Organic Irritant Poisons — MCQs
Toxic megacolon is seen in -
Abrus precatorius poisoning resembles which poison?
A child accidentally ingested a fruit from a tree while playing. After the ingestion, he presented with symptoms of restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature. What is the most likely cause of poisoning, and what is the appropriate antidote for it?
Which of the following is a stomach poison?
Artificial bruises are produced by:
Poisoning with which of the following retards putrefaction:
Vitreous humor is preserved in suspected poisoning with:
Chronic arsenic poisoning does not cause:
A person working in a dye factory presented with nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach. Which poisoning do you suspect in this case?
Postmortem caloricity is seen in
Organic Irritant Poisons Indian Medical PG Practice Questions and MCQs
Question 1: Toxic megacolon is seen in -
- A. Crohn's disease
- B. Colonic diverticulosis
- C. Hamartomatous polyp
- D. Chronic nonspecific ulcerative colitis (Correct Answer)
Explanation: ***Chronic nonspecific ulcerative colitis*** - **Toxic megacolon** is a severe complication of **ulcerative colitis**, characterized by acute toxic symptoms and **colonic dilation**. [1] - It results from inflammation extending into the **muscularis propria**, leading to colonic dysfunction and paralysis. *Crohn's disease* - While Crohn's disease can affect any part of the gastrointestinal tract and cause severe inflammation, **toxic megacolon is rarer** in Crohn's than in ulcerative colitis. [1] - Crohn's disease is more commonly associated with **strictures**, **fistulas**, and **skip lesions**. [1] *Colonic diverticulosis* - **Colonic diverticulosis** refers to the presence of small outpouchings in the colon wall, which can become inflamed (diverticulitis). - It does not typically lead to direct **toxic megacolon**, although severe diverticulitis can rarely cause a localized form of colonic distension. *Hamartomatous polyp* - A **hamartomatous polyp** is a non-neoplastic growth that results from an abnormal mixture of normal tissues. - These polyps are associated with various syndromes (e.g., Peutz-Jeghers syndrome) but are **not a cause of toxic megacolon**.
Question 2: Abrus precatorius poisoning resembles which poison?
- A. Arsenic
- B. Ricin (Correct Answer)
- C. Cyanide
- D. Thallium
Explanation: ***Ricin*** - The toxic protein in *Abrus precatorius* seeds, **abrin**, is structurally and functionally similar to **ricin** from *Ricinus communis* seeds. - Both abrin and ricin are **ribosome-inactivating proteins**, leading to similar clinical presentations of multi-organ failure. *Arsenic* - Arsenic poisoning primarily affects the GI tract, cardiovascular system, and nervous system, causing symptoms like **rice-water stools** and **garlic odor** on breath. - It works through enzyme inhibition, specifically targeting **pyruvate dehydrogenase**, unlike the ribosome-inactivating mechanism of abrin. *Cyanide* - Cyanide poisoning rapidly impairs **cellular respiration** by inhibiting cytochrome c oxidase, leading to cellular hypoxia and lactic acidosis. - Clinical features include **rapid onset of symptoms**, bright red venous blood, and **almond odor**, which are distinct from abrin poisoning. *Thallium* - Thallium poisoning is characterized by **neurological symptoms** (e.g., severe peripheral neuropathy), **alopecia**, and gastrointestinal distress. - It interferes with potassium channels and ATPase pumps, a different mechanism of toxicity compared to abrin.
Question 3: A child accidentally ingested a fruit from a tree while playing. After the ingestion, he presented with symptoms of restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature. What is the most likely cause of poisoning, and what is the appropriate antidote for it?
- A. Datura poisoning & Physostigmine (Correct Answer)
- B. Yellow Oleander poisoning & Atropine
- C. Datura poisoning & Pralidoxime
- D. Organophosphate poisoning & Pralidoxime
- E. Mushroom (Amanita) poisoning & Atropine
Explanation: ***Datura poisoning & Physostigmine*** - The symptoms of **restlessness, painful swallowing, photophobia, dry skin, urinary retention, and elevated body temperature** are classic signs of **anticholinergic toxicity**, which is characteristic of **Datura poisoning**. - **Physostigmine** is an **acetylcholinesterase inhibitor** that increases acetylcholine levels, effectively reversing the anticholinergic effects of Datura. *Yellow Oleander poisoning & Atropine* - **Yellow Oleander poisoning** primarily causes **cardiac effects** (e.g., bradycardia, arrhythmias) due to cardiac glycosides, not the anticholinergic symptoms described. - **Atropine** is an **anticholinergic agent** and would worsen the symptoms of Datura poisoning rather than being an antidote for it. *Datura poisoning & Pralidoxime* - While **Datura poisoning** is correct given the symptoms, **Pralidoxime** is an antidote for **organophosphate poisoning**, acting as a cholinesterase reactivator, and has no efficacy in anticholinergic toxicity. *Organophosphate poisoning & Pralidoxime* - **Organophosphate poisoning** presents with **cholinergic symptoms** (e.g., salivation, lacrimation, urination, defecation, GI upset, emesis, miosis, bronchospasm, bradycardia), which are opposite to the anticholinergic signs seen here. - Although **Pralidoxime** is a correct antidote for organophosphate poisoning, the clinical picture does not support this diagnosis. *Mushroom (Amanita) poisoning & Atropine* - **Certain mushroom poisonings** (e.g., muscarine-containing mushrooms like *Inocybe* and *Clitocybe* species) cause **cholinergic symptoms** (salivation, sweating, miosis, bradycardia), not anticholinergic symptoms. - While **Atropine** would be the correct antidote for muscarinic mushroom poisoning, the clinical presentation here shows anticholinergic toxicity, not cholinergic excess.
