Isolation of Campylobacter upsaliensis from stool specimens

Walmsley and Karmali (6) reported on the isolation from the stools of six children of Campylobacter strains corresponding phenotypically to Campylobacter upsaliensis. This is an important observation, adding evidence to the possible enteropathogenic role of these organisms. However, we disagree with the recommendations of the authors regarding the isolation procedure for C. upsaliensis from stools. Indeed, the authors suggest that their previously described CSM medium (4), consisting of Columbia agar base, activated charcoal, cefoperazone (32 ,ug/ml), vancomycin (20 ,ug/ml), and cycloheximide (100 ,ug/ml), is a suitable medium for the isolation of C. upsaliensis from stool specimens. We introduced an antibiotic-free filtration method (5) on 1 July 1986 and have compared it, for the isolation of campylobacters from 12,799 stool specimens, with our previously described solid (2) and semisolid (3) selective media, as well as with the blood-free charcoal medium (1) supplemented with cefoperazone (SR 125; Oxoid). A total of 93 catalase-negative or weakly reacting (CNW) strains were isolated; these were subsequently found to belong to the C. upsaliensis group, as described by K. Sandstedt and J. Ursing (Abstr. 14th Int. Congr. Microbiol. 1986, PB 8-17). Eighty-nine strains were isolated with the filtration method only. The susceptibilities of 52 of 93 CNW strains to drugs present in selective isolation media are shown in Table 1. Clearly, a wide range of susceptibilities can be observed for these organisms, and it is obvious from Table 1 that none of the existing selective isolation media are suitable for the isolation of CNW campylobacters from stool specimens. There may be several reasons why these six C. upsaliensis strains were isolated on CSM medium in Walmsley and Karmali's paper (6). Looking at Fig. 1 in their paper, it would appear that they have been dealing with an outbreak of CNW strains. These strains may have been resistant to cefoperazone, vancomycin, and cycloheximide; however, only 19.2% of our strains were resistant to cefoperazone. In conclusion, we would suggest that microbiologists interested in the isolation of these CNW campylobacters include the filtration method (5). Indeed, none of the presently available selective isolation media are satisfactory for the isolation of these strains. The results of our study have been presented at the 4th and 5th International Workshops on Campylobacter Infections in Goteborg, Sweden (16 to 18 June 1987), and Puerto Vallarta, Mexico (25 February to 1 March 1989). A manuscript is in preparation. LITERATURE CITED 1. Bolton, F. J., D. N. Hutchinson, and D. Coates. 1984. Blood-free selective medium for isolation of Campylobacter jejuni from feces. J. Clin. Microbiol. 19:169-171. 2. Goossens, H. , M. De Boeck, H. Coignau, L. Vlaes, C. Van Den Borre, and J.-P. Butzler. 1986. Modified selective medium for isolation of Campylobacter spp. from feces: comparison with Preston medium, a blood-free medium, and a filtration system. J. Clin. Microbiol. 24:840-843. 3. Goossens, H. , L. Vlaes, I. Galand, C. Van Den Borre, and J.-P. Butzler. 1989. Semisolid blood-free selective-motility medium for the isolation of campylobacters from stool specimens. J. Clin. Microbiol. 27:1077-1080. 4. Karmali, M. A. , A. E. Simor, M. Roscoe, P. C. Fleming, S. S. Smith, and J. Lane. 1986. Evaluation of a blood-free, charcoalbased, selective medium for the isolation of Campylobacter organisms from feces. J. Clin. Microbiol. 23:456-459. 5. Steele, T. W. , and S. N. McDermott. 1984. The use of membrane filters applied directly to the surface of agar plates for the isolation of Campylobacter jejuni from feces. Pathology 16: 263-265. 6. Walmsley, S. L. , and M. A. Karmali. 1989. Direct isolation of atypical thermophilic Campylobacter species from human feces on selective agar medium. J. Clin. Microbiol. 27:668-670.