Question

Biofilms are implicated in intractable urinary tract infections, in the lung infections (such as in Cystic fibrosis), on teeth, on implanted medical devices-to name a few scenarios. Nosocomial (hospital acquired) infections are the fourth leading cause of death in the U.S. Biofilms contribute to the failure of antibiotic treatment, particularly in hospitalized patients.

In this assignment:

Describe the formation of biofilms, their persistence, and interactions with the host immune system.

Describe how quorum sensing plays a role in the development of biofilms. Describe the methods used for controlling medical biofilms.

Answer 1

Biofilms are complex microbial communities that develop forming a succession. Starts with the colonization of a surface, so that this can happen a clean surface must be submerged in some aquatic environment, this produces a sequence of events of biological deposition (fouling), whose result is a succession of colonizing species that dominate in various moments.

The adherence to the surface of a wide variety of bacteria occurs very soon (it can be even in a few minutes). The molecular film can be formed and bacterial colonization is already significant at 24 hours. In the colonization of the surfaces the motility is critical for the success of different bacteria, since some studies have shown that the adsorption of Pseudomonas aeruginosa cells decreases up to 90% by mechanically eliminating their flagella.

Microorganisms that first access exposed surfaces can physically exclude potential competitors, thereby enjoying significant advantages in terms of surface positioning and nutrient utilization.

(In the next paragraph I describe the relevance of quorum sensing in the formation of biofilms)
Often the colonizing bacteria form microcolonies or aggregates of cells from individual bacterial colonization sites. Subsequently, successive layers of bacterial cells develop. The overpopulation of the surface leads to the depletion of nutrients, the cessation of growth and the indiction of a phase of starvation-survival.

Some of the microbial populations that colonize the surface produce exopolymers during their growth, the production of extracellular polymers is fundamental for the development of the biofilm because it provides an interphace between the cell and the external environment influencing the rates of chemical exchange and availability of nutrients (Mechanism to protect against antibiotics and antimicrobial agents).

To date, effective methods for the control of biofilms in medical applications are unknown, many are prophylactic (that is, the design teams try to avoid the formation of biofilms, equipment inspection, etc.) In other fields the biofilms are eliminated by removal mechanical, use of soundings among other things.