Infectious Diseases — MCQs

Which of the following statements with regard to Enteric perforation are correct? 1. Salmonella typhi is the causative organism for Enteric fever 2. Enteric perforation characteristically occurs during the third week of illness 3. Typhoid ulcers are placed transversely to the long axis of the gut 4. Terminal ileum is the most common site for enteric perforation

Q758

A 50 year old female presents to the emergency with pain, swelling and redness over the left foot following a trivial trauma 3 days back. On examination, the swelling over the left foot is poorly localised; local tenderness and erythema are present and crepitus is absent; distal pulsations are palpable. The most likely clinical diagnosis is

Q759

Which of the following statements is not true regarding HIV infection?

Q760

Consider the following features of cholera: 1. Onset with purging. 2. No nausea or retching. 3. No tenesmus. 4. Leukocytosis. Which of the above features of cholera differentiate it from food poisoning?

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 751: The following statements regarding small bowel tuberculosis are correct except

A. There are two types : ulcerative and hyperplastic
B. In the ulcerative type, the bowel serosa is studded with tubercles
C. The ulcerative type occurs when the virulence of the organism is greater than the host defence
D. The strictures are common in the ulcerative type (Correct Answer)

Explanation: ***The strictures are common in the ulcerative type*** - While both ulcerative and hyperplastic types of small bowel tuberculosis can lead to complications, **strictures are more characteristic of the hyperplastic type**. - In the **hyperplastic form**, chronic inflammation, fibrosis, and granuloma formation cause wall thickening and luminal narrowing, resulting in strictures. *There are two types : ulcerative and hyperplastic* - This statement is correct. Small bowel tuberculosis is broadly classified into **ulcerative** and **hyperplastic** forms, with mixed types also occurring. - The type is often determined by the interplay between the virulence of the organism and the host's immune response. *In the ulcerative type, the bowel serosa is studded with tubercles* - This statement is correct. The **ulcerative type** is often associated with the **spread of infection to the serosa**, leading to the formation of visible **tubercles**. - This indicates more extensive disease and possible peritoneal involvement. *The ulcerative type occurs when the virulence of the organism is greater than the host defence* - This statement is correct. The **ulcerative form** is often observed when the **organism's virulence is high** and/or the host's **immune response is weak**, leading to destructive lesions. - This imbalance results in caseating necrosis and ulceration of the bowel wall.

Question 752: Match List-I with List-II and select the correct answer using the code given below the Lists:

A. A→1 B→2 C→3 D→4
B. A→3 B→1 C→4 D→2
C. A→3 B→4 C→1 D→2 (Correct Answer)
D. A→2 B→4 C→1 D→3

Explanation: ***A→3 B→4 C→1 D→2*** - This option correctly matches each condition with its primary causative agent: **Viral hepatitis** with **Hepatitis A, B, C**; **Amoebic liver abscess** with **Entamoeba histolytica**; **Ascending cholangitis** with **Enteric bacteria**; and **Hydatid liver disease** with **Echinococcus granulosus**. - This mapping accurately reflects established medical knowledge regarding the etiology of these liver and biliary tract conditions. *A→1 B→2 C→3 D→4* - This option incorrectly associates viral hepatitis with enteric bacteria and amoebic liver abscess with Echinococcus granulosus, which are not the primary causes. - The link between ascending cholangitis and hepatitis viruses is also incorrect, as ascending cholangitis is typically bacterial. *A→3 B→1 C→4 D→2* - This option correctly matches viral hepatitis, but incorrectly attributes amoebic liver abscess to enteric bacteria and ascending cholangitis to Entamoeba histolytica. - The causative agent for amoebic liver abscess is *Entamoeba histolytica*, not enteric bacteria, and ascending cholangitis is caused by bacteria, not *Entamoeba histolytica*. *A→2 B→4 C→1 D→3* - This option incorrectly links viral hepatitis to Echinococcus granulosus and hydatid liver disease to hepatitis viruses. - Hydatid liver disease is caused by *Echinococcus granulosus*, and viral hepatitis is caused by hepatitis viruses, so these are mismatched.

