Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1041: A patient with a recent upper respiratory infection develops facial pain and tenderness over the maxillary sinuses. What is the most appropriate initial treatment?

A. Amoxicillin-clavulanate (Correct Answer)
B. Corticosteroid
C. Antihistamine
D. Topical decongestant

Explanation: ***Amoxicillin-clavulanate*** - This antibiotic combination is the **first-line empirical treatment** for **acute bacterial rhinosinusitis**, especially if symptoms persist or worsen after 7-10 days, or are severe at presentation. - It provides broad-spectrum coverage against common bacterial pathogens, including gram-positive and gram-negative bacteria, and addresses **beta-lactamase producing strains**. *Corticosteroid* - While **intranasal corticosteroids** can be used as an adjunct to reduce inflammation in acute rhinosinusitis, they are **rarely sufficient as initial monotherapy** in cases highly suggestive of bacterial infection. - Oral corticosteroids are generally reserved for more severe or refractory cases due to systemic side effects. *Antihistamine* - Antihistamines are primarily used for **allergic rhinitis** to block histamine release and reduce symptoms like sneezing and rhinorrhea. - They are **ineffective against bacterial infections** and can paradoxically dry out mucous membranes, potentially hindering mucociliary clearance in sinusitis. *Topical decongestant* - Topical decongestants provide temporary relief by reducing **nasal congestion** but do not treat the underlying bacterial infection. - Prolonged use (more than 3-5 days) can lead to **rhinitis medicamentosa**, a rebound congestion.

Question 1042: A 35-year-old woman presents with facial pain, nasal congestion, and purulent nasal discharge for 10 days. What is the most likely diagnosis?

A. Migraine
B. Tension headache
C. Trigeminal neuralgia
D. Acute sinusitis (Correct Answer)

Explanation: ***Acute sinusitis*** - The combination of **facial pain**, **nasal congestion**, and **purulent nasal discharge** for 10 days is highly characteristic of acute sinusitis, indicating inflammation and infection of the paranasal sinuses. - The persistence of symptoms for over 7-10 days, or worsening symptoms after initial improvement, supports a bacterial etiology rather than a self-limiting viral infection. *Migraine* - Migraines typically present with **unilateral, throbbing headache**, often accompanied by **photophobia, phonophobia**, and nausea, without purulent nasal discharge [1]. - While facial pain can occur, it's usually not associated with nasal congestion or discharge [1]. *Tension headache* - Tension headaches are usually characterized by **bilateral, pressing or tightening pain**, often described as a band around the head, and are not associated with nasal symptoms or purulent discharge [1]. - They typically lack the other features of sinusitis or migraines. *Trigeminal neuralgia* - This condition involves **sudden, severe, brief, stabbing or shock-like pain** in the distribution of the trigeminal nerve, often triggered by light touch or movement. - It does not present with nasal congestion or purulent discharge.

Question 1043: A 25-year-old woman presents with a sudden onset of high fever, chills, and rigors. Blood cultures are pending. What is the next appropriate step in her management?

A. Administer broad-spectrum antibiotics (Correct Answer)
B. Wait for blood culture results
C. Start antipyretic therapy only
D. Order a CT scan

Explanation: ***Administer broad-spectrum antibiotics*** - The patient presents with classic signs of **sepsis** (high fever, chills, rigors), which is a medical emergency requiring prompt intervention [2]. - **Early administration of broad-spectrum antibiotics** is crucial to improve outcomes and reduce mortality in suspected sepsis, even before culture results are available [1]. *Wait for blood culture results* - Delaying antibiotic treatment in a patient with suspected sepsis can lead to rapid clinical deterioration and increased mortality [1]. - While blood cultures are essential to guide definitive therapy, initial empiric broad-spectrum antibiotics should not be withheld [3]. *Start antipyretic therapy only* - Antipyretics only address the symptom of fever and do not treat the underlying infection causing the fever and chills. - This approach would leave the potentially life-threatening infection untreated, leading to worsening patient condition. *Order a CT scan* - A CT scan is not the immediate priority in a patient presenting with acute signs of systemic infection and suspected sepsis. - While it may be useful later to identify a source of infection, controlling the infection with antibiotics is the most urgent step.

Question 1044: A 30-year-old male presents with chills and a high fever of 40°C. Which of the following symptoms would most likely suggest an infectious cause?

A. Rigors (Correct Answer)
B. Excessive sweating
C. Skin rash
D. Vomiting

Explanation: ***Rigors*** - **Rigors** (generalized shivering with a sensation of cold) are strong indicators of a rapid and significant rise in body temperature, often seen with **bacteremia** or other severe infections [1]. - The body's defense mechanisms are fighting off a severe infection, leading to an exaggerated physiological response. *Excessive sweating* - **Excessive sweating (diaphoresis)** typically occurs as the body attempts to cool down during the defervescence (fever reduction) phase [1]. - While associated with fever, it is less specific for the *onset* or active phase of an infection compared to rigors [1]. *Skin rash* - A **skin rash** can be a symptom of certain infections (e.g., viral exanthems, meningococcemia) but is not a universal or primary indicator of *any* infectious cause [2]. - Many febrile illnesses do not present with a rash, and rashes can also be non-infectious in origin (e.g., allergic reactions). *Vomiting* - **Vomiting** can accompany many illnesses, both infectious (e.g., gastroenteritis, meningitis) and non-infectious (e.g., migraine, drug reaction). - It is a non-specific symptom that does not singularly point to an infectious etiology as strongly as rigors in the context of a high fever.

