TABLE 1.
Strains from the non-LCT-producing REA groups tested for the binary toxin (CDT) genes cdtB and cdtAa
| REA type | No. of isolates in collection | Presence of cdt genes |
|---|---|---|
| AA | ||
| AA1 | 5 | + |
| AA2b | 1 | + |
| AD1 | 13 | − |
| AE1 | 1 | − |
| AI1 | 1 | − |
| AK1 | 7 | − |
| AM1 | 1 | + |
| AP1 | 20 | − |
| AQ1 | 1 | − |
| AR1 | 1 | − |
| AU1 | 1 | − |
| AX1 | 1 | − |
| AY1 | 1 | − |
| AZ1 | 2 | − |
| BB1 | 4 | − |
| BC1 | 1 | − |
| BD1 | 1 | − |
| BF1 | 1 | − |
| BG1 | 2 | − |
| BJ1 | 1 | − |
| BO1 | 1 | − |
| BP1 | 3 | − |
| BQ1 | 4 | − |
| BS1 | 5 | − |
| BU1 | 1 | − |
| BY1 | 2 | − |
| C1 | 19 | − |
| CA1 | 1 | − |
| CC1 | 1 | − |
| CD1 | 3 | − |
| CE1 | 1 | − |
| CH1 | 1 | − |
| CI1 | 1 | − |
| CM1 | 2 | − |
| CQ | ||
| CQ1c | 2 | +/− |
| CQ2 | 1 | − |
| CQ3 | 1 | − |
| CQ4 | 1 | − |
| CR1 | 1 | − |
| CS1 | 1 | + |
| CV1 | 1 | − |
| CZ1 | 1 | − |
| DE1 | 2 | − |
| DC1 | 1 | − |
| H1 | 4 | − |
| M | ||
| M1 | 6 | − |
| M23 | 58 | − |
| M3 | 109 | − |
| P1 | 4 | − |
| Q1 | 2 | − |
| S1 | 27 | − |
| T | ||
| T1 | 23 | − |
| T7 | 47 | − |
One representative isolate from each non-LCT-producing REA group was tested, except for REA groups AA and CQ, where all isolates were tested, and REA groups M and T, where three additional REA type isolates were tested, as these types (M3, M23, and T7) were the most prevalent non-LCT-producing REA types in the collection (9). All together 58 isolates representing 53 REA types were screened for cdtB. The total number of isolates was 403, and nine isolates were cdt+.
AA2 produced TcdB and was identified as a new A− B+ C. difficile variant despite relatedness to other non-LCT-producing (A− B−) isolates (REA type AA1 strains) within the same REA group.
Only one of the two REA type CQ1 isolates was positive for binary toxin genes.