Multiple virulence factors regulated by quorum sensing may help in establishment and colonisation of urinary tract by Pseudomonas aeruginosa during experimental urinary tract infection.

Purpose: Damage caused by an organism during infection is attributed to production of virulence factors. Different virulence factors produced by the organism contribute to its pathogenicity, individually. During infectious conditions, role of virulence factors produced by the pathogen is different, depending upon the site of involvement. Pseudomonas aeruginosa is an opportunistic nosocomial pathogen known to cause infections of the respiratory tract, burn wound, urinary tract and eye. Importance of virulence factors produced by P. Aeruginosa during infections such as keratitis, burn wound and respiratory tract is known. The present study was designed to understand the importance of different virulence factors of P. aeruginosa in urinary tract infection in vivo. Materials and methods: An ascending urinary tract infection model was established in mice using standard parent strain PAO1 and its isogenic mutant, JP2. Mice were sacrificed at different time intervals and renal tissue homogenates were used for estimation of renal bacterial load and virulence factors. Results: Both parent and mutant strains were able to reach the renal tissue. PAO 1 PAO1was isolated from renal tissue till day 5 post-infection. However, the mutant strain was unable to colonise the renal tissue. Failure of mutant strain to colonise was attributed to its inability to produce protease, elastase and rhamnolipid. Conclusion: This study suggests that protease, elastase and rhamnolipid contribute to pathogenesis and survival of P. aeruginosa during urinary tract infection.

Pyelonephritic potential of Pseudomonas aeruginosa in ascending mouse model.

The suitability of female BALB/c and Swiss Webster (LACA) strains of mice for an ascending model of pyelonephritis for human uroisolate of Pseudomonas aeruginosa, was assessed. A fresh isolate of Ps. aeruginosa elaborating virulence factors like elastase, protease, phospholipase C, pyochelin and haemolysin was selected and introduced transuretherally in mice without any manipulation of the urinary tract. This isolate was able to colonize and persist in the renal tissue till day 12 post infection. Histopathologically, severe renal lesions i.e., abscesses formation was observed. The LACA strain was found to be more susceptible to infection with the selected Ps. aeruginosa isolate.

Hereditary spherocytosis: experience of 145 cases.

145 patients were diagnosed to have hereditary spherocytosis (HS) over a period of 25 years. Jaundice (66.9%), fever (65.5%), weakness (44.8%), and abdominal pain (35.8%) were the commonest complaints. 94.5% had splenomegaly (JP-17 cm) and 71.7% had hepatomegaly (JP-6 cm). Spherocytes were detected in the peripheral smears of all patients at presentation on careful examination. 67 patients had been investigated elsewhere and spherocytes missed in 86.6%. Gall stones were seen in 20 of the 54 patients investigated. Family history suggestive of HS was available in only 16.6% of cases, whereas examination and investigations revealed HS in almost all families. Splenectomy was done in all symptomatic patients. In the 39 patients followed up for 1-9 years after splenectomy.