Most cases of cellulitis stem from bacterial infection; however, cellulitis resulting from non-infectious (eg, autoimmune, malignant, foreign-body) etiologies may mimic bacterial cellulitis. Defining the etiology of the cellulitis allows prompt and effective treatment.
Bacterial infections of the orbit or periorbital soft tissues originate from 3 primary sources:
Preseptal cellulitis involves structures anterior to the orbital septum. Eyelid edema, erythema, and inflammation may be severe, but the globe and deep orbital tissues remain uninvolved (Fig 4-1). Therefore, pupillary reaction, vision, ocular motility, and globe position are not disturbed. Furthermore, pain on eye movement and chemosis are noticeably absent.
Table 4-1 Differential Diagnosis of Major Orbital Inflammations
Figure 4-1 A patient with preseptal cellulitis of the right upper eyelid with formation of a localized abscess. The eye remains quiet with no chemosis or proptosis.
(Courtesy of Bobby S. Korn, MD, PhD.)
Although preseptal cellulitis in adults usually arises from penetrating cutaneous trauma or dacryocystitis, in children, it commonly arises from underlying sinusitis. Most pediatric cases are now caused by gram-positive cocci, but Haemophilus influenzae type B should still be considered, especially in nonimmunized children.
Antibiotic therapy and workup should begin as promptly as possible, particularly in children. If eyelid swelling precludes motility evaluation and, thus, the ability to exclude orbital cellulitis, workup should include computed tomography (CT) imaging of the orbit and sinuses. An optimal antibiotic regimen may be developed in collaboration with the patient’s primary care physician or an infectious disease specialist.
In children with a reliable examination and follow-up plan, oral antibiotics (eg, cephalexin for an anterior etiology; amoxicillin clavulanate for a sinusitis-associated infection), frequent warm compresses, and nasal decongestants (eg, oxymetazoline nasal spray) for associated sinusitis typically improve the infection. For infants, children with an unreliable examination or follow-up plan, or for infections that progress on oral antibiotics, hospital admission and intravenous (IV) antibiotics (eg, ceftriaxone, vancomycin) may be considered.
In teenagers and adults, preseptal cellulitis usually arises from a superficial source and responds quickly to appropriate oral antibiotics (eg, ampicillin-sulbactam, trimethoprim-sulfamethoxazole [TMP-SMX], doxycycline, clindamycin) and warm compresses. Initial antibiotic selection depends on the history, clinical findings, and initial laboratory studies. Prompt culture and sensitivity studies allow for revising antibiotic therapy in unresponsive cases.
In older adults, infections behave differently and may not produce typical signs, such as erythema, calor, or fever. Response to antibiotics in patients in this age group may also be delayed, and surgical intervention to excise devitalized tissue may be necessary to clear an infection. Imaging studies and hospital admission for IV antibiotics should be considered to rule out underlying sinusitis if no direct inoculation site is identified, if the patient does not respond to oral antibiotics within 48 hours, or if orbital involvement becomes evident.
Preseptal cellulitis in any age group may require surgical drainage if it progresses to a localized abscess (see Fig 4-1). Incision and drainage directly over the abscess typically improve the infection, but dissection of the upper eyelid should preserve the orbital septum to avoid contaminating the orbital soft tissues and to prevent injury to the underlying levator aponeurosis.
In patients with preseptal cellulitis resulting from trauma, Staphylococcus aureus represents the most common pathogen. The infection usually responds rapidly to a penicillin used against penicillinase-resistant organisms, such as methicillin or ampicillin-sulbactam. However, methicillin-resistant S aureus (MRSA), previously recognized as a cause of severe nosocomial infections, is now increasingly encountered in the community setting as well.
Community-acquired (CA)-MRSA infections tend to present as a fluctuant abscess with surrounding cellulitis. Eyebrow abscesses have a particularly high rate of CA-MRSA–positive cultures. The pain associated with the lesion is often out of proportion to its appearance. Classically, CA-MRSA has been susceptible to a wider range of antibiotics (including TMP-SMX, rifampin, or clindamycin), compared with susceptibility of hospital-associated (HA)-MRSA. Over the past decade, however, antibiotic-resistant CA-MRSA strains have migrated into the health care setting, and the genetic differences and outcomes between CA-MRSA and HA-MRSA infections have increasingly overlapped. Both types of MRSA may result in acute morbidity and long-term disability. MRSA has also been associated with necrotizing fasciitis, orbital cellulitis, endogenous endophthalmitis, panophthalmitis, and cavernous sinus thrombosis.
Carniciu AL, Chou J, Leskov I, Freitag SK. Clinical presentation and bacteriology of eyebrow infections: the Massachusetts Eye and Ear Infirmary experience (2008–2015). Ophthalmic Plast Reconstr Surg. 2017;33(5):372–375.
Mathias MT, Horsley MB, Mawn LA, et al. Atypical presentations of orbital cellulitis caused by methicillin-resistant Staphylococcus aureus. Ophthalmology. 2012;119(6):1238–1243.
Pelton RW, Klapper SR. Preseptal and orbital cellulitis. Focal Points: Clinical Modules for Ophthalmologists. San Francisco: American Academy of Ophthalmology; 2008, module 11.
