Bacterial endophthalmitis: Difference between revisions
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==Classification== | ==Classification== | ||
Bacterial endophthalmitis may be classified based on | Bacterial endophthalmitis may be classified based on how Infectious agents generally gain access to the posterior segment of the eye into 2 subtypes: exogenous and endogenies. | ||
Based on | Based on how Infectious agents generally gain access to the posterior segment of the eye, bacterial endophthalmitis may be classified into: | ||
*Exogenous bacterial endophthalmitis | *Exogenous bacterial endophthalmitis | ||
**Postoperative bacterial endophthalmitis (consequence of [[intraocular]] surgery) | **Postoperative bacterial endophthalmitis (consequence of [[intraocular]] surgery) | ||
**delayed postoperative bacterial endophthalmitis | |||
**Posttraumatic bacterial endophthalmitis (following a penetrating injury of the globe) | **Posttraumatic bacterial endophthalmitis (following a penetrating injury of the globe) | ||
*Endogenous bacterial endophthalmitis ([[hematogenous]] spread of [[bacteria]] to the eye from a distant anatomical site) | *Endogenous bacterial endophthalmitis ([[hematogenous]] spread of [[bacteria]] to the eye from a distant anatomical site) | ||
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===Exogenous bacterial endophthalmitis=== | ===Exogenous bacterial endophthalmitis=== | ||
'''Postoperative endophthalmitis''' has been reported following nearly every type of ocular surgery, such as cataract, glaucoma, retinal, radial keratotomy, and intravitreal injections. | '''Postoperative endophthalmitis''' has been reported following nearly every type of ocular surgery, such as cataract, glaucoma, retinal, radial keratotomy, and intravitreal injections. | ||
Following surgical procedure, the eye globe integrity disturbed | Following surgical procedure, the eye globe integrity disturbed. As a result microorganisms of the eyelid margin and preocular tear film, most commonly [[coagulase-negative staphylococci]], may invade to the eye. | ||
Preoperative topical antimicrobial agents can decrease colony counts in the tear film, but they do not sterililize the area. The exact low rate of clinical infection following eye surgery (despite the relatively high prevalence of microorganisms in the eye) is not fully understood. It is thought that low rate of clinical infection following surgical procedure is explained by combination of low inoculum levels, low pathogenicity, and the innate ocular defenses against infection. | Preoperative topical antimicrobial agents can decrease colony counts in the tear film, but they do not sterililize the area. The exact low rate of clinical infection following eye surgery (despite the relatively high prevalence of microorganisms in the eye) is not fully understood. It is thought that low rate of clinical infection following surgical procedure is explained by combination of low inoculum levels, low pathogenicity, and the innate ocular defenses against infection. | ||
Postoperative bacterial endophthalmitis may also occur weeks to years following surgery. | Postoperative bacterial endophthalmitis may also occur weeks to years following surgery. | ||
The exact pathogenesis of '''delayed postoperative bacterial endophthalmitis''' is not fully understood. It is thought that delayed postoperative bacterial endophthalmitis is caused by either sequesteration of low-virulence organisms introduced at the time of surgery or delayed inoculation of organisms to the eye through either [[wound abnormalities]], [[suture tracks]], or [[filtering blebs]]. | |||
''[[Propionibacterium acnes]]'' is the most common microorganism encountered, and clinically evident moderate grade [[inflammation]] may occur weeks to months after surgery. In addition to reflecting the colonization of the preocular tear film, delayed infection is also associated with a higher prevalence of [[streptococcal species]]. | ''[[Propionibacterium acnes]]'' is the most common microorganism encountered, and clinically evident moderate grade [[inflammation]] may occur weeks to months after surgery. In addition to reflecting the colonization of the preocular tear film, delayed infection is also associated with a higher prevalence of [[streptococcal species]]. | ||
'''Posttraumatic bacterial endophthalmitis''' is accompanied by infection at a much higher rate than those following ocular surgery. | |||
Following penetrating injury, the eye globe integrity disturbed. The broad prevalence range is due to factors such as: | |||
*presence of an intraocular foreign body | |||
*Delay in closure of the globe | |||
*Location and extent of laceration of the globe | |||
Posttraumatic endophthalmitis associated with a greater variety of organisms than those following ocular surgery. The most common isolated organisms include Gram-positive [''[Staphylococcus epidermidis]]'' and ''[[Streptococcus species]]'', (part of the normal skin flora and regularly contaminate open wounds). Bacillus cereus is ranked second and some cases are polymicrobial. | |||
===Endogenous bacterial endophthalmitis=== | ===Endogenous bacterial endophthalmitis=== | ||
Endogenous bacterial endophthalmitis, is often seen in patients who are [[bacteremic]] in situations such as [[endocarditis]]. | |||
Under normal circumstances, the [[blood-ocular barrier]] provides a natural resistance against invading organisms. | |||
Following bacteremia, the blood-borne organisms permeate the blood-ocular barrier either by direct invasion ([[septic emboli]]) or by changes in [[vascular endothelium]] (inflammatory mediators released during infection). | |||
In endogenous endophthalmitis, blood-borne organisms (seen in patients who are bacteremic in situations such as endocarditis) permeate the blood-ocular barrier either by direct invasion (eg, septic emboli) or by changes in vascular endothelium caused by substrates released during infection. Destruction of intraocular tissues may be due to direct invasion by the organism and/or from inflammatory mediators of the immune response. | In endogenous endophthalmitis, blood-borne organisms (seen in patients who are bacteremic in situations such as endocarditis) permeate the blood-ocular barrier either by direct invasion (eg, septic emboli) or by changes in vascular endothelium caused by substrates released during infection. Destruction of intraocular tissues may be due to direct invasion by the organism and/or from inflammatory mediators of the immune response. | ||
