INTRODUCTION — Orbital cellulitis is an infection involving the contents of the orbit (fat and extraocular muscles). It must be distinguished from preseptal cellulitis (sometimes called periorbital cellulitis), which is an infection of the anterior portion of the eyelid. Neither infection involves the globe itself.
Although preseptal and orbital cellulitis may be confused with one another because both can cause ocular pain and eyelid swelling and erythema, they have very different clinical implications. Preseptal cellulitis is generally a mild condition that rarely leads to serious complications, whereas orbital cellulitis may cause loss of vision and even loss of life. Orbital cellulitis can usually be distinguished from preseptal cellulitis by its clinical features (ophthalmoplegia, pain with eye movements, and proptosis) and by imaging studies; in cases in which the distinction is not clear, clinicians should treat patients as though they have orbital cellulitis. Both conditions are more common in children than in adults, and preseptal cellulitis is much more common than orbital cellulitis.
The pathogenesis, microbiology, clinical manifestations, diagnosis, and treatment of orbital cellulitis will be reviewed here. Preseptal cellulitis and other complications of sinusitis are discussed separately. Orbital infections caused by fungi, mainly the Mucorales (which cause mucormycosis) and Aspergillus spp, and, much more rarely, Mycobacterium tuberculosis are also presented separately. (See "Preseptal cellulitis" and "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Complications' and "Mucormycosis (zygomycosis)" and "Epidemiology and clinical manifestations of invasive aspergillosis" and "Tuberculosis and the eye" and "Septic dural sinus thrombosis".)
TERMINOLOGY — Preseptal cellulitis and orbital cellulitis involve different anatomic sites, with preseptal cellulitis referring to infections of the soft tissues anterior to the orbital septum, and orbital cellulitis referring to infections posterior to it (figure 1). Orbital cellulitis involves the muscle and fat located within the orbit. Orbital cellulitis does not involve the globe. (See 'Anatomy' below and "Preseptal cellulitis", section on 'Anatomy'.)
There is some debate regarding the appropriate terminology for these infections. Some clinicians use the term "periorbital cellulitis" rather than "preseptal cellulitis" or use the terms interchangeably. We prefer the term "preseptal cellulitis" to make a clear distinction between this infection and the more serious infection, "orbital cellulitis." Orbital cellulitis is sometimes referred to as "postseptal cellulitis"; we favor the term "orbital cellulitis," and will use it throughout this topic.
ANATOMY — Basic familiarity with the anatomy of the eye is fundamental to understanding the pathogenesis, clinical manifestations, and complications of orbital cellulitis. The orbit is a cone-shaped structure, lying horizontally, with its apex in the skull. It is surrounded by paranasal sinuses, namely, the frontal (lying superior), ethmoid (medial), and maxillary (inferior) sinuses (figure 2). The orbit is lined by periosteum. The ethmoid sinuses are separated from the orbit by a paper-thin layer called the lamina papyracea, which contains many perforations for nerves and blood vessels as well as some natural fenestrations termed Zuckerkandl's dehiscences. The most common route of infection of the orbit is by extension from the ethmoid sinuses, likely facilitated through these perforations.
The orbital septum is a membranous sheet that extends from the periosteum of the orbit to the tarsal plate and forms the anterior boundary of the orbital compartment (figure 1). The superior and inferior orbital veins drain blood directly into the cavernous sinus (figure 3). Because of this communication and because the inferior orbital veins are valveless, infection can pass readily from the orbit to intracranial structures . (See "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Intracranial complications'.)
EPIDEMIOLOGY AND PATHOGENESIS — Orbital cellulitis is more common in young children than in older children or adults. Orbital cellulitis is an uncommon complication of bacterial rhinosinusitis, but rhinosinusitis is the source of most cases of orbital cellulitis; coexisting rhinosinusitis is present in 86 to 98 percent of cases of orbital cellulitis [2-5]. Ethmoid sinusitis and pansinusitis are the forms of rhinosinusitis most likely to lead to orbital cellulitis. (See "Acute sinusitis and rhinosinusitis in adults: Clinical manifestations and diagnosis" and "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Complications'.)
As noted above, the ethmoid sinuses are separated from the orbit by the lamina papyracea, a thin structure with many fenestrations. Computed tomography (CT) scanning often shows the predominant site of inflammation to be the medial aspect of the orbit, adjacent to the ethmoid sinuses, and subperiosteal abscesses most often occur in the same location (figure 2). (See 'Anatomy' above and "Preseptal cellulitis", section on 'Anatomy'.)