Question 753: WHO defines a multi-drug resistant (MDR) Tuberculosis strain as one that is:

A. Resistant to INH and Rifampicin with or without resistant to other anti TB drugs (Correct Answer)
B. At least resistant to INH
C. At least resistant to Rifampicin
D. Resistant to Streptomycin only

Explanation: The World Health Organization (WHO) defines **multi-drug resistant tuberculosis (MDR-TB)** as resistance to at least both **isoniazid (INH)** and **rifampicin**, which are the two most potent first-line anti-TB drugs. This definition is crucial for guiding treatment regimens, as standard first-line therapies are ineffective, necessitating more complex and longer treatment plans [1]. Resistance to INH alone is termed **isoniazid monoresistance**, not MDR-TB. While INH resistance is significant, it does not meet the WHO criteria for multi-drug resistance without concurrent rifampicin resistance [1]. Resistance to rifampicin alone is known as **rifampicin monoresistance**. This is a serious form of drug resistance, as rifampicin is a cornerstone of TB treatment, but it does not equate to MDR-TB unless INH resistance is also present [1]. Resistance to **streptomycin** alone is a form of drug resistance, but streptomycin is a second-line injectable agent, not a core first-line drug [1].

Question 754: A pregnant woman in third trimester having fever was diagnosed as a case of Falciparum malaria. Under the National Health Programme, which drug is recommended?

A. ACT only (Correct Answer)
B. Only Quinine
C. ACT accompanied by single dose of Primaquine on day 2
D. Chloroquine

Explanation: **ACT only** - **Artemisinin-based Combination Therapy (ACT)** is the recommended first-line treatment for uncomplicated *P. falciparum* malaria in pregnant women during the second and third trimesters under national health programs [1]. - ACTs are generally considered safe and effective in these trimesters, providing rapid parasite clearance and preventing recrudescence [1]. *Only Quinine* - While quinine is effective against *P. falciparum* and can be used in pregnancy, it is often reserved for severe malaria or in cases where ACT is contraindicated [1]. - It has a higher incidence of side effects like **cinchonism** (tinnitus, headache, nausea) compared to ACT. *ACT accompanied by single dose of Primaquine on day 2* - **Primaquine** is an antimalarial drug used for radical cure of *P. vivax* and *P. ovale* to prevent relapse, and as a gametocytocide for *P. falciparum* [1]. - It is **contraindicated in pregnancy** due to the risk of inducing **hemolysis** in the fetus if they have glucose-6-phosphate dehydrogenase (G6PD) deficiency. *Chloroquine* - **Chloroquine** is largely ineffective against *P. falciparum* malaria in many endemic regions due to widespread **drug resistance**. - Its use is primarily limited to sensitive *P. vivax*, *P. ovale*, and *P. malariae* infections.

Question 755: Current WHO recommendations for initiating Antiretroviral treatment (ART) in HIV +ve individuals is:

A. All HIV positive individuals regardless of CD4 count
B. CD4 cells less than 200 cells/mm3
C. CD4 cells less than or equal to 350 cells/mm3 (Correct Answer)
D. CD4 cells less than 300 cells/mm3

Explanation: ***CD4 cells less than or equal to 350 cells/mm3*** - This option reflects the historical WHO guideline for initiating ART [1]. While guidelines have evolved, at one point, starting ART when CD4 count was **≤350 cells/mm³** was the standard. - This threshold aimed to prevent opportunistic infections and disease progression by initiating treatment before significant immune compromise [2]. *All HIV positive individuals regardless of CD4 count* - This represents the **current WHO recommendation** for initiating ART, known as "Test and Treat," where all HIV-positive individuals are recommended to start ART immediately upon diagnosis [3]. - Starting ART regardless of CD4 count has been shown to reduce HIV transmission and improve health outcomes for individuals. *CD4 cells less than 200 cells/mm3* - This was an **earlier and more restrictive threshold** for ART initiation, typically reserved for individuals with severe immune suppression and a high risk of opportunistic infections [2]. - Delaying ART until CD4 count dropped this low was associated with poorer clinical outcomes and increased mortality. *CD4 cells less than 300 cells/mm3* - This threshold was also an **earlier guideline** for ART initiation, indicating a more advanced stage of immune compromise than current recommendations. - It represented an intermediate point between very low CD4 counts and the broader "Test and Treat" approach.

