Table 2.
Curli expression in different EPEC and EHEC serotypes.
| Serotype (Strain) | EM | Congo-red binding | ELISA (OD405±SD) |
|---|---|---|---|
| EPEC | |||
| O111:NM (E1056) | + | + | + (0.35±0.03) |
| O111:NM (E1317) | + | + | + (0.69±0.05) |
| O111:NM (E271) | − | − | − (0.04±0.01) |
| O86:NM (E428174) | + | + | + (0.58±0.15) |
| O55:H- (E55) | + | + | + (0.96±0.05) |
| O128:H2 (E18) | + | + | + (0.41±0.02) |
| O55:H6 (E21) | + | + | + (0.53±0.03) |
| O119:H6 (E10) | + | + | + (0.50±0.09) |
| O119:H6 (E49) | + | + | + (0.45±0.12) |
| O127:H6 (E2348/69) | + | + | + (0.62±0.06) |
| O86:H34 (E28) | + | + | + (0.46±0.07) |
| O86:H34 (E24) | + | + | + (0.54±0.10) |
| O86:H34 (E26) | − | − | − (0.15±0.02) |
| EHEC | |||
| O157:H7 (EDL933) | + | + | + (1.038±0.04) |
| O157:H7 [34(4)AKAN] | + | + | + (0.40±0.03) |
| O157:H7 (275F1) | + | + | + (0.51±0.09) |
| O157:H7 (23380-85) | − | − | − (0.05±0.01) |
| O157:H7 (37-1) | − | − | − (0.12±0.04) |
| O55:H7 (660-79) | + | + | + (0.88±0.07) |
| O111:H8 (H30C5) | + | + | + (1.32±0.04) |
| O111:H8 (202F1) | + | + | + (1.05±0.04) |
| O117:H4 (CL6L) | − | − | − (0.09±0.01) |
| O113:H21 (EH53) | + | + | + (1.17±0.09) |
| O113:H21 (EH71) | + | + | + (0.58±0.13) |
| O113:H21 (EH41) | + | + | + (1.16±0.03) |
Expression of curli was determined by EM, Congo red binding and ELISA. The absorbance values obtained with pre-immune serum were subtracted from absorbance values obtained with the curli antiserum. The cut-off value for the absorbance in ELISA experiment was more than 0.15, which was considered as positive. +, Positive expression of curli; −, negative expression of curli. Congo-red binding was determined by uptake of the dye by curliated bacteria when growing on Congo red plate. The results obtained by EM, Congo red binding and ELISA were consistent.