Human Antibiotic-Resistant Bacteria Not from Chickens

SWEDEN - Researchers have found that vancomycin-resistant enterococci in humans did not originate in chickens but possibly from sewage sludge spread on arable land. Sahlström from Evira in Finalnd and co-authors from Sweden's National Veterinary Institute have published their results in Acta Veterinaria Scandinavica.
calendar icon 12 June 2009
clock icon 3 minute read

Antimicrobial resistance is a serious threat in veterinary medicine and human health-care. Resistance genes can spread from animals, through the food-chain, and back to humans. Sewage sludge may act as the link back from humans to animals. The main aims of this study were to investigate the occurrence of vancomycin resistant enterococci (VRE) in treated sewage sludge, in a Swedish waste water treatment plant (WWTP), and to compare VRE isolates from sewage sludge with isolates from humans and chickens.


During a four month long study, sewage sludge was collected weekly and cultured for VRE. The VRE isolates from sewage sludge were analysed and compared to each other and to human and chicken VRE isolates by biochemical typing (PhenePlate), PFGE and antibiograms.


Biochemical typing (PhenePlate-FS) and pulsed field gel electrophoresis (PFGE) revealed prevalence of specific VRE strains in sewage sludge for up to 16 weeks. No connection was found between the VRE strains isolated from sludge, chickens and humans, indicating that human VRE did not originate from Swedish chicken.


This study demonstrated widespread occurrence of VRE in sewage sludge in the studied WWTP. This implies a risk of antimicrobial resistance being spread to new farms and to the society via the environment if the sewage sludge is used on arable land.


Sahlström L., V. Rehbinder, A. Albihn, A. Aspan and B. Bengtsson. 2009. Vancomycin resistant enterococci (VRE) in Swedish sewage sludge. Acta Veterinaria Scandinavica 2009, 51:24. doi:10.1186/1751-0147-51-24.

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