Bacterial Keratitis Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Bacterial Keratitis. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Bacterial Keratitis Indian Medical PG Question 1: Which of the following findings is typically NOT seen in a patient with allergic conjunctivitis?
- A. Watery discharge
- B. Itching
- C. Bilateral eye redness
- D. Purulent discharge (Correct Answer)
Bacterial Keratitis Explanation: ***Purulent discharge***
- **Purulent discharge** (thick, yellowish, or greenish) is characteristic of **bacterial conjunctivitis** and is usually absent in allergic conjunctivitis.
- Allergic conjunctivitis typically presents with a **clear or watery discharge**.
*Watery discharge*
- **Watery discharge** is a very common symptom of **allergic conjunctivitis**, often accompanied by itching and redness.
- It results from the inflammatory response and increased lacrimation due to allergen exposure.
*Itching*
- **Ocular itching** is the hallmark symptom of allergic conjunctivitis and is considered its most distinctive feature.
- It is caused by the release of **histamine** and other inflammatory mediators from mast cells in response to allergens.
*Bilateral eye redness*
- **Bilateral conjunctival redness** (hyperemia) is a frequent finding in allergic conjunctivitis.
- This is due to **vasodilation** in response to the inflammatory process affecting both eyes, as airborne allergens often affect both simultaneously.
Bacterial Keratitis Indian Medical PG Question 2: Keratitis in contact lens wearers is caused by all except?
- A. Chlamydia
- B. Aspergillus
- C. Pseudomonas
- D. Pneumococcus (Correct Answer)
Bacterial Keratitis Explanation: ***Pneumococcus***
- While *Streptococcus pneumoniae* (Pneumococcus) can cause bacterial keratitis, it is **classically associated with corneal ulcers following trauma** rather than contact lens wear.
- In contact lens-related keratitis, Pneumococcus is **significantly less common** compared to *Pseudomonas*, which dominates as the primary bacterial pathogen in this setting.
- Pneumococcal keratitis typically presents with a **well-demarcated, dense purulent ulcer with hypopyon**, often following corneal injury.
*Pseudomonas*
- **_Pseudomonas aeruginosa_** is **the most common cause of bacterial keratitis in contact lens wearers**, accounting for the majority of severe cases.
- It thrives in moist environments such as contaminated contact lens cases and solutions, producing **exotoxins and proteases that cause rapid corneal destruction and tissue melt**.
- Presents with a **rapidly progressive, dense stromal infiltrate** with a characteristic **ground-glass appearance** and potential for perforation.
*Aspergillus*
- **_Aspergillus_ species** are an important cause of **fungal keratitis**, particularly associated with contact lens wear, poor lens hygiene, and contaminated lens solutions.
- Fungal keratitis presents with **feathery-edged infiltrates, satellite lesions**, and ring-shaped infiltrates, often requiring antifungal therapy.
- More common in tropical climates and agricultural settings.
*Chlamydia*
- **_Chlamydia trachomatis_** is primarily a cause of **trachoma** (chronic follicular conjunctivitis leading to scarring) and **adult inclusion conjunctivitis**.
- While it can cause **superficial punctate keratitis and pannus formation** in trachoma, it is **NOT a typical cause of acute suppurative keratitis in contact lens wearers**.
- The acute bacterial and fungal keratitis seen in contact lens wearers is a different clinical entity from chlamydial conjunctivitis/keratopathy.
Bacterial Keratitis Indian Medical PG Question 3: A patient presents with eye pain, redness, and blurred vision after sleeping in contact lenses. Fluorescein staining reveals a corneal ulcer. What is the most appropriate management?
- A. Topical antibiotics (Correct Answer)
- B. Oral antibiotics
- C. Topical corticosteroids
- D. Saline irrigation
Bacterial Keratitis Explanation: ***Topical antibiotics***
- A **corneal ulcer**, especially in a contact lens wearer, is highly suspicious for **bacterial infection**, necessitating immediate and aggressive topical antibiotic therapy.
- **Broad-spectrum antibiotics** (e.g., fluoroquinolones) are often started empirically and adjusted based on culture results.
*Oral antibiotics*
- **Systemic antibiotics** are generally not indicated for uncomplicated bacterial corneal ulcers, as they don't achieve sufficient concentrations in the cornea to be effective.
- They may be considered for severe cases with limbal involvement or scleral extension, or if there is a concern for concurrent systemic infection.
