Orbital cellulitis
Encyclopedia
Orbital cellulitis
is an infection of eye tissues posterior to the orbital septum
. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. When it affects the rear of the eye, it is known as retro-orbital cellulitis.
It should not be confused with periorbital cellulitis
, which refers to cellulitis
anterior to the septum.
. Other causes include infection of nearby structures, trauma and previous surgery.
Staphylococcus aureus
, Streptococcus pneumoniae
and beta-hemolytic streptococci are three bacteria that can be responsible for orbital cellulitis.
, and optic nerve damage (which could lead to blindness).
is an infection of eye tissues posterior to the orbital septum
Orbital septum
The orbital septum is a membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids...
. It most commonly refers to an acute spread of infection into the eye socket from either the adjacent sinuses or through the blood. When it affects the rear of the eye, it is known as retro-orbital cellulitis.
It should not be confused with periorbital cellulitis
Periorbital cellulitis
Periorbital cellulitis, also known as preseptal cellulitis , is an inflammation and infection of the eyelid and portions of skin around the eye, anterior to the orbital septum...
, which refers to cellulitis
Cellulitis
Cellulitis is a diffuse inflammation of connective tissue with severe inflammation of dermal and subcutaneous layers of the skin. Cellulitis can be caused by normal skin flora or by exogenous bacteria, and often occurs where the skin has previously been broken: cracks in the skin, cuts, blisters,...
anterior to the septum.
Signs and symptoms
Patients commonly complain of pain when moving the eye, sudden loss of vision, bulging of the eye or eyes that are infected and limited eye movement. Along with these symptoms, patients typically have redness and swelling of the eyelid, pain, discharge, inability to open the eye, occasional fever and lethargy. It is usually caused by a previous sinusitisSinusitis
Sinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...
. Other causes include infection of nearby structures, trauma and previous surgery.
Causes
Orbital cellulitis occurs commonly from bacterial infection spread by the paranasal sinuses. Other ways in which orbital cellulitis may occur is from infection in the blood stream and from an eyelid skin infection. Upper respiratory infection, sinusitis, trauma to the eye, ocular or periocular infection and systemic infection all increase one’s risk of orbital cellulitis.Staphylococcus aureus
Staphylococcus aureus
Staphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
, Streptococcus pneumoniae
Streptococcus pneumoniae
Streptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, aerotolerant anaerobic member of the genus Streptococcus. A significant human pathogenic bacterium, S...
and beta-hemolytic streptococci are three bacteria that can be responsible for orbital cellulitis.
- Staphylococcus aureusStaphylococcus aureusStaphylococcus aureus is a facultative anaerobic Gram-positive coccal bacterium. It is frequently found as part of the normal skin flora on the skin and nasal passages. It is estimated that 20% of the human population are long-term carriers of S. aureus. S. aureus is the most common species of...
, 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 pneumoniaeStreptococcus pneumoniaeStreptococcus pneumoniae, or pneumococcus, is Gram-positive, alpha-hemolytic, aerotolerant anaerobic member of the genus Streptococcus. A significant human pathogenic bacterium, S...
, is also a gram-positive bacterium responsible for orbital cellulitis due to its ability to infect the sinuses (sinusitisSinusitisSinusitis is inflammation of the paranasal sinuses, which may be due to infection, allergy, or autoimmune issues. Most cases are due to a viral infection and resolve over the course of 10 days...
). 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.
Treatment
Prompt treatment is vital for a patient when fighting orbital cellulitis. Treatment typically involves IV antibiotics in the hospital and frequent observation (every 4-6 hours). Along with this several laboratory tests are run including a complete blood count, differential, and would culture.- Antibiotic Therapy - Since orbital cellulitis is commonly caused by Staphylococcus and Streptococcus species both penicillins and cephalosporins are typically the best choices for IV antibiotics. However, due to the increasing rise of MRSA (methicillin-resistant Staphylococcus aureus) orbital cellulitis can also be treated with VancomycinVancomycinVancomycin INN is a glycopeptide antibiotic used in the prophylaxis and treatment of infections caused by Gram-positive bacteria. It has traditionally been reserved as a drug of "last resort", used only after treatment with other antibiotics had failed, although the emergence of...
, ClindamycinClindamycinClindamycin rINN is a lincosamide antibiotic. It is usually used to treat infections with anaerobic bacteria but can also be used to treat some protozoal diseases, such as malaria...
, or DoxycyclineDoxycyclineDoxycycline INN is a member of the tetracycline antibiotics group, and is commonly used to treat a variety of infections. Doxycycline is a semisynthetic tetracycline invented and clinically developed in the early 1960s by Pfizer Inc. and marketed under the brand name Vibramycin. Vibramycin...
. If improvement is noted after 48 hours of IV antibiotics, healthcare professions can then consider switching a patient to oral antibiotics (which must be used for 2-3 weeks). - Surgical Intervention - An abscess can threaten the vision or neurological status of a patient with orbital cellulitis, therefore sometimes surgical intervention is necessary. Surgery typically requires drainage of the sinuses and if a subperiosteal abscess is present in the medial orbit, drainage can be performed endoscopically. Post-operatively, patients must follow up regularly with their surgeon and remain under close observation.
Prognosis
Although orbital cellulitis is considered an ophthalmic emergency the prognosis is good if prompt medical treatment is received.Complications
Complications include hearing loss, blood infection, meningitisMeningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
, and optic nerve damage (which could lead to blindness).