NEET-PG 2024 Practice Questions

Q: What is the primary function of IL-8?

Chemotaxis. ***Chemotaxis*** - **IL-8** (also known as **CXCL8**) is a potent **chemokine** that primarily functions to recruit and activate **neutrophils** to sites of inflammation. - It guides these immune cells by forming a chemical gradient, allowing them to extravasate from blood vessels and migrate to the infected or injured tissue. *Lymphocyte proliferation* - Lymphocyte proliferation is primarily stimulated by **IL-2**, which acts as a growth factor for T cells. - While IL-8 contributes to the inflammatory environment, its direct role in inducing lymphocyte cell division is minor compared to its chemotactic function. *TH1 activation* - **TH1 cell activation** is mainly driven by **IL-12** and **IFN-γ**, which promote the differentiation and function of T helper 1 cells, crucial for fighting intracellular pathogens. - IL-8's role is unrelated to guiding TH1 cell differentiation. *Fever* - Fever is primarily induced by **pyrogenic cytokines** such as **IL-1**, **IL-6**, and **TNF-α**, which act on the hypothalamus to raise body temperature. - While IL-8 is part of the inflammatory response that can sometimes coincide with fever, it does not directly act as a pyrogen. *B cell activation* - **B cell activation** and differentiation are primarily regulated by interleukins such as **IL-4**, **IL-5**, **IL-6**, and **IL-21**, which promote antibody production and class switching. - IL-8 does not play a significant role in B cell function; its action is focused on innate immunity, particularly neutrophil recruitment.

Q: Which PCR technique is best suited for identifying a syndrome with multiple causative agents?

Multiplex PCR. ***Multiplex PCR*** - **Multiplex PCR** allows for the simultaneous amplification of **multiple DNA targets** in a single reaction, making it ideal for identifying syndromes with numerous potential causative agents. - This method uses **multiple primer pairs** in one reaction tube, each designed to amplify a specific target sequence, thus efficiently detecting various pathogens or genetic markers. *RT-PCR* - **Reverse Transcription PCR (RT-PCR)** is used to detect **RNA targets** by first converting RNA into cDNA, which is then amplified. - While useful for RNA viruses or gene expression studies, it is not primarily designed for simultaneous detection of multiple diverse causative agents in the same way as multiplex PCR. *Nested PCR* - **Nested PCR** uses two sets of primers in sequential reactions to **increase sensitivity and specificity** by reducing non-specific binding. - This technique is generally employed to detect very low copies of a specific target or to overcome issues with non-specific amplification, rather than for identifying multiple different agents concurrently. *Conventional PCR* - **Conventional PCR** amplifies a **single specific DNA target** using one pair of primers per reaction. [1] - It requires separate reactions for each potential causative agent, making it inefficient and labor-intensive when testing for a syndrome with multiple etiologies. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 56-57.

Q: A patient from Bihar is admitted with splenomegaly and clinical features suggestive of leishmaniasis. What is the vector responsible for transmitting this disease?

Phlebotomus. ***Phlebotomus*** - **Phlebotomus** (sandfly), specifically ***Phlebotomus argentipes*** in India, is the principal vector for transmitting **Leishmania donovani** parasites causing **visceral leishmaniasis (kala-azar)**. - Bihar is a highly endemic region for kala-azar in India. - The sandfly transmits the parasite when it takes a blood meal from an infected host and then bites an uninfected individual. *Rat flea* - The **rat flea** (**Xenopsylla cheopis**) is the primary vector for diseases like **bubonic plague** and **murine typhus**, not leishmaniasis. - It transmits bacteria such as *Yersinia pestis* and *Rickettsia typhi*. *Black fly* - **Black flies** (**Simulium species**) are vectors for **onchocerciasis** (river blindness), caused by the parasitic worm *Onchocerca volvulus*. - They transmit the microfilariae when biting humans. *Chrysops fly* - The **Chrysops fly** (deer fly or mango fly) is the vector for **Loa loa filariasis** (African eye worm). - It transmits *Loa loa* eyeworm larvae when it bites humans.

Q: A woman presents with a chronic history of fever and lower limb swelling. The microscopic image of a parasite in her blood smear is shown. Identify the pathogen responsible for her condition.