Although bacterial rhinosinusitis is the most common cause of orbital cellulitis, other potential causes are:
●Peribulbar anesthesia [9,10].
●Orbital trauma with fracture or foreign body [11,12].
●Dacryocystitis [13,14]. (See "Congenital nasolacrimal duct obstruction (dacryostenosis) and dacryocystocele", section on 'Infection'.)
●An infected mucocele that erodes into the orbit .
●Endogenous seeding of bacteria from the bloodstream .
MICROBIOLOGY — The causative organisms of orbital cellulitis are often difficult to identify. Cultures from the orbit are only obtained if surgical intervention is needed, usually to drain an abscess. Sinus cultures obtained during surgery can be used to guide antimicrobial therapy , but may not accurately reflect the pathogen(s) in the orbit. Blood cultures are sometimes positive in children, the percentages ranging from 0 to 33 percent in various retrospective series [20-24]. They are rarely positive in adults. In one series of patients with orbital cellulitis, blood cultures were positive in 33 percent of children younger than four years of age but in only 5 percent of adults .
In one series of 94 children admitted to a tertiary care children's hospital with orbital cellulitis between 2004 and 2009, members of the Streptococcus anginosus (milleri) group were the most commonly identified pathogens (15 percent) followed by S. aureus (9 percent), group A streptococci (Streptococcus pyogenes, 6 percent), and Streptococcus pneumoniae (4 percent) . Only one patient had methicillin-resistant S. aureus (MRSA) infection, but there may be an increasing proportion of MRSA infections given the variable prevalence of community-acquired MRSA (CA-MRSA) among strains of S. aureus. In another series of 46 children and adults with orbital or subperiosteal abscesses, S. aureus was isolated in 28 percent of cases, and one-quarter of those isolates were MRSA . Cases of neonatal and infantile orbital cellulitis caused by CA-MRSA have also been reported .
Haemophilus influenzae type b, formerly an important cause of orbital cellulitis in children, has become rare with the widespread use of the Hib vaccine [25,28,29]. Nontypeable H. influenzae, however, remains an important cause of orbital complications of acute bacterial sinusitis. Two series from the post Hib vaccine era that did not report serotyping found that H. influenzae caused 7 to 22 percent of culture-positive orbital abscesses [30,31].
Uncommon isolates in orbital cellulitis or abscess cases include anaerobes [25,32], such as Fusobacterium , and Peptostreptococcus , and gram-negative bacilli, such as Pseudomonas aeruginosa , Klebsiella , Morganella , and Eikenella corrodens [26,34].
Some cases of orbital cellulitis are polymicrobial, often with a combination of aerobic and anaerobic bacteria [4,26]. As an example, in a study of 20 children with orbital cellulitis who had positive cultures from specimens obtained during surgery (from an orbital or subperiosteal abscess and/or a paranasal sinus), seven (35 percent) had more than one organism isolated . Two small studies have observed polymicrobial infections in all patients [35,36].
Fungi and mycobacteria — Although bacteria are the most common cause of orbital cellulitis, fungi, especially Mucorales (which causes mucormycosis) and Aspergillus spp can cause life-threatening invasive orbital infections. Mucormycosis and invasive aspergillosis should be considered in patients with defects in host defenses. Mucormycosis primarily affects patients with diabetic ketoacidosis and sometimes in patients with renal acidosis. Aspergillus infection of the orbit occurs in patients with severe neutropenia or other immune deficiencies, including HIV infection. These infections are discussed briefly below and more fully elsewhere. (See 'Diagnosis' below and "Mucormycosis (zygomycosis)" and "Fungal rhinosinusitis" and "Epidemiology and clinical manifestations of invasive aspergillosis".)
Fungal causes of orbital cellulitis have been reported rarely in apparently immunocompetent infants .
CLINICAL MANIFESTATIONS — It is important to distinguish preseptal from orbital cellulitis because the two conditions have very different clinical implications (table 2 and table 3) [2-5,39]. Both orbital cellulitis and preseptal cellulitis cause ocular pain and eyelid swelling with erythema (picture 1); in some cases of orbital cellulitis, eyelid erythema is absent. Only orbital cellulitis causes swelling and inflammation of the extraocular muscles and fatty tissues within the orbit, leading to pain with eye movements, proptosis, and in some cases ophthalmoplegia with diplopia. Chemosis (conjunctival swelling) may occasionally occur in severe cases of preseptal cellulitis, but is more common with orbital cellulitis. In both conditions, but especially in orbital cellulitis, there may be fever and peripheral leukocytosis with a predominance of neutrophils [2,40]. In a retrospective study that included 262 children, fever occurred more commonly in those with orbital cellulitis than in those with preseptal cellulitis (94 versus 47 percent) . Rarely in orbital cellulitis, there may be visual impairment, and even blindness, arising from inflammation or ischemia of the optic nerve .
