Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 1251: Which viral infection is primarily associated with hemolysis?

A. Hepatitis-C
B. Epstein-Barr virus (Correct Answer)
C. Hepatitis A virus
D. Hepatitis B virus

Explanation: **Epstein-Barr virus** - **Epstein-Barr virus (EBV)** is strongly associated with **cold agglutinin disease**, an **autoimmune hemolytic anemia** where cold-reacting antibodies agglutinate and lyse red blood cells. [4] - Hemolysis in EBV infection can also occur due to direct viral effects on red blood cells or immune-mediated mechanisms beyond cold agglutinins. [1] *Hepatitis B virus* - Hepatitis B virus is primarily known for causing **liver inflammation** and **hepatocellular damage**, rather than direct or immune-mediated hemolysis. [2] - While chronic HBV infection can lead to complications such as cirrhosis or liver cancer, it is not a common cause of hemolytic anemia. *Hepatitis-C* - Hepatitis C virus is a common cause of **chronic liver disease**, leading to **fibrosis**, **cirrhosis**, and **hepatocellular carcinoma**. [3] - Although HCV is sometimes associated with mixed cryoglobulinemia, which can cause vasculitis and organ damage, it does not typically cause significant hemolysis. *Hepatitis A virus* - Hepatitis A virus causes **acute, self-limiting liver inflammation** and is primarily transmitted through the **fecal-oral route**. [2] - It does not typically cause sustained or severe hemolysis; any hemolytic events are rare and usually mild.

Question 1252: Exanthems are caused by all except which of the following?

A. Typhoid
B. Malaria (Correct Answer)
C. Rubella
D. Measles

Explanation: ***Malaria*** - **Malaria** is a parasitic disease that affects red blood cells and typically causes symptoms like **fever, chills, and headache**, but does not present with a characteristic skin rash or exanthem [3]. - While skin manifestations like **petechiae or jaundice** can occur in severe cases, a widespread rash defining an exanthem is not typical [3]. *Typhoid* - **Typhoid fever**, caused by *Salmonella Typhi*, can present with a characteristic exanthem known as **"rose spots"** on the trunk and abdomen [3]. - These are small, erythematous macules that blanch on pressure and are an important diagnostic clue. *Measles* - **Measles**, caused by the measles virus, is well-known for its characteristic **maculopapular rash** (exanthem) that typically starts on the face and spreads downwards [1]. - This rash is often preceded by **Koplik spots** in the mouth [1]. *Rubella* - **Rubella** (German measles), caused by the rubella virus, also presents with a classic exanthem, which is a **fine, pinkish-red maculopapular rash** that begins on the face and neck and spreads to the trunk and extremities [2]. - The rash is typically milder and resolves more quickly than measles.

Question 1253: Commonest fungal infection of the female genitalia in diabetes is?

A. Cryptococcal
B. Madura mycosis
C. Aspergellosis
D. Candidal (Correct Answer)

Explanation: ***Candidal*** - **Candida albicans** is the most common cause of fungal infections, particularly **vulvovaginal candidiasis**, in diabetic women due to high glucose levels providing a favorable environment for fungal growth. - Diabetes leads to **immunosuppression** and elevated vaginal glycogen, both of which promote Candida proliferation. *Cryptococcal* [1] - **Cryptococcus neoformans** primarily causes infections in immunocompromised individuals, typically affecting the **lungs** and **central nervous system**, not the genitalia. - Genital cryptococcosis is exceedingly rare and usually a manifestation of disseminated disease, not a common primary infection. *Madura mycosis* - **Madura mycosis** (also known as mycetoma) is a chronic, localized infection of the **skin and subcutaneous tissue**, usually affecting the feet, and is caused by certain fungi or bacteria. - It is not a common cause of genital infection, even in diabetic patients, and is typically associated with **traumatic inoculation in tropical regions**. *Aspergellosis* - **Aspergillus** species typically cause respiratory infections (e.g., **aspergilloma**, **invasive aspergillosis**) mainly in immunocompromised patients. - Genital involvement is extremely rare and usually occurs as part of **disseminated disease**, not as a common primary infection in diabetic women.

Question 1254: Commonest cause for acute sinusitis is:

A. Swimming/Diving
B. Acute rhinitis (Correct Answer)
C. Nasal tumours
D. Deviated nasal septum

Explanation: **Acute rhinitis** - **Acute rhinitis**, commonly known as the common cold, is the most frequent precursor to acute sinusitis due to inflammation and obstruction of the ostia. - The **inflammation** and **edema** of the nasal passages in rhinitis can block the sinus drainage pathways, leading to fluid accumulation and secondary bacterial infection within the sinuses. *Swimming/Diving* - While **swimming** and **diving** can introduce water and pathogens into the sinuses, leading to sinusitis, they are not the most common cause overall. - **Pressure changes** and chemical irritants like chlorine can also contribute, but usually as an exacerbating factor rather than the primary etiology. *Nasal tumours* - **Nasal tumors** can cause chronic sinusitis by physically obstructing sinus drainage, but they are relatively rare and not the most common cause of acute sinusitis. - Symptoms typically develop **gradually** and may include unilateral nasal obstruction, epistaxis, or facial pain, which are distinct from acute inflammatory onset. *Deviated nasal septum* - A **deviated nasal septum** can predispose individuals to sinusitis by impairing mucociliary clearance and ventilation of the sinuses, but it is a predisposing factor rather than the direct cause of acute sinusitis itself. - Often contributes to **recurrent** or **chronic sinusitis** by creating anatomical blockages, but an acute infectious trigger is usually necessary for an acute episode.

