Pathogen resistance to drugs rising, according to UK study

The Department of Environment, Food & Rural Affairs (Defra) study points to the growing resistance of specific food pathogens to antimicrobials, drugs used to kill them off in animals at the production stage. The report serves as a warning to processors about the problems of resistant pathogens being passed along the food chain to consumers. The three-year project could eventually lead to more testing and controls, and restrictions on the type of animicrobials that can be used to control pathogens. The survey found that cephalosporin resistance in E. coli from bacteraemia is increasing. Over half of the E. coli bacteraemia isolates were resistant to ampicillin or amoxicillin, and up to 9 to 19 per cent were resistant to ciprofloxacin. In humans E. coli is one of the two most important bacterial pathogens causing sickness in the UK. The majority of E. coli O157, one of the most dangerous forms of the pathogen, were susceptible to all the antimicrobials tested, the survey found. Some of the E. coli 0157 foundin humans showed resistance to tetracyclines, sulphonamides and streptomycin, with some variation by region. Salmonella, the most common causes in cases of human infection in the UK, also had low resistance to common antimicrobials. However resistance to more than one drug in S. Typhimurium, the second most common form of the pathogen, is common. S. Typhimurium commonly has resistance to nalidixic acid, the report stated. There was no resistance detected to amikacin, cefotaxime, ceftazidime or ciprofloxacin in Salmonella isolates of animal origin from England and Wales. Similarly, no resistance was detected to cefotaxime or ciprofloxacin in animal Salmonella isolates from Northern Ireland or Scotland. All human and animal isolates of L. monocytogenes were found to be susceptible to penicillin or ampicillin. Antimicrobial resistance continues to be extremely rare in L. monocytogenes, the survey found. The survey found that between 22 to 24 per cent of C. jejuni and 28 to 29 per cent of C. coli were resistant to ciprofloxacin. C. jejuni accounted for 90 per cent of infections in humans in the UK. The survey also showed that resistance rates of the virus in cattle, sheep and pigs at slaughter were lower than in humans. For C. jejuni, the prevalence of resistance seen in humans is about the same as that detected in retail chicken. The report showed that about half of the total tonnage of antimicrobials was used in animals in 1994. Approximately 80 per cent of antimicrobial prescribing in humans was for patients in the community while 87 per cent of antimicrobial use in animals was in food-producing animals. Tetracyclines accounted for 54 per cent of total antimicrobial use in animals, while ß-lactams accounted for 14 per cent.