Question 756: Cellulitis is:

A. Infection caused by Gram negative bacilli
B. A nonsuppurative invasive infection of tissues
C. A suppurative invasive infection of skin and subcutaneous tissues (Correct Answer)
D. Infection caused by anaerobic Streptococci

Explanation: ***A suppurative invasive infection of skin and subcutaneous tissues*** - Cellulitis is characterized by **inflammation** and **infection** of the dermis and subcutaneous fat, often leading to pus formation (**suppurative**). - It involves an **invasive** spread of bacteria through these layers of tissue, rather than just superficial involvement [1]. *Infection caused by Gram negative bacilli* - While Gram-negative bacilli can cause soft tissue infections, **cellulitis is most commonly caused by Gram-positive bacteria** like *Staphylococcus aureus* or *Streptococcus pyogenes* [1]. - Attributing cellulitis solely to Gram-negative bacilli is too restrictive and often incorrect for typical presentations. *A nonsuppurative invasive infection of tissues* - Cellulitis is typically a **suppurative infection**, meaning it involves the formation of pus, which contradicts the "nonsuppurative" description [1]. - While it is an **invasive infection**, the lack of pus formation distinguishes it from classic cellulitis. *Infection caused by anaerobic Streptococci* - **Anaerobic Streptococci** are not the primary or most common cause of typical cellulitis; rather, **aerobic *Streptococcus pyogenes*** and *Staphylococcus aureus* are the main culprits. - Infections caused by anaerobic bacteria often present with **foul-smelling discharge** and specific clinical contexts like deep wound infections or abscesses.

Question 757: Which of the following statements with regard to Enteric perforation are correct? 1. Salmonella typhi is the causative organism for Enteric fever 2. Enteric perforation characteristically occurs during the third week of illness 3. Typhoid ulcers are placed transversely to the long axis of the gut 4. Terminal ileum is the most common site for enteric perforation

A. 2, 3 and 4
B. 1, 2 and 4 (Correct Answer)
C. 1, 3 and 4
D. 1, 2 and 3

Explanation: ***1, 2 and 4*** * **Salmonella typhi** is indeed the causative organism for **enteric fever**, often known as typhoid fever. * **Enteric perforation** characteristically occurs during the **third week of illness** due to progressive ulceration of **Peyer's patches** [1]. * The **terminal ileum** is the **most common site** for enteric perforation because it has the highest concentration of **Peyer's patches**, which are target sites for Salmonella typhi [1]. *2, 3 and 4* * While enteric perforation typically occurs in the third week and the terminal ileum is the most common site, the statement about **typhoid ulcers** being placed transversely is incorrect. * **Typhoid ulcers** are characteristically oriented **longitudinally** along the long axis of the gut, following the orientation of the underlying Peyer's patches [1]. *1, 3 and 4* * Although Salmonella typhi is the causative organism and the terminal ileum is the most common site, the statement about **typhoid ulcers** being placed **transversely** is incorrect. * Perforation typically occurs during the **third week of illness**, which is an important clinical detail missed in this option [1]. *1, 2 and 3* * **Salmonella typhi** is the causative organism for enteric fever, and perforation does occur during the **third week of illness** [1]. * However, the statement that **typhoid ulcers** are placed **transversely** is incorrect; they are **longitudinal** in orientation.

Question 758: A 50 year old female presents to the emergency with pain, swelling and redness over the left foot following a trivial trauma 3 days back. On examination, the swelling over the left foot is poorly localised; local tenderness and erythema are present and crepitus is absent; distal pulsations are palpable. The most likely clinical diagnosis is

A. Abscess
B. Fasciitis
C. Compartment syndrome
D. Cellulitis (Correct Answer)

Explanation: **Cellulitis** - The clinical presentation of **pain, swelling, redness, poorly localized swelling**, and local tenderness following a minor trauma strongly suggests **cellulitis** [1]. - The absence of crepitus and presence of palpable distal pulses argue against severe infections like necrotizing fasciitis or compartment syndrome. *Abscess* - An abscess typically presents as a **localized, fluctuant** collection of pus, distinct from the poorly localized swelling described. - While an abscess can cause pain, swelling, and redness, its **well-demarcated nature** would differentiate it from the diffuse presentation of cellulitis [1]. *Fasciitis* - **Necrotizing fasciitis** is characterized by severe pain out of proportion to examination findings, rapid progression, systemic toxicity, and often **crepitus** due to gas production by bacteria. - The description lacks signs of overwhelming infection and crepitus, making fasciitis less likely. *Compartment syndrome* - Compartment syndrome involves severe pain, **pallor, paresthesia, pulselessness**, and paralysis (the 5 Ps), caused by increased pressure within a fascial compartment. - The presence of **palpable distal pulsations** makes compartment syndrome highly unlikely, as it typically impairs blood flow.