Question 1045: A 35-year-old male presents with fever, night sweats, and unintentional weight loss over the past 3 months. He has a history of intravenous drug use. Most appropriate next step in the diagnosis?

A. HIV test (Correct Answer)
B. Chest X-ray
C. Tuberculin skin test
D. Blood culture

Explanation: ***HIV test*** - The patient's **risk factors** (intravenous drug use) and constitutional symptoms (fever, night sweats, unintentional weight loss) are highly suggestive of **HIV infection**, [2], [5] which can lead to opportunistic infections or directly cause these symptoms. - An HIV test is crucial for **early diagnosis** and management to prevent progression to AIDS and initiate highly active antiretroviral therapy (HAART) [4]. *Chest X-ray* - While a Chest X-ray can detect pulmonary infections often associated with immunosuppression, it is a **secondary investigation** and not the most appropriate initial diagnostic step for the underlying cause of immunosuppression. - It would be more useful after identifying an underlying condition like HIV, especially if respiratory symptoms were prominent. *Tuberculin skin test* - Tuberculosis is a common opportunistic infection in immunocompromised individuals, including those with HIV, and can present with these symptoms [1]. - However, performing a **Tuberculin skin test** or **IGRA** is typically done after initial screening for HIV, as the interpretation relies on the patient's immune status. *Blood culture* - Blood cultures are useful for detecting **bacteremia or fungemia** and can help identify specific infections [3]. - While relevant for fever and night sweats, they are a **specific diagnostic test** for active bloodstream infection and do not address the underlying systemic cause of immunosuppression and constitutional symptoms like HIV.

Question 1046: A patient with a fever presents with a heart rate of 120 beats per minute and a respiratory rate of 30 breaths per minute. What does this indicate?

A. Tachypnea due to anxiety
B. Early sepsis (Correct Answer)
C. Expected response to fever
D. Normal physiological response to fever

Explanation: ***Early sepsis*** - A heart rate of 120 bpm (**tachycardia**) and a respiratory rate of 30 bpm (**tachypnea**) in the setting of fever meet the criteria for **Systemic Inflammatory Response Syndrome (SIRS)**, which can indicate early sepsis. - Sepsis is defined by life-threatening organ dysfunction caused by a dysregulated host response to infection, and these vital sign abnormalities are key indicators. *Tachypnea due to anxiety* - While anxiety can cause tachypnea and tachycardia, the presence of **fever** suggests an underlying infectious or inflammatory process rather than isolated anxiety. - Relying solely on anxiety as the cause without considering other indicators can lead to delayed diagnosis and treatment of serious conditions. *Expected response to fever* - While a moderate increase in heart rate and respiratory rate is expected with fever (e.g., 8-10 bpm increase per degree Celsius of fever), a heart rate of **120 bpm** and especially a respiratory rate of **30 bpm** are disproportionately elevated and exceed a typical physiological response. - These elevated vital signs signal a more significant physiological stress or dysregulation beyond a simple febrile response. *Normal physiological response to fever* - A "normal" physiological response to fever would involve a mild-to-moderate elevation in heart rate and respiratory rate; however, a heart rate of **120 bpm** and a respiratory rate of **30 bpm** are considered *abnormal* for a typical febrile response. - These values are sufficiently high to raise concern for **SIRS** or early sepsis, requiring further investigation.

Question 1047: A 30-year-old male presents with high fever, muscle aches, and a history of swimming in freshwater lakes. Examination reveals schistosome cercariae on skin biopsy. What are the implications of this finding for potential systemic involvement?

A. No systemic involvement expected
B. Risk of hepatosplenic involvement (Correct Answer)
C. Localized skin reaction only
D. Potential for CNS complications

Explanation: ***Risk of hepatosplenic involvement*** - The presence of **schistosome cercariae** indicates exposure to *Schistosoma* parasites, which can mature into adult worms and migrate to the **mesenteric veins**, leading to **hepatosplenic schistosomiasis** [1]. - Systemic involvement, particularly of the **liver and spleen**, is a well-known complication of schistosomiasis as eggs laid by adult worms can embolize to these organs, causing chronic inflammation and fibrosis [1]. *Localized skin reaction only* - While initial penetration of cercariae can cause a **localized dermatitis** (swimmer's itch), the presence of cercariae suggests a recent and significant exposure that could lead to systemic infection [1]. - This option overlooks the **life cycle** of *Schistosoma* parasites, which involves migration beyond the skin to internal organs once they transform into schistosomulae [1]. *No systemic involvement expected* - This statement is incorrect because **schistosome infection** is inherently a systemic disease once the cercariae successfully penetrate the skin and develop into schistosomulae [1]. - The adult worms reside in **venous plexuses**, and their eggs cause widespread inflammatory responses, leading to various systemic manifestations, including in the **gastrointestinal** and **urinary systems**, as well as the liver and spleen [1]. *Potential for CNS complications* - While **CNS complications** like **spinal cord schistosomiasis** or **cerebral schistosomiasis** can occur, they are less common forms of systemic involvement compared to hepatosplenic manifestations. - CNS involvement is usually due to **ectopic egg deposition** in the brain or spinal cord, which is a possible but not the most likely primary systemic implication.

