in vitro activity against staphylococci, with all tested strains showing full sensitivity. Regression analysis confirmed a significant correlation between linezolid
Area of Science:
- Microbiology
- Pharmacology
- Clinical Science
Background:
- Linezolid is an oxazolidinone antibiotic effective against gram-positive infections.
- Includes resistance to methicillin-resistant staphylococci, vancomycin-resistant enterococci, and penicillin-resistant pneumococci.
- In vitro susceptibility testing is crucial for antibiotic efficacy assessment.
Purpose of the Study:
- To evaluate the in vitro activity of linezolid against staphylococci.
- To establish the correlation between minimum inhibitory concentration (MIC) and inhibition zone diameter.
- To validate disk diffusion as a reliable method for linezolid susceptibility testing.
Main Methods:
- Tested 100 Staphylococcus aureus isolates from nasopharyngeal swabs.
- Determined antibiotic susceptibility using disk diffusion and agar dilution methods.
- Performed regression analysis correlating MIC values with inhibition zone diameters.
Main Results:
- Linezolid demonstrated high activity with a MIC 90 of 1 mg/L.
- All tested staphylococci strains were fully susceptible to linezolid.
- Regression analysis showed a significant linear correlation (y= -0.188x + 8.048) between MIC and zone diameter.
Conclusions:
- Linezolid is highly effective against staphylococci strains.
- Disk diffusion testing reliably predicts linezolid's in vitro activity.
- The established regression equation can aid in susceptibility interpretation.
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