How Biofilms Evade Host Defenses

Abstract

The steps involved during the biofilm growth cycle include attachment to a substrate followed by more permanent adherence of the microorganisms, microcolony arrangement, and cell detachment required for the dissemination of single or clustered cells to other organ systems. Various methods have been developed for biofilm detection and quantitation. Biofilm-producing microorganisms can be detected in tissue culture plates, using silicone tubes and staining methods, and by visual assessment using scanning electron microscopy or confocal scanning laser microscopy. Quantitative measurement of biofilm growth is determined by using methods that include dry cell weight assays, colony-forming-unit counting, DNA quantification, or XTT 2,3-bis (2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide reduction assay. Upon infection, innate immune defense strategies are able to establish an immediate response through effector mechanisms mediated by immune cells, receptors, and several humoral factors. We present an overview of the life cycle of biofilms and their diversity, detection methods for biofilm development, and host immune responses to pathogens. We then focus on current concepts in bacterial and fungal biofilm immune evasion mechanisms. This appears to be of particular importance because the use of host immune responses may represent a novel therapeutic approach against biofilms.

Regenerative endodontics: a comprehensive review

“…Planktonic cells from biofilm are easy to kill; however, bacteria in a biofilm are harder to eradicate because they are able to evade killing by antimicrobial agents and host's immune defence mechanism (Stewart & Costerton , Roilides et al . ). The heterogeneous nature and age of the biofilm also appear to provide resistance to antimicrobial agents (Mah & O'Toole ).…”

Impact of Actinobacillus pleuropneumoniae biofilm mode of growth on the lipid A structures and stimulation of immune cells

“…Many studies support this hypothesis. 64,65 Daw et al showed that macrophages infected with of Enterococcus faecalis biofilm cells secreted lower pro-inflammatory cytokine levels compared to planktonic cells. 66 Similarly, macrophages infected with Legionella pneumophila biofilm exhibited significantly lower levels of pro-inflammatory cytokine IL-1β, compared to those infected with planktonic bacteria.…”

Inflammatory potential of monospecies biofilm matrix components

“…When compared to planktonic bacteria and microbial components/antigens, the biofilm mode of bacterial growth would mask these components recognized by the immune system (Roilides et al . ). Considering the complex interplay involved in apical periodontitis, several factors including host immune status, anatomic location of biofilm, type of resident bacteria and biofilm constituents can either suppress and/or stimulate the immune reaction (Watters et al .…”