In vitro attachment and distribution of pasteurella multocida B:2 in the lung and urinary bladder of buffaloes

Haemorrhagic septicaemia is caused by Pasteurella multocida B:2 that leads to septicaemia following adherence and colonization of the respiratory tract. However, recent studies revealed the possible involvement of urinary tract in the pathogenesis of haemorrhagic septicaemia. This study is conducted to determine the in vitro adherence and distribution of P. multocida B:2 in the lungs and urinary bladder of buffaloes. Three buffalo calves with no history of vaccination against haemorrhagic septicaemia were killed before lung and bladder explants were prepared. The explants were then challenged with 109 cfu/ml of live P. multocida B:2. At the same time, a known respiratory tract bacterium, Mannhemia haemolytica A:2 and a septicaemic E. coli were used as comparison. The explants were harvested at 2-h intervals until 12 hours before the rate of adherence was determined using scanning electron microscopy while the distribution was determined using immunoperoxidase staining. All bacterial strains showed similar adherence and distribution patterns. Pasteurella multocida B:2 showed significantly (P<0.05) increased rates of adherence and distribution with time to reach peak at 8-10 h and 12 h post-inoculation, respectively. There were significant (P<0.05) correlation between the rate of adherence and distribution. In general, M. haemolytica A:2 remained least septicaemic bacterium with relatively low rates of adherence and distribution while E. coli was the most septicaemic with highest rates of adherence and distribution.