Biofilm formation stages (Figure)

The social biofilm network 2020

Currently attending The social biofilm network 2020 online via ZOOM from June 1-5

Many interesting talks heard since Tuesday (missed that of Monday)

best Biofilm researchers presenting their work

Acute vs chronic infections

These terms can be understood by taking the example of Pseudomonas aeruginosa as model organism.

ACUTE INFECTION

Acute infections are characterised by bacteria which can flow or motile. They have overexpression of virulence factors e.g. Type 3 secretion. During acute infection, bacteria can move in blood or through mucin layers.

CHRONIC INFECTIONS

Chronic infection is characterised by sessile bacterial colonies called biofilms. 

Difference between MIC and MBEC for antibiotic experiments

MIC - Minimal inhibition concentration

The minimal concentration of antibiotic at which no bacterial growth is observed is called MIC. For instance, MIC of colistin for Pseudomonas aeruginosa ranges 1-2 ug/ml. The strains which can grow above MIC may be considered resistant or tolerant strains.

MBEC- Minimal Biofilm Eradication Concentration

The minimum concentration of antibiotic required to eradicate mature biofilms is termed as MBEC. In general, MBEC are higher than MIC e.g. Pseudomonas aeruginosa MBEC ranges >100 ug/ml colistin. 

Antibiotic resistance and biofilms?

Share your thoughts on why biofilms are antibiotic-resistant?

• Restricted penetration
• resistant cells
• persisitors

Best articles nature rev microbiology on biofilms

• https://www.nature.com/articles/nrmicro.2016.94
• https://www.nature.com/articles/nrmicro.2017.99
• https://www.nature.com/articles/nrmicro2695
• https://www.nature.com/articles/nrmicro3433

Free cell or planktonic cells, biofilms, dispersed cells

To understand the concept of biofilms we must know three phenotypes of bacteria

• Planktonic cells- These are free cells or free-floating cells. In other words, they are not attached to any surfaces. Examples- culturing bacteria in the flask (in the lab) with 200 rpm, acute bacterial infection in the blood.
• Biofilms- These are surface-attached bacteria. The biofilm formation may be divided into phases- initiation includes a bacterial approach to surface and adhering, followed by microcolony formation, mature biofilms 
• Dispersed cells- these are bacterial cells which come out from biofilms. This part is not very very clear amongst the biofilm world.