Present situation of national surveillance of antimicrobial resistance in bacteria isolated from farm animals in Japan and correspondence to the issue

Abstract

The Japanese Veterinary Antimicrobial Resistance Monitoring System (JVARM) was formed in 1999 in response to international concerns about the impact of antimicrobial resistance on public health. The aim of the present investigation was to provide insight into the occurrence of antimicrobial resistance among bacterial strains isolated from cattle, swine and poultry on farms across Japan. In this paper, we summarize a nationwide investigation (1999-2003) on antimicrobial susceptibility of the targeted bacterial species for the JVARM, namely Salmonella, Campylobacter, Enterococcus and Escherichia coli, isolated from the feces of healthy domestic animals. Minimum inhibitory concentrations (MICs) of 10-18 antimicrobial agents including the major generic groups were determined using an agar dilution method according to the international NCCLS guideline in principle. The outline of present results is as follows: (1) A total of 307 Salmonella, 3,225 Escherichia coli, 2,822 Enterococcus and 1,122 Campylobacter were isolated from healthy domestic animals and examined for antimicrobial susceptibility. (2) The isolates of all targeted bacterial species represent high rates of antimicrobial resistance to both oxytetracycline (OTC) and dihydrostreptomycin (DSM). (3) Among the isolates of Campylobacter and E. coli, the frequency of isolation of resistance to fluoroquinolones ranged from 14 to 24% and 2 to 3%, respectively. (4) Resistance to fluoroquinolones was not observed among the isolates of Salmonella or Enterococcus. Continious investigation at the nation level of antimicrobial resistance among the isolates from healthy domestic animals remains a high priority for the JVARM program. Furthermore, appropriate and prudent use of antimicrobials for diseased animals should be considered essential.