Lower Prevalence of Antibiotic Resistance

A study published this month in Environmental Health Perspectives has found lower antibiotic resistance on newly organic farms compared to conventional farms in the US.

In conventional poultry production, antimicrobials are used for therapeutic, prophylactic and non-therapeutic purposes. Researchers have shown that this can select for antibiotic-resistant commensal and pathogenic bacteria on poultry farms and poultry-derived products. The following study investigated on-farm changes in resistance as conventional poultry farms converted to organic practices and ceased using antibiotics.

Litter, feed and water samples were tested from 10 conventional and 10 newly converted organic farms. The percentages of resistant E. faecalis and resistant E. faecium were significantly lower (p<0.05) among isolates from newly organic versus conventional houses for two (erythromycin and tylosin) and five (ciprofloxacin, gentamicin, nitrofurantoin, penicillin and tetracycline) antimicrobials respectively.

Forty-two percent of E. faecalis isolates from conventional poultry houses were multi-drug resistant (MDR) (to¡Ý3 antimicrobial classes) compared to 10% of isolates from newly organic houses (p=0.02), and 84% of E. faecium isolates from conventional houses were MDR compared to 17% of isolates from newly organic poultry houses (p<0.001).

The authors concluded that the transition to organic practices is associated with a lower prevalence of antibiotic resistant and multi-drug resistant Enterococcus.

Sapkota AR, Hulet RM, Zhang G, McDermott P, Kinney E, Schwab K, et al. 2011. Lower Prevalence of Antibiotic-resistant Enterococci On U.S. Conventional Poultry Farms That Transitioned to Organic Practices. Environ Health Perspect :-. doi:10.1289/ehp.1003350

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