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Cefixime–tellurite rhamnose MacConkey agar for isolation of Vero cytotoxin-producing Escherichia coli serogroup O26 from Scottish cattle and sheep faeces |
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| Authors: | J Evans HI Knight AW Smith MC Pearce M Hall G Foster JC Low GJ Gunn |
| Institution: | SAC Epidemiology Research Unit, Animal Health Group, SAC Research, Edinburgh, UK; Centre for Tropical and Veterinary Medicine, University of Edinburgh, Midlothian, UK; Veterinary Services, Scottish Agricultural College, Inverness IV2 4JZ, UK |
| Abstract: | Aims: To compare rhamnose MacConkey agar supplemented with cefixime and tellurite (CT-RMac) and tryptone bile X-glucuronide (TBX) agars as isolation media for Vero cytotoxin-producing Escherichia coli (VTEC) serogroup O26 from animal faeces. Methods and Results: Nine VTEC O26 were isolated from sheep faeces; out of which six were isolated only on CT-RMac and one was isolated only on TBX. One hundred and twelve VTEC O26 were isolated from calf faeces; out of which 97% were from CT-RMac and 52% were from TBX. In a study of E. coli O26 strains, 84% of VT-positive O26 did not ferment rhamnose when compared with 16% of VT-negative O26. VT-positive (19%) and VT-negative (39%) E. coli O26 strains did not grow on CT-RMac agar. Conclusions: It is important to consider that VTEC O26 strains either may ferment rhamnose or may be sensitive to the CT supplement of CT-RMac agar. Significance and Impact of the Study: This work compares CT-RMac and TBX agars as isolation medium for VTEC O26 from Scottish animal faeces and highlights that VTEC O26 may be missed if only CT-RMac agar is used. |
| Keywords: | CT-RMac Escherichia coli O26 rhamnose TBX |