Biofilms Role in Chronic Infections

Original Editor - Lucinda hampton Top Contributors - Lucinda hampton, Vidya Acharya, Admin, Kim Jackson and Nupur Smit Shah

Introduction

A biofilm is an architectural colony of microorganisms, that is irreversibly associated (not removed by gentle rinsing) with a surface and enclosed in a matrix of primarily polysaccharide material. Biofilm contains microbial cells adherent to one-another and to a static surface (living or non-living). Depending on the environment it is developed, a biofilm may also contain noncellular materials such as mineral crystals, corrosion particles, clay or silt particles, or blood components. Biofilm-associated organisms also differ from their planktonic (freely suspended) counterparts with respect to the genes that are transcribed. Biofilms may form on various surfaces, like living tissues, indwelling medical devices, industrial or potable water system piping, or natural aquatic systems.

Bacterial biofilms are usually pathogenic in nature and can cause hospital infections. The National Institutes of Health (NIH) revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation.

The image shows a colony of biofilm.

A common misconception of microbial life is that bacteria exist as individual organisms in a ‘planktonic state’. However microorganisms have been shown to naturally accumulate on a wide variety of surfaces; where they form sessile, sedentary communities. Those surfaces include biomaterials such as contact lenses, medical devices including implants and urinary catheters. Bacterial contamination on implants and prosthetic medical devices causing infections can be life-threatening, leading to device failure, chronic infections and high mortality and morbidity rates.

Infections Associated with Biofilm

It is estimated that about 65% of all bacterial infections are associated with bacterial biofilms. These include both, device- and non-device-associated infections. These include:

• Device related infections (device related infections affecting 2% of joint replacements, 4% for heart valves, 10% for ventricular shunts, 40% for ventricular assisted devices)
• Native valve endocarditis
• Central venous catheters
• Urinary Tract Infection
• Cellulitis
• Perodontitis
• Osteomyelitis
• Cystic Fibrosis infections
• COPD (Chronic Obstructive Pulmonary Disease) infections
• Otitis media
• Rhinosinusitis
• Non-healing chronic wounds
• Meningitis,
• Hospital Acquired Pneumonia
• Clostridium Difficile Infection CDI
• Kidney infections,

Current Treatment Approaches

In patients, biofilms that form are resistant to the host's endogenous defences. Biofilms causing infections are progressive, and in some cases can become a chronic problem. They are treated with a combination of antibacterial therapies and tissue debridement. In the case of implant-associated infections treatment includes the delivery of high dose antibiotics according to the severity of infection, and if symptoms persist, then surgical replacement must take place. 

Adversely, the large doses of antibiotics used to treat biofilms clinically have also contributed to the development of antibiotic-resistant bacteria strains. Also it has been seen that some bacteria within biofilms, called “persister cells,” are dormant variants that exhibit antibiotic tolerance and can become active when the therapy is withdrawn.

See also Infection Control

Future Directions

Due to the widespread distribution of biofilms in diseases and their resilience to numerous antimicrobial treatments, biofilm research is receiving more attention. Owing to increasing antimicrobial resistance, the focus of current research is shifting from targeting bacterial growth/division that causes cell death or dormancy, towards novel approaches.

The 4 videos below (approx 10 minutes in total) show some of these novel approaches, take a look.