Gastrointestinal Infections Indian Medical PG Practice Questions and MCQs
Practice Indian Medical PG questions for Gastrointestinal Infections. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Gastrointestinal Infections Indian Medical PG Question 1: A child with fever with abdominal cramps & pus in stools, causative organism is ?
- A. EHEC
- B. ETEC
- C. EAEC (Correct Answer)
- D. EPEC
Gastrointestinal Infections 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.
Gastrointestinal Infections Indian Medical PG Question 2: A tourist with a travel history to India presents with complaints of abdominal pain and multiple episodes of watery diarrhea. He reports having food at a local restaurant the previous night. Which of the following antidiarrheal agents is used in this condition?
- A. Bismuth subsalicylate
- B. Octreotide
- C. Loperamide
- D. Rifaximin (Correct Answer)
- E. Ciprofloxacin
Gastrointestinal Infections Explanation: ***Rifaximin***
- This patient's symptoms, including **abdominal pain**, **watery diarrhea**, and a recent **travel history to India** coupled with eating at a local restaurant, strongly suggest **traveler's diarrhea**, often caused by bacterial pathogens.
- **Rifaximin** is a non-absorbable antibiotic specifically approved for treating non-invasive traveler's diarrhea, as it targets causative bacteria in the gut lumen with minimal systemic absorption.
- Rifaximin is preferred due to its **excellent safety profile**, minimal systemic effects, and targeted action against enteric pathogens.
*Ciprofloxacin*
- **Ciprofloxacin** is a fluoroquinolone antibiotic that can be effective for traveler's diarrhea and has been used historically for this indication.
- However, rifaximin is now preferred over ciprofloxacin due to increasing **fluoroquinolone resistance** among enteric pathogens, systemic absorption leading to more side effects, and FDA warnings about serious adverse effects associated with fluoroquinolones.
- Ciprofloxacin may be reserved for more severe or invasive diarrhea cases.
*Bismuth subsalicylate*
- While **bismuth subsalicylate** can be used for symptomatic relief in traveler's diarrhea due to its anti-secretory and anti-inflammatory properties, it is not an antimicrobial agent.
- It works by reducing fluid secretion and inflammation but does not directly address the underlying bacterial infection to the same extent as rifaximin.
*Octreotide*
- **Octreotide** is a somatostatin analog primarily used to treat severe, refractory diarrhea associated with conditions like neuroendocrine tumors or chemotherapy, not typical bacterial traveler's diarrhea.
- Its mechanism involves inhibiting gastrointestinal hormone secretion and reducing intestinal motility, which is too potent for this common, self-limiting condition.
*Loperamide*
- **Loperamide** is an opioid-receptor agonist that acts as an anti-motility agent, reducing the frequency of bowel movements.
- It is generally contraindicated as a primary treatment for traveler's diarrhea when an invasive bacterial infection is suspected, as it can prolong the retention of toxins and pathogens in the gut.
Gastrointestinal Infections Indian Medical PG Question 3: 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
Gastrointestinal Infections 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.
Gastrointestinal Infections Indian Medical PG Question 4: The most common causative organism for traveler's diarrhea is which of the following?
- A. E. coli (Correct Answer)
- B. Shigella
- C. Norwalk virus
- D. Rotavirus
Gastrointestinal Infections Explanation: ***Correct: E. coli***
- **Enterotoxigenic Escherichia coli (ETEC)** is the most frequent cause of **traveler's diarrhea** worldwide, accounting for **30-40% of cases**.
- It produces heat-labile (LT) and heat-stable (ST) enterotoxins that lead to **watery diarrhea** without significant fever or bloody stools.
- Particularly common in travelers to **developing countries** in Latin America, Africa, and South Asia.
*Incorrect: Shigella*
- While it can cause severe diarrheal illness (dysentery) characterized by **bloody stools**, it accounts for only **5-10% of traveler's diarrhea cases**.
- **Shigella infection** is more often associated with person-to-person spread and outbreaks in crowded settings.
*Incorrect: Norwalk virus*
- Also known as **Norovirus**, it is a very common cause of **gastroenteritis** globally, affecting people of all ages.
- However, it is primarily responsible for widespread outbreaks, often in cruise ships or institutions, rather than being the predominant cause of individual traveler's diarrhea cases.
*Incorrect: Rotavirus*
- This virus is a major cause of **severe dehydrating diarrhea** in **infants and young children** worldwide.
- While it can affect travelers, it is less common in adults and generally not considered the predominant cause of traveler's diarrhea in the general traveling population.