Question 1048: Which bacterial infection is characterized by a 'strawberry tongue'?

A. Scarlet fever (Correct Answer)
B. Impetigo
C. Cellulitis
D. Erysipelas

Explanation: ***Scarlet fever*** - **Scarlet fever**, caused by **Group A Streptococcus**, is classically associated with a **strawberry tongue** due to inflamed papillae [1]. - Other characteristic symptoms include a **diffuse red rash** that feels like sandpaper, a sore throat, and fever [1]. *Impetigo* - **Impetigo** is a superficial skin infection characterized by **honey-colored crusted lesions**, typically on the face. - It does not involve systemic symptoms like fever or have oral manifestations such as a strawberry tongue. *Cellulitis* - **Cellulitis** is a deeper skin infection affecting the dermis and subcutaneous tissue, presenting as a **red, swollen, warm, and tender area of skin** [2]. - It does not cause a rash or a strawberry tongue; its manifestations are localized to the affected skin area [2]. *Erysipelas* - **Erysipelas** is a superficial form of cellulitis, characterized by a **sharply demarcated, raised, red, and warm rash**, often on the face or legs [2]. - While it's a skin infection, it does not involve the characteristic oral findings of a strawberry tongue.

Question 1049: A 23-year-old male returns from a hiking trip with complaints of diarrhea, abdominal cramps, and fatigue. Stool microscopy reveals flagellated trophozoites. What is the most likely diagnosis?

A. Entamoeba histolytica
B. Giardia lamblia (Correct Answer)
C. Cryptosporidium hominis
D. Trichomonas vaginalis

Explanation: Giardia lamblia - The presence of flagellated trophozoites in a stool sample from a patient with a history of a hiking trip strongly points to Giardia lamblia infection, often acquired from contaminated water [1]. - Symptoms like diarrhea, abdominal cramps, and fatigue are characteristic of giardiasis, which can lead to malabsorption [1]. Entamoeba histolytica - While it causes diarrhea and abdominal pain, this parasite is identified by amoeboid trophozoites with pseudopods and often presents with bloody stools, not flagella [2]. - It can also cause liver abscesses, which is not indicated here [2]. Cryptosporidium hominis - This parasite is identified by its oocysts in stool samples, not flagellated trophozoites, and can cause severe, protracted watery diarrhea, particularly in immunocompromised individuals. - It does not present as a flagellated form in diagnostic samples. Trichomonas vaginalis - This is a flagellated parasite, but it primarily causes genitourinary infections and is found in the reproductive tract, not typically in stool samples causing gastrointestinal symptoms. - It is transmitted sexually and does not cause traveler's diarrhea.

Question 1050: A patient from a Lyme disease-endemic area presents with erythema migrans, fatigue, and arthralgia. Laboratory tests show positive IgM antibodies against Borrelia burgdorferi. Evaluate the stage of Lyme disease.

A. Early localized (Correct Answer)
B. Early disseminated
C. Late disseminated
D. Post-Lyme disease syndrome

Explanation: ***Early localized*** - **Erythema migrans** is the hallmark rash of early localized Lyme disease, typically appearing within days to weeks of a tick bite [1]. - The presence of **fatigue** and **arthralgia** are non-specific symptoms that can occur at any stage, but along with positive **IgM antibodies**, are consistent with early infection. *Early disseminated* - This stage involves multiple erythema migrans lesions, **cranial nerve palsies** (e.g., Bell's palsy), **meningitis**, or **cardiac involvement** like AV block, none of which are described. - While fatigue and arthralgia can persist, the specific presentation points to the earliest stage before systemic spread with major organ involvement. *Late disseminated* - Characterized by chronic **arthritis** (especially in large joints), **encephalopathy**, or **neuropathy**, which typically develop months to years after the initial infection. - The patient's current symptoms are not indicative of these severe, chronic manifestations. *Post-Lyme disease syndrome* - Refers to persistent symptoms such as fatigue, joint pain, and cognitive difficulties lasting for more than 6 months after successful treatment of Lyme disease. - This patient presents with active infection symptoms, not chronic residual symptoms after treatment.

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

Practice Questions

HIV/AIDS and Related Infections

Practice Questions

Tuberculosis and Mycobacterial Diseases

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Tropical and Parasitic Infections

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Viral Infections (Hepatitis, Herpes, etc.)

Practice Questions

Healthcare-Associated Infections

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Fungal Infections

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Sepsis and Septic Shock

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Infection in Immunocompromised Hosts

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Emerging and Re-emerging Infections

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Antimicrobial Resistance

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Vaccination Principles

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