Question 1255: What should you do next for a 35-year-old man who is positive for HBsAg and HBeAg, discovered incidentally during blood donation screening, with normal SGOT and SGPT laboratory values?

A. HBV-DNA estimation (Correct Answer)
B. Observation
C. Liver biopsy
D. Interferon therapy

Explanation: ***HBV-DNA estimation*** - The presence of **HBsAg** and **HBeAg** indicates **active viral replication**, necessitating quantification of HBV-DNA to assess viral load [1]. - Normal SGOT and SGPT suggest compensated liver function, but **viral load** is crucial for staging the disease and guiding future management [1]. *Observation* - While liver enzymes are normal, the presence of **HBsAg** and **HBeAg** indicates active hepatitis B infection, which warrants further investigation, not just observation [1]. - Undiagnosed and untreated chronic hepatitis B can lead to serious complications such as **cirrhosis** and **hepatocellular carcinoma** [1]. *Liver biopsy* - **Liver biopsy** is an invasive procedure typically reserved for cases where histological assessment is required to confirm **fibrosis** or **inflammation severity**, or when there's discordance between viral markers and clinical presentation. - It's not the initial step for a patient with normal transaminases and clear serological markers of active infection; **HBV-DNA estimation** is generally performed first [1]. *Interferon therapy* - **Interferon therapy** is a treatment for chronic hepatitis B, but initiating treatment requires a comprehensive assessment including **HBV-DNA levels**, in addition to liver enzyme levels and evaluation of liver damage [2]. - It would be premature to consider treatment without a **viral load** measurement and a full workup to determine the phase of infection and the need for therapy [2].

Question 1256: Which live vaccine is contraindicated in AIDS patients?

A. Measles
B. Varicella (Chickenpox)
C. Oral Polio Vaccine (OPV)
D. BCG (Correct Answer)

Explanation: **BCG** - The **BCG vaccine** is a live attenuated vaccine, and due to the immunocompromised state of AIDS patients, there is a significant risk of developing disseminated BCG infection. - This risk is particularly high in individuals with **severe immunodeficiency** (low CD4 count), making it a strong contraindication. *Oral Polio Vaccine (OPV)* - While OPV is a live vaccine, it is generally considered safe in asymptomatic HIV-infected individuals, but contraindicated in **symptomatic AIDS patients** due to the risk of vaccine-associated paralytic poliomyelitis [1]. - However, in many regions, the inactivated polio vaccine (IPV) is preferred for all HIV-infected individuals to completely eliminate this risk. *Varicella (Chickenpox)* - The **varicella vaccine** is a live attenuated vaccine; however, it is generally recommended for HIV-infected children and adults who are not severely immunocompromised (CD4 count >200 cells/µL). - The benefits of preventing severe chickenpox often outweigh the risks of vaccination in these individuals. *Measles* - The **measles vaccine (MMR)** is a live attenuated vaccine and is generally recommended for HIV-infected individuals who are not severely immunocompromised (CD4 count >200 cells/µL). - The severe morbidity and mortality associated with measles in immunocompromised individuals prioritize vaccination when appropriate.

Question 1257: A 65-year-old male presents with fever, chills, and a productive cough with rust-colored sputum. What is the most likely diagnosis?

A. TB
B. Klebsiella pneumonia
C. Pneumocystis pneumonia
D. Pneumococcal Pneumonia (Correct Answer)

Explanation: Pneumococcal Pneumonia - This presentation with fever, chills, and rust-colored sputum is classic for pneumococcal pneumonia, caused by Streptococcus pneumoniae [1]. [2] - The rust color results from the presence of hemolyzed red blood cells from the inflamed alveoli [3]. TB - While TB can cause fever and cough, the sputum is typically mucoid or purulent, and sometimes hemoptysis (frank blood) is seen, but not usually rust-colored [4]. - TB symptoms tend to be more chronic, including night sweats and weight loss, which are not mentioned here. Klebsiella pneumonia - Klebsiella pneumoniae typically causes severe pneumonia, often in individuals with alcoholism or diabetes [1]. - It classically presents with currant jelly sputum, which is distinct from rust-colored sputum [2]. Pneumocystis pneumonia - Pneumocystis jirovecii pneumonia (PCP) primarily affects immunocompromised individuals, particularly those with HIV [4]. - Symptoms are usually more insidious, involving dyspnea, non-productive cough, and hypoxia, and sputum is not typically rust-colored [4].

