Gastrointestinal Infections — MCQs
A frequent traveler presented with 4 days of continuous fever, abdominal pain, and bradycardia. What is the best diagnostic test to confirm the pathogen?
A child with fever with abdominal cramps & pus in stools, causative organism is ?
A 1-year-old child weighing 6 kg is suffering from acute gastroenteritis with signs of sunken eyes and skin pinch returning to normal very rapidly. What will be your management?
Which disease is characterized by severe watery diarrhea and is associated with a toxin-producing bacterium?
A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are "pea-soup" in consistency. Rose spots are seen on his body. He is most probably infected with:
Which of the following pathogens is most commonly associated with acute infectious diarrhea?
A person returns to Delhi from Bangladesh after 2 days and has diarrhea. Stool examination shows RBC's in stool. The likely organism causing is ?
A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?
According to WHO clinical staging of HIV in children oral hairy leukoplakia belongs to which clinical stages?
Gastrointestinal Infections Indian Medical PG Practice Questions and MCQs
Question 1: A frequent traveler presented with 4 days of continuous fever, abdominal pain, and bradycardia. What is the best diagnostic test to confirm the pathogen?
- A. Widal test
- B. Blood culture (Correct Answer)
- C. Urine culture
- D. Stool culture
Explanation: ***Blood culture*** - **Blood culture** is the most sensitive and specific test for confirming **typhoid fever** in the first week of illness. - The presence of **continuous fever** (step-ladder pattern), **abdominal pain**, and **relative bradycardia** in a traveler strongly suggests typhoid fever caused by *Salmonella Typhi*. *Widal test* - The **Widal test** detects antibodies against *Salmonella Typhi* antigens and is often positive later in the disease course. - It has **limited sensitivity and specificity**, especially in endemic areas or with prior vaccination, leading to false positives and negatives. *Urine culture* - **Urine culture** has a low yield for *Salmonella Typhi*, as bacteria are intermittently shed in urine, usually later in the disease. - It's primarily useful for diagnosing **urinary tract infections** or in chronic carriers of typhoid. *Stool culture* - **Stool culture** yield is higher in the later stages of typhoid fever, as *Salmonella Typhi* is shed in feces. - Its sensitivity is lower than blood culture in the early acute phase when bacteremia is most prominent.
Question 2: A child with fever with abdominal cramps & pus in stools, causative organism is ?
- A. EHEC
- B. ETEC
- C. EAEC (Correct Answer)
- D. EPEC
Explanation: ***EAEC (Enteroaggregative E. coli)*** - Among the E. coli strains listed, EAEC is the answer for this question, though **this is an atypical presentation**. - EAEC classically causes **persistent watery diarrhea** (>14 days) in children, often with **low-grade fever** and **abdominal pain**. - While EAEC primarily causes non-bloody diarrhea, it can occasionally produce **mucoid stools** with inflammatory cells due to mucosal inflammation from biofilm formation. - **Note:** The classic organism for fever + cramps + pus in stools would be **Shigella**, **Campylobacter**, or **EIEC (Enteroinvasive E. coli)** - not listed here. *EHEC (Enterohemorrhagic E. coli)* - EHEC (O157:H7) causes **hemorrhagic colitis** with bloody diarrhea due to **Shiga toxins**. - Can lead to **hemolytic uremic syndrome (HUS)** in children. - Characterized by **blood** rather than pus in stools, distinguishing it from typical dysentery. *ETEC (Enterotoxigenic E. coli)* - Most common cause of **traveler's diarrhea** and watery diarrhea in developing countries. - Produces **heat-labile (LT)** and **heat-stable (ST)** enterotoxins causing secretory diarrhea. - Results in profuse **watery stools without inflammation, blood, or pus**. *EPEC (Enteropathogenic E. coli)* - Leading cause of infantile diarrhea in developing countries. - Causes **attaching and effacing** lesions on intestinal mucosa. - Results in **watery diarrhea without significant inflammatory cells or pus** in stools.
Question 3: A 1-year-old child weighing 6 kg is suffering from acute gastroenteritis with signs of sunken eyes and skin pinch returning to normal very rapidly. What will be your management?
