[Problems of resistance (author's transl)].

The results of sensitivity tests performed during the period from 1970 up to 1973 inclusive are compared with those obtained in pervious years. This showed that resistance to penicillin had increased in staphylococci causing bovine mastitis. During each single year, however, there was a decrease. S. typhimurium isolated from cattle showed increased resistance to chloramphenicol, neomycin and ampicillin; S. dublin showed an increase in resistance to chloramphenicol. E. coli isolated from calves with coli-bacillosis had become less sensitive to all the antibiotics studied. Pathogenic strains of E. coli isolated from swine also showed increased resistance, among others to tetracycline, neomycin and ampicillin. The danger constituted by this development and the factthat comparison with the results obtained by other presents difficulties in some cases are stressed.