Vancomycin resistant enterococci (VRE) in Swedish sewage sludge.
BACKGROUND
Antimicrobial resistance is a serious threat in veterinary medicine and human healthcare. 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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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
Leena
L
Finnish Food Safety Authority, Evira, Mustialankatu 3, Helsinki, Finland. Leena.Sahlstrom@evira.fi
Rehbinder
Verena
V
Albihn
Ann
A
Aspan
Anna
A
Bengtsson
Björn
B
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015373:Bacterial Typing Techniques; D002645:Chickens; D015169:Colony Count, Microbial / Q000662:veterinary; D016521:Electrophoresis, Gel, Pulsed-Field; D016983:Enterococcus / Q000145:classification / Q000187:drug effects / Q000302:isolation & purification; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D012722:Sewage / Q000382:microbiology*; D013548:Sweden; D014640:Vancomycin / Q000494:pharmacology; D020713:Vancomycin Resistance; D014865:Waste Disposal, Fluid
D000900:Anti-Bacterial Agents; D012722:Sewage; D014640:Vancomycin