Under normal circumstances, the blood-ocular barrier provides a natural resistance against invading organisms. | Under normal circumstances, the blood-ocular barrier provides a natural resistance against invading organisms. | ||
Destruction of intraocular tissues may be due to direct invasion by the organism and/or from inflammatory mediators of the immune response. | |||
Endophthalmitis may be as subtle as white nodules on the lens capsule, iris, retina, or choroid. It can also be as ubiquitous as inflammation of all the ocular tissues, leading to a globe full of purulent exudate. In addition, inflammation can spread to involve the orbital soft tissue. | Endophthalmitis may be as subtle as white nodules on the lens capsule, iris, retina, or choroid. It can also be as ubiquitous as inflammation of all the ocular tissues, leading to a globe full of purulent exudate. In addition, inflammation can spread to involve the orbital soft tissue. | ||
Revision as of 16:46, 19 July 2016
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sara Mehrsefat, M.D. [2]
Overview
Bacterial endophthalmitis means bacterial infection inside the eye, involving the vitreous and/or aqueous humors. Most cases of endophthalmitis are exogenous, and organisms are introduced into the eye via trauma, surgery, or an infected cornea. Endogenous endophthalmitis occurs when the eye is seeded via the bloodstream. Patients usually have symptoms from their underlying systemic infection, but sometimes present only with eye symptom
Historical Perspective
Classification
Bacterial endophthalmitis may be classified based on how Infectious agents generally gain access to the posterior segment of the eye into 2 subtypes: exogenous and endogenies.
Based on how Infectious agents generally gain access to the posterior segment of the eye, bacterial endophthalmitis may be classified into:
- Exogenous bacterial endophthalmitis
- Postoperative bacterial endophthalmitis (consequence of intraocular surgery)
- delayed postoperative bacterial endophthalmitis
- Posttraumatic bacterial endophthalmitis (following a penetrating injury of the globe)
- Endogenous bacterial endophthalmitis (hematogenous spread of bacteria to the eye from a distant anatomical site)
Pathophysiology
Exogenous bacterial endophthalmitis
Postoperative endophthalmitis has been reported following nearly every type of ocular surgery, such as cataract, glaucoma, retinal, radial keratotomy, and intravitreal injections. Following surgical procedure, the eye globe integrity disturbed. As a result microorganisms of the eyelid margin and preocular tear film, most commonly coagulase-negative staphylococci, may invade to the eye. Preoperative topical antimicrobial agents can decrease colony counts in the tear film, but they do not sterililize the area. The exact low rate of clinical infection following eye surgery (despite the relatively high prevalence of microorganisms in the eye) is not fully understood. It is thought that low rate of clinical infection following surgical procedure is explained by combination of low inoculum levels, low pathogenicity, and the innate ocular defenses against infection.
Postoperative bacterial endophthalmitis may also occur weeks to years following surgery. The exact pathogenesis of delayed postoperative bacterial endophthalmitis is not fully understood. It is thought that delayed postoperative bacterial endophthalmitis is caused by either sequesteration of low-virulence organisms introduced at the time of surgery or delayed inoculation of organisms to the eye through either wound abnormalities, suture tracks, or filtering blebs. Propionibacterium acnes is the most common microorganism encountered, and clinically evident moderate grade inflammation may occur weeks to months after surgery. In addition to reflecting the colonization of the preocular tear film, delayed infection is also associated with a higher prevalence of streptococcal species.
Posttraumatic bacterial endophthalmitis is accompanied by infection at a much higher rate than those following ocular surgery.
Following penetrating injury, the eye globe integrity disturbed. The broad prevalence range is due to factors such as:
- presence of an intraocular foreign body
- Delay in closure of the globe
- Location and extent of laceration of the globe
Posttraumatic endophthalmitis associated with a greater variety of organisms than those following ocular surgery. The most common isolated organisms include Gram-positive [[Staphylococcus epidermidis]] and Streptococcus species, (part of the normal skin flora and regularly contaminate open wounds). Bacillus cereus is ranked second and some cases are polymicrobial.
Endogenous bacterial endophthalmitis
Endogenous bacterial endophthalmitis, is often seen in patients who are bacteremic in situations such as endocarditis. Under normal circumstances, the blood-ocular barrier provides a natural resistance against invading organisms. Following bacteremia, the blood-borne organisms permeate the blood-ocular barrier either by direct invasion (septic emboli) or by changes in vascular endothelium (inflammatory mediators released during infection).
In endogenous endophthalmitis, blood-borne organisms (seen in patients who are bacteremic in situations such as endocarditis) permeate the blood-ocular barrier either by direct invasion (eg, septic emboli) or by changes in vascular endothelium caused by substrates released during infection. Destruction of intraocular tissues may be due to direct invasion by the organism and/or from inflammatory mediators of the immune response. Under normal circumstances, the blood-ocular barrier provides a natural resistance against invading organisms. Destruction of intraocular tissues may be due to direct invasion by the organism and/or from inflammatory mediators of the immune response. Endophthalmitis may be as subtle as white nodules on the lens capsule, iris, retina, or choroid. It can also be as ubiquitous as inflammation of all the ocular tissues, leading to a globe full of purulent exudate. In addition, inflammation can spread to involve the orbital soft tissue.