Dr Dirk J Verwoerd BSc.Agric BVSc MRCVS

Executive Summary

Biofilms are simple to complex microbial ecosystems on surfaces. The study of Biofilms combine expertise from a wide variety of scientific disciplines such as Engineering (components, alloys, non-corrosive paints etc), Physics (surfaces, flow dynamics etc), Veterinary / Medical (microbiology, pharmacology and therapeutics) and Food Hygiene.

These surfaces can be inert and thus indirectly linked to diseases in animal populations and patients, such as plastic water pipes in a reticulation system, air conditioning, humidification and filtration systems, intravenous catheters, prosthetic devices or they can be biological and thus more directly associated with animal health such as granulomatous wound healing tissue, respiratory epithelium and epithelial to glandular mucosae in the udder. The ecosystems can consist of bacteria, fungi and / or yeasts that communicate with each other in various ways. The microbial organisms build a framework of an extracellular polysaccharide matrix (slime) that prevent the effective action of simple disinfectants / antimicrobials. Several studies have indicated a 10 -1000 fold higher resistance to certain antimicrobials by bacteria in the biofilm growth phase, compared to the same isolate in the planktonic (free-floating) form. 

Some of these aspects have major practical implications regarding recurrent / reservoir infections, horizontal spread of resistance, nosocomial complications during long-term hospital and intensive care situations to individual patients and populations. Effective strategies against biofilms consist of an integrated approach where appropriate antibiotics / antifungals are combined with surface cleaning and disinfection using a compound chosen for its detergent plus disinfectant plus tissue friendly properties, such as the broad spectrum F10SC Veterinary Disinfectant / F10 Antiseptic Solution. Biofilm found on hard surfaces and the insides of pipes can be effectively removed by the combined use of a purpose built cleaner such as F919 Biofilm Remover followed by the application of the F10 disinfectant.

The formation of the microcolony

The formation of bacterial biofilms begin with the adhesion of a small number of bacterial cells to a surface (making the selection of effective biocidal disinfectants/antiseptics and use of fogging applications to access difficult to reach surfaces of critical importance). After a planktonic bacterial cell has sensed and ‘explored’ a surface, the cell may commit to the active process of adhesion and biofilm formation through the upregulation of a large variety of genes. Amongst these are the genes that rapidly stimulate the formation of an Exopolysaccharide material (EPS) framework, also known as “bacterial slime”. Studies of the basic architecture of biofilms have shown that the microcolony is the basic structural unit of the biofilm. Bacterial cells within the matrix are characterized by their lack of Brownian motility (movement).

Careful structural analysis of the shape of many microcolonies often reveals a mushroom-like shape, most of the cells are found in the ‘crown’ of the mushroom and very few are in the ‘stalk’. Microcolonies are arranged in a horizontal array in thin biofilms, but they may also form vertical arrays in very thick sessile communities. Flow of water or blood through these biofilms occur through discrete channels, restricting the exposure of these bacteria to antimicrobials/disinfectants.

The 5 classic stages of biofilm formation; from initial colonization of surfaces by planktonic bacteria (1-3) to growth into mushroom-shaped “adolescent” microcolonies (4) to “seeding” via the aquous medium from mature microcolonies to establish secondary foci (5).


Summary of characteristics of biofilm growth.


The biofilm mechanisms

These bacterial biofilms form on the surfaces of medical devices and on tissue surfaces within compromised organs, and they grow in exactly the same way that biofilms grow in environmental and industrial systems. The natural laws that cause bacteria to grow preferentially in biofilms on surfaces operates in all ecosystems. The same mechanisms that protect biofilm bacteria in lakes and streams from predatory amoeba, also protect bacteria in animal systems from phagocytosis by white blood cells. Similarly, the same mechanisms that protect environmental biofilms from bacteriophage and chemical antagonists in streams and lakes also protect biofilms in animal bodies from antibodies and antibiotics. The survival value of biofilm formation inside the animal body is probably even higher than it is in most environmental systems, because the body is so relentless and implacable in its coordinated immunological attack on the ‘foreign’ materials that enters it.

Bacterial biofilms in medical systems are virtually identical with biofilms in any other aquatic ecosystem. This fundamental understanding is very valuable, because it allowed important advances in other areas of biofilm research.


It follows logically from the above that only an integrated approach; where surface (mucosal) disinfection/antiseptics PLUS systemic antimicrobials and other supportive substances where appropriate, such as Cortisones, will have a good prognosis in these medical conditions. Such a disinfectant/antiseptic has to combine biocidal efficacy with safety (tissue-friendliness) and a detergent effect to break up the EPS slime; which are exactly the unique characteristic combination of F10 disinfectants. The elimination of biofilms from hard surfaces and the inside of pipes is made easier with the use of a product such as F919 Biofilm Remover. The mechanism of action of F919 is not reliant upon a mechanical brushing action or HP washer jet but interacts chemically with the organic film to release it from the surface and take it up into suspension where is can be washed away. Such an application is always followed by an application of F10 disinfectants.

Biofilm buildup has been detected in endotracheal tubes

Respiratory and Nosocomial infections:

Complicated Bovine Respiratory Disease, a complex comparable in many respects to “Community-Aquired Pneumonia” in humans, is the result of the interaction between stressed/compromised hosts and a variety of microorganisms that include various viruses, bacteria and Mycoplasmas. Recent studies have indicated that the refractory and recurrent nature of these conditions can often be explained through the role of Mycoplasma biofilms. Bacterial biofilms often complicated by Mycoplasma spp and fungal elements are common as part of the airsacculitis syndrome in avians.

