Comparison of susceptibility of inbred and outbred infant mice to Escherichia coli heat-stable enterotoxin STa.

Comparison of the susceptibility of outbred OF1 and inbred BALB/c, C57BL/6, DBA/2, and CBA mice to heat-stable toxin (STa) of enterotoxigenic Escherichia coli was made at different levels of induced secretion. STa was able to elicit fluid accumulation into the intestine of each strain of mice; however, quantitatively different results were obtained. Results were as usual expressed by gut weight/remaining body weight ratios. Fluid accumulation weight and fluid accumulation weight/remaining body weight ratios were also estimated. Values obtained for BALB/c and OF1 mice were never significantly different, but values for OF1 mice were significantly higher than those for DBA and C57BL/6 mice at the highest concentrations of toxin (toxin dilutions of 1/2, 1/4, and 1/5). At the highest toxin concentration, gut weight/remaining body weight ratio in C57BL/6 mice was significantly lower than that for every other strain, but the fluid accumulation value obtained for DBA mice did not differ from that for C57BL/6 mice. Fluid accumulation values for DBA mice were also significantly lower at toxin dilutions of 1/5 and 1/8 than those for every other strain, and this was also the case when estimating the fluid accumulation weight/remaining body weight ratio at a dilution of 1/8. Although the intestine of each strain of mice was able to respond to STa by fluid accumulation, differences in susceptibility of the STa receptor could exist and make DBA mice more resistant to enterotoxigenic E. coli diarrhea.