The frequencies with which the signs and symptoms of orbital and preseptal cellulitis have been reported in different studies are summarized in the table (table 2).
Subperiosteal or orbital abscesses can occur concurrently with orbital cellulitis. Infection may rarely extend to the orbital apex, causing visual loss, or intracranially, causing epidural or subdural empyema, brain abscess, meningitis, cavernous sinus thrombosis, or dural sinus thrombosis . Orbital cellulitis results in loss of vision in 3 to 11 percent of patients and in death in 1 to 2 percent of patients, although data are overall limited [42,43]. The visual loss associated with orbital cellulitis is thought to result from any of the following processes :
●Optic neuritis as a result of inflammation from nearby infection
●Ischemia resulting from thrombophlebitis along the orbital veins
●Pressure resulting in central retinal artery occlusion
Intracranial complications may be heralded by severe headache, protracted vomiting, mental status changes and, in patients with cavernous sinus thrombosis, cranial nerve palsies. Bilateral cranial nerve palsies can be a sign of bilateral cavernous sinus thrombosis.
These complications may develop rapidly; therefore, close monitoring is indicated, with daily checks of visual acuity and assessment of the pupillary light reflex. A sluggish or absent pupillary light reflex or a relative afferent pupillary defect indicates optic nerve involvement. Any worsening of the patient's symptoms or signs should lead to a contrast-enhanced computed tomography (CT) scan of the orbits and sinuses (or repeat CT if one was done earlier) to determine the necessity for surgical intervention. (See 'Imaging studies' below.)
These complications are discussed in more detail elsewhere. (See "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Complications'.)
DIFFERENTIAL DIAGNOSIS — The differential diagnosis of orbital cellulitis includes a range of infectious and noninfectious diseases. Although orbital cellulitis is most commonly caused by bacteria, in patients with certain risk factors, fungal pathogens (and occasionally tuberculosis) should be considered. As noted below, it is critical to distinguish preseptal cellulitis from the more serious orbital cellulitis. (See 'Diagnosis' below.)
Diseases that should be considered in the differential diagnosis of orbital cellulitis include:
●Preseptal cellulitis (see "Preseptal cellulitis")
●Subperiosteal and orbital abscess (see "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Postseptal orbital complications')
●Mucormycosis or aspergillosis involving the orbit (see "Mucormycosis (zygomycosis)" and "Epidemiology and clinical manifestations of invasive aspergillosis")
●Cavernous sinus thrombosis (see "Septic dural sinus thrombosis")
●Herpes simplex or varicella zoster virus infections involving the eye (see "Herpes simplex keratitis" and "Epidemiology, clinical manifestations, and diagnosis of herpes zoster", section on 'Herpes zoster ophthalmicus')
●Tuberculosis involving the orbit (see "Tuberculosis and the eye")
●Panophthalmitis (see "Bacterial endophthalmitis")
●Posterior scleritis 
●Periocular dermoid cyst 
●Granulomatosis with polyangiitis of the orbit 
●Allergic response [52,53]
●Severe conjunctivitis [54,55]
●Sinus mucocele with superinfection
●Thrombosed orbital varix
●Thyroid eye disease
Certain findings are suggestive of the following serious conditions:
●Cavernous sinus thrombosis should be suspected if signs of orbital inflammation (redness and swelling of the eyelids, ophthalmoplegia, decreased visual acuity) also occur in the contralateral eye. The second eye may become involved a day or two after the first eye. The cranial nerves III, IV, V1, V2, and VI pass through the cavernous sinus and account for many of the manifestations. In addition, there may be decreased visual acuity due to edema of the optic disc and there may be numbness over the upper face due to involvement of V1 and V2. These patients often have sphenoid and posterior ethmoid sinusitis. This topic is discussed in greater detail elsewhere. (See "Septic dural sinus thrombosis".)
