Infectious Diseases Practice Questions

Q: A patient with acute leukemia is admitted with febrile neutropenia. On day four of being treated with broad-spectrum antibiotics, his fever increases. Chest X-ray shows bilateral fluffy infiltrates. Which of the following should be the most appropriate next step in the management?

Add antifungal therapy. Correct: Add antifungal therapy - Increasing fever despite broad-spectrum antibiotics in a neutropenic patient with bilateral fluffy infiltrates on chest X-ray strongly indicates an underlying fungal infection [1], [3]. - Empirical antifungal therapy is a crucial next step in this high-risk population to prevent severe morbidity and mortality associated with invasive fungal infections [1]. Add antiviral therapy - While viral infections can occur in immunocompromised patients, the presentation of persistent fever despite antibiotics and fluffy infiltrates is less characteristic of a primary viral pneumonia requiring targeted antiviral therapy at this initial stage [2]. - The patient's clinical picture is more suggestive of a fungal etiology after failing antibacterial treatment. Add cotrimoxazole - Cotrimoxazole (trimethoprim/sulfamethoxazole) is primarily used for Pneumocystis jirovecii pneumonia (PCP) prophylaxis or treatment, or for certain bacterial infections. - The clinical scenario, particularly the bilateral fluffy infiltrates in a neutropenic patient failing broad-spectrum antibiotics, is less typical for a PCP presentation and doesn't point to a need for this specific antibiotic. Continue chemotherapy - The patient is currently experiencing febrile neutropenia [2], a life-threatening complication of chemotherapy. - Continuing chemotherapy would further exacerbate the neutropenia and potentially worsen the infection, without addressing the underlying cause of the persistent fever and infiltrates.

Q: What is the etiology of the rash in a 20-year-old college student who presented with fever, sore throat, and malaise, and was previously diagnosed with streptococcal pharyngitis and treated with intramuscular ampicillin, despite having no history of travel?

Exanthematous drug eruption. ***Exanthematous drug eruption*** - This patient's history of **ampicillin administration** for streptococcal pharyngitis, followed by the development of a rash, points strongly to an **exanthematous drug eruption** [1]. - **Ampicillin** and amoxicillin are known to cause a maculopapular rash in patients with **Epstein-Barr virus (EBV) infection**, which can present with similar symptoms to streptococcal pharyngitis (fever, sore throat, malaise), making this the most likely scenario [1]. *Parvovirus B19 infection* - **Parvovirus B19** causes **Fifth disease**, characterized by a "slapped cheek" rash on the face and a lacy rash on the trunk and extremities, which is not described. - While it can cause fever and malaise, the preceding **streptococcal pharyngitis** and **ampicillin use** make a drug reaction more probable. *Chikungunya virus infection* - **Chikungunya virus** typically presents with severe **arthralgia**, fever, and rash, often in patients with recent travel to endemic areas. - The patient has no history of travel, and **arthralgia** is not mentioned as a primary symptom. *Measles infection* - **Measles** presents with a characteristic **maculopapular rash** that starts on the face and spreads downwards, often preceded by **Koplik spots**. - While measles causes fever and malaise, the diagnosis of **streptococcal pharyngitis** and subsequent **ampicillin use** strongly suggest a drug-induced rash rather than measles.

Q: Death in poliomyelitis is due to:

Respiratory muscle failure. Respiratory muscle failure [1] - The poliovirus primarily targets and destroys motor neurons within the anterior horn cells of the spinal cord and brainstem. - When the motor neurons controlling the diaphragm and intercostal muscles are affected, it leads to paralysis and inability to breathe, resulting in death. *Severe neurogenic shock* - While poliomyelitis can affect the nervous system, neurogenic shock (characterized by hypotension and bradycardia due to loss of sympathetic tone) is not the primary mechanism of death. - The direct paralysis of respiratory muscles is a more immediate and common cause of fatality. *Secondary infection complications* - Secondary infections, such as pneumonia, can occur in severely ill polio patients due to prolonged immobility and compromised pulmonary function. - However, these are typically complications arising from the primary respiratory muscle paralysis, rather than the initial and direct cause of death. *Cardiac complications* - Although rare, some cases of poliomyelitis can involve myocarditis or other cardiac issues. - These are not the most common or direct cause of death; respiratory failure remains the overwhelming primary cause. [1]

Q: A primigravida in the first trimester was observed to be sputum positive for acid-fast bacilli, with no previous history of tuberculosis. Which treatment strategy should be employed?