Orbital cellulitis involves structures posterior to the orbital septum, and in the majority of cases it occurs as a secondary extension of acute or chronic bacterial sinusitis (Table 4-2). Clinical findings include fever, leukocytosis (75% of cases), erythema, proptosis, chemosis, ptosis, and restriction of and pain with ocular movement (Fig 4-2A, B). Decreased vision, impaired color vision, restricted visual fields, and pupillary abnormalities suggest optic neuropathy that demands immediate investigation and aggressive management. Delay in treatment may result in blindness, cavernous sinus thrombosis, cranial neuropathy, meningitis, or death. Treatment may require a multidisciplinary approach.
Orbital findings indicate that imaging is needed to identify sinusitis, which may require treatment from an otolaryngologist. Antibiotic therapy in adults should provide broad-spectrum coverage because such infections usually involve multiple organisms that may include gram-positive cocci, such as H influenzae and Moraxella catarrhalis, and anaerobes. Although nasal decongestants promote drainage of the infected sinus, sinus surgery is often required, especially if orbital findings progress during IV antibiotic therapy. In contrast, orbital cellulitis in children is more often caused by a single gram-positive organism and is less likely to require surgical sinus drainage.
Progressive proptosis, globe displacement, or lack of response to appropriate antibiotic therapy suggests abscess formation, which can be identified on orbital CT imaging with contrast. Abscesses usually localize in the subperiosteal space (Fig 4-2C, D), adjacent to the infected sinus, but may extend through the periosteum into the orbital soft tissues. When initial medical treatment fails, further imaging may identify an abscess and determine an approach for surgical intervention.
Table 4-2 Causes of Orbital Cellulitis
Figure 4-2 Left-sided orbital cellulitis. A, Marked periocular erythema is present, as well as upper eyelid ptosis. B, Chemosis is present with elevation of the eyelid. C and D, T-1 weighted magnetic resonance imaging (MRI) with gadolinium contrast reveals a superior subperiosteal abscess (arrows).
(Courtesy of Cat N. Burkat, MD.)
However, not all subperiosteal abscesses (SPAs) require surgical drainage. Isolated medial or inferior SPAs in children younger than 9 years with underlying isolated ethmoid sinusitis, intact vision, and only moderate proptosis typically respond to medical therapy. Management may consist of careful observation unless any of the following criteria are present:
patient aged 9 years or older
presence of frontal sinusitis
nonmedial SPA location
suspicion of anaerobic infection (eg, presence of gas in abscess on CT)
recurrence of SPA after prior drainage
evidence of chronic sinusitis (eg, nasal polyps)
acute optic nerve or retinal compromise
infection of dental origin (anaerobic infection more likely)
In patients with these criteria or with infections refractory to medical therapy, surgical drainage coupled with appropriate antibiotic therapy typically leads to clinical improvement within 24–48 hours. Sinusitis may improve with concomitant sinus surgery. The refractory nature of orbital abscesses in adolescents and adults may relate to the frequent involvement of multiple and drug-resistant pathogens, particularly anaerobic organisms.
Treatment with corticosteroids may speed resolution of inflammation and decrease the length of hospital admission, although the timing and dose remain controversial. Their use should be balanced by the risk of masking infection progression.
Because orbital cellulitis and abscesses respond to therapy in most patients, orbital infections rarely spread posteriorly to the cavernous sinus. Cavernous sinus thrombosis is often heralded by the rapid progression of proptosis, the development of ipsilateral ophthalmoplegia, and the onset of anesthesia in both the first and second divisions of the trigeminal nerve. In rare instances, contralateral ophthalmoplegia, meningitis, or frank brain abscess may develop. Lumbar puncture may reveal acute inflammatory cells and the causative organism on stain and culture. Contrast-enhanced magnetic resonance imaging (MRI) confirms the diagnosis.
Orbital cellulitis caused by MRSA may occur without antecedent respiratory illness or trauma and without adjacent paranasal sinus disease on imaging. MRSA-caused orbital cellulitis may require surgical intervention more often than typical orbital cellulitis, and it may also lead to significant decrease in visual acuity more often, especially in cases in which referral for surgical intervention has been delayed. Because of the potentially aggressive nature of this pathogen, successful management demands a high degree of clinical suspicion and prompt medical and surgical intervention. In addition, consultation with specialists in infectious diseases may be warranted.
Orbital cellulitis following blowout fractures generally occurs in patients with underlying sinus disease or a medial wall fracture. Prophylactic antibiotics can be considered in these cases.
Odontogenic infections may spread through the sinuses to cause orbital cellulitis. These infections account for 2%–5% of all orbital cellulitis cases and can arise from any tooth, although most develop from maxillary premolar teeth. These infections are typically polymicrobial, often consisting of gram-positive aerobes and anaerobes.
Garcia GH, Harris GJ. Criteria for nonsurgical management of subperiosteal abscess of the orbit: analysis of outcomes 1988–1998. Ophthalmology. 2000;107(8):1454–1456, discussion 1458.
Pushker N, Tejwani LK, Bajaj MS, Khurana S, Velpandian T, Chandra M. Role of oral corticosteroids in orbital cellulitis. Am J Ophthalmol. 2013;156(1):178–183.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.