●Mucormycosis and aspergillosis arise by spread from the upper airway, especially the posterior ethmoid or sphenoid sinuses. Accordingly, they sometimes present as the "orbital apex syndrome" with ophthalmoplegia and progressive visual loss, but otherwise minimal signs of inflammation (eg, mild eyelid swelling, little or no fever). They may begin in indolent fashion, but may progress quickly to involve critical structures in the eye, nose, and brain. (See "Mucormycosis (zygomycosis)", section on 'Rhino-orbital-cerebral mucormycosis' and "Epidemiology and clinical manifestations of invasive aspergillosis", section on 'Rhinosinusitis'.)
●Panophthalmitis, or a combination of endophthalmitis and orbital cellulitis, should be considered if there is evidence of intraocular inflammation on eye examination. Most cases of panophthalmitis result from extension of the infection from a fulminant bacterial endophthalmitis into the adjacent orbital soft tissues.
DIAGNOSIS — The diagnosis of orbital cellulitis is suspected clinically and can be confirmed by computed tomography (CT) scanning. During the initial evaluation, it is critical to distinguish preseptal cellulitis from the more serious orbital cellulitis. It is also important to look for complications of orbital cellulitis, such as subperiosteal abscess, orbital abscess, visual loss, and intracranial extension. Although both preseptal cellulitis and orbital cellulitis typically cause eyelid swelling with or without erythema, the presence of ophthalmoplegia, pain with eye movement, decreased vision, relative afferent pupillary defect, and/or proptosis occur only with orbital cellulitis. Another finding that is more common with orbital cellulitis, and rare or absent with preseptal cellulitis, is chemosis. Fever is more common with orbital cellulitis than with preseptal cellulitis [2,4].
It is important for an ophthalmologist to evaluate patients with suspected orbital cellulitis in order to evaluate the extraocular movements and visual acuity, and to assess for proptosis. In patients in whom rhinosinusitis is also present, an otolaryngologist should generally be consulted as well. (See 'Surgery' below.)
Imaging studies — The goals of imaging studies are to support the diagnosis of orbital cellulitis and to search for an abscess or other complications requiring surgical drainage. (See 'Surgery' below.)
Imaging modalities — CT scanning and magnetic resonance imaging (MRI) are useful for the diagnosis of orbital cellulitis and its complications. There are no controlled trials comparing these modalities and the choice is usually based on the availability of the test and on the clinical experience of the physicians involved. CT scanning of the orbits and sinuses is used most commonly to evaluate for possible orbital cellulitis and its complications. MRI is superior to CT scan in following the progression of soft tissue disease , but may not be readily available and may require sedation in young children.
When cavernous sinus thrombosis is suspected, an imaging study that includes venography should be performed, such as magnetic resonance (MR) venography or CT venography. These modalities are discussed in detail separately. MR venography is used most commonly, and would show nonfilling of the cavernous sinus in patients with cavernous sinus thrombosis. (See "Cerebral venous thrombosis: Etiology, clinical features, and diagnosis", section on 'Diagnosis'.)
Imaging findings — In preseptal cellulitis, inflammation is confined to the eyelids. In orbital cellulitis, inflammation of extraocular muscles, fat stranding, and anterior displacement of the globe are common findings. It is important to note that some cases of orbital cellulitis will have subtle abnormalities by CT scan. There is almost always evidence of rhinosinusitis, most commonly ethmoid sinusitis, and the most intense inflammatory response in the orbit is often seen adjacent to the ethmoid sinus.
Indications for imaging — Whether every patient with suspected orbital cellulitis should have a CT scan is controversial [20,32,57,58]. Clinicians may be reluctant to obtain a CT scan due to concern about exposure of the pediatric patient to radiation. Guidelines for the management of orbital cellulitis from the United Kingdom offer the following indications for CT scanning: inability to assess vision; proptosis, ophthalmoplegia, bilateral edema, or deteriorating visual acuity; lack of improvement after 24 hours of administration of intravenous antibiotics; "swinging" fevers not resolving within 36 hours; or signs or symptoms of central nervous system (CNS) involvement .
In the study of CT scanning in children with suspected acute preseptal or orbital cellulitis described above, the presence of edema beyond the eyelid margin or an absolute neutrophil count (ANC) >10,000 cell/microL were independent risk factors for an orbital abscess; the authors concluded that the presence of either of these findings should necessitate an expedited evaluation, including emergent CT scanning . (See "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Postseptal orbital complications'.)
In addition, CT scanning should be done in all patients in whom surgical drainage is being considered .