- A. RL infusion 120 ml in the first hour followed by 360 ml in the next 5 hours
- B. RL infusion 180 ml in the first hour followed by 480 ml in the next 5 hours
- C. RL infusion 240 ml in the first hour followed by 360 ml in the next 5 hours
- D. RL infusion 180 ml in the first hour followed by 270 ml in the next 5 hours (Correct Answer)
Explanation: ***RL infusion 180 ml in the first hour followed by 270 ml in the next 5 hours*** - The child shows signs of **some dehydration** (sunken eyes, skin pinch returning very rapidly). According to **WHO Plan B**, some dehydration requires **75 ml/kg over 6 hours** for rehydration. - For a 6 kg child: **75 × 6 = 450 ml total** - **Distribution:** 30 ml/kg in first hour (180 ml) + 45 ml/kg over next 5 hours (270 ml) - This option provides exactly **450 ml (180 + 270)**, perfectly matching WHO guidelines for some dehydration *RL infusion 120 ml in the first hour followed by 360 ml in the next 5 hours* - First hour: 120 ml = only **20 ml/kg**, which is **below the recommended 30 ml/kg** initial bolus for some dehydration - Total volume: **480 ml** exceeds the required **450 ml** for a 6 kg child - Incorrect fluid distribution pattern for WHO Plan B *RL infusion 180 ml in the first hour followed by 480 ml in the next 5 hours* - First hour volume is correct at **30 ml/kg (180 ml)** - However, next 5 hours: **480 ml = 80 ml/kg**, far exceeding the recommended **45 ml/kg** - Total: **660 ml** significantly exceeds **450 ml**, risking **fluid overload** in a small child *RL infusion 240 ml in the first hour followed by 360 ml in the next 5 hours* - Initial rate: **240 ml = 40 ml/kg** is appropriate for **severe dehydration (WHO Plan C)**, not some dehydration - This child shows **some dehydration** signs, not severe (no lethargy, unconsciousness, or very slow skin pinch) - Total: **600 ml** exceeds the **450 ml** requirement, indicating overtreatment for this clinical scenario
Question 4: Which disease is characterized by severe watery diarrhea and is associated with a toxin-producing bacterium?
- A. Gastroenteritis
- B. Cholera (Correct Answer)
- C. Dysentery
- D. Typhoid fever
Explanation: ***Cholera*** - Cholera is known for causing **severe, watery diarrhea** (often described as "rice water stools") due to the action of **cholera toxin** produced by *Vibrio cholerae* [1], [2]. - The toxin stimulates excessive fluid and electrolyte secretion in the small intestine, leading to rapid **dehydration** and electrolyte imbalance [2]. *Gastroenteritis* - This is a general term for **inflammation of the stomach and intestines**, which can be caused by various pathogens (viruses, bacteria, parasites) and toxins. - While it often presents with diarrhea, it doesn't specifically imply the **severe watery diarrhea** linked to a specific toxin as seen in cholera. *Dysentery* - Dysentery is characterized by **bloody diarrhea**, often accompanied by **fever and abdominal cramps**, indicating inflammation and damage to the intestinal lining [3]. - It is typically caused by bacteria like *Shigella* or *entamoeba histolytica*, distinct from the purely watery diarrhea of cholera [3]. *Typhoid fever* - Typhoid fever is a systemic illness caused by *Salmonella typhi*, characterized by **sustained fever, headache, malaise**, and can include **constipation or mild diarrhea**. - It does not primarily present with **severe watery diarrhea** induced by a specific toxin, unlike cholera.
Question 5: A 17 year old adolescent, presented with fever since one week which is step-ladder in pattern. He also has loose stools which are "pea-soup" in consistency. Rose spots are seen on his body. He is most probably infected with:
- A. Salmonella typhi (Correct Answer)
- B. Adenovirus
- C. Rotavirus
- D. Vibrio cholerae
Explanation: ***Salmonella typhi*** - The combination of **step-ladder fever**, **"pea-soup" diarrhea**, and **rose spots** is a classic presentation of **typhoid fever**, caused by *Salmonella typhi* [1]. - This bacterial infection predominantly affects the gastrointestinal tract and can lead to systemic symptoms [1]. *Adenovirus* - **Adenovirus** typically causes **respiratory tract infections**, **conjunctivitis**, or **gastroenteritis**, but not with the specific symptom profile of step-ladder fever or rose spots. - While it can cause diarrhea, it's usually not described as "pea-soup" and lacks the other systemic features. *Rotavirus* - **Rotavirus** is a common cause of **severe gastroenteritis** in infants and young children, characterized by **watery diarrhea** and vomiting. - It does not present with step-ladder fever or rose spots, which are pathognomonic for typhoid. *Vibrio cholerae* - **Vibrio cholerae** causes **cholera**, an acute diarrheal illness characterized by **profuse watery diarrhea** (often described as "rice-water stools") and rapid dehydration. - It does not typically cause step-ladder fever or skin manifestations like rose spots.
