Abstract

Pseudomonas aeruginosa is a major cause of nosocomial infections. Recently multidrug resistance and extended-spectrum ß-lactamase (ESBL)-producing P. aeruginosa isolates are emerging worldwide. These isolates are reported to be more virulent than the non multidrug resistance and non ESBL producing isolates. In order to find a correlation between ESBL production and virulence, we tested two cell surface factors involved in pathogenicity, hydrophobicity and biofilm formation in ESBL and non ESBL producing isolates. ESBL was determined phenotypically by combined disc method. Hydrophobicity was tested by microbial adhesion to hydrocarbon; biofilm formation was determined by microtiter plate. Mean of hydrophobicity in ESBL and non ESBL producing isolates was 38.85 and 30% respectively. Weak reaction in hydrophobicity was significantly higher in the non ESBL isolates (6%); while percent of moderate and strong reaction was higher in the ESBL producing isolates (94%). In biofilm formation mean of ESBL and non ESBL isolates were 0.182 and 0.136 respectively. Percent isolates producing moderate and strong biofilm was 72% for ESBL and 32% for non ESBL isolates (p value < 0.001). Our data demonstrate that hydrophobicity and biofilm formation was higher in the ESBL producing compared with non ESBL producing isolates. The properties can render the ESBL positive isolates more pathogenic.

Key words: Pseudomonas aeruginosa, ESBL, hydrophobicity, biofilm formation, virulence