Purpose built chamber to nebulise using F10SC

Fogger used to overspray in aviaries and poultry houses in the presence of the birds


Here in particular an integrated approach where systemic antimicrobials plus surface disinfection via fogging with F10 (with the animals present) has proven itself both in pig and poultry production systems as well as (nebulising) in individual avian (and other species) patients. Similar complicated respiratory conditions often occur in Zoo’s and other collections of exotic mammals, avians, reptiles and amphibia where F10 fogging and irrigation (wound irrigation and nasal/sinus flushing) has proven to be the crucial difference between success and failure during particular treatment regimes.

Open misting/fogging system used in a nebulising therapy to treat airsaccullitis in adult ostriches

Immune complexes in biofilm-affected organs

Many challenges remain, particularly in chronic infections with a prominent  immunological component and/or resistant (“hospital”) bacteria. These aspects combine in cystic fibrosis patients and thus illustrate the principles involved. One of the invidious characteristics of chronic P. aeruginosa pulmonary infections in cystic fibrosis patients is the formation of large amounts of immune complexes in the lung. Because individual cystic fibrosis patients may be infected with P. aeruginosa for two to three decades, these patients form huge amounts of antibodies against the antigens of this persistent pathogen. These anti Pseudomonas antibodies cannot penetrate the exopolysaccharide matrix of the microcolonies of pseudomonas cells in the alveoli of the lung. But they can and do react with their specific antigens at the surface of these cryptic microcolonies to form immune complexes. Immune complexes cause severe collateral damage to surrounding tissue, in the cystic fibrosis lung and in other biofilm-infected organs, and some clinicians have now turned to the use of prednisone to reduce the immune response and thus to minimize collateral tissue damage in cystic fibrosis and other biofilm infections. The new perception that device-related and other chronic bacterial infections are caused by bacteria growing in biofilms has encouraged clinicians to use higher doses of antibiotics, to remove devices early when antibiotic therapy fails, and to use immune suppression when immune complexes threaten to cause tissue damage.

Multiple drug resistance



Antimicrobial resistance is often transferred horizontally between related bacteria and this happens with remarkable ease within a biofilm community. Thus biofilms in pipes (from endotracheal tubes to reticulation systems) form part of the range of mechanisms whereby multiple drug resistance is cultured, retained and transferred in both human and veterinary hospital settings as well as in production animal environments such as dairies and poultry & pig production systems. The complex overlapping chemical structure of F10 to inhibit microbial resistance build-up is confirmed by its continued effectiveness in daily use over a period of 14 years in hygiene applications in a major veterinary hospital.

Examples of antibiotic resistance in veterinary pathogens and conditions where biofilm formation is an important contributor to the problem:

Wound Management

Few if any wounds seen by veterinarians can be regarded as “clean”, and even if they start off clean has to heal under essentially dirty, recontamination-prone environments often complicated by blow fly strike. Specific challenges include superficial damage to the distal extremities of equines, where the tensions involved plus constant exposure to environmental microorganisms (even under bandages) often delay wound healing out of all proportion to the size of the defect. Common complications include sepsis, cellulitis and excessive granulation (proud flesh). Other situations with traditionally very poor prognoses include extensive burn wounds, dog bites accompanied by major areas of skin loss, extensive tissue necrosis due to (cytotoxic) snake bites etc. These are often infected by environmental opportunists such as staphs, streps and pseudomonas, all with extremely well developed biofilm formation characteristics that remain refractory to conventional treatments.

F10 in various formats is highly effective as part of an integrated treatment protocol; F10 SC Veterinary Disinfectant / F10 Antiseptic Solution (1:250 dilution) as an irrigation solution, F10 Germicidal Barrier Ointment and F10 Germicidal Wound Spray with Insecticide. The latter is particularly effective in the (sheep) farm treatment of trauma and other superficial wounds and cuts as well as after tail docking and castration procedures where its long residual effect protects the wound against reinfection and repels insects (this product is also effective in the elimination of infestations due to blow fly strikes).


Veterinary and medical practitioners have largely been unaware of the rapid increase in our understanding of interactions within intricate microbial ecosystems, especially where these have a major impact on the therapeutic outcome of challenging, refractory disease complexes. An appreciation and understanding of the pivotal role that biofilms play in the progression of such syndromes will greatly aid in the design of effective, integrated preventative and treatment protocols where surface disinfection (inert & biological) combine with systemic antimicrobials plus supportive agents. This combined approach has radically changed the success: failure ratio in a large number of veterinary / medical applications and promises to open up new possibilities to all who have the imagination and drive to pursue this.

Further Reading

  1. Biofilms and their relevance to veterinary medicine A.L. Clutterbuck, E.J. Woods, D.C. Knottenbelt, P.D. Clegg, C.A. Cochrane and S.L. Perciva.
    Veterinary Microbiology Volume 121, Issue 1-2, 31 March 2007, Pages 1-17
  2. Biofilm formation as microbial development George O’Toole, Heidi B, Kaplan and Roberto Kolter.
    Annual Review of Microbiology Vol.54:49-79 (Volume publication date October 2000)
  3. Bacterial biofilm in upper respiratory tract infections. Morris SP.
    Curr Infect Dis Rep. 2007 May;9(3):186-92
  4. Biofilm formation by mycoplasma species and its role in environmental persistence and survival.
    Laura McAuliffe, Richard J.Ellis, Katie Miles, Roger D.Ayling and Robin A.J.Nicholas
    Microbiology 152 (2006), 913-922
  5. A novel disinfectant in psittacine respiratory disease. Chitty J (2002)
    Proceedings of the Association of Avian Veterinarians, Monterey. 25-27