Infectious Diseases Practice Questions

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].

Q: An adult woman presents with the clinical condition shown in the image, and a Gram stain reveals Gram-negative diplococci. What is the most appropriate treatment?

Ceftriaxone. ***Ceftriaxone*** - The image shows **cervicitis** (discharge from the cervix), and the Gram stain revealing **Gram-negative diplococci** is characteristic of **Neisseria gonorrhoeae**. - **Ceftriaxone** is the recommended first-line treatment for **gonorrhea**, often administered as a single intramuscular dose. *Azithromycin* - While often co-administered with ceftriaxone to cover potential **Chlamydia coinfection**, it is not the primary treatment for gonorrhea alone. - Doxycycline is generally preferred for uncomplicated **Chlamydia trachomatis** infections in nonpregnant adults. *Doxycycline* - **Doxycycline** is a highly effective antibiotic for treating **Chlamydia trachomatis** infections and certain other bacterial STIs. - It is not the primary treatment for **gonorrhea** due to resistance concerns and preferred efficacy of cephalosporins. *Acyclovir* - **Acyclovir** is an antiviral medication used to treat infections caused by the **herpes simplex virus (HSV)**. - It has no activity against **bacterial infections** like gonorrhea, making it inappropriate for this presentation.

Q: A 25-year-old woman with HIV (CD4 count 320/μL) presents with vulvar ulceration for 3 weeks. Initial testing for HSV, syphilis, and chancroid is negative. Empiric treatment for these conditions does not improve the lesion. Biopsy shows a dense lymphoplasmacytic infiltrate with CMV inclusions. What is the most appropriate management?

Intravenous ganciclovir for 14-21 days. The biopsy showing **CMV inclusions** confirms **cytomegalovirus (CMV) infection** as the cause of the vulvar ulceration. **Ganciclovir** is the first-line antiviral treatment for serious CMV infections, especially in immunocompromised patients, and intravenous administration provides sufficient systemic efficacy. *Oral fluconazole for 14 days* - **Fluconazole** is an antifungal medication primarily used to treat candidiasis [1]. - It would be ineffective against **CMV**, which is a viral infection, and is not indicated for her current diagnosis. *Topical corticosteroids* - **Corticosteroids** are anti-inflammatory agents that could potentially worsen a viral infection by further suppressing the immune response [1]. - They do not address the underlying **CMV infection** and are therefore contraindicated as primary treatment for this condition. *Oral valacyclovir for 14 days* - **Valacyclovir** is an antiviral medication effective against **herpes simplex virus (HSV)** and **varicella-zoster virus (VZV)** [2]. - While initial HSV testing was negative, and valacyclovir is not effective against **CMV** [2].

Q: A 30-year-old woman presents with dysuria, urinary frequency, and lower abdominal pain for 3 days. She has a new sexual partner. On examination, she has suprapubic tenderness but no cervical motion tenderness or vaginal discharge. Urine dipstick shows positive leukocyte esterase but negative nitrites. Microscopy reveals numerous WBCs but no bacteria. What is the most likely diagnosis and appropriate management?

Acute urethral syndrome due to C. trachomatis - Doxycycline. ### Acute urethral syndrome due to C. trachomatis - Doxycycline - The presence of **dysuria**, **frequency**, **pyuria** (leukocyte esterase, WBCs) without **bacteriuria** or positive nitrites, especially in a sexually active young woman with a new partner, is highly suggestive of **acute urethral syndrome** often caused by *Chlamydia trachomatis* [1]. - **Doxycycline** is the recommended first-line treatment for *Chlamydia trachomatis* infections [3]. *Gonorrheal urethritis - Ceftriaxone* - While *Neisseria gonorrhoeae* can cause **urethritis**, it typically presents with purulent urethral discharge, which is absent here [2]. - While Ceftriaxone is appropriate for gonorrhea, the clinical picture and lab findings (no bacteria, high WBCs) are more consistent with chlamydia [3]. *Interstitial cystitis - Pain management and urinary analgesics* - **Interstitial cystitis** typically presents with chronic (more than 6 weeks) pelvic pain, urinary urgency, and frequency, often without evidence of infection or a clear trigger like a new sexual partner. - The acute onset and clear inflammatory markers (pyuria) make this diagnosis less likely. *Acute bacterial cystitis - Empiric antibiotic therapy* - Although there is **dysuria** and **frequency**, the **absence of nitrites** and **bacteria** on microscopy and dipstick makes bacterial cystitis less likely. - The presence of pyuria without bacteriuria in this context points to urethritis, likely non-gonococcal [1].

