Infectious Diseases Practice Questions

Q: A patient presents with lower gastrointestinal bleeding. Sigmoidoscopy shows ulcers in the sigmoid. Biopsy from this area shows flask-shaped ulcers. Which of the following is the most appropriate treatment?

Intravenous metronidazole. **Explanation:** The clinical presentation of lower gastrointestinal bleeding combined with the pathognomonic finding of **flask-shaped ulcers** on biopsy is diagnostic of **Amoebic Colitis**, caused by *Entamoeba histolytica* [1]. 1. **Why Option B is correct:** *Entamoeba histolytica* trophozoites invade the intestinal mucosa, causing lateral spread in the submucosa, which creates the classic "flask-shaped" appearance. **Metronidazole** (or Tinidazole) is the drug of choice for invasive amoebiasis as it is a potent tissue amoebicide. In cases of severe colitis or systemic symptoms, intravenous administration is preferred to ensure rapid therapeutic levels. 2. **Why the other options are incorrect:** * **Option A (Ceftriaxone):** This is a third-generation cephalosporin used for bacterial infections like Enteric fever or Shigellosis. It has no activity against protozoa like *E. histolytica*. * **Options C & D (Steroids/Sulphasalazine):** These are used to treat Inflammatory Bowel Disease (IBD), specifically Ulcerative Colitis [2]. While IBD also presents with bloody diarrhea and ulcers, the biopsy would show crypt abscesses rather than flask-shaped ulcers. Importantly, giving steroids in a case of amoebiasis can lead to toxic megacolon or perforation. **Clinical Pearls for NEET-PG:** * **Pathology:** The "flask shape" occurs because the organism cannot easily penetrate the muscularis propria, leading to lateral expansion in the submucosa. * **Diagnosis:** Stool microscopy may show trophozoites with ingested RBCs (erythrophagocytosis) [1]. * **Treatment Protocol:** Always follow a tissue amoebicide (Metronidazole) with a **luminal amoebicide** (e.g., Diloxanide furoate or Paromomycin) to eradicate the cyst stage and prevent relapse/transmission. * **Complication:** The most common extra-intestinal manifestation is an Amoebic Liver Abscess (anchovy sauce pus) [1].

Q: Which of the following is NOT a characteristic feature of cerebral malaria?

Bloody cerebrospinal fluid. **Explanation:** Cerebral malaria is a severe neurological complication of *Plasmodium falciparum* infection, characterized by unarousable coma (Glasgow Coma Scale <11) in the absence of other identifiable causes [2]. **Why "Bloody Cerebrospinal Fluid" is the correct answer:** In cerebral malaria, the cerebrospinal fluid (CSF) is typically **clear and colorless**. While there may be a mild increase in opening pressure and a slight elevation in protein levels (<100 mg/dL), the CSF cell count is usually normal (pleocytosis is rare). The presence of bloody or xanthochromic CSF suggests an alternative diagnosis, such as subarachnoid hemorrhage or a traumatic tap, and is **not** a feature of malaria [1]. **Analysis of Incorrect Options:** * **Retinal Hemorrhages:** This is a key diagnostic and prognostic marker. "Malarial retinopathy" (including retinal whitening, vessel changes, and hemorrhages) is highly specific for cerebral malaria and correlates with the severity of brain sequestration. * **Extensor Plantar Reflex:** Upper motor neuron signs are common. Patients often exhibit decerebrate or decorticate posturing, hyperreflexia, and a positive Babinski sign (extensor plantar response) due to diffuse encephalopathy. * **Absent Abdominal Reflex:** This is a classic clinical finding in cerebral malaria, reflecting the involvement of the corticospinal tracts. **High-Yield NEET-PG Pearls:** * **Pathogenesis:** Sequestration of parasitized RBCs in cerebral microvasculature (cytoadherence via PfEMP-1) [3]. * **Drug of Choice:** Intravenous **Artesunate** is the gold standard (preferred over Quinine). * **Hypoglycemia:** Always check blood glucose, as both the disease and Quinine treatment can cause severe hypoglycemia [2]. * **Mortality:** Even with treatment, mortality remains 15–20%.

Q: What is the drug of choice for craniofacial mucormycosis?

Liposomal amphotericin B. **Explanation:** **Liposomal Amphotericin B** is the drug of choice for craniofacial (rhinocerebral) mucormycosis because *Mucorales* fungi are highly aggressive, angioinvasive, and naturally resistant to most conventional antifungals. Amphotericin B acts by binding to ergosterol in the fungal cell membrane, creating pores that lead to cell death. The **liposomal formulation** is preferred over the conventional deoxycholate form because it allows for higher dosing with significantly reduced nephrotoxicity and better penetration into the central nervous system. **Analysis of Incorrect Options:** * **Voriconazole:** This is the drug of choice for Invasive Aspergillosis but has **no activity** against *Mucorales*. Using it in suspected mucormycosis can lead to treatment failure. * **Itraconazole:** While it has some activity against certain fungi, it is ineffective against the species causing mucormycosis. * **Hyperbaric Oxygen:** This is an adjunctive therapy that may inhibit fungal growth in some cases, but it is never a primary treatment or the "drug of choice." **Clinical Pearls for NEET-PG:** * **Risk Factors:** Uncontrolled Diabetes Mellitus (especially Ketoacidosis), neutropenia, and post-transplant immunosuppression. * **Diagnosis:** Definitive diagnosis requires biopsy showing **broad, ribbon-like, non-septate hyphae** with **right-angle (90°) branching**. * **Management Triad:** 1. Aggressive surgical debridement (most critical step), 2. Liposomal Amphotericin B, 3. Control of underlying risk factors (e.g., reversing ketoacidosis). * **Step-down therapy:** Once the patient is stable, oral **Isavuconazole** or **Posaconazole** can be used for maintenance.

