Overview of the developments in the resistance of porcine pathogens in theex-GDR and in the New Lander from 1976 to 1998

The results of a study of the resistance of porcine pathogens in the ex-GDR from 1976 to 1990 and in the new Lander from 1991 onwards are presented as a review. E. coli was observed to display a resistance development that is cleat-ly dependent on selection pressure, especially to tetracyclines and sulphonamides. Resistance levels have also developed to many other antimicr obials such as ampicillin. No particular developments in the resistance of Pasteurella multocida were observed with prevalences of resistance from 10- 17% to benzylpenicillin, 5-13% to ampicillin, 9-12% to potentiated sulphona mides and 3-6% to enrofloxacine. For Actinobacillus pleuropnemoniae there w ere indications of a continuous increase, up to a doubling, in resistance t o some antibiotic such as benzylpenicillin, ampicillin and tetracycline ol er the last 23 years, bur no change in resistance patterns were observed fo r chloramphenicol, enrofloxacine and potentiated sulphonumides. There was n o increase in the prevalence of resistance of streptococci to benzylpenicil lin, ampicillin and potentiated sulphonamides over the 23 years, bur the se nsitivity to tetracycline has decreased markedly since 1990 and at present 88% of isolated are resistant. After banning the nitrofurans, ampicillin re mained as the chemotherapeutic agent of choice for Clostridium perfringens, with 13% of isolated resistant, and for Bordetella bronchiseptica tetracyc line (10% resistance), neomycin (5% resistance) and enrofloxacine (15% resi stance) remained as effective antimicrobials.