Infectious Diseases Practice Questions

Q: A recently married woman presents with dysuria and increased urinary frequency of two-days duration. On physical examination, her body temperature is 38°C and her vital signs are normal. Her gynaecologic examination does not reveal any vaginal discharge, vaginitis or cervicitis. Her urine analysis reveals 14 WBC per high power field and many gram negative rods. Which of the following is the most appropriate pharmacotherapy ?

Nitrofurantoin. ***Nitrofurantoin*** - **Nitrofurantoin** is a first-line agent for **uncomplicated cystitis** due to its good efficacy, low resistance rates, and minimal systemic side effects. - Its concentration in the urine is high, making it effective against common urinary pathogens like **Gram-negative rods**. - **Note:** The patient has a temperature of 38°C, which is borderline. Current guidelines suggest that **fever may indicate upper tract involvement** (pyelonephritis), where nitrofurantoin would be less appropriate due to poor tissue penetration. However, with **normal vital signs** and localized symptoms, this may represent uncomplicated cystitis with mild pyrexia. *Ciprofloxacin* - **Fluoroquinolones** like ciprofloxacin are highly effective and achieve excellent tissue penetration, making them ideal for **complicated UTIs or pyelonephritis**. - The presence of **fever (38°C)** could justify fluoroquinolone use, as it may indicate upper tract involvement. - However, fluoroquinolones are increasingly reserved for complicated cases due to concerns about promoting **antibiotic resistance** and potential side effects (e.g., tendon rupture, C. difficile). - **Current IDSA guidelines** recommend fluoroquinolones when pyelonephritis is suspected. *Trimethoprim-sulfamethoxazole* - While effective for UTIs, **trimethoprim-sulfamethoxazole** resistance rates have increased significantly, particularly among *E. coli* strains. - It can be used for uncomplicated cystitis when local resistance rates are <20%, but is less preferred than nitrofurantoin in many settings. *Amoxicillin* - **Amoxicillin** is not recommended as first-line treatment for acute cystitis due to high rates of **bacterial resistance**, particularly from common uropathogens like *E. coli*. - Its efficacy against **Gram-negative rods** is limited, especially with prevalent beta-lactamase production.

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

CD4 cells less than or equal to 350 cells/mm3. ***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.

Q: A pregnant woman in 2nd trimester of pregnancy from North Eastern State has been diagnosed with uncomplicated P. falciparum. She should be treated with:

Artemether and Lumefantrine. ***Artemether and Lumefantrine*** - This combination is a **fixed-dose artemisinin-based combination therapy (ACT)** specifically recommended by WHO for treating uncomplicated *P. falciparum* malaria in the **second and third trimesters of pregnancy**. - ACTs are highly effective against *P. falciparum* and have a favorable safety profile compared to other antimalarials during this period of pregnancy. *Chloroquine and Primaquine* - **Chloroquine** is primarily used for treatment of *P. vivax* and *P. ovale* malaria, as *P. falciparum* has widespread resistance. - **Primaquine** is contraindicated in pregnancy due to the risk of **hemolysis** in the fetus if there is G6PD deficiency and is used for radical cure of *P. vivax* and *P. ovale*. *Artesunate and Sulphadoxine* - While **artesunate** is an artemisinin derivative, **sulphadoxine** is often combined with pyrimethamine (as SP, sulphadoxine-pyrimethamine) for intermittent preventive treatment in pregnancy (IPTp) but is not the first-line for *uncomplicated P. falciparum* treatment in the second trimester, especially with increasing resistance. - This combination lacks the **lumefantrine** component, which provides a longer duration of action and higher efficacy when combined with artemether. *Artesunate, Sulphadoxine and Pyrimethamine* - The combination of **sulphadoxine-pyrimethamine (SP)** alone or with artesunate can be used for intermittent preventive treatment in pregnancy (IPTp), but it is generally *not* the first-line treatment for **uncomplicated P. falciparum malaria** in the 2nd trimester due to resistance concerns and the superior efficacy of Artemether-Lumefantrine. - **Pyrimethamine** is a folate antagonist and generally avoided in significant doses during pregnancy if alternatives are available, although it is part of SP for IPTp.

Q: 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

Cellulitis. **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.

Q: 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?

1, 2 and 3. ***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.

Q: Tuberculosis in HIV positive individuals is characterized by which of the following? 1. More frequent negative sputum smears. 2. More false–negative tuberculin test results. 3. More extra–pulmonary tuberculosis. 4. More cavitating lesions in lungs as shown by chest X-ray. Select the correct answer using the code given below:

