Infectious Diseases Practice Questions

Q: What does the acronym I.R.I.S. stand for in the context of immunology?

Immune reconstitution inflammatory syndrome. ***Immune reconstitution inflammatory syndrome*** - **IRIS** refers to a paradoxical worsening, unmasking, or new manifestation of opportunistic infections or inflammatory disorders during **immune recovery**, typically following the initiation of **antiretroviral therapy (ART)** in HIV-infected individuals [1]. - It occurs when a weakened immune system, suddenly bolstered by treatment, mounts an excessive inflammatory response to pre-existing or newly recognized pathogens or antigens [1]. *Immune reconstitution idiopathic syndrome* - The term **"idiopathic"** implies an unknown cause, which is not accurate for IRIS, as its pathophysiology is linked to **immune recovery**. - While some cases might have less clear triggers, the overall syndrome is understood to be inflammation driven by specific **immune responses**. *Immune reconstitution immunological syndrome* - This option uses the redundant term **"immunological"** after "immune reconstitution," which does not form the correct acronym or accurately describe the syndrome's hallmark: **inflammation** [1]. - The key feature of IRIS is the **inflammatory response**, not merely an "immunological" event [1]. *Inflammatory reconstitution immune syndrome* - This arrangement of words reverses the correct order and meaning of the acronym **IRIS**, placing "inflammatory" before "reconstitution." - The syndrome describes **immune reconstitution** leading to **inflammatory** manifestations, not the other way around [1].

Q: Which of the following statements about gas gangrene is true?

High-dose penicillin is the drug of choice. ***High-dose penicillin is the drug of choice*** - **High-dose penicillin G** is the primary antibiotic therapy for gas gangrene due to the sensitivity of *Clostridium perfringens* to penicillin. - This aggressive antibiotic treatment is crucial in conjunction with surgical debridement to control the rapidly spreading infection. *Most common cause is Staphylococcus aureus* - The most common cause of gas gangrene is **Clostridium perfringens**, not *Staphylococcus aureus*. - *Staphylococcus aureus* is primarily associated with **pyogenic infections**, cellulitis, and abscesses, not gas gangrene. *Causes mild inflammation of muscles* - Gas gangrene causes **severe myonecrosis** (muscle death) and rapid tissue destruction, not mild inflammation. - The infection leads to necrosis, gas formation in tissues, and systemic toxicity. *Clostridium perfringens produces heat-sensitive spores* - *Clostridium perfringens* produces **heat-resistant spores**, which allow it to survive in harsh conditions and contribute to its pervasive nature in the environment. - The spores are resistant to boiling and can survive for extended periods, making sterilization a challenge.

Q: What is the most common form of leptospirosis?

Anicteric form. ***Anicteric form*** - The **anicteric form** accounts for about 90% of all leptospirosis cases, presenting with milder, flu-like symptoms without jaundice. - Patients typically experience **fever, headache, myalgia**, and conjunctival suffusion during the initial septicemic phase [1], followed by an immune phase that can involve meningitis or uveitis [1]. *Icteric form* - The **icteric form** (Weil's disease) is a severe manifestation, characterized by jaundice, renal failure, and hemorrhage, occurring in a minority of cases (5-10%). - Although more severe and often life-threatening, it is **less common** than the anicteric presentation [1]. *Hepatorenal form* - This term describes the severe complications of leptospirosis, including **liver and kidney dysfunction**, specifically associated with Weil's disease. - While a critical aspect of severe leptospirosis, it is a description of the organ involvement rather than a distinct common form of the disease. *Weil's disease* - **Weil's disease** is the most severe and potentially fatal form of leptospirosis, characterized by **jaundice, renal failure, hemorrhage, and myocarditis**. - It is a severe subset of the icteric form, making it a very serious but **uncommon variant** of the overall disease.

Q: What is the causative agent of trench fever?

Bartonella quintana. ***Bartonella quintana*** - **Trench fever** is a **rickettsial-like illness** primarily transmitted by the human body louse. - The causative agent is the bacterium **Bartonella quintana**, which causes recurrent fever, headache, and body pains. *Q-fever* - Q-fever is caused by the bacterium **Coxiella burnetii** and is typically transmitted through airborne exposure to contaminated aerosols from infected animals. - It presents with fever, headache, and atypical pneumonia, and is not associated with human body lice. *Boutonneuse fever* - This fever is caused by **Rickettsia conorii**, transmitted by the **brown dog tick**. - Characterized by a **maculopapular rash** and an **eschar (tache noire)** at the site of the tick bite. *Indian tick typhus* - This is a form of spotted fever group rickettsiosis caused by **Rickettsia conorii subspecies indica**, transmitted by ticks [1]. - It presents with fever, rash, and an eschar, similar to boutonneuse fever, but is specified for the Indian subcontinent [1].