Q: What is the recommended post-exposure prophylaxis for HIV?

Raltegravir, Emtricitabine, and Tenofovir. **Explanation:** The current NACO (National AIDS Control Organisation) and WHO guidelines recommend a **triple-drug regimen** for HIV Post-Exposure Prophylaxis (PEP) to ensure maximum efficacy in preventing viral integration. **1. Why Option A is Correct:** The preferred regimen consists of **Tenofovir (TDF) 300 mg + Emtricitabine (FTC) 200 mg** (or Lamivudine) once daily, combined with **Raltegravir (RAL) 400 mg** twice daily (or Dolutegravir 50 mg once daily). This combination is favored because it is highly effective, has a superior safety profile, and involves minimal drug-drug interactions compared to older protease inhibitor-based regimens. **2. Analysis of Incorrect Options:** * **Option B:** This was an older regimen. Indinavir is rarely used now due to significant side effects like nephrolithiasis and metabolic disturbances. * **Option C:** Abacavir is not used in PEP due to the risk of life-threatening hypersensitivity reactions (associated with HLA-B*5701), which requires genetic testing before initiation—a delay not feasible in emergency PEP. * **Option D:** Maraviroc is an entry inhibitor (CCR5 antagonist) and is not part of the standard first-line PEP protocol; it requires a tropism assay before use. **High-Yield Clinical Pearls for NEET-PG:** * **Timing:** PEP should be started as soon as possible, ideally within **2 hours**, and no later than **72 hours** post-exposure. * **Duration:** The total duration of PEP treatment is **28 days**. * **Baseline Testing:** Always perform a baseline HIV test for the exposed individual to rule out pre-existing infection. * **Preferred Integrase Inhibitor:** While Raltegravir is a standard answer, **Dolutegravir (DTG)** is now increasingly preferred in many updated guidelines due to its once-daily dosing.

Question 1

Which of the following statements are true regarding tuberculous meningitis?

Accepted Answer

CSF is stored at 4°C during transportation; Hydrocephalus is a common sequela; Meningoencephalitis is a common manifestation.

Answer

Exudates are formed on the convexities of the brain; CSF is stored at 4°C during transportation; Hydrocephalus is a common sequela; Meningoencephalitis is a common manifestation.

Answer

Exudates are formed on the convexities of the brain; Meningoencephalitis is a common manifestation.

Answer

CSF is stored at 4°C during transportation; Meningoencephalitis is a common manifestation.

Question 2

An HIV patient developed goiter. On examination, there was non-tender diffuse enlargement of the thyroid. All of the following can be causes of this condition, except:

Accepted Answer

Aspergillus

Answer

Toxoplasma

Answer

Cryptococcus

Answer

Pneumocystis

Question 3

A patient presents with lower gastrointestinal bleeding. Sigmoidoscopy shows ulcers in the sigmoid. Biopsy from this area shows flask-shaped ulcers. Which of the following is the most appropriate treatment?

Accepted Answer

Intravenous metronidazole

Answer

Intravenous ceftriaxone

Answer

Intravenous steroids and sulphasalazine

Answer

Hydrocortisone enemas

Question 4

What is the recommended duration of treatment for multidrug-resistant tuberculosis (MDR-TB)?

Accepted Answer

16-24 months

Answer

8-12 months

Answer

12-16 months

Answer

2-3 years

Question 5

Which of the following is NOT a characteristic feature of cerebral malaria?

Accepted Answer

Bloody cerebrospinal fluid

Answer

Retinal hemorrhages

Answer

Extensor plantar reflex

Answer

Absent abdominal reflex

Question 6

Which of the following organisms is known to cause endocarditis?

Accepted Answer

HACEK

Answer

Coxiella

Answer

Chlamydia

Answer

Salmonella

Question 7

A 20-year-old male presents with fever and chronic cough. His ESR is 35 mm. Sputum cytology is negative for AFB, and a tuberculin test shows indurations of 19 x 23 mm. What is the probable diagnosis?

Accepted Answer

Pulmonary tuberculosis

Answer

Fungal pneumonia

Answer

Viral pneumonia

Answer

Bacterial pneumonia

Question 8

What is the drug of choice for craniofacial mucormycosis?

Accepted Answer

Liposomal amphotericin B

Answer

Voriconazole

Answer

Hyperbaric oxygen

Answer

Itraconazole

Question 9

What is the recommended post-exposure prophylaxis for HIV?

Accepted Answer

Raltegravir, Emtricitabine, and Tenofovir

Answer

Zidovudine, Lamivudine, and Indinavir

Answer

Zidovudine, Lamivudine, and Abacavir

Answer

Raltegravir, Emtricitabine, and Maraviroc

Question 10

A 40-year-old male presented with altered mental status, seizures, and vomiting. He has no history of fever or neck stiffness. On CECT and MRI, a ring-enhancing lesion at the gray-white interface is seen. General hygiene was poor, and he has multiple dental caries. What is the next best step in the management of this patient?

Accepted Answer

Urgent parenteral antibiotics

Answer

Placement of ICP monitor

Answer

Lumbar puncture

Answer

Craniotomy

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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