Going Organic Cuts Poultry Farms? ?Superbug? Bacteria in Single Generation

[Gert van der Hoek]

Going Organic Cuts Poultry Farms’ “Superbug” Bacteria in Single Generation

By Katherine Harmon | August 12, 2011

The government has come under fire this week for revelations that it knew about antibiotic resistant Salmonella in poultry products that has killed at least one person and sickened more than 100 across the country. Although this is one of the largest turkey recalls—affecting some 36 million pounds of ground turkey—the prevalence of bacteria that is immune to common drugs is on the rise on animal farms, which is where the bulk of U.S. antibiotics get used.

But by going organic, poultry farms can cut the amount of antibiotic resistant bacteria in a single generation by nearly five times, according to a new study published online this week in Environmental Health Perspectives.

“We were surprised to see that the differences were so significant across several different classes of antibiotics even in the very first flock that was produced after the transition to organic standards,” Amy Sapkota, of the University of Maryland School of Public Health, and co-author of the new study, said in a prepared statement.

Read more: Scientific American

Lower Prevalence of Antibiotic-resistant Enterococci On U.S. Conventional Poultry Farms That Transitioned to Organic Practices

Abstract

Background: In U.S. 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. However, no U.S. studies have investigated on-farm changes in resistance as conventional poultry farms transition to organic practices and cease using antibiotics.

Objective: To evaluate the prevalence of antibiotic-resistant Enterococcus on U.S. conventional poultry farms that transitioned to organic practices.

Methods: Poultry litter, feed, and water samples were collected from 10 conventional and 10 newly organic poultry houses in 2008 and tested for Enterococcus. Enterococcus (n=259) was identified using the Vitek ®Compact 2 System, and tested for susceptibility to 17 antimicrobials using the Sensititre™ microbroth dilution system. Data were analyzed using SAS v9.2 and statistical associations were derived based on generalized linear mixed models.

Results: Litter, feed and water samples were Enterococcus-positive. 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≥3 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).

Conclusions: Our findings suggest that the voluntary removal of antibiotics from large-scale U.S. poultry farms that transition to organic practices is associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.

Environmental Health Perspectives