In the previous set of blogs, we discussed about the biofilm formation, how it escapes the antibiotic attack and the host’s immune system.

Today we shall see the different health conditions associated with biofilms, here they are

  1. Dental plaque:


Dental plaque is a biofilm attached to teeth. The first step in the formation of a dental plaque is the attachment of the bacteria to pellicle. Pellicle is a thin film of proteins made from saliva, bacterial and host cell material covering the teeth. This film normally protects the teeth from the attack of the acids. The pellicle favours the adhesion of the normal oral bacteria. If the bacteria is allowed to attach and flourish on the pellicle, the formation of biofilm begins with the production of the exopolysaccharides. As mentioned in the earlier posts, there are many advantages like protection from the antibiotics and the host’s immune system and a greater metabolic benefits for the bacteria within the biofilm.

Plaque forming biofilm
Healthy tooth Vs Tooth with Plaque

The plaque, i.e. the biofilms if left undisturbed will thicken and mature with time. In 12 to 24 hrs it becomes detectable and quiet noticeable within 5 days. Eventually it hardens to form yellow colored calculus or tartar, that further causes inflammation and bleeding of gum around the base of the teeth.

Organisms involved:

Streptococcus mutans is the most important bacterium in the initiation and progress of this disease in combination with lactobacilli.

Early colonizers can attach to pellicle and include gram-positive cocci and rods, mostly facultative anaerobes. Examples are Streptococcus sanguis and Actinomyces naeslundii.

As the plaque formation progresses, gram-negative cocci, filaments, rods (e.g., Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Porphyromonas gingivalis, Tannerella forsythia), and finally spirochetes (e.g., Treponema denticola) dominate the scenario. Most of them are obligate anaerobes and motile bacteria.


Poor oral health care and consumption of high sugar containing fermentable food increase the chance of developing a plaque.

2. Cystic fibrosis


CF is a genetic (autosomal recessive) disease characterised by a mutation in the gene, cystic fibrosis  transmembrane regulator (CFTR). This controls the flow of salt and fluids in and out of the cells, which is essential for the production of mucus, sweat, saliva, and tears.

The mutation affects the secretory glands and results in the production of large amount of thick and sticky mucus instead of normal thin lubricating consistency. Hence instead of acting as a lubricant, the thick mucus clog the ducts, tubes, and passageways in organs like lungs, pancreas, digestive tract and reproductive organs. This can lead to life-threatening problems, including malnutrition, respiratory failure and infections. Lung is one of the most critically effected organ.

The biofilms get entrapped and flourish in the accumulated mucus. The host immune system is unable to deal with the biofilm and causes immune complex-mediated chronic inflammation, specially by polymorphonuclear leukocytes (Read previous post Biofilm: and the Immune System). Such chronic inflammation is one of the major cause of the lung tissue damage in CF.


Several bacteria infect CF patients and change over period of time. Early coloniser is the Gram-positive Staphylococcus aureus, which are taken over by Gram-negative Pseudomonas aeruginosa. Biofilm-forming mucoid (alginate-producing) strains of P. aeruginosa can cause chronic and persistent infection.

Other bacteria also known to infect the CF airways include H. influenza, MRSA and  S. maltophillia. Burkholderia (ceno)cepaecia infection occurs less often but can be very harmful.


Predisposition is definitely the thick mucus filled passages entrapping the bacteria. The bacterial biofilms thrive successfully in such environment.


Biofilms can be prevented by early antibiotic treatment. A chronic suppressive therapy can give relief from such infections.

3. Infectious kidney stones:


There are 4 different types of kidney stone, 3 of which are caused by abnormal accumulation of metabolites and the fourth one is caused by bacteria and is known as infectious kidney stone or struvite kidney stone. This type of stone is more common in women with urinary tract infections (UTIs).

Infective bacterial kidney stone struvite stone
Healthy kidney Vs Kidney with stones

Struvite stones are composed of magnesium, ammonium, phosphate crystals mixed with carbonate-apatite. They are formed when urease-producing bacteria, which hydrolyze urea to ammonium, cause an increase in the pH is urine to neutral or alkaline. The minerals get precipitated in alkaline urine.

The bacterial biofilm then interacts with precipated mineral substances derived from urine to form a complex. In this complex the bacteria are organized to form microcolonies surrounded by an anionic matrix composed of complex polysaccharides and minerals.

These infectious stones obstruct the urine flow, cause severe inflammation and infection and may even lead to the kidney failure.


Urea-splitting (Urease-producing) organisms include Proteus, Pseudomonas, Klebsiella, Staphylococcus and mycoplasma.


The UTI with urease producing bacteria is a major factor to predispose a person to the infectious kidney stone. These bacteria cause alkaline urine, pH favourable for precipitation of crystal-forming minerals.


Diagnosis of kidney stone is best accomplished during an ultrasound, intravenous pyleography (IVP) or a CT scan.