Gastrointestinal Infections Indian Medical PG Question 5: A 7-year-old girl passed 15 stools in the last 24 hours and vomited thrice in the last 4 hours. She is irritable but drinking fluids. What is the optimal therapy?
- A. IV fluids
- B. IV fluids followed by ORS
- C. ORS (Correct Answer)
- D. Home fluids
Gastrointestinal Infections Explanation: ***Correct: ORS (Oral Rehydration Solution)***
- The child has **some dehydration** (15 stools/24h, irritable, recent vomiting)
- **Key feature: She is able to drink fluids** - this is the critical determinant for ORS therapy
- According to **WHO Plan B** and **IAP guidelines**, children with some dehydration who can drink should receive ORS
- ORS should be given at **75 mL/kg over 4 hours** for some dehydration
- This is the **optimal first-line therapy** for this dehydration level
*Incorrect: IV fluids*
- Too aggressive for a child who can drink fluids
- Reserved for **severe dehydration** or inability to tolerate oral intake
- Unnecessary invasive intervention with associated risks
*Incorrect: IV fluids followed by ORS*
- IV therapy is not indicated as first-line when child can drink
- This approach is used when IV rehydration is needed initially but child improves
- Overtreatment for this clinical scenario
*Incorrect: Home fluids*
- Insufficient for documented dehydration with high stool frequency
- Does not provide the **balanced electrolyte composition** of ORS
- Home fluids (water, juices) may worsen electrolyte imbalance
Gastrointestinal Infections Indian Medical PG Question 6: All of the following cause hemolytic uremic syndrome except
- A. Vibrio cholera (Correct Answer)
- B. EHEC
- C. Campylobacter
- D. Shigella
Gastrointestinal Infections Explanation: ***Vibrio cholera***
- *Vibrio cholerae* causes **cholera**, characterized by severe watery diarrhea, dehydration, and electrolyte imbalance, but does not typically produce **Shiga toxin** or cause microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury characteristic of HUS.
- While it can lead to acute kidney injury due to severe dehydration, it does not directly cause the **microangiopathic hemolytic anemia** and thrombocytopenia seen in HUS.
*EHEC*
- **Enterohemorrhagic *E. coli* (EHEC)**, particularly serotype O157:H7, is the most common cause of **Shiga toxin-producing E. coli (STEC)-HUS** [2].
- The **Shiga toxin** produced by EHEC damages endothelial cells, leading to platelet aggregation, hemolysis, and renal damage [2].
*Campylobacter*
- **Campylobacter jejuni** infections can sometimes precede the development of **HUS**, particularly in children.
- While less common than EHEC, *Campylobacter* can produce a **cytolethal distending toxin** which has been implicated in endothelial damage and HUS.
*Shigella*
- Certain species of **Shigella**, especially *Shigella dysenteriae type 1*, produce **Shiga toxin** and are a known cause of **HUS**.
- Similar to EHEC, the Shiga toxin from *Shigella* leads to widespread endothelial damage, resulting in microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury [1].
Gastrointestinal Infections Indian Medical PG Question 7: Traveller's diarrhea is caused by:
- A. EPEC
- B. EIEC
- C. ETEC (Correct Answer)
- D. EHEC
Gastrointestinal Infections Explanation: ***ETEC***
- **Enterotoxigenic E. coli (ETEC)** is the most common cause of **traveler's diarrhea**, primarily through the production of **heat-labile (LT)** and **heat-stable (ST)** toxins.
- These toxins stimulate **fluid and electrolyte secretion** in the small intestine, leading to watery diarrhea.
*EPEC*
- **Enteropathogenic E. coli (EPEC)** causes diarrhea, particularly in infants, by forming characteristic **attaching and effacing (A/E) lesions** on intestinal epithelial cells.
- EPEC does not produce the toxins typically associated with traveler's diarrhea.
*EIEC*
- **Enteroinvasive E. coli (EIEC)** causes a form of dysentery by invading and destroying the colonic epithelium, similar to Shigella.
- Its clinical presentation involves fever, abdominal cramps, and bloody diarrhea, which is distinct from the watery diarrhea of traveler's diarrhea.
*EHEC*
- **Enterohemorrhagic E. coli (EHEC)**, especially O157:H7, is known for causing **hemorrhagic colitis** and **hemolytic uremic syndrome (HUS)**, through the production of **Shiga toxins**.
- While it causes severe gastrointestinal disease, it is not the primary cause of typical traveler's diarrhea.