Question 6: Which of the following pathogens is most commonly associated with acute infectious diarrhea?
- A. Salmonella
- B. Escherichia coli
- C. Shigella
- D. Rotavirus (Correct Answer)
Explanation: ***Rotavirus*** - **Rotavirus** is the leading cause of **severe, acute diarrheal disease** in **infants and young children worldwide**, especially in unvaccinated populations. - It causes significant **morbidity and mortality** globally, primarily through dehydration. *Salmonella* - While *Salmonella* can cause acute infectious diarrhea, particularly **foodborne outbreaks**, it is **less common overall** than rotavirus, especially in children. - It often presents with **fever, abdominal cramps**, and **bloody or non-bloody diarrhea**, and can lead to systemic infections. *Escherichia coli* - Various strains of *E. coli* can cause diarrhea (e.g., **ETEC, EPEC, EHEC**), but collectively they do not surpass rotavirus as the single most common cause of acute infectious diarrhea globally. - **Enterohemorrhagic *E. coli* (EHEC)**, particularly O157:H7, is known for causing **hemorrhagic colitis** and **hemolytic uremic syndrome**. *Shigella* - *Shigella* species cause **bacillary dysentery**, characterized by **bloody diarrhea, fever, and severe abdominal cramps**. - While it is a significant cause of diarrheal disease, its prevalence is generally **lower than rotavirus**, especially in developed countries.
Question 7: A person returns to Delhi from Bangladesh after 2 days and has diarrhea. Stool examination shows RBC's in stool. The likely organism causing is ?
- A. Enteropathogenic E. Coli
- B. Salmonella typhi
- C. Enterotoxigenic E. Coli
- D. Shigella dysenteriae (Correct Answer)
Explanation: ***Shigella dysenteriae*** - This organism causes **bacillary dysentery**, characterized by fever, abdominal cramps, and frequent, small-volume stools containing **blood and mucus (RBCs)**, which fits the clinical picture of a traveler experiencing diarrhea with RBCs in stool. - The rapid onset (within 2 days of return) and the presence of **RBCs in stool** are highly suggestive of an invasive bacterial pathogen like *Shigella*. *Enteropathogenic E. Coli* - **EPEC** typically causes **watery diarrhea**, particularly in infants, by disrupting intestinal microvilli. - It does **not usually cause bloody stools** or significant red blood cells in the stool. *Salmonella typhi* - While *Salmonella typhi* causes **typhoid fever**, its initial presentation is typically with fever, headache, and constipation, followed by a **pea-soup diarrhea** in later stages, which is usually not bloody. - The rapid onset of bloody diarrhea within 2 days is less characteristic of typhoid fever, which has a longer incubation period. *Enterotoxigenic E. Coli* - **ETEC** is a common cause of **traveler's diarrhea**, but it produces toxins that lead to **watery, non-bloody diarrhea**. - The presence of **RBCs in the stool** makes ETEC an unlikely cause in this scenario.
Question 8: A child presents with a fever and a rash. Urine examination showed cells with owl's eye appearance. What is the most likely diagnosis?
- A. Herpes simplex virus infection
- B. Toxoplasmosis caused by Toxoplasma gondii
- C. Cytomegalovirus (CMV) infection (Correct Answer)
- D. Infectious mononucleosis caused by Epstein-Barr virus
Explanation: ***Cytomegalovirus (CMV) infection*** - The presence of cells with an **owl's eye appearance** in urine sediment is a classic histological hallmark of **CMV infection**. - CMV can cause a variety of symptoms in children, including **fever and rash**, making this the most likely diagnosis. *Herpes simplex virus infection* - HSV causes characteristic **vesicular lesions** on mucocutaneous surfaces, often associated with fever. - While HSV can cause systemic illness, it does not typically present with **owl's eye inclusions** in urine cells. *Toxoplasmosis caused by Toxoplasma gondii* - **Toxoplasmosis** can cause fever and rash, especially in congenital infections or immunocompromised individuals. - However, it does not lead to **owl's eye inclusions** in urinary cells, which are pathognomonic for CMV. *Infectious mononucleosis caused by Epstein-Barr virus* - **Infectious mononucleosis** commonly presents with fever, fatigue, and lymphadenopathy, sometimes with a rash. - **Epstein-Barr virus (EBV)** infection does not produce cells with an **owl's eye appearance** in the urine; that is specific to CMV.
