Related Experiment Videos
Pseudomonas aeruginosa isolate typing by esterase electrophoresis
1Service de Microbiologie, Hôpital Beaujon (Faculté de Médecine Xavier Bichat, Université Paris VII), Clichy, France.
Abstract:
Esterase electrophoretic typing was used to classify clinical isolates of Pseudomonas aeruginosa. One hundred and twenty-seven P. aeruginosa strains belonging to 16 serotypes (including 16 non-typeable strains) and isolated from diverse human infections in three hospitals, and the type strain ATCC 10 145, were tested. Four main kinds of esterase and 4 additional esterases were distinguished by their spectra of hydrolytic activity toward synthetic substrates and by their sensitivity or resistance to di-isopropyl fluorophosphate. The electrophoretic variations of these enzymes were used to define 42 zymotypes. Electrophoretic typing of esterase appeared to be more sensitive than serotyping and the results of the two methods did not correlate. When the two typing methods were used in parallel, 78 different combinations of serotype and zymotype were obtained.
Insights
Esterase electrophoretic typing offers a more sensitive method for classifying Pseudomonas aeruginosa clinical isolates than traditional serotyping. This enzyme-based approach identified 42 distinct zymotypes, revealing greater strain diversity in infections.
Area of Science:
- Clinical microbiology
- Enzyme typing
- Bacterial identification
Background:
- Pseudomonas aeruginosa is a significant opportunistic pathogen.
- Accurate classification of bacterial isolates is crucial for infection control and epidemiology.
- Existing typing methods like serotyping may not fully capture the genetic diversity of P. aeruginosa.
Purpose of the Study:
- To evaluate esterase electrophoretic typing as a method for classifying clinical isolates of Pseudomonas aeruginosa.
- To compare the discriminatory power of esterase typing with conventional serotyping.
- To assess the correlation between esterase zymotypes and serotypes.
Main Methods:
- Esterase electrophoretic typing was performed on 127 clinical isolates of P. aeruginosa and one type strain.
- Enzymes were characterized by hydrolytic activity and sensitivity to di-isopropyl fluorophosphate.
- Isolates were also serotyped to allow for direct comparison.
- Zymotypes were defined based on electrophoretic variations of esterases.
Main Results:
- Four main and four additional esterases were identified.
- Electrophoretic typing defined 42 distinct zymotypes.
- Esterase typing demonstrated higher sensitivity and discriminatory power compared to serotyping.
- Serotyping and esterase typing results showed no correlation.
- Combining both methods yielded 78 unique serotype-zymotype combinations.
Conclusions:
- Esterase electrophoretic typing is a sensitive and valuable tool for classifying Pseudomonas aeruginosa.
- This method provides a more detailed picture of strain diversity than serotyping alone.
- Parallel use of serotyping and esterase typing enhances the resolution of isolate characterization.