Based on the studies and guidelines described above, we obtain a contrast-enhanced CT scan of the orbits and sinuses in patients with suspected orbital cellulitis with any of the following features:
●Limitation of eye movements
●Pain with eye movements
●Relative afferent pupillary defect
●Signs or symptoms of CNS involvement
●Inability to examine the patient fully (usually patients less than one year of age)
●Patients who do not begin to show improvement within 24 to 48 hours of initiating appropriate therapy
Microbiologic studies — Despite the low yield, we obtain blood cultures in all patients with suspected orbital cellulitis before the administration of antibiotics. In patients with concomitant acute bacterial sinusitis who are examined by an otolaryngologist, any purulent sinus drainage seen on endoscopic examination should be cultured although it must be recognized that these culture results are not always an accurate reflection of what is infecting the sinuses. If surgery is performed, the material obtained should be examined by Gram stain and, in patients with risk factors for a fungal and/or mycobacterial etiology, by special stains for fungi and mycobacteria. Cultures should be done for ordinary bacterial pathogens and, depending on the circumstances, fungi and mycobacteria.
Antibiotic therapy — Most patients with uncomplicated orbital cellulitis can be treated with antibiotics alone [4,5,59]. Even in patients who are initially treated with antibiotics alone, an ophthalmologist and an otolaryngologist (if rhinosinusitis is present) should be consulted because the physical examination requires ophthalmologic and/or otolaryngologic expertise and surgery is sometimes required. (See 'Surgery' below.)
There are no randomized controlled trials evaluating empiric antibiotic regimens for the treatment of orbital cellulitis. Treatment regimens are usually empiric and designed to address the most common pathogens because, in the absence of surgical intervention, reliable culture results are difficult to obtain.
The usual choices for initial therapy are a parenterally administered broad-spectrum regimen aimed at S. aureus (including methicillin-resistant S. aureus [MRSA]), S. pneumoniae and other streptococci, as well as gram-negative bacilli. When intracranial extension is suspected, the regimen should also include coverage for anaerobes. Prompt treatment is important because delayed intervention can lead to loss of vision and/or other serious complications [12,19,41].
Initial therapy — Appropriate antibiotic regimens for initial empiric treatment in patients with normal renal function include a combination of:
●Vancomycin (in children: 40 to 60 mg/kg IV per day in three or four divided doses, maximum daily dose 4 g; in adults: dosing as summarized in the table (table 4)). Target dosage depends on extent of disease and clinical presentation of the patient.
●One of the following:
•Ceftriaxone (in children: 50 mg/kg per dose IV once or twice per day [the higher dose should be used if intracranial extension is suspected], maximum daily dose 4 g/day; in adults: 2 g IV every 24 hours [2 g IV every 12 hours if intracranial extension is suspected]) or
•Cefotaxime (in children: 150 to 200 mg/kg IV per day in three doses, maximum daily dose 12 g; in adults: 2 g IV every four hours); not available in the United States
Anaerobic coverage is warranted in certain situations:
●Until the possibility of intracranial involvement has been assessed and excluded, we add metronidazole (in children: 30 mg/kg IV or orally per day in divided doses every eight hours; in adults: 500 mg IV or orally every eight hours) for anaerobic coverage. (See "Treatment and prognosis of bacterial brain abscess".)
●For patients who have orbital cellulitis associated with chronic sinusitis or an odontogenic source, we also add metronidazole (at the doses above) if they are being treated with a ceftriaxone- or cefotaxime-containing regimen given the involvement of anaerobes with such processes. Alternatively, a regimen containing ampicillin-sulbactam or piperacillin-tazobactam can be used if intracranial extension has been excluded; in these cases, metronidazole does not need to be added. (See "Microbiology and antibiotic management of chronic rhinosinusitis", section on 'Anaerobes' and "Epidemiology, pathogenesis, and clinical manifestations of odontogenic infections", section on 'Microbiology of odontogenic infections'.)
Ampicillin-sulbactam and piperacillin-tazobactam have good activity against pathogens involved in orbital cellulitis (other than MRSA), but because of concerns of central nervous system (CNS) penetration in the case of intracranial extension, we do not use them as initial therapy. Daptomycin, linezolid and telavancin, like vancomycin, are also active against MRSA, but there is little experience using them for orbital or intracranial infections. Moreover, linezolid concentrations in the CNS have been inconsistent in children and, accordingly, linezolid is not recommended for children with CNS infections . Therefore, unless there is a contraindication to its use (eg, allergy), vancomycin is the preferred agent for MRSA coverage of orbital cellulitis.