Question 9: An asymptomatic infant with a history of TB exposure, is 3 months old and had taken 3 months of chemoprophylaxis, what is to be done next?
- A. Immunise with BCG and stop prophylaxis
- B. Continue prophylaxis for 3 months
- C. Test sputum, then decide
- D. Tuberculin test, then decide (Correct Answer)
Explanation: ***Tuberculin test, then decide*** - A **tuberculin skin test (TST)** or **IGRA** should be performed after completing the initial chemoprophylaxis period to determine if the infant has developed **latent TB infection (LTBI)**. - According to **IAP guidelines**, if TST is **negative**, complete a total of **6 months of prophylaxis** and then administer **BCG vaccine**. - If TST is **positive**, it indicates LTBI and the infant should complete the full course of treatment as per standard protocols. - The decision to continue, modify, or stop treatment depends on **TST results** and **clinical evaluation**. *Immunise with BCG and stop prophylaxis* - **BCG vaccination** should not be given during or immediately after stopping prophylaxis without first performing a **TST**. - In TB-endemic areas, BCG is ideally given at birth, but if delayed due to TB exposure, it should only be given after **ruling out infection** with a negative TST. - Stopping prophylaxis prematurely without assessment can increase the risk of developing **active TB**. *Continue prophylaxis for 3 months* - While the standard duration of prophylaxis is **6 months total**, blindly continuing for another 3 months without TST assessment is not the most appropriate next step. - The decision to continue should be based on **TST results** performed at this juncture, not arbitrary time extension. - Prolonged unnecessary prophylaxis can lead to **drug toxicity** and **poor compliance**. *Test sputum, then decide* - An **asymptomatic infant** is unlikely to produce sputum, making this test impractical and inappropriate. - Sputum testing is used for diagnosing **active pulmonary TB**, which is not suspected in this asymptomatic child. - Sputum testing is invasive and reserved for children with **clinical symptoms** suggestive of active disease such as persistent cough, fever, or weight loss.
Question 10: According to WHO clinical staging of HIV in children oral hairy leukoplakia belongs to which clinical stages?
- A. Clinical stage 1
- B. Clinical stage 3
- C. Clinical stage 4
- D. Clinical stage 2 (Correct Answer)
Explanation: ***Clinical stage 2*** - **Oral hairy leukoplakia** is classified under WHO clinical stage 2 for HIV infection, representing mild symptomatic disease with moderate immune compromise. - Stage 2 includes conditions such as **angular cheilitis**, **papular pruritic eruptions**, **recurrent oral ulcerations**, **herpes zoster**, **lineal gingival erythema**, and **recurrent upper respiratory tract infections**. - **Note:** Oral hairy leukoplakia is **rare in children** and is more commonly seen in adults with HIV; it is caused by **Epstein-Barr virus** reactivation. *Clinical stage 1* - This stage includes **asymptomatic** HIV infection or **persistent generalized lymphadenopathy**. - Stage 1 represents minimal or no immune compromise with no clinical manifestations requiring intervention. *Clinical stage 3* - Clinical stage 3 represents **advanced symptomatic disease** with conditions like **unexplained severe malnutrition**, **unexplained persistent diarrhea**, **oral candidiasis**, **pulmonary tuberculosis**, and **severe recurrent bacterial pneumonia**. - These conditions indicate more severe immunodeficiency than oral hairy leukoplakia. *Clinical stage 4* - Clinical stage 4 represents **severe HIV disease** with AIDS-defining illnesses such as **Pneumocystis jirovecii pneumonia**, **extrapulmonary tuberculosis**, **Kaposi's sarcoma**, **HIV encephalopathy**, **CMV retinitis**, and **disseminated mycobacterial infections**. - Stage 4 conditions are life-threatening and indicate severe immunosuppression.
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