Infectious Diseases Practice Questions

Q: All of the following statements about Fungal Endocarditis are true except?

Good prognosis with treatment. **Explanation:** Fungal Endocarditis (FE) is a severe form of infective endocarditis associated with high morbidity and mortality. **Why Option D is the correct answer (The "Except"):** Contrary to bacterial endocarditis, **Fungal Endocarditis has a very poor prognosis**, even with aggressive treatment. The mortality rate remains high (approx. 50%) due to the bulky nature of fungal vegetations, frequent embolic complications, and the difficulty of eradicating fungi from valvular tissue. Therefore, saying it has a "good prognosis" is incorrect. **Analysis of other options:** * **Option A:** *Candida* species (especially *C. albicans*) are indeed the **most common** cause of fungal endocarditis, followed by *Aspergillus* [1][3]. *Candida* is frequently associated with IV drug use and prosthetic valves. * **Option B:** Because fungi are difficult to clear and have a high rate of recurrence, **long-term (often life-long) suppressive antifungal therapy** (e.g., oral Fluconazole) is frequently required after the initial intensive course [1]. * **Option C:** **Surgical intervention** (valve replacement) combined with medical therapy is the **standard of care**. Surgery is necessary because fungal vegetations are typically large, friable, and penetrate deeply into the myocardium, making them poorly responsive to antifungal drugs alone. **NEET-PG High-Yield Pearls:** * **Risk Factors:** Prosthetic heart valves (most common), Indwelling central venous catheters [1], IV drug abuse, and prolonged immunosuppression. * **Clinical Feature:** Fungal vegetations are characteristically **larger and more friable** than bacterial ones, leading to a higher risk of **major arterial embolization** (e.g., to the lower extremities or brain) [3]. * **Diagnosis:** Blood cultures are often negative in *Aspergillus* endocarditis; histopathological examination of the vegetation [2] or molecular methods (PCR) may be required.

Q: Which of the following serological status is seen only in acute hepatitis B infection?

HBsAg Positive + HBeAg Positive + HBc IgM Positive. To master Hepatitis B serology for NEET-PG, the key is to differentiate between **acute, chronic, and past infections** based on specific markers. ### **Explanation of the Correct Answer** **Option A (HBsAg+ / HBeAg+ / HBc IgM+)** is the hallmark of **Acute Hepatitis B**. [2] * **HBsAg:** The first marker to appear; indicates active infection. [2] * **HBeAg:** Indicates high viral replication and high infectivity. * **HBc IgM (IgM anti-HBc):** This is the **most critical marker** for acute infection. It appears shortly after HBsAg and is the only marker present during the "window period." [2] Its presence definitively distinguishes an acute infection from a chronic one. ### **Analysis of Incorrect Options** * **Option B:** Represents the **"Window Period."** HBsAg has disappeared, but anti-HBs hasn't appeared yet. While HBc IgM is present, the presence of HBc IgG suggests the transition toward recovery. * **Option C:** Represents **Chronic Hepatitis B (High Replicativity).** The presence of HBsAg for >6 months defines chronicity. [1] In chronic states, IgM is replaced by **HBc IgG**. * **Option D:** Represents **Recovery/Natural Immunity.** The person has cleared the virus, developed protective antibodies (anti-HBs), and possesses markers of past exposure (anti-HBc IgG). [1] ### **High-Yield Clinical Pearls for NEET-PG** 1. **Window Period Marker:** IgM anti-HBc is the only positive marker when both HBsAg and anti-HBs are negative. [2] 2. **Chronic Infection:** Defined by the persistence of **HBsAg for >6 months**. [1] 3. **Vaccination vs. Natural Immunity:** * **Vaccinated:** Only Anti-HBs is positive. [1] * **Prior Infection:** Both Anti-HBs and Anti-HBc IgG are positive. [1] 4. **Best Indicator of Prognosis:** Persistence of HBeAg beyond 10 weeks suggests progression to a chronic state.

