This article describes what biofilms are and the important roles they appear to play in disrupting wound healing. In addition, it discusses potential interventions aimed at removing/reducing biofilms and preventing their reformation in wounds.

WHAT ARE BIOFILMS?

Biofilms are complex microbial communities containing bacteria and fungi. The microorganisms synthesise and secrete a protective matrix that attaches the biofilm firmly to a living or non-living surface [1].

Biofilms are dynamic heterogeneous communities that are continuously changing [2]. They may consist of a single bacterial or fungal species, or more commonly, may be polymicrobial, ie contain multiple diverse species [3,4]. At the most basic level a biofilm can be described as bacteria embedded in a thick, slimy barrier of sugars and proteins. The biofilm barrier protects the microorganisms from external threats.

HOW ARE BIOFILMS RELEVANT TO WOUNDS?

Biofilms have long been known to form on surfaces of medical devices, such as urinary catheters, endotracheal and tympanostomy tubes, orthopaedic and breast implants, contact lenses, intrauterine devices (IUDs) and sutures [5,6]. They are a major contributor to diseases that are characterised by an underlying bacterial infection and chronic inflammation, eg periodontal disease, cystic fibrosis, chronic acne and osteomyelitis [2,5,7].

Biofilms are also found in wounds and are suspected to delay healing in some. Electron microscopy of biopsies from chronic wounds found that 60% of the specimens contained biofilm structures in comparison with only 6% of biopsies from acute wounds [8]. Since biofilms are reported to be a major factor contributing to multiple chronic inflammatory diseases, it is likely that almost all chronic wounds have biofilm communities on at least part of the wound bed.  

HOW DO BIOFILMS FORM?

Stage one: reversible surface attachment
Microorganisms are commonly perceived to be free-floating and solitary (ie planktonic). However, under natural conditions most microorganisms tend to attach to surfaces and eventually form biofilms [1,9] (Fig 1).The initial attachment is reversible.