Question 4: Which of the following is a stomach poison?
- A. Paris green (Correct Answer)
- B. DDT
- C. Malathion
- D. Pyrethrum
Explanation: ***Paris green*** * **Paris green** (copper(II) acetoarsenite) is primarily used as a **stomach poison** for insects, meaning it needs to be ingested to be effective. * It is a **highly toxic inorganic compound** that disrupts cellular respiration. * *DDT* * **DDT (dichlorodiphenyltrichloroethane)** is a **contact poison** and neurotoxin, primarily absorbed through the insect's cuticle. * It primarily affects the insects' **nervous system**, causing uncontrolled firing of neurons. * *Malathion* * **Malathion** is an **organophosphate insecticide** that acts as a **contact and stomach poison**, but its primary mode of action is through contact and fumigant effects. * It inhibits **acetylcholinesterase**, leading to paralysis and death in insects. * *Pyrethrum* * **Pyrethrum** is a natural insecticide derived from **chrysanthemum flowers** that acts primarily as a **contact poison** and repellent. * It causes **rapid knockdown** of insects by affecting their nervous system, though many insects may recover if not exposed to high enough doses.
Question 5: Artificial bruises are produced by:
- A. Capsicum
- B. Marking nut (Correct Answer)
- C. Rati
- D. Croton
Explanation: ***Marking nut*** - The **marking nut** (*Semecarpus anacardium*) contains a vesicant oil that causes a chemical burn, mimicking a true bruise. - This effect is often described in forensic medicine as producing **artificial bruises** or **factitious injuries**. *Capsicum* - **Capsicum** (found in chili peppers) causes irritation and a burning sensation, but typically does not produce dermal lesions that resemble a bruise. - It might cause redness due to vasodilatation but not the characteristic blue-black discoloration of a bruise. *Rati* - **Rati**, or **Abrus precatorius** (rosary pea), is highly toxic due to abrin, a potent toxin. - While ingestion or injection can cause severe systemic effects, it is not known to produce localized artificial bruises on the skin. *Croton* - **Croton** oil, derived from *Croton tiglium*, is a strong purgative and skin irritant. - It can cause severe blistering and inflammation upon topical application but does not typically create lesions that are mistaken for a bruise.
Question 6: Poisoning with which of the following retards putrefaction:
- A. Arsenic (Correct Answer)
- B. Lead
- C. Aluminium phosphide
- D. Copper
Explanation: ***Arsenic*** - **Arsenic** is a known **preservative** of tissues due to its ability to inhibit bacterial growth and enzyme activity, thereby retarding putrefaction. - In cases of arsenic poisoning, the decomposition of a body may be noticeably slower, and the tissues can appear unusually well-preserved. *Lead* - While **lead** is a heavy metal and can have toxic effects, it is not primarily known for its ability to significantly **retard putrefaction**. - Its toxic mechanisms do not involve direct inhibition of bacterial and enzymatic processes in a way that typically preserves tissues post-mortem. *Aluminium phosphide* - **Aluminium phosphide** is a highly toxic pesticide that can cause rapid death, but it does not have properties that actively **retard the process of putrefaction**. - Its mechanism of toxicity primarily involves the release of phosphine gas, which causes cellular damage, rather than tissue preservation. *Copper* - **Copper**, another heavy metal, has antimicrobial properties but is not recognized as an agent that significantly **retards putrefaction** in the same manner as arsenic. - Its acute and chronic toxic effects do not typically lead to the preservation of tissues after death.
Question 7: Vitreous humor is preserved in suspected poisoning with:
- A. Cyanide
- B. Morphine
- C. Alcohol (Correct Answer)
- D. Carbon monoxide
Explanation: ***Alcohol*** - **Vitreous humor** is an ideal sample for postmortem alcohol analysis due to its **sequestration** from other body fluids, which minimizes postmortem production or degradation of alcohol. - Its **avascular nature** and **slow diffusion** rates ensure that the alcohol concentration in the vitreous humor closely reflects the ante-mortem blood alcohol concentration. *Cyanide* - Sampling **vitreous humor** is generally not the primary choice for detecting cyanide because cyanide is rapidly absorbed and metabolized, making its detection more reliable in other tissues. - Cyanide can degrade in biological samples, and its concentration in the vitreous humor may not accurately reflect the lethal dose or recent exposure. *Morphine* - While **vitreous humor** can be used for opiate detection, **blood and urine** are generally preferred for initial screening and quantitative analysis of morphine. - Morphine undergoes metabolism during its elimination, and its distribution into the vitreous humor might not always accurately reflect the **pharmacodynamics** or precise time of exposure compared to blood. *Carbon monoxide* - **Carbon monoxide (CO) poisoning** is primarily diagnosed by measuring **carboxyhemoglobin levels** in blood, as CO binds avidly to hemoglobin. - The vitreous humor is not a suitable sample for detecting carbon monoxide or carboxyhemoglobin as it lacks red blood cells and hemoglobin, which are the targets of CO toxicity.