*Topical corticosteroids*
- **Corticosteroids** are contraindicated in the initial management of suspected infectious corneal ulcers because they can suppress the immune response and worsen the infection.
- They may be cautiously used later in treatment to reduce inflammation after the infection is well-controlled.
*Saline irrigation*
- While helpful for removing foreign bodies or debris, **saline irrigation alone** is insufficient to treat a bacterial corneal ulcer.
- It does not eradicate the infection and delaying definitive antibiotic treatment can lead to severe complications.
Bacterial Keratitis Indian Medical PG Question 4: A young boy who used to wash his contact lenses in tap water or with unhygienic lens fluid developed keratitis. Microscopy revealed an organism with spiked or star-shaped structures. Identify the correct organism responsible.
- A. Balantidium
- B. Pseudomonas
- C. Acanthamoeba (Correct Answer)
- D. Staphylococcus aureus
Bacterial Keratitis Explanation: ***Acanthamoeba***
- *Acanthamoeba* is a **free-living amoeba** found in water, soil, and inadequately disinfected contact lens solutions, specifically linked to **keratitis** in contact lens wearers.
- Its characteristic morphology, often described as having **spiked or star-shaped structures**, refers to the **acanthopodia** (spine-like pseudopods) that are distinctive features visible microscopically.
*Balantidium*
- *Balantidium coli* is a **ciliated protozoan** and primarily causes **intestinal infections** (balantidiasis), not keratitis.
- It would be distinguished microscopically by its **large size**, **kidney-shaped macronucleus**, and **cilia**, not spiked structures.
*Pseudomonas*
- *Pseudomonas aeruginosa* is a **bacterium** and a common cause of **bacterial keratitis**, especially in contact lens wearers, but it is not a protozoan.
- Microscopically, it would appear as **rod-shaped bacteria**, not organisms with spiked or star-shaped structures.
*Staphylococcus aureus*
- *Staphylococcus aureus* is a **bacterium** and a frequent cause of various infections, including **bacterial keratitis**.
- Under a microscope, it presents as **Gram-positive cocci in clusters**, not as an amoeba with spiked or star-shaped protrusions.
Bacterial Keratitis Indian Medical PG Question 5: Which fungus is most commonly associated with orbital cellulitis in patients with diabetic ketoacidosis?
- A. Candida
- B. Mucor
- C. Rhizopus (Correct Answer)
- D. Aspergillus
Bacterial Keratitis Explanation: ***Rhizopus***
- *Rhizopus* is the most common cause of **mucormycosis** (also called zygomycosis), an aggressive fungal infection that frequently affects immunocompromised patients, especially those with **diabetic ketoacidosis (DKA)**.
- *Rhizopus arrhizus* (formerly *R. oryzae*) accounts for approximately **70% of all mucormycosis cases**, making it the single most common causative organism.
- In DKA, the acidic environment and high glucose levels favor the growth of **Mucorales fungi**, leading to rapid progression from the sinuses to the orbit and brain (rhinoorbital-cerebral mucormycosis).
*Candida*
- While *Candida* is a common cause of fungal infections, it typically manifests as **candidemia**, **esophagitis**, or **vulvovaginitis**, and is rarely associated with orbital cellulitis in DKA.
- *Candida* infections are more likely in patients with indwelling catheters or those on broad-spectrum antibiotics, rather than specifically linked to DKA-induced orbital cellulitis.
*Mucor*
- The genus *Mucor* is part of the **Mucorales order** and can cause **mucormycosis** with identical clinical presentations to *Rhizopus*.
- However, *Mucor* species account for only **10-20% of mucormycosis cases**, making *Rhizopus* the **most commonly** associated genus as asked in the question.
- While both are clinically grouped under "mucormycosis," *Rhizopus* is the more specific and statistically correct answer when identifying the most common causative fungus.
*Aspergillus*
- *Aspergillus* species are common environmental fungi that can cause invasive infections, particularly in immunocompromised patients, leading to conditions like **aspergilloma** or **invasive aspergillosis**.
- While *Aspergillus* can cause sinus and orbital infections, it is less commonly associated with the rapid, aggressive form of orbital cellulitis seen in DKA compared to mucormycosis caused by *Rhizopus*.
Bacterial Keratitis Indian Medical PG Question 6: Which of the following is a known complication of vernal keratoconjunctivitis?