Q: Faget sign is:

Bradycardia with hyperthermia. **Explanation:** **Faget sign**, also known as **sphygmothermic dissociation**, refers to the clinical finding of a slow pulse (relative bradycardia) in the presence of a high fever. Normally, according to **Liebermeister’s rule**, the heart rate increases by approximately 8–10 beats per minute for every 1°C rise in body temperature. In Faget sign, this compensatory tachycardia is absent, and the heart rate remains inappropriately low despite the hyperthermia. **Analysis of Options:** * **Option B (Correct):** Bradycardia with hyperthermia is the classic definition. It occurs when the physiological link between temperature and heart rate is disrupted. * **Option A & C:** These are incorrect because tachycardia is the *expected* physiological response to fever or stress; Faget sign is specifically the absence of this response. Fever is generally diagnosed when a body temperature over 38°C is recorded [1]. * **Option D:** Bradycardia with hypothermia is a common finding in environmental cold exposure or hypothyroidism, but it does not constitute Faget sign. **Clinical Pearls for NEET-PG:** Faget sign is a high-yield "spotter" for specific infectious diseases. Memorize these common causes: 1. **Yellow Fever:** The original disease where Jean-Charles Faget described the sign. 2. **Typhoid Fever (Enteric Fever):** The most common cause tested in Indian exams. 3. **Atypical Pneumonias:** Specifically **Legionnaires' disease** and Psittacosis. 4. **Tularemia and Brucellosis.** 5. **Drug Fever:** A non-infectious cause of relative bradycardia. *Note: In Typhoid, Faget sign usually appears during the second week of illness.*

Q: A 24-year-old male with a history of primary syphilis presented with genital ulcers and mucocutaneous lesions. He now exhibits features suggestive of neurosyphilis, including meningitis, for which appropriate treatment has been initiated. What is the recommended method for monitoring treatment response?

Venereal Disease Research Laboratory test (VDRL). ### **Explanation** The monitoring of treatment response in neurosyphilis relies on **quantitative non-treponemal tests**. [1] **Why Option A is Correct:** The **VDRL (Venereal Disease Research Laboratory)** test is a non-treponemal test that measures antibodies (reagin) against a cardiolipin-cholesterol-lecithin antigen. Unlike treponemal tests, VDRL titers correlate with disease activity. In neurosyphilis, the CSF-VDRL is the gold standard for diagnosis (high specificity). [1] For monitoring, a successful response to treatment is indicated by a **fourfold decrease in titer** (e.g., from 1:32 to 1:8) over 6–12 months. If titers do not decline or if CSF pleocytosis persists, retreatment is indicated. **Why the Other Options are Incorrect:** * **Options B, C, and D (TPI, FTA-ABS, ELISA):** These are **treponemal-specific tests**. They detect antibodies against *Treponema pallidum* proteins. [1] Once a patient tests positive, these tests usually remain positive for life (**"treponemal memory"**), regardless of successful treatment. Therefore, they cannot be used to distinguish between an active infection and a past, treated infection, making them useless for monitoring treatment response. **Clinical Pearls for NEET-PG:** * **Drug of Choice for Neurosyphilis:** Aqueous Crystalline Penicillin G (18–24 million units per day, administered IV) for 10–14 days. * **CSF Findings:** The first sign of treatment response is a decrease in the CSF white cell count; the VDRL titer falls more slowly. * **Jarisch-Herxheimer Reaction:** An acute febrile reaction occurring within 24 hours of starting syphilis treatment (due to cytokine release from dying spirochetes); it is managed symptomatically with NSAIDs. * **Screening vs. Confirmation:** Use non-treponemal tests (RPR/VDRL) for screening and treponemal tests (FTA-ABS/TPPA) for confirmation. [1]

Q: What is a common causative agent of atypical pneumonia?