Adults and children with a serious allergy to penicillins and/or cephalosporins can be treated with a combination of vancomycin and a fluoroquinolone (with or without metronidazole, depending on the indications for anaerobic coverage, as above). In adults, levofloxacin is given at a dose of 500 to 750 mg IV or orally once daily, and moxifloxacin is given at a dose of 400 mg IV or orally once daily. In children, levofloxacin is given at a dose of 16 to 20 mg/kg IV per day divided every 12 hours (maximum daily dose 750 mg) for infants ≥6 months and children <5 years, and at a dose of 10 mg/kg IV per dose every 24 hours (maximum daily dose 750 mg) for children ≥5 years.
If a pathogen is retrieved on cultures of blood or orbital or subperiosteal aspirates, or from sinuses from cultures obtained by endoscopic sinus surgery, treatment should be modified accordingly. For example, if a methicillin-susceptible strain of S. aureus (MSSA) is recovered, treatment should be changed from vancomycin to oxacillin or nafcillin (in children: 100 to 200 mg/kg/day in divided doses every six hours, maximum daily dose 12 g; in adults: 2 g IV every four hours) because these agents are more rapidly bactericidal for MSSA than vancomycin. Because these infections are often polymicrobial, broad-spectrum therapy is usually continued until anaerobic culture data are available, usually for approximately five days after collection.
Response to therapy — Patients should begin to show improvement within 24 to 48 hours of initiating appropriate therapy; if this does not occur, repeat imaging should be performed to search for an abscess or another indication for surgery. (See 'Surgery' below.)
Switch to oral therapy — For patients with uncomplicated orbital cellulitis (ie, without abscess or other complications) whose infection responds well, it is reasonable to switch to oral therapy. We generally switch to oral therapy after the patient is afebrile and the eyelid and orbital findings have begun to resolve substantially, which usually takes three to five days. When a range of doses can be used for an oral antibiotic, we favor the higher end of the dose range if penicillin-resistant S. pneumoniae is a concern.
If definitive culture data are available, oral therapy should be directed against the infecting organism(s). If there are no definitive culture data, appropriate empiric oral regimens include:
One of the following agents:
•For children − The dose range is 40 to 45 mg/kg per day (in divided does every 8 to 12 hours) to 90 mg/kg per day divided every 12 hours (using the 600 mg/5 mL suspension)
•For adults − 875 mg every 12 hours
•For children <12 years of age − 10 mg/kg per day divided every 12 hours, usual maximum 200 mg per dose; for children ≥12 years of age: 400 mg every 12 hours
•For adults − 400 mg every 12 hours
•For children <12 years age − 20 to 30 mg/kg per day divided every 8 to 12 hours. Usually maximum dose 400 mg per dose; for children ≥12 years age: 500 mg every 12 hours not to exceed 1000 mg per day
•For adults − 500 mg every 12 hours not to exceed 1000 mg per day
•For children − 14 mg/kg per day, divided every 12 hours, not to exceed 600 mg/day
•For adults − 300 mg twice daily
PLUS an agent active against MRSA:
•For children <12 years − 20 mg/kg per day, divided every 12 hours, not to exceed 1200 mg per day; for children ≥12 years: 600 mg every 12 hours
•For adults − 600 mg every 12 hours
•For children − 10 to 12 mg/kg per day of the TMP component divided every 12 hours
•For adults − One to two double-strength tablets (each tablet contains 160 mg TMP and 800 mg SMX) every 12 hours
•For children − 30 to 40 mg/kg per day in three to four equally divided doses, maximum 1.8 grams per day
•For adults − 300 mg every eight hours
In the absence of informative culture data, we generally continue MRSA coverage given the prevalence of MRSA and the difficulties in ruling out its involvement, particularly in higher-risk patients, such as neonates, postoperative or post-trauma patients, and those who are known to be colonized with MRSA. For lower-risk patients in settings where the prevalence of community-acquired MRSA is low, it is reasonable to transition to amoxicillin-clavulanate, cefpodoxime, or cefdinir alone.
In adults and children who have serious allergies to penicillins and cephalosporins, fluoroquinolones are appropriate alternatives to the agents listed above. For adults, appropriate fluoroquinolones are moxifloxacin (400 mg orally once daily) and levofloxacin (500 to 750 mg orally once daily). For children, levofloxacin is the appropriate fluoroquinolone. Limited information regarding levofloxacin use in pediatric patients is available. Some centers recommend a levofloxacin dose for infants ≥6 months and children <5 years of 10 mg/kg per dose every 12 hours, and for children ≥5 years of 10 mg/kg per dose every 24 hours (maximum daily dose 500 mg). Ciprofloxacin is not appropriate because it has suboptimal activity against streptococci, including S. pneumoniae. In regions where MRSA is prevalent, if levofloxacin or (in adults) moxifloxacin is used, it should be combined with an agent active against MRSA. Desensitization to a penicillin or cephalosporin may be considered in patients with a history of an IgE-mediated (anaphylactic) reaction to these agents. (See "Penicillin allergy: Immediate reactions", section on 'Desensitization'.)
