Which organismal infection is highly virulent & cause corneal ulcer perforation within 48 hr?
**Core Concept**
Pseudomonas aeruginosa is a gram-negative bacterium known for its aggressive virulence and ability to cause severe eye infections, particularly corneal ulcers. This organism thrives in moist environments, making it a common cause of infections in contact lens wearers.
**Why the Correct Answer is Right**
Pseudomonas aeruginosa produces a range of virulence factors, including exotoxin A, elastase, and alkaline protease, that contribute to its aggressive behavior. These enzymes can break down corneal tissue, leading to rapid progression of the infection. In addition, Pseudomonas aeruginosa can form biofilms, which provide a protective barrier against antibiotics and host immune defenses. This allows the infection to spread quickly, often resulting in corneal perforation within 48 hours.
**Why Each Wrong Option is Incorrect**
**Option A:** Streptococcus pneumoniae can cause severe eye infections, including corneal ulcers, but it is typically less virulent than Pseudomonas aeruginosa and does not usually cause perforation within 48 hours.
**Option B:** Staphylococcus aureus can cause corneal ulcers, but it is often less aggressive than Pseudomonas aeruginosa and may not lead to perforation as quickly.
**Option C:** Haemophilus influenzae can cause eye infections, including conjunctivitis and corneal ulcers, but it is typically less virulent than Pseudomonas aeruginosa and does not usually cause perforation within 48 hours.
**Clinical Pearl / High-Yield Fact**
When diagnosing a corneal ulcer, it's essential to obtain a culture to identify the causative organism. Pseudomonas aeruginosa is a common cause of corneal ulcers in contact lens wearers, so this should be a high suspicion in patients with a history of contact lens use.
**Correct Answer:** C. Pseudomonas aeruginosa.