Chlamydia. Pneumonia is clinically classified into **Typical** and **Atypical** based on presentation and causative organisms [1]. **Atypical pneumonia** is characterized by an insidious onset, non-productive cough, constitutional symptoms (headache, myalgia), and a "dissociation" where physical findings are minimal despite significant interstitial infiltrates on X-ray. **Why Chlamydia is Correct:** * **Chlamydia pneumoniae** and **Chlamydia psittaci** are classic "atypical" pathogens [1]. They are obligate intracellular organisms that do not have a peptidoglycan cell wall (making them resistant to Beta-lactams) and cannot be visualized on a standard Gram stain. Other common atypical agents include *Mycoplasma pneumoniae* (most common) and *Legionella pneumophila* [1]. **Why Other Options are Incorrect:** * **Streptococcus pneumoniae (B):** The most common cause of **typical** community-acquired pneumonia (CAP) [1]. It presents acutely with high fever, productive cough (rusty sputum), and lobar consolidation [1], [2]. * **Staphylococcus aureus (A):** A typical pathogen often causing secondary bacterial pneumonia post-influenza [1]. It is associated with cavitary lesions and pneumatoceles. * **Haemophilus influenzae (D):** A common cause of typical pneumonia, particularly in patients with underlying COPD or smoking history [1]. **NEET-PG High-Yield Pearls:** 1. **Treatment of Choice:** Macrolides (Azithromycin) or Tetracyclines (Doxycycline) are preferred because they target protein synthesis, bypassing the lack of a cell wall. 2. **Cold Agglutinins:** Positive in *Mycoplasma* infections (IgM antibodies). 3. **Legionella:** Often associated with hyponatremia, diarrhea, and exposure to contaminated water/AC systems [1], [3]. 4. **Walking Pneumonia:** A clinical term for atypical pneumonia where the patient remains ambulatory despite illness.

Q: A 40-year-old man develops erythema nodosum, conjunctivitis, and a pleural effusion. Over several weeks, pulmonary lesions lead to cavitation and a large, thin-walled cavity. He was traveling in Arizona before becoming ill. Sputum samples reveal mature spherules. Which of the following is the most likely diagnosis?

coccidioidomycosis. **Explanation:** The clinical presentation and laboratory findings are pathognomonic for **Coccidioidomycosis** (Valley Fever), caused by the dimorphic fungi *Coccidioides immitis* or *posadasii*. **Why the correct answer is right:** 1. **Geographic History:** The patient’s travel to **Arizona** (Southwestern United States) is a classic epidemiological clue for Coccidioidomycosis. 2. **Clinical Triad:** The combination of respiratory symptoms (pleural effusion, cavitation) and hypersensitivity reactions like **erythema nodosum** and **conjunctivitis** (often part of "Desert Rheumatism") is highly characteristic. 3. **Microscopy:** The definitive diagnostic feature is the presence of **mature spherules** (thick-walled structures containing endospores) in sputum or tissue samples. Unlike other fungi, *Coccidioides* does not form yeast cells in the body. 4. **Radiology:** While many cases resolve, chronic infection can lead to thin-walled, solitary pulmonary cavities. **Why incorrect options are wrong:** * **Streptococcus & Staphylococcus:** These are pyogenic bacteria. While they cause pneumonia and effusions, they typically present with acute high fever and purulent sputum. They do not form spherules or show a strong geographic predilection for the American Southwest. * **Candidiasis:** *Candida* is part of the normal flora and rarely causes primary cavitary pneumonia in immunocompetent hosts. On microscopy, it presents as budding yeast and pseudohyphae, not spherules. **High-Yield Pearls for NEET-PG:** * **Morphology:** In soil, it exists as hyphae with **arthroconidia** (infective stage); in the body, it forms **spherules** (diagnostic stage). * **Erythema Nodosum:** In the context of Valley Fever, this is a positive prognostic sign indicating a robust cell-mediated immune response. * **Dissemination:** Most common site of extrapulmonary dissemination is the **Skin**, followed by the **Meninges** (Coccidioidal meningitis).