Duration — For patients with uncomplicated orbital cellulitis that quickly respond to antibiotics and have no evidence of abscess formation, we continue antibiotics until all signs of orbital infection have resolved, and for a total of at least two to three weeks. A longer period (at least four weeks), is recommended for patients with severe ethmoid sinusitis and bony destruction of the sinus [32,62]. The management of the complications associated with orbital cellulitis is discussed separately. (See "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Complications' and "Septic dural sinus thrombosis" and "Treatment and prognosis of bacterial brain abscess" and "Intracranial epidural abscess".)
There have been no controlled trials to define the optimal duration of antimicrobial therapy in orbital cellulitis.
Surgery — For patients with a poor response to antibiotic treatment, including worsening visual acuity or pupillary changes, surgical biopsy is indicated to identify pathogens not treated by the empiric regimen (eg, fungal pathogens) and to rule out noninfectious causes of orbital inflammation, such as idiopathic orbital inflammatory disease or granulomatosis with polyangiitis.
Surgical drainage is indicated for some radiologically identified abscesses, especially if they are large (>10 mm in diameter), fail to respond to antibiotic treatment within 24 to 48 hours of appropriate antimicrobial therapy, or threaten vision [63,64]. Surgery is almost always indicated in patients with intracranial extension of the infection. In some cases, drainage of affected sinuses is also required to control the infection. The results of cultures and susceptibility testing from samples obtained during surgery can be used to tailor therapy. (See "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Postseptal orbital complications'.)
External approaches (through the orbit) and endoscopic transcaruncular surgery have been employed [65-68]. The transcaruncular approach involves a conjunctival incision just medial or lateral to the caruncle .
Sinus surgery is indicated for debridement in patients with severe, destructive rhinosinusitis.
Limited role for adjunctive glucocorticoids — We do not routinely use glucocorticoids in addition to antibiotic therapy for orbital cellulitis. Although some oculoplastic specialists advocate their use, the efficacy of glucocorticoids in this setting is uncertain. Furthermore, glucocorticoids may mask inflammatory signs that would alert the clinician to worsening of disease.
Evidence informing the effect of adjunctive glucocorticoids is conflicting. In a large, retrospective, multicenter study of over 5000 children with orbital cellulitis, corticosteroid prescription was associated with more operative episodes and 30-day readmissions . Some of the smaller studies have suggested a shorter time to resolution and shorter hospitalization with glucocorticoids, but potential for bias and confounders in these studies reduce confidence in the findings [70-74]. Additionally, the impact on long-term outcomes is unknown.
OUTCOMES — The outcome of patients with orbital cellulitis is variable. The majority of patients respond rapidly and completely to appropriate therapy. The most serious complications are cavernous sinus thrombosis, intracranial extension, and vision loss, which can lead to permanent sequelae and, in the case of complications in the former two, death. These complications are rare.
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Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Cellulitis around the eye (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Terminology − Orbital cellulitis is an infection involving the contents of the orbit (fat and ocular muscles). (See 'Terminology' above.)
●Anatomy − Preseptal cellulitis and orbital cellulitis involve different anatomic sites, with preseptal cellulitis referring to infections of the soft tissues anterior to the orbital septum and orbital cellulitis referring to infections posterior to it (figure 1). (See 'Anatomy' above.)
●Distinguishing between preseptal and orbital cellulitis
•It is important to distinguish between preseptal and orbital cellulitis because they have very different clinical implications. Preseptal cellulitis is generally a mild condition that rarely leads to serious complications, whereas orbital cellulitis may cause loss of vision and even loss of life (table 3 and table 2). (See 'Introduction' above.)
•Although both preseptal cellulitis and orbital cellulitis typically cause eyelid swelling with or without erythema, features such as ophthalmoplegia, pain with eye movements, and/or proptosis occur only with orbital cellulitis. Imaging studies can also be helpful with distinguishing between the two conditions (table 3 and table 2). (See 'Clinical manifestations' above and 'Diagnosis' above.)
