What are the common organisms causing secondary orbital cellulitis from sinus infection?

The primary organisms associated with secondary orbital cellulitis stemming from a sinus infection include Staphylococcus aureus and Streptococcus pneumoniae. These bacteria are commonly found in the nasal flora and can easily spread from the sinuses to the orbit, especially during instances of sinusitis, which can lead to inflammation and the formation of cellulitis.

Staphylococcus aureus is known for causing various infections, including skin and soft tissue infections, and its ability to potentially lead to more serious conditions like cellulitis due to its virulence. Streptococcus pneumoniae, a common pathogen in respiratory infections, can also contribute to infections associated with sinusitis. The combination of these organisms reflects their prevalence in causing complications as a result of sinus infections, making them the most likely culprits in cases of orbital cellulitis.

Other organisms listed in the alternatives, such as E. coli, Pseudomonas aeruginosa, Mycobacterium tuberculosis, Listeria monocytogenes, Clostridium perfringens, and Bacillus cereus, are predominantly associated with other types of infections or specific conditions that do not align with typical secondary orbital cellulitis caused by sinus infections. This reinforces the understanding that the choice involving Staphylococcus aureus and