Q: Eschar is seen in all the Rickettsial diseases except:

Endemic typhus. ***Endemic typhus*** - **Endemic typhus**, caused by *Rickettsia typhi*, is transmitted by **fleas** and typically presents without an eschar. - The disease is characterized by fever, headache, and a maculopapular rash, but the **inoculation site lesion (eschar) is rare or absent**. *Scrub typhus* - **Scrub typhus**, caused by *Orientia tsutsugamushi*, is known for causing a prominent **eschar** [1] at the site of the **chigger mite bite**. - This **painless black scab** is a classic diagnostic feature of the disease [1]. *Rickettsial pox* - **Rickettsial pox**, caused by *Rickettsia akari*, almost invariably presents with an **eschar**, often referred to as an **inoculation lesion**. - This lesion appears as a papule that vesiculates and then forms a scab, indicating the site of the **mite bite**. *Indian tick typhus* - **Indian tick typhus** (part of the **spotted fever group rickettsioses**), caused by *Rickettsia conorii*, frequently presents with a characteristic **eschar** at the site of the **tick bite**. - This eschar, known as a **tache noire**, is a valuable diagnostic clue in affected patients.

Q: Which of the following statements about post-exposure prophylaxis (PEP) for HIV is correct?

Should be started within 72 hours of exposure. ***Should be started within 72 hours of exposure*** - PEP is most effective when initiated as soon as possible after a potential HIV exposure, with the **maximum benefit observed within 72 hours**. - Delaying initiation beyond this window significantly **reduces its efficacy** in preventing HIV seroconversion. *Should be continued for 4 weeks* - PEP is typically continued for 28 days, which is approximately **four weeks**. While this statement is generally true, it is not the most crucial initial action. - The duration of 28 days is crucial for ensuring the antiretroviral drugs effectively interrupt the **HIV replication cycle** before it can establish a permanent infection. *Standard protocol includes three antiretroviral drugs* - The standard PEP regimen typically involves a **combination of three antiretroviral drugs**. However, this option alone does not capture the critical timing aspect of PEP. - The combination of three drugs aims to target different stages of the **HIV life cycle** to maximize the chances of preventing infection. *Involves a combination of antiretroviral drugs for 28 days* - This statement accurately describes the components and duration of PEP but does not emphasize the **critical time window** for initiation, which is the most important factor for its effectiveness. - The **28-day duration** with a combination of drugs is designed to cover the period during which initial HIV replication could occur, allowing the drugs to suppress viral activity.

Q: Buboes form is which stage of LGV?

Secondary. ***Secondary*** - Buboes, which are swollen, painful lymph nodes, are a hallmark of the **secondary stage** of **Lymphogranuloma Venereum (LGV)** [1]. - This stage typically develops weeks after the initial infection, following the unnoticed or transient primary lesion. *Primary* - The primary stage of LGV is characterized by a **small, painless papule or ulcer** at the site of inoculation, which often goes unnoticed. - **Buboes are not formed** during this initial, often asymptomatic, phase. *Tertiary* - The tertiary stage of LGV involves **chronic inflammation** and **tissue destruction**, leading to complications like **genital elephantiasis**, rectal strictures, and fistulas. - While there is chronic lymphedema, the acute, painful buboes are characteristic of the secondary stage, not this late, destructive phase. *Latent* - The concept of a latent stage is not typically used to describe the progression of LGV in the same way as other infections like syphilis. - LGV progresses through distinct symptomatic primary, secondary, and potentially tertiary stages without a prolonged asymptomatic latency period between symptom presentations.

Q: Which of the following statements is true regarding amoebic liver abscess?

