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Updated: Sep 3, 2026
Biosensor for Detection of Antibiotic Resistant Staphylococcus Bacteria
Published on: May 8, 2013
[Determination of the susceptibility of staphylococci and enterococci to plycopeptides by the E-test method]
N Plotton1, J D Cavallo, Y Crenn
1Laboratoire de Biologie Médicale, HIA Bégin, St-Mandé, France.
Abstract:
E-test was evaluated by comparison with the reference agar dilution method on 15 enterococci and 15 staphylococci with variable resistance to glycopeptides and isolated from clinical samples: 15 enterococci with 3 glycopeptide-resistant (2 E. facalis and 1 E. faecium), 1 glycopeptide intermediate E. gallinarum and 11 glycopeptide-sensible E. faecalis; 15 staphylococci with 4 teicoplanine-resistant (1 S. aureus, 1 S. epidermidis and 2 S. hominis), 3 teicoplanin-intermediate (1 S. epidermidis, 2 S. haemolyticus) and 8 teicoplanin sensible strains (6 S. aureus, 1 S. epidermidis and 1 S. hominis). Repeatability (10 determinations by strain) and exactitude were tested for all strains. Our data shows very good results for repeatability and exactitude with the reference method except in the case of coagulase negative staphylococci and teicoplanin. Some technical problems appear in our experience: for staphylococci, a 48 h incubation is necessary to detect teicoplanin-intermediate strains but 24 h is sufficient for enterococci. E-test is expensive, require a strict methodology, but is a good method to detect glycopeptide resistance for staphylococci and enterococci except for coagulase negative staphylococci and teicoplanine.
Insights
The E-test demonstrates good repeatability and accuracy for detecting glycopeptide resistance in enterococci and staphylococci. However, it requires specific incubation times and has limitations with coagulase-negative staphylococci and teicoplanin.
Area of Science:
- Microbiology
- Antimicrobial Susceptibility Testing
- Clinical Diagnostics
Context:
- Glycopeptide resistance in enterococci and staphylococci poses a significant clinical challenge.
- Accurate and reliable methods for detecting antimicrobial resistance are crucial for effective patient management.
- The E-test is a commonly used method for determining antibiotic susceptibility.
Purpose:
- To evaluate the performance of the E-test compared to the agar dilution method for detecting glycopeptide resistance.
- To assess the repeatability and accuracy of the E-test for various resistant and susceptible strains of enterococci and staphylococci.
- To identify any technical challenges or limitations associated with using the E-test for these specific bacteria and resistance patterns.
Summary:
- The study compared the E-test with the agar dilution method for 30 clinical isolates (15 enterococci, 15 staphylococci) exhibiting variable glycopeptide resistance.
- The E-test showed very good repeatability and accuracy, particularly for enterococci and most staphylococci.
- Technical considerations included longer incubation times (48h) for detecting teicoplanin-intermediate staphylococci and noted limitations with coagulase-negative staphylococci and teicoplanin.
Impact:
- The E-test is a viable method for detecting glycopeptide resistance in enterococci and staphylococci, aiding in clinical decision-making.
- Understanding the specific limitations, such as with coagulase-negative staphylococci and teicoplanin, is essential for accurate interpretation of results.
- Optimized methodologies, including appropriate incubation times, can enhance the utility of the E-test in clinical microbiology laboratories.