•In cases in which the distinction is not clear, clinicians should treat patients as though they have orbital cellulitis. (See 'Treatment' above.)
●Epidemiology and pathogenesis – Orbital cellulitis (as well as preseptal cellulitis) is more common in children than in adults. The most common underlying factor that leads to orbital cellulitis is acute sinusitis, particularly ethmoid sinusitis; less common causes are ophthalmic surgery and orbital trauma. (See 'Epidemiology and pathogenesis' above.)
●Microbiology − Orbital cellulitis is sometimes a polymicrobial infection. The most commonly identified pathogens in orbital cellulitis are Staphylococcus aureus and streptococci (table 1). (See 'Microbiology' above.)
•Orbital cellulitis is characterized by eyelid swelling, pain with eye movements, proptosis, and chemosis (picture 1). Ophthalmoplegia with diplopia can occur in severe cases. Fever and peripheral leukocytosis with a predominance of neutrophils is also common. (See 'Clinical manifestations' above.)
•Infection may rarely extend to the orbital apex, causing visual loss, or intracranially, causing epidural or subdural empyema, brain abscess, meningitis, cavernous sinus thrombosis, or dural sinus thrombosis. Orbital cellulitis can also be associated with subperiosteal or orbital abscess. (See 'Clinical manifestations' above and "Acute bacterial rhinosinusitis in children: Clinical features and diagnosis", section on 'Complications'.)
•The diagnosis can be made clinically in a patient who presents with clinical signs and symptoms consistent with orbital cellulitis, including ophthalmoplegia, proptosis, impaired vision, and pain on motion of the eye. In some cases, radiographic imaging with computed tomography scan of the orbits and sinuses is helpful to establish the diagnosis or evaluate for complications. (See 'Diagnosis' above.)
•Indications for imaging include the presence of any of the following features:
-Limitation of eye movements
-Pain with eye movements
-Relative afferent pupillary defect
-Signs or symptoms of central nervous system (CNS) involvement
-Inability to examine the patient fully (usually patients less than one year of age)
-Patients who do not begin to show improvement within 24 to 48 hours of initiating appropriate therapy (see 'Indications for imaging' above)
•Common radiographic findings include inflammation of extraocular muscles, fat stranding, and anterior displacement of the globe. (See 'Imaging findings' above.)
•Initial empiric antibiotic therapy − For patients with orbital cellulitis, we suggest initial empiric antibiotic treatment with parenteral broad-spectrum therapy with activity against S. aureus (including methicillin-resistant S. aureus [MRSA]), streptococci, and gram-negative bacilli (Grade 2B). Such a regimen should include vancomycin plus ceftriaxone or cefotaxime. If there is concern for intracranial extension, we suggest adding anaerobic coverage (eg, with metronidazole) (Grade 2C). (See 'Antibiotic therapy' above.)
•Multidisciplinary management − Although initial treatment may consist of intravenous antibiotics alone, management should be in consultation with an ophthalmologist and an otolaryngologist (if rhinosinusitis is present) because the physical examination requires ophthalmic and/or otolaryngologic expertise and surgery is sometimes required. (See 'Antibiotic therapy' above.)
•Monitoring on therapy − Signs and symptoms should begin to show improvement within 24 to 48 hours following the initiation of appropriate therapy; if this does not occur, repeat imaging should be performed and surgery with biopsy for culture and histology should be considered. (See 'Response to therapy' above.)
•Switch to oral therapy − For patients with orbital cellulitis whose infection responds promptly and in whom there is no evidence of abscess, it is reasonable to switch to oral therapy after the patient is afebrile and the eyelid and orbital findings have begun to resolve substantially. If definitive culture data are available, oral therapy should be directed against the infecting organism(s). (See 'Switch to oral therapy' above.)
•Duration of therapy − For patients with orbital cellulitis, we continue antibiotics until all signs of orbital inflammation have resolved, and for a total of at least two to three weeks (including both intravenous and oral therapy). A longer period (at least four weeks) is recommended for patients with severe ethmoid sinusitis and bony destruction of the sinus. The management of the complications of orbital cellulitis is discussed separately. (See 'Duration' above and "Acute bacterial rhinosinusitis in children: Microbiology and management", section on 'Complicated ABRS'.)
●Indications for surgery − The main indications for surgery are a poor response of the infection to antibiotic treatment, worsening visual acuity or pupillary changes, or evidence of an abscess, especially a large abscess (>10 mm in diameter) or one that fails to respond promptly to antibiotic treatment. (See 'Surgery' above.)
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