Category I DOTS. ***Category I DOTS*** - This patient is a **newly diagnosed, sputum-positive pulmonary TB case**, and Category I DOTS is the standard treatment regimen for such patients. [1] - The regimen includes daily fixed-dose combinations of **Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol** for an intensive phase, followed by a continuation phase. [1] *Category II DOTS* - Category II DOTS is reserved for **retreatment cases** (e.g., relapse, treatment failure, treatment after default) with previously treated tuberculosis. - The patient has **no previous history of tuberculosis**, making Category II inappropriate. *Category III DOTS* - Category III DOTS is typically for **new sputum-negative pulmonary tuberculosis** or **extra-pulmonary tuberculosis** cases. - The patient is **sputum-positive for acid-fast bacilli**, excluding Category III. [1] *Defer treatment* - **Tuberculosis in pregnancy** poses significant risks to both the mother and the fetus, including increased maternal morbidity, prematurity, and congenital TB. - **Prompt treatment is essential** and should not be deferred, as the benefits of treatment generally outweigh the risks of medication to the fetus. Pyridoxine should be prescribed in pregnant women to reduce the risk of peripheral neuropathy with isoniazid. [1]

Q: Which of the following parasitic infestations is most commonly associated with malabsorption?

Giardia lamblia. ***Giardia lamblia*** - **Giardia lamblia** is a common cause of **giardiasis**, an intestinal infection characterized by **malabsorption** due to damage to the intestinal villi [2]. - It often presents with **diarrhea, steatorrhea, abdominal cramps, and weight loss**, all indicative of malabsorption. *Ascaris lumbricoides* - While *Ascaris lumbricoides* can cause malnutrition, it primarily affects nutrient absorption less directly through its sheer biomass or mechanical obstruction rather than specific villous damage associated with malabsorption. - Heavy infestations can cause **intestinal obstruction** or **biliary obstruction**, but malabsorption as a primary symptom is less common than with *Giardia*. *Necator Americanus* - *Necator americanus* (New World hookworm) primarily causes **iron deficiency anemia** due to chronic blood loss from the intestinal attachment sites [1]. - While it can contribute to malnutrition, direct **malabsorption** of macronutrients is not its most common presentation or primary mechanism of pathology [1]. *Ancylostoma duodenale* - *Ancylostoma duodenale* (Old World hookworm) also primarily leads to **iron deficiency anemia** through blood sucking in the small intestine [1]. - Similar to *N. americanus*, its main impact on health is through **blood loss** rather than significant malabsorption of nutrients [1].

Q: Which of the following is not seen in tubercular meningitis:

Cerebrospinal fluid reveals a low leukocyte count.. ***Cerebrospinal fluid reveals a low leukocyte count*** - **Tubercular meningitis** typically causes a **leukocytosis** in the cerebrospinal fluid, predominantly lymphocytic, not a low leukocyte count. - A low leukocyte count would be highly atypical for an active meningeal infection. *Evidence of old pulmonary lesions or a miliary pattern is found on chest radiography.* - **Tubercular meningitis** is often a manifestation of **disseminated tuberculosis**, and a chest X-ray commonly reveals signs of current or past pulmonary tuberculosis, or **miliary patterns** [2]. - These findings suggest an underlying source of *Mycobacterium tuberculosis* infection. *CSF culture provides rapid diagnosis in most cases within 24-48 hours.* - CSF culture for *Mycobacterium tuberculosis* is known to be **slow-growing** and can take several weeks (typically 3-6 weeks) to yield results, making it unsuitable for rapid diagnosis within 24-48 hours. - While highly specific, its lack of speed necessitates starting empiric treatment based on clinical suspicion and other CSF parameters. *It is seen most often in young children but also develops in adults.* - **Tuberculous meningitis** affects both children and adults, but it is particularly common and severe in **young children** due to their developing immune systems [1]. - It remains a significant health concern across all age groups, especially in endemic areas and among immunocompromised individuals [1].

Q: In humans, cryptosporidiosis typically presents as?

