Table 1.

Colony-forming units of E. coli and toxin titers (CD₅₀/ml in Vero cell assays) of Stx containing crude extracts used, as inocula for ileal loops

Strains and toxin crude extracts	Colony-forming units per milliliter*	Toxin (CD50/ml)
E. coli strain 933 (O157∶H7, Stx1+, Stx2+)	3  × 108	NA†
Streptomycin-resistant mutant of E. coli strain 933	5  × 108	NA
E. coli strain 123 (non pathogenic)	7  × 109	NA
Stx1+ crude extract	NA	1  × 108
Stx2+ crude extract	NA	1  × 107
Stx− crude extract (negative control)	NA	1  × 103

^*Viable E. coli. 

^† NA, not applicable.