TABLE 4.
Genotypes and phenotypes of E. coli strainsa
| Strains | Sero- group | Genotype
|
Phenotype
|
|||||
|---|---|---|---|---|---|---|---|---|
| cdt | cdt type | cnf | eae | Hly | Lysate | Super- natant | ||
| E6468/62 | O86 | + | I | − | + | − | +++ | +++ |
| 34 | O2 | + | I | 1 | − | − | +++ | +++ |
| 66LS | O2 | + | I | − | − | − | +++ | +++ |
| H52 | O2 | + | I | 1 | − | + | +++ | ++ |
| 67LS | O18 | + | I | − | − | − | +++ | +++ |
| KS159 | O23 | + | I | − | − | − | ++ | ++ |
| OS (outbreak strain) | O86:K61 | + | I | − | + | − | +++ | +++ |
| HB101(p21213) | K-12 | + | II | − | − | − | ND | ND |
| 1404 | O78 | + | III | 2 | − | − | ++ | − |
| 33KH89 | O2 | + | III | 2 | − | + | ++ | ++ |
| B20a | O15 | + | III | 2 | − | − | ++ | − |
| B26a | O78 | + | III | 2 | − | − | ++ | − |
| BM2-10 | O88 | + | III | 2 | − | − | + | − |
| 89-201-2/3 | O123 | + | III | 2 | − | − | + | − |
| B28b | O123 | + | III | 2 | − | − | + | − |
| S5 | O15 | + | III | 2 | − | − | ++ | − |
| 28c | O75 | + | IV | 1 | − | + | ++ | − |
| H173 | O2 | + | IV | − | − | − | + | − |
| AII-40 | O6 | + | IV | 1 | − | + | ++ | − |
| H78 | O75 | + | IV | 1 | − | + | ++ | − |
| E253 | O115 | + | IV | − | − | − | ++ | − |
| 8 | O123 | + | IV | − | − | − | + | − |
| J96 | O4 | − | − | 1 | − | + | * | − |
| DH5α | K-12 | − | − | − | − | − | − | − |
| E2348/49 | O127 | − | − | − | − | − | − | − |
The cytotoxic activity in the sonic lysate and the culture supernatant was titrated as previously described (30) by using as the endpoint the CD50 value. The amounts of proteins in each extract were determined by using a bicinchoninic acid assay (Pierce), and the cytotoxic activity was expressed as the number of CD50 per milligram of protein (+++, ≥1,000; ++, 1,000 to 100; +, <100; −, no specific CDT or CNF effect). If a strain produced CNF and CDT, both cytopathic effects were observed. At the endpoint dilution the transformed HeLa cells were enlarged and polynucleated (CNF effect), and at lower dilutions only the CDT-specific enlargement effect was observed (large mononucleated cells). ND, not done; *, CNF cytopathic effect only.