Gastrointestinal Infections Indian Medical PG Question 8: Patient presenting with abdominal pain, diarrhea taking clindamycin for 5 days. Treated with metronidazole symptoms subsided. What is the causative agent -
- A. Clostridium difficile (Correct Answer)
- B. Clostridium welchii
- C. Clostridium perfringens
- D. Clostridium botulinum
Gastrointestinal Infections Explanation: ***Clostridium difficile***
- **Clindamycin** is a common antibiotic associated with **Clostridium difficile** infection, which causes **antibiotic-associated diarrhea** and **colitis**.
- The successful treatment with **metronidazole** further supports the diagnosis of *C. difficile* infection.
*Clostridium welchii* (also known as *Clostridium perfringens*)
- Primarily causes **gas gangrene** and **food poisoning**, with symptoms more acute and severe than described.
- Not typically associated with antibiotic-induced diarrhea but rather **contaminated food** or **wound infections**.
*Clostridium perfringens*
- This bacterium is a common cause of **food poisoning** (type A) featuring **abdominal cramps** and **diarrhea**, and **gas gangrene** (type C) due to deep tissue infections.
- While it can cause diarrhea, it's not the classic cause of **antibiotic-associated diarrhea** like *C. difficile*.
*Clostridium botulinum*
- Produces a **neurotoxin** that causes **flaccid paralysis**, not abdominal pain and diarrhea due to antibiotic use.
- The infection is typically acquired through **improperly canned food** or **wound contamination**.
Gastrointestinal Infections Indian Medical PG Question 9: Traveller's diarrhoea is caused by:
- A. E. histolytica
- B. E. coli (Correct Answer)
- C. Giardia lamblia
- D. Shigella
Gastrointestinal Infections Explanation: ***E. coli***
- **Enterotoxigenic E. coli (ETEC)** is the most common cause of **traveler's diarrhea**, producing toxins that lead to watery stools.
- The disease is typically acquired through ingestion of **contaminated food or water**, particularly in regions with poor sanitation.
*E. histolytica*
- This parasite causes **amoebiasis**, which can lead to **dysentery** (bloody diarrhea) or liver abscesses.
- While it can cause diarrhea in travelers, it is not the most frequent pathogen associated with typical traveler's diarrhea.
*Giardia lamblia*
- **Giardiasis** typically results in **chronic, greasy, foul-smelling stools**, bloating, and malabsorption rather than acute watery diarrhea.
- It's a common cause of **protracted diarrhea** in travelers but not the most frequent cause of acute onset.
*Shigella*
- This bacterium causes **shigellosis**, characterized by **dysentery (bloody, mucoid stools)**, fever, and abdominal cramps.
- While a cause of bacterial diarrhea in travelers, it is less common than ETEC and presents with a more severe, invasive illness.
Gastrointestinal Infections Indian Medical PG Question 10: All of the following statements are true regarding central nervous system infections, except:
- A. Prions infection causes spongiform encephalopathy
- B. JC virus is causative agent for progressive multifocal leucoencephalopathy
- C. Cytomegalovirus is a common cause of bilateral temporal lobe hemorrhagic infarction (Correct Answer)
- D. Measles virus is the causative agent for subacute sclerosing pan encephalitis (SSPE)
Gastrointestinal Infections Explanation: ***Cytomegalovirus is a common cause of bilateral temporal lobe hemorrhagic infarction.***
- **Cytomegalovirus (CMV)** typically causes **ventriculoencephalitis or periventricular necrosis** and microglial nodules in immunocompromised patients, not bilateral temporal lobe hemorrhagic infarction.
- **Herpes simplex virus type 1 (HSV-1)** is the classic infectious cause of **bilateral temporal lobe hemorrhagic infarction (necrotizing encephalitis)**.
*Prions infection causes spongiform encephalopathy*
- **Prions** are misfolded proteins that cause transmissible spongiform encephalopathies (TSEs), such as Creutzfeldt-Jakob disease, characterized by **neuronal loss** and vacuolation (spongiform changes).
- These diseases are invariably fatal and lead to rapid neurological deterioration.
*JC virus is causative agent for progressive multifocal leucoencephalopathy*
- The **JC virus** specifically targets and destroys **oligodendrocytes**, the myelin-producing cells of the central nervous system.
- This leads to **demyelination** in multiple areas of the brain, causing the characteristic lesions seen in progressive multifocal leukoencephalopathy (PML).
*Measles virus is the causative agent for subacute sclerosing pan encephalitis (SSPE).*
- **Subacute sclerosing panencephalitis (SSPE)** is a rare, fatal, progressive neurodegenerative disease caused by a persistent and defective **measles virus infection** in the brain.
- It occurs years after the initial measles infection, leading to cognitive decline, seizures, and motor dysfunction.
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