P0564 BLACK TEA INHIBITS ETEC K88+ AND ENTEROTOXIN-INDUCED FLUID LOSS IN SMALL INTESTINAL SEGMENTS OF ANAESTHETISED PIGLETS

Introduction: Evidence for the anti-diarrhoeal property of tea is mainly anecdotal. Tea has the capacity to inhibit pathogen growth and toxicity of enterotoxins (¹). We, therefore, studied the effect of black tea on ETEC K88⁺ growth, Forskolin-induced intestinal Cl- secretion and ETEC K88⁺ and heat-labile enterotoxin (LT)-induced intestinal fluid loss.

Methods: To test the anti-bacterial capacity of black tea, ETEC K88⁺ overnight cultures were harvested at the exponential phase and diluted in AOAC broth to ~10³ cells/mL and incubated with black tea extract during 24 h at 37°C. Samples were taken hourly and optical density measured as an indication of bacterial growth. The capacity of black tea to inhibit Forskolin-induced Cl⁻secretion was tested on rat intestinal mucosa mounted in Ussing chambers by measuring the change in short-circuit current (DeltaI_SC) over 3 h. To test the anti-diarrhoeal capacity of tea, isotonic and equiosmolar solutions of black tea-leaf extract were perfused (8 mL/h) into ETEC K88⁺ or LT-infected small intestinal segments of ETEC K88⁺ receptor-positive anaesthetized piglets. After 8-h perfusion, changes in net fluid and electrolyte absorption were determined per cm² gut surface area. Significances were tested by ANOVA and set at P<0.05.

Results: Black tea significantly extended the lag phase of ETEC K88⁺ in vitro. When rat intestinal tissue was pre-incubated with black tea the Forskolin-induced increase in DeltaI_SC or Cl⁻ flux was significantly inhibited (from 4.97±0.56 to 2.01±0.19 muEq h⁻¹ cm⁻²). In piglet intestinal segments, ETEC significantly reduced the net fluid absorption from 494±112 muL/cm² (control segments) to 171±112 muL/cm². Black tea perfusion significantly counteracted (56%) this reduction in net fluid absorption to 352±112 muL/cm² and also improved the reduced net Na⁺ and Cl⁻ absorption (data not shown). Infection of intestinal segments with LT resulted in a small but significant reduced net fluid absorption (from 494 to 322 muL/cm²) as well as reduced Na⁺ and Cl⁻ absorption (data not shown) which were all significantly compensated by black tea perfusion.

Conclusion: Consuming black tea may be beneficial in treating ETEC K88⁺ diarrhoea. Black tea probably not only acts against pathogen growth or adhesion, but also against labile enterotoxin induced fluid secretion.