Diarrhea. ***Diarrhea*** - Cryptosporidiosis is primarily a **gastrointestinal infection** caused by the parasite *Cryptosporidium parvum* and typically manifests as **watery diarrhea** [1]. - The parasite infects the **epithelial cells of the small intestine**, leading to malabsorption and fluid loss. *Meningitis* - **Meningitis** is an inflammation of the membranes surrounding the brain and spinal cord, commonly caused by bacterial or viral infections. - While *Cryptosporidium* can cause disseminated disease in severely immunocompromised individuals, **meningitis is not a typical or primary presentation**. *Pneumonia* - **Pneumonia** is an infection that inflames the air sacs in one or both lungs, typically caused by bacteria, viruses, or fungi. - Although **pulmonary cryptosporidiosis** can occur, especially in immunocompromised patients, it is a relatively rare and atypical presentation, not the primary clinical picture. *Hepatitis* - **Hepatitis** is an inflammation of the liver, most commonly caused by viral infections (e.g., hepatitis A, B, C). - While *Cryptosporidium* can potentially affect the **biliary tract** and cause cholangitis or cholecystitis, **true hepatitis is not a typical symptom** of cryptosporidiosis.

Q: A 50-year-old HIV-positive patient presents with a painless, purple lesion on the skin. What is the most likely diagnosis?

Kaposi's sarcoma. ***Kaposi's sarcoma*** - The presentation of **painless, purple skin lesions** in an **HIV-positive patient** is highly characteristic of Kaposi's sarcoma. - This is a vascular tumor caused by **Human Herpesvirus 8 (HHV-8)**, often seen in immunocompromised individuals. *Malignant melanoma* - Malignant melanoma typically presents as a **dark, irregularly shaped lesion** with varying colors and often exhibits change in size, shape, or color over time (**ABCDEs of melanoma**). - While it can be purple or dark, the multiple, widespread nature and association with HIV points away from typical melanoma. *Squamous cell carcinoma* - Squamous cell carcinoma usually presents as a **red, scaly patch, nodule, or an open sore** that doesn't heal, often found in sun-exposed areas. - It is not typically described as a painless purple lesion, and while HIV patients have increased risk, the lesion morphology is more consistent with Kaposi's. *Basal cell carcinoma* - Basal cell carcinoma commonly appears as a **pearly or waxy bump**, a **flat, flesh-colored lesion**, or a **brown, scar-like lesion**, often with a rolled border and telangiectasias. - Unlike the description, it is not typically purple and painless, and while common, the clinical picture with HIV is not classic for BCC.

Question 1

A patient with acute leukemia is admitted with febrile neutropenia. On day four of being treated with broad-spectrum antibiotics, his fever increases. Chest X-ray shows bilateral fluffy infiltrates. Which of the following should be the most appropriate next step in the management?

Accepted Answer

Add antifungal therapy

Answer

Add antiviral therapy

Answer

Add cotrimoxazole

Answer

Continue chemotherapy

Question 2

What is the etiology of the rash in a 20-year-old college student who presented with fever, sore throat, and malaise, and was previously diagnosed with streptococcal pharyngitis and treated with intramuscular ampicillin, despite having no history of travel?

Accepted Answer

Exanthematous drug eruption

Answer

Parvovirus B19 infection

Answer

Chikungunya virus infection

Answer

Measles infection

Question 3

Death in poliomyelitis is due to:

Accepted Answer

Respiratory muscle failure

Answer

Severe neurogenic shock

Answer

Secondary infection complications

Answer

Cardiac complications

Question 4

A primigravida in the first trimester was observed to be sputum positive for acid-fast bacilli, with no previous history of tuberculosis. Which treatment strategy should be employed?

Accepted Answer

Category I DOTS

Answer

Category II DOTS

Answer

Category III DOTS

Answer

Defer treatment

Question 5

Which of the following parasitic infestations is most commonly associated with malabsorption?

Accepted Answer

Giardia lamblia

Answer

Ascaris lumbricoides

Answer

Necator Americanus

Answer

Ancylostoma duodenale

Question 6

Which of the following is not seen in tubercular meningitis:

Accepted Answer

Cerebrospinal fluid reveals a low leukocyte count.

Answer

Evidence of old pulmonary lesions or a miliary pattern is found on chest radiography.

Answer

CSF culture provides rapid diagnosis in most cases within 24-48 hours.

Answer

It is seen most often in young children but also develops in adults.

Question 7

In humans, cryptosporidiosis typically presents as?

Accepted Answer

Diarrhea

Answer

Meningitis

Answer

Pneumonia

Answer

Hepatitis

Question 8

A 50-year-old HIV-positive patient presents with a painless, purple lesion on the skin. What is the most likely diagnosis?

Accepted Answer

Kaposi's sarcoma

Answer

Squamous cell carcinoma

Answer

Malignant melanoma

Answer

Basal cell carcinoma

Infectious Diseases — MCQs

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