Table 2.
Summary of the results on the reference collection of two Shigella and 60 E. coli strains (9 Stx1 and 51 Stx2) submitted to the WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella after serotyping and using the subtyping protocol (Table 1)
| Strain or plasmid used for validation of the detection and subtyping protocol (reference)a | Strain serotyped as part of this studyb(original published serotype) | Result(s) obtained using the protocol described in Table 1 and in the text | Result(s) obtained using PCR/RFLP stx subtypingc |
|---|---|---|---|
| 3818T (61) | S. dysenteriae | stx | |
| CB7888 (9) | S. sonnei [H16] | stx | stx1 |
| EDL933 (43) | O157:H7 | stx1a and stx2a | stx1 |
| H-19B (30) | O26:H11 | stx1a | stx1 |
| H30 (30) | O26:H11 | stx1a | stx1 |
| 04-06263 (67) | O111:NM | stx1a | |
| CB168 (47) | O111:[H8] | stx1a | stx1 |
| PH (48) | O111:[H8 defective] | stx1a and stx2a | stx1 |
| 94C (47) | O48:H21 | stx1a and stx2a | stx1 |
| DG131/3 (29, 47) | O174:H8 | stx1c and stx2b | stx1c |
| MHI813 (11) | O8:K85ab:HR (ONT:H19) | stx1d | stx1d |
| 258/98d | O157:[H7] | stx2a | stx2 |
| 126814 (4) | O26:H11 | stx2a | stx2 |
| VTB60 (40) | O165:H25 (O136:H-) | stx2a and stx2c | stx2 and stx2v-ha gene |
| A397 (40) | O157:H7 | stx2a and stx2c | stx2 and stx2v-ha gene |
| 93-111 (32) | O157:H7 | stx1a and stx2a | |
| 928/91 (32) | O111:H- | stx1a and stx2a | |
| EBC201 (13) | O101:[H10] | stx2a | stx2 |
| pEHEC400e(13) | OR:H48 | stx2a | stx2 |
| EBC217 (13) | O22:H8 (NT) | stx1a and stx2a | stx1 and stx2 |
| I6581 (32) | O157:H7 | stx2a and stx2c | |
| G5506 (32) | O104:H21 | stx2a | |
| VTB178 (40) | O8:H19 | stx2a | stx2 |
| CL-3 (32) | O113:H21 | stx2a and stx2d | |
| 031 (49) | O174:H21 | stx2b and stx2c | stx2b |
| EH250 (51) | O118:H12 | stx2b | stx2b |
| 3143/97 (52) | O22:H8 | stx1c and stx2b | stx1c and stx2b |
| 5293/98 (65) | O40:H8 | stx2b | stx2b |
| 24196/97 (65) | O128:H2 (O86:H-) | stx2b | stx2b |
| E32511 (60) | O157:[H7] | stx2a and stx2c | stx2 and stx2v-ha gene |
| C394-03 (50) | O157:[H7 defective] | stx1a and stx2c | stx2v-ha gene |
| 469 (40) | O157:H7 | stx2c | |
| EBC287 (13) | O171:K49:H2 (NT) | stx2c and stx2b and stx2d | stx2v-ha gene and stx2v-hb gene |
| 310 (40) | O157:H7 | stx2c | stx2v-ha gene |
| A75 (40) | O157:H7 | stx1a and stx2c | stx1 and stx2v-hb gene |
| pVTEC9 (13) | OR:K+:H- | stx2c | stx2v-ha gene |
| EBC219 (13) | O?:K17:H7 (NT) | stx2c | stx2v-ha gene |
| 06-5121 (20) | O177:[H25] | stx2c and stx2d | stx2v-ha gene and stx2-NV206 |
| B2F1 (22) | O91:H21 | stx2d | stx2v-ha gene |
| MT 71 (26) | O28ab:H9 (O28:H28) | stx2d | |
| 7279 (39) | O157:H7 | stx2c | stx2v-ha gene |
| C466-01B (50) | O8:H19 | stx2d | stx2v-hb gene |
| EC173b (21) | O174:H21 | stx2b and stx2d | stx2v-hb gene and stxb |
| EC1720a (21) | O174:H21 | stx2b and stx2d | stx2v-ha gene and stx2b |
| EC1871a (21) | O165:H11 (NT) | stx2d | stx2v-hb gene |
| EBC275 (13) | O2:H29 (NT) | stx2b and stx2d | stx2v-ha gene |
| pVTEC7 (13) | OR:K+:H48 | stx2d | stx2v-hb gene |
| C165-02 (50) | O73:H18 | stx2d | stx2d-O73 |
| NV206 (5) | O6:H10 | stx2d | stx2-NV206 |
| 5905 (32) | O55:[H7] | stx2d | |
| S1191 (63) | O139:K12:H1 | stx2e | |
| 3615-99 (52) | O8:H10 (O22:H8) | stx2e | stx2e |
| E-D42 (15) | O101:H- | stx2e | stx2e |
| E-D43 (15) | O101:[H9] (O101:[H14]) | stx2e | stx2e |
| E-D53 (15) | O101:[H9] (O101:[H14]) | stx2e | stx2e |
| E-D68 (15) | O101:[H9] (O101:[H14]) | stx2e | stx2e |
| 2771 (41) | OR:H- | stx2e | |
| FHI-1106-1092 | O8:H2f | stx2a and stx2d | |
| T4/97 (59) | O128ac:[H2] | stx2f | stx2f |
| H.I.8. (18) | O89:[H2] (O128:H2) | stx2f | stx2f |
| 7v (33) | O2:H25 | stx2g | stx2g |
| S86 (19) | O2:H25 | stx2g | stx2g |
The 48 strains selected for validation of detection and subtyping are shown in bold type. The availability of these strains is described in the supplemental material.
Serotyping was done independently in two of the participating laboratories. Square brackets around an H type indicate genotypic fliC typing by PCR and RFLP analysis of nonmotile strains using the method described by Beutin et al. (6).
Results obtained using the PCR/RFLP stx subtyping described by Beutin et al. (7).
Deposited into the Entrez Nucleotide database by M. Bielaszewská et al. in 2002 under accession number AF524944.
The original gene was cloned from wild-type strain EBC201 into plasmid pEHEC400 and published as such. Both EBC201 and pEHEC400 (with the cloned gene) were used in the validation of the subtyping protocol. We have resequenced and confirmed the stx2a gene and serotyped the EBC201 wild-type strain.
Serotype confirmed on a non-toxin-producing isolate by the WHO Collaborating Centre for Reference and Research on Escherichia and Klebsiella.