Most kidney stones will pass through the ureter to the bladder on their own with time. Treatment may include medication for pain control or to facilitate the passage of urine. Lithotripsy or surgical techniques may be used if the stones do not pass through the ureter to the bladder on their own.

4. Otitis media with effusion:


The eustachian tube connects the inside of the ear to the back of the throat. This tube helps drain fluid to prevent it from building up in the ear. The fluid drains from the tube and is swallowed.

After most ear infections are treated fluid remains in the middle ear for a few days or weeks. When the Eustachian tube is partially blocked fluid builds up in the middle ear. Bacteria inside the ear become trapped and begin to grow. This may lead to ear infection.

Fluid accumulates in the middle ear cavity of the patient, does affecting speech development and learning capacity of the patient. However, the complete etiology of the problem is still not clearly understood.


Most commonly, P. aeruginosa and S. aureus are responsible from these chronic infections.

Other biofilm organisms have also been reported to be cause acute otitis media like E. coli S. pneumonae and H.influenzae.


An ear infection which results in the blocking Eustachian tube with fluid. The biofilm bacteria may be trapped in such fluid. Children are more prone to the infection. Allergies, craniofacial abnormalities, exposure to infection, weak immune system and upper respiratory tract infections may increase the risk.


Suitable antibiotic course usually cures the infection. In some serious cases tympanostomy tubes may used to drain off the fluid in the ear.

5. Bacterial Endocarditis


Also known as infective endocarditis Endocarditis is an infection of the endocardium, which is the inner lining of your heart chambers and heart valves. This is a fatal disease, wherein the infection can lead to damage of the heart valve(s). The blood may leak back through the damaged valve(s) and in the heart becomes unable to pump the blood to the body. This in turn may result in congestive heart failure and can cause symptoms such as shortness of breath or swelling of the ankles.

Bacterial or Infective endocarditis, Biofilm
Bacterial Endocarditis

The biofilm aggregates may also break off and travel to the other body parts through the blood vessels. These pieces of biofilm aggregates are called emboli, which can cause damage to organs such as brain (a stroke), eyes, lungs, kidneys, spleen, liver and intestines when deposited there. Endocarditis can also cause heart rhythm changes that may require a pacemaker for correction.


Causative microorganisms differs with site of infection, source of bacteremia and host risk factors. Streptococci and Staphylococcus aureus are causative agents in 80 to 90% of cases. Enterococci, gram-negative bacilli, Haemophilus sp, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae (the HACEK organisms), and fungi are responsible for the remaining cases.


People at highest risk of endocarditis are those who already have a heart ailment, as the bacteria stick well to rough heart walls. So the people more predisposed are the ones having one of the issues like artificial heart valves, congenital heart defects, previous case of endocarditis and already damaged heart valves. Certain medical conditions, such as rheumatic fever or other infection may also increase the risk.


May include treatment with suitable antibiotics. Some cases valve debridement, repair, or replacement may be performed. Removal of potential source of bacteremia (eg, internal catheters, devices) is also considered.

6. Implant associated osteomyelitis:


This is an infection of bones caused by bacterial biofilms on endoprostheses or osteosynthesis materials, such as screws, plates, or nails. Infection or implanted materials is a major complication of orthopaedic and trauma surgery.

The infection can cause loss of function of the particular part of the body and may even result into amputation.

However the implant associated myelitis, may aid in studying the local immune response, as the infected implant has to be removed. Infiltrating immuno competent cells can be recovered, characterised and analyzed.


Staphylococcus aureus (S. aureus) is the most common causative pathogen in chronic bone infections. Artificial surfaces, like dwelling catheter or tubing, maybe colonised by bacteria such as by P. aeruginosa, Staphylococci sps Streptococcus pneumoniae or Haemophilus influenzae and cause infection. Beta-lactamase-producing strains of H. influenzae and Moraxella (Branhamella) catarrhalis are becoming more prevalent recently.


The people prone to implant associated osteomyelitis are ones already suffering from polyneuropathy and/or peripheral arterial disease (e.g., patients with diabetes mellitus) and patients with surgery or trauma around the bone. In patients with S. aureus bacteremia, the bacteria may gain access to the bone, hence at risk. Weak immune system and drug abuse may also increase the risk.


Antibiotics alone may not be successful. A multidisciplinary approach is required involving knowledge on orthopaedic surgery, infectious diseases, and plastic surgery, and vascular surgery (in case of soft-tissue loss). If the blood flow has been effected, vascular bypass or endovascular stenting maybe required. Debridement in some cases may be done.

These are few of the diseases which are associated with the biofilms. There are many more complications related or caused by biofilms, tell us if you want Notes on any disease left out.

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Do read other posts by The Biotech Notes:

Neurons: Introduction

Let’s go FISH’ ing

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