Implants Create Niche for Fungi and Bacteria

A new study reveals that implants provide a distinct alcove for microbial colonization, but that the most prevalent microbes are not those responsible for implant infections.

Researchers at the University of Copenhagen (KU; Denmark), Rigshopitalet University Hospital (Copenhagen, Denmark), the Georgia Institute of Technology (Atlanta, USA), and other institutions conducted a study of 106 implants (ranging from screws and knees to pacemakers) surrounding tissues in four groups (aseptic loosening, healed fractures, craniofacial complications, and the recently deceased) in five different hospitals in the Capital region of Denmark. The aim of the study was to detect and identify implant microbiomes from patients with no prior indications of implant-related infections.

The researchers also made 39 controls to ensure the implants were not contaminated during collection or subsequent analysis. This was done by opening a sterile implant in the laboratory, during surgery or an implant removed shortly after placement. The results revealed 78 implants (70%) were colonized by bacteria, fungi or both. A significant majority of screws were colonized by bacteria, but the prevalence of fungi was the same for all implants. None of the bacteria or fungi detected were pathogens, none of the patients showed signs of infection, and all controls were negative. The study was published on July 2, 2018, in APMIS.

“We have always believed implants to be completely sterile. It is easy to imagine, though, that when you insert a foreign body into the body, you create a new niche, a new habitat for bacteria. The question is whether this is beneficial, like the rest of our microbiome, whether they are precursors to infection, or whether it is insignificant,” said senior author Professor Thomas Bjarnsholt, PhD, of the KU department of immunology and microbiology. “This opens up a brand new field and understanding of the interplay between the body and bacteria and microbiomes.”

“It is important to stress that we have found no direct pathogens, which normally cause infection. Of course if they had been present, we would also have found an infection,” concluded lead author Tim Holm Jakobsen, PHd, of Rigshopitalet. “The study shows a prevalence of bacteria in places where we do not expect to find any, and they manage to remain there for a very long time, probably without affecting the patient negatively.”

Related Links:
University of Copenhagen
Rigshopitalet University Hospital
Georgia Institute of Technology