- A. Keratoconus (Correct Answer)
- B. Retinal detachment
- C. Vitreous hemorrhage
- D. Cataract
Bacterial Keratitis Explanation: ***Keratoconus***
- **Vernal keratoconjunctivitis (VKC)** is a chronic allergic eye condition associated with persistent eye rubbing, which can lead to thinning and bulging of the cornea, a condition known as **keratoconus**.
- Long-term inflammation and mechanical stress from allergic reactions and *eye rubbing* contribute to the corneal structural changes seen in keratoconus.
- This is the **most common and well-recognized complication** of VKC.
*Cataract*
- While cataracts can occur in VKC patients (particularly from **chronic topical steroid use** or severe disease with shield ulcers), they are **less common than keratoconus** as a direct complication.
- Keratoconus remains the more characteristic and frequently encountered complication specifically associated with the mechanical trauma of eye rubbing in VKC.
*Retinal detachment*
- **Retinal detachment** is a condition where the retina separates from its underlying support tissues and is typically associated with trauma, high myopia, or diabetic retinopathy, not VKC.
- VKC primarily affects the conjunctiva and cornea, and its inflammatory processes do not directly cause retinal detachment.
*Vitreous hemorrhage*
- **Vitreous hemorrhage** involves bleeding into the gel-like substance that fills the eye and is commonly caused by conditions like diabetic retinopathy or retinal tears, not VKC.
- VKC does not involve the posterior segment of the eye in a way that would lead to vitreous hemorrhage.
Bacterial Keratitis Indian Medical PG Question 7: What is the most common infection in contact lens users?
- A. Streptococcus
- B. Staphylococcus
- C. Neisseria
- D. Pseudomonas (Correct Answer)
Bacterial Keratitis Explanation: ***Pseudomonas***
- **Pseudomonas aeruginosa** is the leading cause of **bacterial keratitis** in contact lens wearers, accounting for 60-70% of culture-positive cases
- This bacterium can **adhere to lenses**, form **biofilms**, and thrive in moist lens storage cases
- Can cause rapid and severe corneal damage with **corneal ulceration**, potentially leading to **vision loss**
*Staphylococcus*
- **Staphylococcus aureus** and **Staphylococcus epidermidis** are common commensals of the skin and can cause eye infections, including keratitis and blepharitis
- However, in the context of contact lens-related keratitis, **Pseudomonas aeruginosa** remains the primary pathogen for severe corneal infections
*Streptococcus*
- While various **Streptococcus species** (especially S. pneumoniae) can cause bacterial keratitis, they are less commonly associated with contact lens-related keratitis compared to Pseudomonas
- **Streptococcal keratitis** typically occurs in non-contact lens wearers or after trauma
*Neisseria*
- **Neisseria gonorrhoeae** can cause hyperacute bacterial conjunctivitis with severe purulent discharge, but is not the most common cause of contact lens-related keratitis
- **Neisseria meningitidis** can rarely cause conjunctivitis, but these infections usually indicate specific exposure or systemic disease
Bacterial Keratitis Indian Medical PG Question 8: In uveitis, site of keratic precipitate is:
- A. Lens anterior capsule
- B. Corneal endothelium (Correct Answer)
- C. Lens posterior capsule
- D. Corneal stroma
Bacterial Keratitis Explanation: ***Corneal endothelium***
- **Keratic precipitates (KPs)** are inflammatory cellular deposits that adhere to the **posterior surface of the cornea**, specifically the endothelial layer, in uveitis.
- They represent aggregates of inflammatory cells, such as macrophages and lymphocytes, that have migrated from the inflamed anterior chamber.
*Lens anterior capsule*
- The **anterior capsule of the lens** is a smooth, acellular membrane and does not typically accumulate inflammatory deposits like **keratic precipitates**.
- While inflammatory cells can be observed in the **anterior chamber**, they do not specifically adhere to the lens capsule in this manner.
*Lens posterior capsule*
- Similar to the anterior capsule, the **posterior capsule of the lens** is not the site for deposition of **keratic precipitates**.
- Inflammation affecting the lens would typically present as cataract formation or direct lens inflammation, not KPs.
*Corneal stroma*
- The **corneal stroma** is the thickest layer of the cornea and is primarily composed of collagen fibrils and keratocytes.