Question 8: Chronic arsenic poisoning does not cause:
- A. Mesothelioma (Correct Answer)
- B. Anemia
- C. Hyperkeratosis of skin
- D. Mixed sensory and motor neuropathy
Explanation: ***Mesothelioma*** - **Mesothelioma** is a rare cancer of the lining of the lungs, abdomen, or heart, strongly associated with **asbestos exposure**, not chronic arsenic poisoning. - While arsenic is carcinogenic, it primarily causes cancers of the skin, bladder, and lung, but not typically mesothelioma. *Anemia* - **Chronic arsenic poisoning** can lead to **anemia** through various mechanisms, including **bone marrow suppression** and hemolysis. - Arsenic interferes with red blood cell production and survival, contributing to reduced hemoglobin levels. *Hyperkeratosis of skin* - One of the classic dermatological manifestations of **chronic arsenic poisoning** is **hyperkeratosis**, particularly on the palms and soles. - This often presents as thickened, discolored skin lesions following prolonged exposure. *Mixed sensory and motor neuropathy* - **Chronic arsenic exposure** is well-known to cause **peripheral neuropathy**, affecting both sensory and motor nerves. - Patients often experience numbness, tingling, weakness, and pain, especially in a "stocking-glove" distribution.
Question 9: A person working in a dye factory presented with nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach. Which poisoning do you suspect in this case?
- A. Potassium permanganate (Correct Answer)
- B. Lead
- C. Arsenic
- D. Thallium
Explanation: ***Potassium permanganate*** - The presence of **nausea, vomiting, dark bloody stools, conjunctivitis, and a burning sensation in the throat and stomach** is highly indicative of **potassium permanganate poisoning**, which is a caustic agent. - Exposure in a **dye factory** setting further supports this, as potassium permanganate is used as an **oxidizing agent** and **dyeing agent** in various industries. *Lead* - Lead poisoning typically presents with **neurological symptoms** (e.g., foot drop, wrist drop, encephalopathy), **gastrointestinal complaints** (e.g., colic, constipation), and **hematological abnormalities** (e.g., anemia with basophilic stippling). - The acute caustic effects like **burning sensation in the throat and bloody stools** are not characteristic of lead poisoning. *Arsenic* - Acute arsenic poisoning often involves **severe gastroenteritis** ("rice-water stools"), **garlic odor on breath**, **peripheral neuropathy**, and **cardiac arrhythmias**. - While it can cause gastrointestinal distress, the specific caustic burn and conjunctivitis alongside the industrial exposure profile point away from arsenic. *Thallium* - Thallium poisoning is characterized by **rapid hair loss (alopecia)**, **severe peripheral neuropathy**, and **gastrointestinal symptoms** (e.g., abdominal pain, vomiting, diarrhea). - The constellation of symptoms described, particularly the caustic burn and dark bloody stools, does not align with the typical presentation of thallium toxicity.
Question 10: Postmortem caloricity is seen in
- A. Datura poisoning
- B. Strychnine poisoning (Correct Answer)
- C. Ergot poisoning
- D. Organophosphorus poisoning
Explanation: ***Strychnine poisoning*** - **Postmortem caloricity**, an abnormal persistence of body heat after death, is a classic sign associated with **strychnine poisoning**. - This symptom arises due to intense **muscular spasms** and convulsions caused by strychnine, leading to excessive heat generation. *Datura poisoning* - **Datura poisoning** typically presents with symptoms related to **anticholinergic effects**, such as dry mouth, dilated pupils, tachycardia, and delirium. - It does not characteristically cause postmortem caloricity, as muscle rigidity is not a primary feature. *Ergot poisoning* - **Ergot poisoning**, or **ergotism**, is characterized by symptoms like gangrene of the extremities (St. Anthony's Fire) due to **vasoconstriction** and neurological effects such as seizures and hallucinations. - It does not typically lead to postmortem caloricity. *Organophosphorus poisoning* - **Organophosphorus poisoning** primarily manifests with **cholinergic overstimulation** symptoms, including salivation, lacrimation, urination, defecation, gastrointestinal upset, emesis (SLUDGE syndrome), bradycardia, miosis, and muscle fasciculations. - It is not associated with postmortem caloricity; rather, the body temperature may remain normal or decrease postmortem.
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