Orbital Infections
Michelle W. Latting, MD
INTRODUCTION
Infectious processes of the orbit can develop from contiguous spread from the eyelids, sinuses, face, and oropharynx, or from foreign bodies or secondary to bacteremia. They occur as a result of bacterial, fungal, viral, and parasitic pathogens and present a serious threat to vision and function of the orbit and, in severe cases, can lead to meningitis and death. Because of these potential complications, orbital and periorbital infections require prompt recognition and aggressive medical and — when indicated — surgical treatment.
PRESEPTAL CELLULITIS
Disease Description
Encompasses any periocular soft tissue inflammation anterior to the orbital septum (Figure 34.1)
Most common etiologies
Sinusitis
Contiguous infection of the soft tissues of the face or eyelids (hordeolum, acute dacryocystitis)
Local trauma (insect or animal bites)
Recent periocular surgery
FIGURE 34.1. Preseptal cellulitis in the setting of dacryocystitis.
Most common pathogen
Staphylococcus aureus and Staphylococcus epidermidis
Streptococcus pyogenes and Streptococcus pneumoniae
Haemophilus influenzae no longer common because of vaccination
Management Options
Attempts to culture the offending organism typically grow skin contaminants. Blood cultures rarely return positive findings. Treat empirically based on likely microbial pathogens.
In adults and children older than age 1 who do not show signs of systemic illness, treat with oral antibiotics on an outpatient basis.
Admit the following groups for intravenous (IV) antibiotics:
Children younger than age 1 year
Patients of any age with severe disease concerning for possible orbital involvement
Patients with signs of systemic illness (fever, leukocytosis)
Patients unable to adhere to treatment or follow-up
Patients who have failed an initial trial of oral antibiotic
If no improvement or any worsening after 48 hours of oral therapy
Admit for broad spectrum antibiotics.
Computed tomography (CT) of the orbit with and without contrast to assess for orbital involvement and presence of subperiosteal abscess (SPA)
Choice of antibiotic
Treat empirically based on most common pathogens (Staphylococcus and Streptococcus species)
Many clinicians prefer monotherapy with amoxicillin-clavulanic acid or cephalexin because of ease of use and historically excellent response; however, these agents do not cover methicillin-resistant S. aureus (MRSA). For community-acquired MRSA coverage, add trimethoprim-sulfamethoxazole (TMP-SMX), clindamycin, or doxycycline (doxycycline is contraindicated in children).
If associated with penetrating eyelid injury from organic material or a bite, must also cover for anaerobic organisms
Metronidazole or clindamycin
Duration of therapy
Seven days or until examination findings have nearly completely resolved
Indications for Surgery
If the patient fails to respond to appropriate oral or IV antibiotic therapy, and there is an identifiable source of infection that can be addressed surgically (chalazion, dacryocystitis, dacryoadenitis with focal abscess), consider surgical intervention to address the source.
Prognosis
Excellent. With appropriate antibiotic therapy, an improvement in clinical signs is seen typically within 24 to 48 hours.
PERIOCULAR NECROTIZING FASCIITIS
Disease Description
A necrotizing soft tissue infection (NSTI) that spreads rapidly along avascular tissue planes (Figure 34.2)
May be polymicrobial (type I) in immunocompromised host or monomicrobial (type 2) in healthy individuals without antecedent trauma. Most commonly caused
by Group A β-hemolytic Streptococcus (S. pyogenes) whose bacterial exotoxins give rise to streptococcal toxic shock syndrome.
FIGURE 34.2. A, Periocular necrotizing fasciitis. B, Intraoperative photograph following debridement demonstrating the surgical mantra of “cut until it bleeds.”
Initial spread is horizontal due to avascularity of fascial planes.
As the condition progresses, skin develops ischemic necrosis and dermis and subcutaneous fat become gangrenous.
Deeper tissues, including muscle and bone, are usually preserved until very advanced disease.
Clinical signs that suggest necrotizing infection include
Dusky appearance of the overlying skin before the development of frank necrosis
Rapidly spreading borders, crepitus, anesthesia of the involved or adjacent skin
Pain out of proportion to examination
Systemic manifestations (fever, tachycardia, hypotension)
The LRINEC (Laboratory Risk Indicator for Necrotizing Fasciitis) score can be used to calculate the likelihood of NSTI when the diagnosis is unclear (Table 34.1).
Management Options
Admit the patient.
Provide hemodynamic support.
Obtain wound cultures and blood cultures before initiating antimicrobial therapy.
Treat empirically with a three drug regimen.
Carbapenem or β-lactam with β-lactamase inhibitor
Antibiotic with activity against MRSA (typically vancomycin)
Clindamycin (inhibits protein synthesis limiting elaboration of the bacterial exotoxin)
Consider addition of aminoglycoside and/or metronidazole for type I polymicrobial infections.
Consider hyperbaric oxygen therapy, although its role in management is controversial.
Proceed with immediate surgical exploration and aggressive debridement.
Indications for Surgery
In general, immediate, aggressive surgical debridement is the standard of care for NSTIs; however, there is evidence that periocular NSTIs behave differently than do NSTIs elsewhere (possibly due to the robust blood supply to the eyelids) and may be managed more conservatively with antibiotic therapy and close observation.
TABLE 34.1. Laboratory Risk Indicator for Necrotizing Fasciitis Score Can Be Used to Calculate the Likelihood of Necrotizing Soft Tissue Infection When the Diagnosis Is Unclear | |||||||||||||||||||||||||||||||||
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