Question

UPM (A). What in vivo conditions might the bacteria experience to promote biofilm development? (B). Explain why growth of the bacteria in the presence of ethanol increases PIA/PNAG production and biofilm development? (C). What makes bacterial biofilms resistant to antibiotics and host immune responses? (D). What future strategies might be used to combat device related infections?

Answer 1

A) In vivo conditions such as flow rate, nutrient content, temperature etc are some of the condiitons for developing biofilms. Biofilms have resistance to forces produced by blood flow and washing out of saliva. They can withstand nutreint deprivation and pH changes. Another feature is their sticky matrix which may contain DNA and other polymers and is composed of exopolysaccarides.Another mechanism is colonization(biofilm formation as a mechanism to remain in the favorable niche). Some of the substrates like topography, nutritional vues, chemical treatment, have been strongly impacting on biofilm formation.

B. This can be explained with an example of bacteria P. aerugunosa. In these bacteria ethanol stimulates Wsp system leading to Wsp-R dependent increase in ci-di-GMP levels and concominant increase in Pel production and biofilm formation. Synthesis of extracellular polysaccaride is important for mature biofilm formation. aerugunosa produces 3 types- alginate, Pel, Psl. Ethanol promotes extracellular polymeric substance synthesis-alginate synthesis and biofilm formation in staphylococcus. Low concentrations of ethanol increased the biofilm development and its effects are dependent on Psl and Pel synthesis.

C. Bacteria that attaches to the surface and grow as biofilms are protected by killing antibiotics this is because in biofilms there is poor antibiotic penetration, nutrient limitation, slow groeth, adaptive stress responses, and the formation of persister cells constitutes a multilayered defense. In host immune cells biofilms acts as a physical barrier, helping bacteria to avoid detection and phagocytosis. Genetic switches or supressors can affect immune cell activity.

D.Some of the strategies includes hand hygiene and aseptic techniques, antimicrobial impregnanted cuffs, antibiotic lock prophylaxis,