Comparison of Virulence Factors in Pseudomonas aeruginosa Strains Isolated from Cystic Fibrosis Patients

Abstract

Background: Pseudomonas aeruginosa, is a Gram-negative opportunistic bacterium which establishes itself in vulnerable patients, such as those with cystic fibrosis or hospitalized in intensive care units. Methods: Forty-five P. aeruginosa strains isolated from 26 cystic fibrosis patients were obtained. Both qualitative and quantitative assays were conducted to determine a number of virulence factors such as elastase, alkaline proteases and pyocyanin. Elastase gene expression profiling was conducted using RT-PCR. Spirometry was used to measure lung function and this was correlated to the severity of P. aeruginosa infection. Spirometry measurements i.e. forced expiratory volume (FEV) and forced vital capacity (FVC) were made to measure lung function and to see if there was any correlation with the production of virulence factors. Results: Virulence factors profiling revealed that about 30% of the isolates were of clinical significance having expressed a number of virulence factors, in particular elastase (lasB). Conclusion: Some strains of P. aeruginosa produce greater quantities of virulence factors and are more damaging to the lungs of patients with cystic fibrosis, although statistical analysis revealed no correlation between the virulence factors tested and the level of lung function. In addition, other factors such as biofilm formation may play a larger role for CF lung infections.