Vergleichende Anwendung von zwei im Handel erhältlichen Selektivnährböden

Comparative study of culture methods to detect Yersinia enterocolitica serogroup O3 on swine tongues

Swine tongues were used as a model for evaluation of culture methods for Y. enterocolitica O3. The following three methods were used: Method A consisting of primary culture on DC, McConkey, CIN and SSD agar with additional long-term cold enrichment in PBS and/or selenite broth. Method B--2 min, treatment of samples with 0.5 per cent KOH solution followed by the same cultivation as above and Method C--"cold shock" i.e. incubation of swabs without any medium at -20 degrees C overnight and then inoculated in selenite broth and/or PBS. Methods B and C were approximately twice as effective as Method A. The percentage of detectability ranged from 70 to 90 per cent. CIN agar yielded 20 of 23 positive results when compared with other solid media. A total of 247 smears from pig tongues yielded 60 positive Y. enterocolitica O3 isolations i.e. 27 per cent on average.

New selective agar medium for isolation of virulent Yersinia enterocolitica

A selective agar medium for isolation of virulent Yersinia enterocolitica (VYE agar) was developed for the rapid and accurate isolation of virulent Y. enterocolitica from environmental samples highly contaminated with environmental Yersinia organisms, as well as for isolation from clinical specimens. VYE agar provided a quantitative recovery of 51 different strains of virulent Y. enterocolitica at 32 degrees C after incubation for 24 h. The cefsulodin, irgasan, josamycin, and oleandomycin content of the medium resulted in a high selectivity, and the mannitol and esculin content provided some differentiation. The greatest advantage of VYE agar is that virulent Y. enterocolitica, which forms red colonies, is easily differentiated from most environmental Yersinia organisms and other gram-negative bacteria, which form dark colonies with a dark peripheral zone as a result of esculin hydrolysis. Use of VYE agar led to a high recovery of Y. enterocolitica biotype 3B serotype O:3 strains from experimentally inoculated meat samples, compared with use of CIN agar. Biotype 2 serotypes O:5,27 and O:9 and biotype 1 esculin-negative serotypes O:4,32, O:8, O:13a,13b, O:18, O:20, and O:21 (American types) were readily differentiated from other environmental organisms able to grow on VYE agar. Epidemiological studies on Y. enterocolitica should be greatly facilitated by the use of this selective agar medium.