Related Experiment Videos
Proficiency testing program for clinical laboratories performing antifungal susceptibility testing of pathogenic
Rama Ramani1, Vishnu Chaturvedi
1Mycology Laboratory, Wadsworth Center, New York State Department of Health, School of Public Health, State University of New York at Albany, Albany, New York 12201-2002, USA.
Abstract:
Antifungal susceptibility testing is expected to facilitate the selection of adequate therapy for fungal infections. The general availability of antifungal susceptibility testing in clinical laboratories is low, even though a number of standard methods are now available. The objective of the present study was to develop and evaluate a proficiency testing program (PTP) for the antifungal susceptibility testing of pathogenic yeasts in laboratories licensed by the New York State Department of Health. A number of quality control standards, and methods for documenting laboratory performance, were developed in consultation with the laboratory directors. The participating laboratories were provided with five American Type Culture Collection strains of pathogenic yeasts for which the minimum inhibitory concentrations (MICs) of amphotericin B and fluconazole were well defined. A majority of laboratories (14 of 17) used broth microdilution, and these were evenly split between the NCCLS M-27A protocol and the Sensititre YeastOne method. The other three laboratories performed susceptibility testing with Etest. Overall, the levels of agreement between MIC reference ranges and the reported MICs were 85 and 74% for amphotericin B and for fluconazole, respectively. All laboratories except one successfully detected fluconazole resistance in a Candida krusei strain. However, amphotericin B resistance in a Candida lusitaniae strain was not detected by any of the participating labs. It is concluded that a suitably designed PTP could adequately monitor the competence of clinical laboratories performing antifungal susceptibility testing.
Insights
A proficiency testing program (PTP) was developed to assess antifungal susceptibility testing in clinical labs. The PTP showed promise in monitoring lab competence, though challenges remain in detecting certain antifungal resistance patterns.
Area of Science:
- Clinical Microbiology
- Mycology
- Laboratory Quality Assurance
Background:
- Antifungal susceptibility testing (AST) is crucial for guiding treatment of fungal infections.
- Limited availability of AST in clinical laboratories hinders optimal patient care.
- Standardized methods for yeast AST are available but not widely implemented.
Purpose of the Study:
- To develop and evaluate a proficiency testing program (PTP) for antifungal susceptibility testing.
- To assess the performance of clinical laboratories in New York State performing yeast AST.
- To establish quality control standards and performance documentation methods for yeast AST.
Main Methods:
- Development of a PTP in collaboration with laboratory directors.
- Distribution of characterized American Type Culture Collection (ATCC) yeast strains.
- Analysis of reported Minimum Inhibitory Concentrations (MICs) against amphotericin B and fluconazole.
- Comparison of laboratory results with established MIC reference ranges.
Main Results:
- Majority of participating laboratories (14/17) utilized broth microdilution methods (NCCLS M-27A or Sensititre YeastOne).
- Agreement levels between reported MICs and reference ranges were 85% for amphotericin B and 74% for fluconazole.
- High detection rate for fluconazole resistance (Candida krusei), but complete failure to detect amphotericin B resistance (Candida lusitaniae).
Conclusions:
- A well-designed PTP can effectively monitor the competence of clinical laboratories in performing antifungal susceptibility testing.
- The study identified specific areas for improvement, particularly in detecting amphotericin B resistance.
- Proficiency testing is essential for ensuring accurate and reliable AST results for improved patient outcomes.