- While inflammation can affect the stroma (e.g., in stromal keratitis), **keratic precipitates** specifically form on the **innermost layer**, the endothelium, facing the anterior chamber.
Bacterial Keratitis Indian Medical PG Question 9: Interstitial keratitis is associated with all of the following except:
- A. Syphilis
- B. Acanthamoeba (Correct Answer)
- C. Chlamydia Trachomatis
- D. Herpes Zoster Virus (HZV)
Bacterial Keratitis Explanation: ***Acanthamoeba***
- **Acanthamoeba keratitis** is a **suppurative keratitis** characterized by a painful, ring-shaped infiltrate with epithelial ulceration, typically associated with contact lens use and contaminated water exposure.
- It causes **ulcerative stromal inflammation**, not the **non-ulcerative deep stromal inflammation** that characterizes classic interstitial keratitis.
- **This is NOT a cause of interstitial keratitis.**
*Syphilis*
- **Congenital syphilis** is the **CLASSIC cause** of bilateral **interstitial keratitis**, often presenting in late childhood with "salmon patch" appearance, photophobia, lacrimation, and eventual ghost vessels.
- The inflammation is **non-ulcerative and chronic**, affecting the **deep corneal stroma** with preservation of epithelium.
- This is the most important association with interstitial keratitis to remember.
*Chlamydia Trachomatis*
- **Chlamydia trachomatis** causes **trachoma**, a chronic keratoconjunctivitis leading to **superficial keratitis with pannus formation** (superficial vascularization from the limbus).
- The corneal involvement in trachoma is **superficial**, not the deep stromal inflammation seen in classic interstitial keratitis.
- While listed in some references, **Chlamydia is NOT a standard cause of interstitial keratitis** in major ophthalmology textbooks.
- **Note:** This option is potentially debatable, but Acanthamoeba is the more definitively incorrect answer.
*Herpes Zoster Virus (HZV)*
- **Herpes zoster ophthalmicus** can lead to **interstitial keratitis** and **disciform keratitis** (immune-mediated stromal inflammation with disc-shaped corneal edema).
- Similarly, **HSV (Herpes Simplex Virus)** causes stromal keratitis, a form of interstitial keratitis.
- The corneal involvement includes **deep stromal inflammation, scarring**, and potential neurotrophic changes leading to vision impairment.
Bacterial Keratitis Indian Medical PG Question 10: A 30 year old man presents to the clinic with pain in the eye, watering, redness, and photophobia. Examination of his eyes shows circumcorneal congestion and keratic precipitates. Assertion: Keratic precipitates (KPs) are proteinaceous deposits that can occur in various patterns on the corneal endothelium. Reason: Mutton fat KPs are seen in granulomatous iridocyclitis and are composed of epithelioid cells and macrophages.
- A. Both Assertion and Reason are true, and Reason is the correct explanation for Assertion
- B. Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion (Correct Answer)
- C. Assertion is true, but Reason is false
- D. Assertion is false but reason is true
Bacterial Keratitis Explanation: ***Both Assertion and Reason are true, and Reason is not the correct explanation for Assertion***
**Why both statements are true:**
- The **Assertion** is correct: Keratic precipitates (KPs) are inflammatory cell and protein deposits that adhere to the **corneal endothelium** and can present in various patterns including fine dusty KPs, medium-sized KPs, and large mutton fat KPs.
- The **Reason** is also correct: **Mutton fat KPs** are characteristic of **granulomatous anterior uveitis** (granulomatous iridocyclitis) and consist of aggregations of **epithelioid cells and macrophages**, appearing as large, greasy, white deposits.
**Why Reason does NOT explain Assertion:**
- The Reason describes a **specific type** of KP (mutton fat) and its cellular composition in one particular form of inflammation (granulomatous).
- The Assertion makes a **general statement** about KPs occurring in various patterns.
- The Reason does not explain **why** KPs can occur in various patterns or what determines these different patterns - it only describes one specific pattern.
*Incorrect: Both true with Reason explaining Assertion* - The Reason is too specific and only describes one type of KP, not the general mechanism of pattern variation.
*Incorrect: Assertion true, Reason false* - Both statements are medically accurate and well-established in ophthalmology literature.
*Incorrect: Assertion false, Reason true* - KPs are well-documented deposits on the corneal endothelium in various forms of uveitis, making the Assertion true.
More Bacterial Keratitis Indian Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
