What is the most common bacterial cause of orbital cellulitis in adults?

What is the most common bacterial cause of orbital cellulitis in adults?

• A. Staphylococcus aureus
• B. Streptococcus pneumoniae
• C. Haemophilus influenzae
• D. Pseudomonas aeruginosa

Answer: (A)

Orbital cellulitis in adults is most commonly caused by Staphylococcus aureus. This organism is a frequent culprit in facial skin and soft-tissue infections and often spread from the adjacent sinuses or facial structures, making it the leading single pathogen identified in adult cases. While other bacteria like Streptococcus species (including Streptococcus pneumoniae) and anaerobes can also be involved, Staphylococcus aureus remains the predominant organism. Haemophilus influenzae is more common in children, partly due to differences in carriage and vaccination effects. Pseudomonas aeruginosa is linked more with specific risk factors such as chronic sinus disease, contact lens–related issues, or healthcare exposure, and is less typically the primary cause in adults. Because of this predominance, empiric treatment often includes coverage for Staphylococcus aureus, including MRSA in settings with higher prevalence.

Orbital cellulitis in adults is most commonly caused by Staphylococcus aureus. This organism is a frequent culprit in facial skin and soft-tissue infections and often spread from the adjacent sinuses or facial structures, making it the leading single pathogen identified in adult cases. While other bacteria like Streptococcus species (including Streptococcus pneumoniae) and anaerobes can also be involved, Staphylococcus aureus remains the predominant organism. Haemophilus influenzae is more common in children, partly due to differences in carriage and vaccination effects. Pseudomonas aeruginosa is linked more with specific risk factors such as chronic sinus disease, contact lens–related issues, or healthcare exposure, and is less typically the primary cause in adults. Because of this predominance, empiric treatment often includes coverage for Staphylococcus aureus, including MRSA in settings with higher prevalence.