New article about clinically important fungal biofilms in Nature Reviews Microbiology

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Dr Riina Rautemaa-Richardson (MRCM) recently co-authored an article for Nature Reviews Microbiology about the different types of fungal biofilms that are relevant to clinicians. This topic is of increasing importance as more patients undergo treatment with implanted medical devices and immunosuppressants.

What do clinicians need to know about biofilms?

Biofilms are populations of bacteria and/or fungi embedded in a matrix of secreted polymers. Fungi in a biofilm are often morphologically and metabolically different from their planktonic (free-living) form. Mature biofilms are tolerant of antifungals because they contain dormant ‘persister’ cells, and because the drugs cannot effectively penetrate their matrix. They also shed fungal cells that can disseminate to other organs via the blood

Thankfully, several antifungals in development (e.g. ibrexafungerp, rezafungin, olorofim) show activity against fungal biofilms, and in future it may be possible to develop drugs that target the biofilm formation process itself

Line lock therapy with an antifungal (e.g. AmBisome) is sometimes appropriate to salvage lines that would be problematic to remove, but must be discussed with your local infection team as protocols and recommendations vary between hospitals.

Examples of clinically-important biofilms

  • Candida frequently grows on medical devices with a lumen (e.g. CVC, endotracheal tubes) and can then disseminate to other organs via the bloodstream. They can also affect inaccessible devices or prostheses (.e.g. hip/knee replacement) and cause them to fail
  • Inhaled Aspergillus spores can grow and form dense fungal balls inside lung cavities (CPA/aspergilloma) or deep within the paranasal sinuses
  • Candida auris requires additional hygiene measures to avoid spread between patients on shared equipment such as axillary thermometers
  • Candida albicans is the most common causative agent in white plaques on the mucosa (e.g. denture stomatitis, oral thrush), and there is increasing evidence that it forms a biofilm with Lactobacillus during recurrent vulvovaginal candidiasis
  • Fungal endocarditis vegetations may contain various species of yeast or mould. It is harder to diagnose and treat than bacterial endocarditis, with poor outcomes