Q: A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?

Strongyloides stercoralis. ***Strongyloides stercoralis*** - The presence of **larvae** in the stool [2], particularly **rhabditiform larvae**, is characteristic of *Strongyloides stercoralis* infection, as this parasite has an **autoinfective cycle** involving larval stages in the human host [2]. - In HIV-positive patients, *Strongyloides* can cause **hyperinfection syndrome**, leading to severe gastrointestinal symptoms like foul-smelling stools, and increased larval shedding [2]. *Ascaris lumbricoides* - *Ascaris lumbricoides* is a large intestinal nematode, but it typically presents with **ova** (eggs) in the stool, not larvae, as the eggs hatch in the small intestine. - While it can cause gastrointestinal symptoms, the hallmark microscopic finding in stool samples is the presence of **mammillated or decorticated eggs**. *Ancylostoma duodenale* - *Ancylostoma duodenale* (hookworm) infections are identified by the presence of **eggs** in the stool [1], which are typically oval with a thin shell and contain a developing larva. - Hookworm larvae usually develop in **soil** and infect humans through skin penetration, rather than being commonly found in stool samples from intestinal infection [1]. *Schistosoma mansoni* - *Schistosoma mansoni* is a **blood fluke** that causes intestinal schistosomiasis, characterized by the presence of **spined eggs** in the stool. - The parasite's life cycle involves **freshwater snails** as intermediate hosts, and a **larval stage (cercariae)** that penetrates human skin, but larvae are not typically found in human stool.

Question 1

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 2

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 3

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 4

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 5

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 6

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

Accepted Answer

Loss of consciousness

Answer

Risus sardonicus

Answer

Respiratory failure

Answer

Opisthotonus

Question 7

An adult woman presents with the clinical condition shown in the image, and a Gram stain reveals Gram-negative diplococci. What is the most appropriate treatment?

Accepted Answer

Ceftriaxone

Answer

Azithromycin

Answer

Doxycycline

Answer

Acyclovir

Question 8

A 25-year-old woman with HIV (CD4 count 320/μL) presents with vulvar ulceration for 3 weeks. Initial testing for HSV, syphilis, and chancroid is negative. Empiric treatment for these conditions does not improve the lesion. Biopsy shows a dense lymphoplasmacytic infiltrate with CMV inclusions. What is the most appropriate management?

Accepted Answer

Intravenous ganciclovir for 14-21 days

Answer

Oral fluconazole for 14 days

Answer

Topical corticosteroids

Answer

Oral valacyclovir for 14 days

Question 9

A 30-year-old woman presents with dysuria, urinary frequency, and lower abdominal pain for 3 days. She has a new sexual partner. On examination, she has suprapubic tenderness but no cervical motion tenderness or vaginal discharge. Urine dipstick shows positive leukocyte esterase but negative nitrites. Microscopy reveals numerous WBCs but no bacteria. What is the most likely diagnosis and appropriate management?

Accepted Answer

Acute urethral syndrome due to C. trachomatis - Doxycycline

Answer

Gonorrheal urethritis - Ceftriaxone

Answer

Interstitial cystitis - Pain management and urinary analgesics

Answer

Acute bacterial cystitis - Empiric antibiotic therapy

Question 10

A patient living with HIV presents with foulsmelling stools. Microscopic examination of the stool reveals no cysts or ova, but a 200-micrometer larva is observed. What is the most likely pathogen?

Accepted Answer

Strongyloides stercoralis

Answer

Ascaris lumbricoides

Answer

Ancylostoma duodenale

Answer

Schistosoma mansoni

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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