Orbital cellulitis causes

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ogheneochuko Ajari, MB.BS, MS [2]; Tarek Nafee, M.D. [3]

Orbital cellulitis occurs most commonly from typical bacterial infections. In some cases, mycobacteria or mycosis may also be implicated. The most common underlying condition is ethmoid sinusitis, which has been reported in 90-98% of orbital cellulitis cases. The most commonly reported pathogens are Staphylococcus aureus, Streptococcus spp., and Haemophilus influenzae. With the rise of microbial resistance, methicillian-resistant Staphylococcus aureus (MRSA) must be considered as a potential cause and correlated with geographic prevalence. Though some causes may be uncommon, orbital cellulitis is a medical emergency and all etiologies must be considered.^{[1][2][3][4][5][6]}

Orbital cellulitis occurs most commonly from bacterial infection. In some cases, mycobacterial or fungal infections are observed.^[1][2][3][4] Difficulty arises in identifying a specific organism due to challenges in culturing the retroseptal orbital region.^[7]

Common bacterial causes of orbital cellulitis include:^[1][2][3]

• Staphylococcus aureus
• Streptococcus spp.
• Haemophilus influenzae
  • With the dissemination of Haemophilus influenza type b (Hib) vaccine, the incidence of Haemophilus influenzae-caused orbital cellulitis has decreased significantly.
• Methicillin-resistant Staphylococcus aureus (MRSA)
  • Rise in microbial resistance, MRSA must be considered as a potential cause and correlated with geographic prevalence.
• Aerobic and anaerobic bacteria

In immunocompromised patients, additional causes may include:^[2]

• Fungal infection
  • Mucormycosis
  • Aspergilliosis
• Mycobacterial infection
  • Mycobacterium tuberculosis

Based on etiology, the most common underlying condition causing orbital cellulitis is ethmoid sinusitis, which occurs in 90-98% of cases.^[1][5][6] Additional causes based on etiology include:^[2][7]

• Sinusitis:
  • Staphylococcus aureus
  • Streptococcus spp.
  • Haemophilus influenzae
• Dacryocystitis, dacryoadenitis, and other lacrimal duct abnormalities
  • Staphylococcus aureus
  • Streptococcus pneumoniae
  • Streptococcus pyogenes
  • Haemophilus influenzae
• Traumatic/Foreign body:
  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Enterococcus spp.
  • Escherichia coli
  • Eikenella spp.
• Spread from superficial infections of the face or adjacent soft tissue:
  • Staphylococcus aureus
  • Streptococcus pyogenes
• Dental caries/Tooth abscess:
  • Bacteroides spp.
  • anaerobes
  • gram negative rods
• Iatrogenic/post-surgical procedures:
  • Staphylococcus aureus
  • Streptococcus spp.
• Immunocompromised patient:
  • Mucormycosis
  • Aspergilliosis
  • Mycobacterium tuberculosis
• Diabetic patients with or without history of diabetic ketoacidosis
  • Pseudomonas aeruginosa
  • Klebsiella pneumoniae

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