Orbital cellulitis pathophysiology: Difference between revisions
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==Pathogenesis== | ==Pathogenesis== | ||
Orbital cellulitis occurs secondary to microbial infiltration of the deep soft tissue cells surrounding the eye, behind the [[Orbital septum]].<ref name="pmid15318671">{{cite journal| author=Hasanee K, Sharma S| title=Ophthaproblem. Orbital cellulitis. | journal=Can Fam Physician | year= 2004 | volume= 50 | issue= | pages= 359, 365, 367 | pmid=15318671 | doi= | pmc=2214559 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15318671 }} </ref> Damage to the cells triggers an [[Inflammation|acute inflammatory response]] resulting in vasodilation, increased vascular permeability, and induction of a cascade of inflammatory markers and white blood cell chemoattractants. <ref name="acute-inflammatory-response"> U.S. National Library of Medicine Medlineplus(2014) https://medlineplus.gov/ency/article/000821.htm</ref> | Orbital cellulitis occurs secondary to microbial infiltration of the deep soft tissue cells surrounding the eye, behind the [[Orbital septum|orbital septum]].<ref name="pmid15318671">{{cite journal| author=Hasanee K, Sharma S| title=Ophthaproblem. Orbital cellulitis. | journal=Can Fam Physician | year= 2004 | volume= 50 | issue= | pages= 359, 365, 367 | pmid=15318671 | doi= | pmc=2214559 | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15318671 }} </ref> Damage to the cells triggers an [[Inflammation|acute inflammatory response]] resulting in vasodilation, increased vascular permeability, and induction of a cascade of inflammatory markers and white blood cell chemoattractants. <ref name="acute-inflammatory-response"> U.S. National Library of Medicine Medlineplus(2014) https://medlineplus.gov/ency/article/000821.htm</ref> | ||
===Extension of adjacent infection=== | ===Extension of adjacent infection=== | ||
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-Otitis media | -Otitis media | ||
-Dental infections | -Dental infections | ||
===Direct inoculation=== | ===Direct inoculation=== | ||
Microbes inoculated in the retroseptal orbital space by traumatic or iatrogenic means. | Microbes inoculated in the retroseptal orbital space by traumatic or iatrogenic means. | ||
====Traumatic==== | ====Traumatic==== | ||
Occur as a result of direct inoculation of the microbe due to trauma: | Occur as a result of direct inoculation of the microbe due to trauma:<br> | ||
-Fracture | -Fracture<br> | ||
-Penetration by a foreign body | -Penetration by a foreign body | ||
====Iatrogenic==== | ====Iatrogenic==== | ||
Occur as a result of direct inoculation during surgical procedures such as: | Occur as a result of direct inoculation during surgical procedures such as:<br> | ||
-Ocular or periocular surgeries | -Ocular or periocular surgeries<br> | ||
-Paranasal Sinus surgeries | -Paranasal Sinus surgeries<br> | ||
-Other ENT surgeries | -Other ENT surgeries | ||
===Hematogeneous Spread=== | ===Hematogeneous Spread=== | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Tarek Nafee, M.D. [2]
Overview
Pathogenesis
Orbital cellulitis occurs secondary to microbial infiltration of the deep soft tissue cells surrounding the eye, behind the orbital septum.[1] Damage to the cells triggers an acute inflammatory response resulting in vasodilation, increased vascular permeability, and induction of a cascade of inflammatory markers and white blood cell chemoattractants. [2]
Extension of adjacent infection
Orbital cellulitis may spread from direct extension of an acute or chronic adjacent infection. This includes the following: -Rhinosinusitis (Ethmoid sinusitis and pansinusitis) -Dacryocystitis, Dacryoadenitis -Otitis media -Dental infections
Direct inoculation
Microbes inoculated in the retroseptal orbital space by traumatic or iatrogenic means.
Traumatic
Occur as a result of direct inoculation of the microbe due to trauma:
-Fracture
-Penetration by a foreign body
Iatrogenic
Occur as a result of direct inoculation during surgical procedures such as:
-Ocular or periocular surgeries
-Paranasal Sinus surgeries
-Other ENT surgeries
Hematogeneous Spread
Genetics
Associated Conditions
Gross Pathology
Microscopic Pathology
- Staphylococcus aureus, is a gram-positive bacterium which is the most common of staph infections. Staphylococcus aureus infection can spread to the orbit from the skin. Staph organisms are able to produce toxins which promote their virulence which leads to the inflammatory response seen in orbital cellulitis. Staphylococcus infections are identified by a cluster arrangement on gram stain. Staphylococcus aureus forms large yellow colonies (which is distinct from other Staph infections such as Staphylococcus epidermis which forms white colonies).
- Streptococcus pneumoniae, is also a gram-positive bacterium responsible for orbital cellulitis due to its ability to infect the sinuses (sinusitis). Strep organisms are able to determine their own virulence and can invade surrounding tissues causing an inflammatory response seen in orbital cellulitis (similar to Staphyloccoccus aureus). Streptococcal infections are identified on culture by their formation of pairs or chains. Streptococcus pneumoniae produce green (alpha) hemolysis, or partial reduction of red blood cell hemoglobin.
References
- ↑ Hasanee K, Sharma S (2004). "Ophthaproblem. Orbital cellulitis". Can Fam Physician. 50: 359, 365, 367. PMC 2214559. PMID 15318671.
- ↑ U.S. National Library of Medicine Medlineplus(2014) https://medlineplus.gov/ency/article/000821.htm