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[Antibiotic-resistant nosocomial pathogens. Part I: diagnostic and typing methods]
W Witte1, B Strommenger, I Klare
1Bereich Wernigerode, Robert Koch-Institut, Wernigerode. wittew@rki.de
Summary
Understanding bacterial resistance mechanisms is crucial for effective chemotherapy. Knowing these mechanisms allows for targeted susceptibility testing and selection of appropriate antimicrobial agents, improving patient outcomes.
Area of Science:
- Microbiology
- Clinical Pharmacology
- Infectious Diseases
Background:
- Routine antimicrobial susceptibility testing faces challenges with numerous available agents and complex bacterial resistance mechanisms.
- Knowledge of specific resistance mechanisms and cross-resistance is essential for selecting appropriate diagnostic tests.
- Current in vitro methods may not fully capture the expression of all resistance mechanisms.
Purpose of the Study:
- To outline strategies for selecting appropriate test substances in antimicrobial susceptibility testing based on known resistance mechanisms.
- To highlight the need for molecular methods beyond standard susceptibility assays for detecting resistance genes.
- To discuss the importance of bacterial typing for tracking the spread of antibiotic-resistant pathogens.
Main Methods:
- Interpretation of results based on known bacterial resistance mechanisms and cross-resistance.
- Selection of test substances aligned with guidelines (e.g., German Infection Protection Act Section 23).
- Complementary molecular tests for detecting resistance genes, in addition to agar-diffusion or microbroth MIC assays.
- Evaluation of bacterial typing methods considering workload, discriminatory power, and reproducibility.
Main Results:
- Knowledge of resistance mechanisms enables targeted selection of antimicrobial test substances.
- Molecular detection of resistance genes is necessary due to limitations of in vitro expression in routine tests.
- Bacterial typing methods are vital for tracing the emergence and spread of nosocomial pathogens.
- Microarray technology is anticipated to enhance routine laboratory capabilities for identifying virulence traits.
Conclusions:
- Effective chemotherapy relies on understanding and testing against specific bacterial resistance mechanisms.
- A combination of phenotypic and genotypic methods, including molecular tests, is required for comprehensive resistance profiling.
- Bacterial typing and emerging technologies like microarrays will play a significant role in combating antibiotic resistance in healthcare settings.