Question 759: Which of the following statements is not true regarding HIV infection?

A. All HIV positive mothers transmit infection to their newborn children. (Correct Answer)
B. Infected blood transfusion leads to 100% transmission among recipients.
C. Every HIV infected person would require antiretroviral treatment during lifetime.
D. HIV does not transmit through fomites.

Explanation: ***All HIV positive mothers transmit infection to their newborn children*** - While **vertical transmission** from mother to child is a significant risk, it is not 100% [1]. With proper antenatal care, **antiretroviral therapy (ART)**, and interventions like elective C-sections or avoiding breastfeeding, the transmission rate can be reduced to less than 1% [1]. - This statement is **false** because various preventative measures can significantly lower the risk of transmission. *Infected blood transfusion leads to 100% transmission among recipients* - This statement is **true**. Although rare due to improved screening, if blood containing HIV is transfused, the recipient will almost certainly become infected due to the direct route of entry of a high viral load directly into the bloodstream [1]. - The high viral load and direct intravascular inoculation bypass natural barriers, making transmission virtually guaranteed. *Every HIV infected person would require antiretroviral treatment during lifetime* - This statement is **true**. Current guidelines recommend that all individuals diagnosed with **HIV infection** should start antiretroviral therapy (ART) regardless of CD4 count, to preserve immune function, prevent opportunistic infections, and reduce transmission [2]. - **ART** is a lifelong commitment, as stopping treatment typically leads to viral rebound and disease progression. *HIV does not transmit through fomites* - This statement is **true**. HIV is a fragile virus that cannot survive long outside the human body and is not transmitted via casual contact or inanimate objects (**fomites**) like doorknoobs, toilet seats, or shared utensils. - Transmission primarily occurs through **blood, semen, pre-ejaculate, rectal fluids, vaginal fluids, and breast milk** [1].

Question 760: Consider the following features of cholera: 1. Onset with purging. 2. No nausea or retching. 3. No tenesmus. 4. Leukocytosis. Which of the above features of cholera differentiate it from food poisoning?

A. 2, 3 and 4
B. 1, 2 and 3 (Correct Answer)
C. 1, 2 and 4
D. 1, 2, 3 and 4

Explanation: ***1, 2 and 3*** - **Cholera** classically presents with abrupt onset of **painless, watery diarrhea** (purging), often described as "rice-water" stools, typically without significant nausea, retching, or tenesmus [1], [2]. Food poisoning caused by bacterial toxins often involves **nausea, vomiting**, and sometimes abdominal cramps and tenesmus, making features 1, 2, and 3 distinguishing [1], [2]. - The absence of significant inflammation in cholera, unlike many forms of food poisoning, also means that systemic inflammatory markers and symptoms like **fever** are less prominent, and there is no **leukocytosis**. *2, 3 and 4* - This option incorrectly includes the absence of **leukocytosis** as a differentiating feature when food poisoning can also be non-inflammatory, and it omits the crucial feature of **onset with purging**, which is highly characteristic of cholera [1]. - While lack of nausea/retching and tenesmus are key, including leukocytosis as a differentiator without considering other factors is misleading. *1, 2 and 4* - This option misses the absence of **tenesmus** (3), which is a key differentiating feature where **cholera** typically causes painless, watery stools without the straining associated with inflammatory bowel conditions or some types of food poisoning [1], [2]. - It also includes **leukocytosis** (4), which is typically absent in cholera but can be present or absent in food poisoning depending on the cause, making it less specific for differentiation than other features. *1, 2, 3 and 4* - While features 1, 2, and 3 are indeed differentiating, feature 4, **leukocytosis**, is **incorrect** as a differentiating factor in the context of cholera. Cholera typically does not cause leukocytosis because it is a non-inflammatory enterotoxin-mediated illness. - Many forms of food poisoning, especially those mediated by toxins or non-invasive bacteria, also do not cause significant leukocytosis.

Practice by Chapter

Principles of Antimicrobial Therapy

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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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