Question:hard
A person with prolonged use of contact lenses presented with irritation of the left eye. After examination, a diagnosis of keratitis was made and corneal scrapings revealed growth of Pseudomonas aeruginosa. The bacteria were observed to be multidrug resistant. Which of the following best explains the mechanism of antimicrobial resistance in these isolated Pseudomonas aeruginosa strains?
A person with prolonged use of contact lenses presented with irritation of the left eye. After examination, a diagnosis of keratitis was made and corneal scrapings revealed growth of Pseudomonas aeruginosa. The bacteria were observed to be multidrug resistant. Which of the following best explains the mechanism of antimicrobial resistance in these isolated Pseudomonas aeruginosa strains?
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Think about the slimy matrix this organism builds on plastic lens surfaces.
Updated On: Jun 24, 2026
- Ability to transfer resistance genes from adjacent commensal flora
- Improper contact lens hygiene
- Frequent and injudicious use of topical antibiotics
- Ability of Pseudomonas to produce biofilms
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The Correct Option is D
Solution and Explanation
Contact lens wearers are a classic group for Pseudomonas keratitis because this bug loves moist plastic surfaces. The key word in the question is mechanism of resistance, so we must explain why the organism shrugs off several antibiotics, not why the patient caught it. Pseudomonas aeruginosa is famous for building biofilms: it secretes a sticky sugar-rich slime and lives inside it as a community, and the lens and corneal surface give it a perfect scaffold. Once that slime layer forms, antibiotic molecules cannot diffuse in well, the cells inside slow their metabolism, and a hardy fraction simply rides out the drug. The net result is a population that behaves as resistant to many agents together, which is exactly what multidrug resistance looks like clinically. Now compare the other choices. Poor lens hygiene and heavy use of topical antibiotics may explain how the infection started or what selected for tougher bugs, but neither is the structural mechanism that makes the strain resist drugs. Picking up genes from neighbouring commensals is a recognised way bacteria gain resistance in general, yet it is not the signature, lens-linked Pseudomonas mechanism being tested here. The biofilm is the unifying answer for why this organism is hard to kill on a contact lens. So the best explanation is the bacterium's ability to make biofilms. \[\boxed{\text{Ability of Pseudomonas to produce biofilms}}\]
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