Phenotypic characters of urinary isolates of Pseudomonas aeruginosa & their association with mouse renal colonization.

BACKGROUND & OBJECTIVE Very few studies regarding production of virulence factors in different predominant serotypes of uropathogenic Pseudomonas aeruginosa are available and they have not been correlated to in vivo pathogenicity in the urinary tract. This study was carriedout with the objective to analyze the phenotypic characters of uroisolates of P. aeruginosa in vitro and to study the association of these virulence traits with their ability to cause nephropathogenicity in mouse model of ascending urinary tract infection (UTI). METHODS Protease, elastase, alginate, haemolysin, pyochelin, pyoverdin and phopholipase C were measured using standard protocols in 18 uroisolates of P. aeruginosa isolated from patients suffering from complicated UTIs. An ascending model of pyelonephritis was established in Swiss Webster (LACA) female mice with these isolates. Quantitative bacterial count and histopathological evaluation of mouse renal tissue was done which were then assessed for a possible association with elaboration of virulence factors. RESULTS All isolates of P. aeruginosa were able to colonize renal tissue of mice. However, renal counts varied amongst different isolates producing different virulence factors. Isolates producing high levels of haemolysin along with other virulence factors were able to colonize and multiply more in mouse renal tissue as compared to those producing low levels of haemolysin. INTERPRETATION & CONCLUSION The findings of this study indicated an association between haemolysin production and renal colonization. High level of haemolysin production in vitro could be used as surrogate information for assessing pyelonephritic potential of P. aeruginosa.