Mostly involving the right lobe of the liver.. ***Mostly involving the right lobe of the liver*** - The **right lobe** of the liver is the most common site for an amoebic liver abscess due to its larger size and preferential blood flow from the portal venous system, which drains the intestines where *Entamoeba histolytica* resides. - The **superior mesenteric vein**, draining the cecum and ascending colon (common sites for amebiasis), primarily feeds the right hepatic lobe. *May rupture into the pleural cavity* - While rupture can occur, the **peritoneal cavity** is a more common site of rupture for amoebic liver abscesses. - Rupture into the pleural cavity or lung is less frequent but can lead to **empyema** or **bronchopleural fistula** [1]. *For asymptomatic luminal carriers, metronidazole is the drug of choice* - **Metronidazole** is effective against invasive amoebiasis (like liver abscess or dysentery) but is not the drug of choice for asymptomatic luminal carriers. - For **asymptomatic luminal carriers**, **luminal amebicides** such as **paromomycin** or **diloxanide furoate** are used to eradicate cysts from the intestine [1]. *Multiple abscesses is less common than a single abscess* - **A single amoebic liver abscess** is more common than multiple abscesses [1]. - Multiple abscesses are typically seen in disseminated disease or immunocompromised individuals, though even then a solitary lesion is more frequent.

Q: Most common complication of diphtheria is -

Myocarditis. ***Myocarditis*** - Diphtheria toxin can directly damage myocardial cells, leading to inflammation and dysfunction of the heart muscle, making **myocarditis** the most common and serious complication. - This can result in **heart failure**, arrhythmias, and even death, highlighting its significance in diphtheria. *Pneumonia* - While respiratory complications can occur in diphtheria, **pneumonia** is not the most common or life-threatening complication associated with the diphtheria toxin itself. - Secondary bacterial infections might lead to pneumonia, but it is not a direct toxic effect like myocarditis. *Meningitis* - **Meningitis**, an inflammation of the membranes surrounding the brain and spinal cord, is an extremely rare complication of diphtheria. - Diphtheria primarily affects the upper respiratory tract and heart [1], with neurological complications typically manifesting as neuropathies rather than meningitis. *Endocarditis* - Although diphtheria can cause cardiac complications, **endocarditis** (inflammation of the heart's inner lining, including the valves) is not a common complication. - Myocarditis, due to the direct toxic effect on heart muscle, is far more prevalent than endocarditis in diphtheria.

Question 1

What does the acronym I.R.I.S. stand for in the context of immunology?

Accepted Answer

Immune reconstitution inflammatory syndrome

Answer

Immune reconstitution idiopathic syndrome

Answer

Immune reconstitution immunological syndrome

Answer

Inflammatory reconstitution immune syndrome

Question 2

Which of the following statements about gas gangrene is true?

Accepted Answer

High-dose penicillin is the drug of choice

Answer

Causes mild inflammation of muscles

Answer

Most common cause is Staphylococcus aureus

Answer

Clostridium perfringens produces heat-sensitive spores

Question 3

What is the most common form of leptospirosis?

Accepted Answer

Anicteric form

Answer

Icteric form

Answer

Hepatorenal form

Answer

Weil's disease

Question 4

What is the causative agent of trench fever?

Accepted Answer

Bartonella quintana

Answer

Q-fever

Answer

Boutonneuse fever

Answer

Indian tick typhus

Question 5

Eschar is seen in all the Rickettsial diseases except:

Accepted Answer

Endemic typhus

Answer

Scrub typhus

Answer

Rickettsial pox

Answer

Indian tick typhus

Question 6

What is the recommended regimen for post-exposure prophylaxis for HIV?

Accepted Answer

Tenofovir disoproxil fumarate + Emtricitabine + Dolutegravir for 28 days

Answer

Zidovudine + Lamivudine + Lopinavir/ritonavir for 28 days

Answer

Tenofovir disoproxil fumarate + Emtricitabine + Raltegravir for 28 days

Answer

Single dose Tenofovir + Emtricitabine + Raltegravir

Question 7

Which of the following statements about post-exposure prophylaxis (PEP) for HIV is correct?

Accepted Answer

Should be started within 72 hours of exposure

Answer

Should be continued for 4 weeks

Answer

Standard protocol includes three antiretroviral drugs

Answer

Involves a combination of antiretroviral drugs for 28 days

Question 8

Buboes form is which stage of LGV?

Accepted Answer

Secondary

Answer

Tertiary

Answer

Latent

Answer

Primary

Question 9

Which of the following statements is true regarding amoebic liver abscess?

Accepted Answer

Mostly involving the right lobe of the liver.

Answer

May rupture into the pleural cavity.

Answer

For asymptomatic luminal carriers, metronidazole is the drug of choice.

Answer

Multiple abscesses is less common than a single abscess.

Question 10

Most common complication of diphtheria is -

Accepted Answer

Myocarditis

Answer

Pneumonia

Answer

Meningitis

Answer

Endocarditis

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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