Which organism is commonly associated with pinkeye conjunctivitis?

Which organism is commonly associated with pinkeye conjunctivitis?

• A. Haemophilus aegyptius
• B. Moraxella lacunata
• C. Chlamydia trachomatis
• D. Klebsiella ozaenae

Answer: (A)

Pinkeye conjunctivitis is most commonly caused by a bacterium that produces a rapid, contagious, mucopurulent discharge and spreads easily between people, especially children. Haemophilus aegyptius fits this scenario and is classically associated with acute conjunctivitis. It’s historically known as the Koch-Weeks bacillus and is a fastidious, Gram-negative coccobacillus that requires specific growth factors (X and V factors) for culture, reflecting why it’s often discussed in the context of this eye infection. Clinically, infections with this organism produce the characteristic red eye with a purulent discharge that many people recognize as pinkeye. In contrast, Moraxella lacunata is more linked to angular conjunctivitis, which affects the corners of the eyes, not the typical pinkeye. Chlamydia trachomatis causes inclusion conjunctivitis or trachoma, which have different clinical courses and presentations, often more chronic. Klebsiella ozaenae is associated with nasal disease such as atrophic rhinitis rather than conjunctivitis. Thus, the organism most characteristically associated with pinkeye conjunctivitis is Haemophilus aegyptius.

Pinkeye conjunctivitis is most commonly caused by a bacterium that produces a rapid, contagious, mucopurulent discharge and spreads easily between people, especially children. Haemophilus aegyptius fits this scenario and is classically associated with acute conjunctivitis. It’s historically known as the Koch-Weeks bacillus and is a fastidious, Gram-negative coccobacillus that requires specific growth factors (X and V factors) for culture, reflecting why it’s often discussed in the context of this eye infection. Clinically, infections with this organism produce the characteristic red eye with a purulent discharge that many people recognize as pinkeye.

In contrast, Moraxella lacunata is more linked to angular conjunctivitis, which affects the corners of the eyes, not the typical pinkeye. Chlamydia trachomatis causes inclusion conjunctivitis or trachoma, which have different clinical courses and presentations, often more chronic. Klebsiella ozaenae is associated with nasal disease such as atrophic rhinitis rather than conjunctivitis. Thus, the organism most characteristically associated with pinkeye conjunctivitis is Haemophilus aegyptius.