Related Experiment Video
Updated: Aug 28, 2026
Colorimetric Analysis of Alkaline Phosphatase Activity in S. aureus Biofilm
Published on: April 12, 2019
Elastase and alkaline protease production by Pseudomonas aeruginosa strains: comparison of two procedures
1Marmara University Faculty of Medicine, Department of Microbiology, Haydarpasa, Istanbul, Turkey.
Abstract:
Pseudomonas aeruginosa is an opportunistic pathogen that can cause fatal infections in immunocompromised hosts. The virulence of P. aeruginosa is associated with the presence of various extracellular factors like elastase and alkaline protease. These enzymes are suggested to contribute to tissue destruction and assist bacterial invasion during infection. Therefore it seems likely that determination of these virulence factors will be an important prognostic marker in the near future especially for follow up of cystic fibrosis patients, to start antimicrobial agents that are directly or indirectly inhibit microbial growth or virulence factor production. Herein, we suggest a simple test procedure to be used in routine laboratories for estimation of elastase and alkaline protease levels and compare them with quantitative methods in the literature. We detected the amount of elastase and alkaline protease in 49 clinical P. aeruginosa isolates by comparing agar plate method and colorimetric assay. The resulting values were in the range reported in the literature and differed from one strain to another(elastase: 0-1390 mg/ml, alkaline protease: 0- 770 mg/ml). Linear relationships were found when assays compared in pairs and significant correlation coefficients were obtained(r>0.788 for alkaline protease, p<0.0001- r>0.926 for elastase, p<0.0001). Our method can be applied in laboratories regardless of the availability of technical equipment.
Insights
A simple lab test can now measure elastase and alkaline protease in Pseudomonas aeruginosa. This helps predict infections and guide treatments, especially for cystic fibrosis patients.
Area of Science:
- Microbiology
- Clinical Diagnostics
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen causing severe infections in immunocompromised individuals.
- Bacterial virulence is linked to extracellular factors like elastase and alkaline protease, contributing to tissue damage and invasion.
Purpose of the Study:
- To develop and validate a simple laboratory method for quantifying elastase and alkaline protease in P. aeruginosa isolates.
- To assess the utility of these enzymes as prognostic markers for P. aeruginosa infections, particularly in cystic fibrosis patients.
Main Methods:
- A novel agar plate method and a colorimetric assay were used to determine elastase and alkaline protease levels.
- These methods were applied to 49 clinical isolates of P. aeruginosa and compared with existing quantitative techniques.
Main Results:
- The study found elastase levels ranging from 0-1390 mg/ml and alkaline protease levels from 0-770 mg/ml across different strains.
- A strong positive correlation was observed between the novel method and quantitative literature methods (r>0.788 for alkaline protease, r>0.926 for elastase, p<0.0001).
Conclusions:
- The proposed simple test procedure is reliable for estimating elastase and alkaline protease levels in routine laboratories.
- Quantification of these virulence factors can serve as a valuable prognostic marker for P. aeruginosa infections, aiding in treatment decisions.