Question 1258: Which of the following statements is true regarding acute epididymitis?

A. Commonly associated with urinary tract infections
B. Typically presents with pain (Correct Answer)
C. Scrotum size is usually enlarged
D. Can mimic testicular torsion

Explanation: ***Typically presents with pain*** - **Acute epididymitis** characteristically causes sudden onset of **unilateral scrotal pain**, which can range from mild to severe. - The pain often radiates to the **inguinal area** or lower abdomen and is accompanied by tenderness of the epididymis. *Commonly associated with urinary tract infections* - While acute epididymitis can occur secondary to **UTIs**, especially in older men or those with obstructive uropathy, it is more commonly associated with **sexually transmitted infections (STIs)** in younger, sexually active men [1]. - In children and prepubertal boys, non-bacterial causes or congenital anomalies are more prevalent. *Scrotum size is usually enlarged* - While the **epididymis** itself becomes **swollen** and tender, leading to a palpable mass, the scrotum itself is not typically described as generally enlarged in its overall size. - The swelling is localized to the affected epididymis and sometimes the testicle (epididymo-orchitis). *Can mimic testicular torsion* - Although both conditions present with acute scrotal pain, **epididymitis pain** usually has a more gradual onset, and fever or urinary symptoms may be present. - **Testicular torsion** typically causes sudden, severe pain with an absent or high-riding cremasteric reflex and requires urgent surgical intervention.

Question 1259: In which of the following conditions is glucocorticoid used?

A. Severe typhoid (Correct Answer)
B. E. coli septicemia
C. Cerebral malaria
D. Leishmaniasis

Explanation: ***Severe typhoid*** * **Glucocorticoids** (e.g., **dexamethasone**) are indicated in **severe typhoid fever** with altered mental status, delirium, stupor, coma, or shock, as they can reduce inflammation and improve neurological outcomes. * Their use in severe typhoid can decrease mortality by attenuating the systemic inflammatory response induced by *Salmonella Typhi*. *E. coli septicemia* * The use of **glucocorticoids** in **bacterial sepsis**, including *E. coli* septicemia, is generally controversial and not recommended unless there is confirmed or suspected **adrenal insufficiency**. * Routine use can increase the risk of secondary infections and other adverse effects without clear mortality benefit in immunocompetent patients. *Cerebral malaria* * **Glucocorticoids** are **contraindicated** in **cerebral malaria** because studies have shown they increase the risk of complications (e.g., gastrointestinal bleeding, seizures, hyperglycemia, infections) without improving neurological outcomes or survival. * Their use can worsen immune suppression in a disease already characterized by significant immune dysregulation. *Leishmaniasis* * **Glucocorticoids** are **not a primary treatment** for **leishmaniasis**, which is caused by a protozoan parasite and requires specific antileishmanial drugs. * While they might be used to manage severe inflammatory reactions in specific forms (e.g., post-kala-azar dermal leishmaniasis), they are not a standard therapeutic intervention and can even exacerbate the infection by suppressing the immune response.

Question 1260: The most common ophthalmic affection of diphtheria is –

A. Ptosis
B. Total ophthalmoplegia
C. Isolated ocular palsies (Correct Answer)
D. Ophthalmoplegia externa

Explanation: ***Isolated ocular palsies*** - Diphtheria exotoxin can lead to localized neuropathies, and **ocular muscle palsies** are common, often affecting individual extraocular muscles rather than generalized paralysis. - Involvement typically presents as problems with **accommodation** or specific ocular movements due to cranial nerve involvement. *Ptosis* - While ptosis can occur due to **oculomotor nerve dysfunction**, it is less common as an isolated, primary ophthalmic manifestation of diphtheria compared to other ocular palsies. - It usually indicates more widespread **Cranial Nerve III involvement**, which is not the most frequent initial or isolated ocular finding. *Total ophthalmoplegia* - This involves paralysis of **all extraocular muscles**, which is a severe and less common manifestation of diphtheria. - Diphtheria typically causes more **localized and incomplete palsies** rather than affecting all eye movements universally. *Ophthalmoplegia externa* - This involves paralysis of the **extraocular muscles** but spares the **intrinsic eye muscles** (pupil and accommodation). - While diphtheria *can* cause external ophthalmoplegia, **isolated ocular palsies** (which include external ophthalmoplegia) more accurately describe the common presentation of affecting specific muscles or nerves.

Practice by Chapter

Principles of Antimicrobial Therapy

Practice Questions

Fever of Unknown Origin

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HIV/AIDS and Related Infections

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Tuberculosis and Mycobacterial Diseases

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Tropical and Parasitic Infections

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Viral Infections (Hepatitis, Herpes, etc.)

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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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