Aims: To develop a selective supplement for the recovery of thermophilic Campylobacter spp, including Campylobacter upsaliensis from faeces, using campylobacter blood free selective agar base as the growth medium.
Methods: Minimum inhibitory concentrations (MICs) of cefoperazone and of teicoplanin were determined for 51 strains of C upsaliensis, 159 strains of other thermophilic Campylobacter spp, and for 66 Enterobacteriaceae (cefoperazone only). From these results a medium using campylobacter blood free selective agar base incorporating cefoperazone (8 mg/l), amphotericin (10 mg/l), and teicoplanin (4 mg/l)--CAT medium--was formulated and compared with the commercially available campylobacter blood free selective medium (modified CCDA) for isolation of Campylobacter spp from 7000 human faecal specimens. The two media were also compared for the recovery of C upsaliensis from 45 spiked human faeces.
Results: Isolation rates of Campylobacter spp other than C upsaliensis were similar for both media, but the CAT medium alone recovered four of the five strains of C upsaliensis from the faecal samples examined. From the spiked faeces specimens, recovery of C upsaliensis was increased by between 35% and over 200-fold on the CAT medium compared with the modified CCDA.
Conclusions: CAT selective agar was a suitable alternative medium to modified CCDA for the growth of thermophilic Campylobacter spp, including C upsaliensis from faeces.