1, 2 and 3 only. ***1, 2, and 3 only*** - HIV coinfection impairs cell-mediated immunity, leading to **atypical presentations** of TB [1]. All three options (more frequent negative sputum smears, more false-negative tuberculin tests, and more extrapulmonary TB) are characteristic of TB in HIV-positive individuals due to this **immunodeficiency** [2]. - The immunocompromised state often results in a **diminished inflammatory response**, making diagnosis more challenging and dissemination more likely. *1, 2, 3 and 4* - This option incorrectly includes "more cavitating lesions in lungs as shown by chest X-ray" as a characteristic feature. HIV-positive individuals, particularly those with advanced immunodeficiency, tend to have **fewer cavitating lesions** because their immune system is less capable of mounting the robust inflammatory response required for cavitation [1]. - Cavitation is more typical of **immunocompetent** individuals with pulmonary TB [1]. *3 and 4 only* - This option is incorrect because, while **more extrapulmonary tuberculosis** is characteristic, **more cavitating lesions** are generally not observed in HIV-positive individuals; in fact, the opposite is true. - The combination of these two points together makes this option largely inaccurate. *1 and 2 only* - While **more frequent negative sputum smears** and **false-negative tuberculin tests** [2] are indeed characteristic, this option is incomplete as it misses the increased prevalence of **extrapulmonary TB** [3], which is a significant feature in HIV-positive individuals. - HIV-related immunodeficiency often leads to the widespread dissemination of *Mycobacterium tuberculosis* outside the lungs [3].

Q: Which of the following is not a clinical feature of tetanus?

Loss of consciousness. ***Loss of consciousness*** - Tetanus is characterized by **spasms** and increased muscle tone, but patients typically remain **fully conscious** throughout the disease course. - The disease primarily affects the **motor neurons**, not the brain structures responsible for consciousness. *Risus sardonicus* - This is a characteristic feature of tetanus, referring to a **sustained, grotesque grin** caused by spasms of the facial muscles. - It is a classic clinical sign resulting from the **excitatory effects** of tetanospasmin on motor neurons [1]. *Respiratory failure* - This is a common and serious complication of tetanus, often leading to death, caused by **spasms of the respiratory muscles** [1]. - **Laryngeal spasms** and rigidity of the chest wall muscles impair breathing, necessitating mechanical ventilation. *Opisthotonus* - This refers to a severe, sustained **arching of the back** due to muscle spasms, causing the head and heels to bend backward. - It is a hallmark sign of generalized tetanus, reflecting profound **muscle rigidity** and uncontrolled muscle contractions [1].

Question 1

A recently married woman presents with dysuria and increased urinary frequency of two-days duration. On physical examination, her body temperature is 38°C and her vital signs are normal. Her gynaecologic examination does not reveal any vaginal discharge, vaginitis or cervicitis. Her urine analysis reveals 14 WBC per high power field and many gram negative rods. Which of the following is the most appropriate pharmacotherapy ?

Accepted Answer

Nitrofurantoin

Answer

Trimethoprim-sulfamethoxazole

Answer

Amoxicillin

Answer

Ciprofloxacin

Question 2

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

Accepted Answer

Resistant to INH and Rifampicin with or without resistant to other anti TB drugs

Answer

At least resistant to INH

Answer

At least resistant to Rifampicin

Answer

Resistant to Streptomycin only

Question 3

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

Accepted Answer

CD4 cells less than or equal to 350 cells/mm3

Answer

All HIV positive individuals regardless of CD4 count

Answer

CD4 cells less than 200 cells/mm3

Answer

CD4 cells less than 300 cells/mm3

Question 4

Cellulitis is:

Accepted Answer

A suppurative invasive infection of skin and subcutaneous tissues

Answer

Infection caused by Gram negative bacilli

Answer

A nonsuppurative invasive infection of tissues

Answer

Infection caused by anaerobic Streptococci

Question 5

A pregnant woman in 2nd trimester of pregnancy from North Eastern State has been diagnosed with uncomplicated P. falciparum. She should be treated with:

Accepted Answer

Artemether and Lumefantrine

Answer

Chloroquine and Primaquine

Answer

Artesunate and Sulphadoxine

Answer

Artesunate, Sulphadoxine and Pyrimethamine

Question 6

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

Accepted Answer

Cellulitis

Answer

Abscess

Answer

Fasciitis

Answer

Compartment syndrome

Question 7

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

Accepted Answer

All HIV positive mothers transmit infection to their newborn children.

Answer

Infected blood transfusion leads to 100% transmission among recipients.

Answer

Every HIV infected person would require antiretroviral treatment during lifetime.

Answer

HIV does not transmit through fomites.

Question 8

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?

Accepted Answer

1, 2 and 3

Answer

2, 3 and 4

Answer

1, 2 and 4

Answer

1, 2, 3 and 4

Question 9

Tuberculosis in HIV positive individuals is characterized by which of the following?

1. More frequent negative sputum smears.
2. More false–negative tuberculin test results.
3. More extra–pulmonary tuberculosis.
4. More cavitating lesions in lungs as shown by chest X-ray.

Select the correct answer using the code given below:

Accepted Answer

1, 2 and 3 only

Answer

1, 2, 3 and 4

Answer

1 and 2 only

Answer

3 and 4 only

Question 10

Which of the following is not a clinical feature of tetanus?

Accepted Answer

Loss of consciousness

Answer

Risus sardonicus

Answer

Respiratory failure

Answer

Opisthotonus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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