BACTERIAL-RESISTANCE MONITORING OF SALMONELLAS ISOLATED FROM ANIMALS,NATIONAL EXPERIENCE OF SURVEILLANCE SCHEMES IN THE UNITED-KINGDOM

Antimicrobial resistance has been monitored in salmonellas isolated fr om animals in England and Wales since 1970. The current trends are ind icated by comparing the results for the years 1981, 1989 and 1990. Sev enty-six per cent of all salmonella isolations are still sensitive to all 16 antimicrobials used for testing. Most antimicrobial resistance is encountered in bovine isolations of Salmonella typhimurium especial ly phage type DT204C. This phage type, which was initially resistant t o at least seven antimicrobials, has however become more susceptible i n recent years. Ninety-eight per cent of S. dublin strains from cattle are still sensitive to all the antimicrobials used for testing. Altho ugh the number of porcine salmonella isolations is small, many show an timicrobial resistance especially to tetracyclines. A large increase i n the number of salmonellas isolated from poultry has occurred in rece nt years and 75% of these strains are sensitive to all the antibiotics used for testing. Although there has been a slight decrease in the pe rcentage of S. enteritidis strains showing susceptibility 87% of isola tions are still sensitive. The emergence of resistance to the newer an timicrobials trimethoprim, apramycin and fluorquinolones has been stud ied and data presented. The results are discussed with regards to the choice of techniques, bacteria monitored and future surveillance progr ammes in relation to the veterinary use of antimicrobials.