Centers for disease control and prevention estimate that about 65% of human bacterial infectious processes involve biofilms. Biofilm is a group of bacteria seen over surface epithelium like mucous membrane, enclosed within a matrix of extracellular polysaccharide material. The presence of this biofilm has been implicated in the following chronic infections:
- Chronic rhinosinusitis
- Chronic bronchitis
- Atrophic rhinitis
- Lung infections following prolonged intubation
- Urinary catheter related infections
- How biofilms protect the bacteria from host defenses?
Biofilm contains multiple types of bacteria. Bacteria from biofilms are difficult to culture & hence difficult to identify. These multiple organisms coexist with each other conferring drug resistance. Antibiotics don't penetrate biofilms in adequate concentrations thus the organisms within are well entrenched and protected. These biofilms surround the microbes with extracellular polymeric substance which constitute a physical non cellular barrier against host defense mechanisms.
Staphylococcus and pseudomonas organisms have been implicated in chronic sinonasal disease associated biofilms.
How to identify Biofilms?
Biofilms have been identified by scanning electron microscopy. Recently Fluorescence insitu hybridization techniques have been used to identify biofilms (FISH technique).
Christian J. Hochstim in his original work has shown that the presence of Biofilms can be identified with reasonable degree of accuracy using H & E stains.
Histologically under H & E staining, biofilms appear as clusters of basophilic bacteria and host cells entrapped in a layer of extracellular polymeric substance.
It is really worthwhile looking for the presence of biofilms in all mucosal specimen sent for biopsy.
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