Question 1

What is the recommended duration of Miltefosine treatment for kala azar?

Accepted Answer

4 weeks

Answer

1 week

Answer

2 weeks

Answer

3 weeks

Question 2

A patient presents with fever for 5 days, altered sensorium, increased JVP, maculopapular rash, and erythema on the back with black necrotic tissue. What is the appropriate initial treatment?

Accepted Answer

Aminoglycosides

Answer

Chloramphenicol

Answer

Tetracycline

Answer

Doxycycline

Question 3

All of the following statements about Fungal Endocarditis are true except?

Accepted Answer

Good prognosis with treatment

Answer

Candida is the most common agent

Answer

Life-long antifungal agents may be required

Answer

Surgical treatment is often recommended

Question 4

A 67-year-old man presents with persistent shooting pains, lower limb ataxia, and bladder dysfunction. Physical examination reveals small, irregular pupils that constrict with accommodation but not in response to light. A VDRL test is positive. A CT scan of the spinal cord would most likely demonstrate atrophy of which of the following structures?

Accepted Answer

Dorsal column

Answer

Dorsal horn

Answer

Lateral column

Answer

Ventral column

Question 5

Which of the following serological status is seen only in acute hepatitis B infection?

Accepted Answer

HBsAg Positive + HBeAg Positive + HBc IgM Positive

Answer

HBsAg Negative + HBc IgM Positive + HBc IgG Positive

Answer

HBsAg Positive + HBeAg Positive + HBc IgM Negative

Answer

HBc IgG Positive + HBe IgG Positive + HBs IgG Positive

Question 6

Faget sign is:

Accepted Answer

Bradycardia with hyperthermia

Answer

Tachycardia with hypertension

Answer

Tachycardia with hyperthermia

Answer

Bradycardia with hypothermia

Question 7

A 24-year-old male with a history of primary syphilis presented with genital ulcers and mucocutaneous lesions. He now exhibits features suggestive of neurosyphilis, including meningitis, for which appropriate treatment has been initiated. What is the recommended method for monitoring treatment response?

Accepted Answer

Venereal Disease Research Laboratory test (VDRL)

Answer

Treponema pallidum immobilization test (TPI)

Answer

Fluorescent treponemal antibody absorption test (FTA-ABS)

Answer

Enzyme-linked immunosorbent assay (ELISA)

Question 8

A 26-year-old woman presents with a 5-day history of fever. On physical examination, her temperature is 38.2°C, pulse is 100/min, respirations are 19/min, and blood pressure is 90/60 mm Hg. A cardiac murmur is heard on auscultation. Her sensorium is clouded, but there are no focal neurologic deficits. Laboratory findings include hemoglobin, 13.1 g/dL; platelet count, 233,300/mm³; and WBC count, 19,200/mm³. Blood cultures are positive for gram-positive bacteria. Urinalysis shows hematuria. An echocardiogram reveals 1.5-cm vegetation on the mitral valve. Which of the following complications is this patient most likely to develop?

Accepted Answer

Cerebral arterial mycotic aneurysm

Answer

Dilated cardiomyopathy

Answer

Myxomatous mitral valve degeneration

Answer

Pericardial effusion with tamponade

Question 9

What is a common causative agent of atypical pneumonia?

Accepted Answer

Chlamydia

Answer

Staphylococcus

Answer

Streptococcus

Answer

Haemophilus influenzae

Question 10

A 40-year-old man develops erythema nodosum, conjunctivitis, and a pleural effusion. Over several weeks, pulmonary lesions lead to cavitation and a large, thin-walled cavity. He was traveling in Arizona before becoming ill. Sputum samples reveal mature spherules. Which of the following is the most likely diagnosis?

Accepted Answer

coccidioidomycosis

Answer

Streptococcus

Answer

candidiasis

Answer

Staphylococcus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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