Brugia. ***Brugia*** - The image shown represents a microfilaria with **two distinct nuclei in the tail**, which is a characteristic morphological feature of *Brugia malayi* or *Brugia timori*. - *Brugia* species cause **lymphatic filariasis**, leading to chronic conditions like **fever** and **lymphatic obstruction** (lower limb swelling), consistent with the patient's presentation. *Mansonella* - *Mansonella* microfilariae typically have a **sheathless appearance** and their nuclei arrangement in the tail does not usually present as two distinct nuclei. - While *Mansonella* can cause symptoms like fever, it typically does not lead to severe **lymphatic pathology** and swelling of the extremities like *Brugia* or *Wuchereria*. *Wuchereria bancrofti* - *Wuchereria bancrofti* microfilariae are **sheathed** and their **tail nuclei are numerous** and extend to the tip, forming an indistinct pattern, unlike the distinct two nuclei seen. - This parasite also causes lymphatic filariasis but the microscopic morphology of its microfilaria differs from the image. *Loa loa* - *Loa loa* microfilariae are **sheathed**, but their distinguishing feature is the **nuclei extending to the tip of the tail** in a continuous, often wavy, column. - This parasite is known for causing **Calabar swellings** and migration across the conjunctiva, which are different clinical manifestations from chronic lower limb swelling.

Q: A man presents with dysuria and urethral discharge after a history of unprotected sex. The Gram stain of his discharge is shown. What is the best culture medium for isolating the organism responsible?

Thayer-Martin agar. ***Thayer-Martin agar*** - The image shows numerous **polymorphonuclear leukocytes (neutrophils)** with intracellular, gram-negative diplococci, which is characteristic of **Neisseria gonorrhoeae**. - **Thayer-Martin agar** is a selective medium specifically formulated for the isolation of *Neisseria gonorrhoeae* from specimens containing flora. *MacConkey agar* - **MacConkey agar** is a selective and differential medium used primarily for the isolation of Gram-negative **enteric bacilli** and differentiation based on lactose fermentation. - It is not suitable for *Neisseria* species, which are fastidious organisms requiring enriched media. *Chocolate agar* - **Chocolate agar** is an enriched, non-selective medium that supports the growth of fastidious organisms like *Neisseria* species and *Haemophilus influenzae*. - While *Neisseria gonorrhoeae* grows on chocolate agar, **Thayer-Martin agar** is preferred for specimens from sites with normal flora as it inhibits contaminants. *TCBS agar* - **Thiosulfate Citrate Bile Salts Sucrose (TCBS) agar** is a selective medium used for the isolation of *Vibrio* species, particularly *Vibrio cholerae*. - This medium is completely unsuitable for the growth of *Neisseria gonorrhoeae*, which has entirely different nutritional and environmental requirements.

Q: A young boy who used to wash his contact lenses in tap water or with unhygienic lens fluid developed keratitis. Microscopy revealed an organism with spiked or star-shaped structures. Identify the correct organism responsible.

Acanthamoeba. ***Acanthamoeba*** - *Acanthamoeba* is a **free-living amoeba** found in water, soil, and inadequately disinfected contact lens solutions, specifically linked to **keratitis** in contact lens wearers. - Its characteristic morphology, often described as having **spiked or star-shaped structures**, refers to the **acanthopodia** (spine-like pseudopods) that are distinctive features visible microscopically. *Balantidium* - *Balantidium coli* is a **ciliated protozoan** and primarily causes **intestinal infections** (balantidiasis), not keratitis. - It would be distinguished microscopically by its **large size**, **kidney-shaped macronucleus**, and **cilia**, not spiked structures. *Pseudomonas* - *Pseudomonas aeruginosa* is a **bacterium** and a common cause of **bacterial keratitis**, especially in contact lens wearers, but it is not a protozoan. - Microscopically, it would appear as **rod-shaped bacteria**, not organisms with spiked or star-shaped structures. *Staphylococcus aureus* - *Staphylococcus aureus* is a **bacterium** and a frequent cause of various infections, including **bacterial keratitis**. - Under a microscope, it presents as **Gram-positive cocci in clusters**, not as an amoeba with spiked or star-shaped protrusions.

Q: A patient in the ICU with a central venous catheter (CVC) develops an infection. Microscopy reveals ovoid budding yeast cells. What is the most likely organism?

Candida. ***Candida*** - **Gram-positive ovoid budding organisms** are characteristic findings for yeast, with **Candida** species being the most common cause of CVC-related fungal infections in ICU patients. - Patients with CVCs are at high risk for candidemia due to compromised skin barriers and often receiving broad-spectrum antibiotics, which can disrupt the normal flora. *Staphylococcus epidermidis* - This is a **Gram-positive coccus** that grows in clusters and is a common cause of CVC-related **bacterial infections**, developing **biofilms** on catheters. - It does not present as an ovoid budding organism on microscopy. *Escherichia coli* - This is a **Gram-negative rod**, typically associated with **urinary tract infections** and sepsis from an abdominal source. - It would not appear as a Gram-positive ovoid budding organism and is not a common cause of primary CVC-related bloodstream infections unless there's an associated abdominal source. *Staphylococcus aureus* - This is a **Gram-positive coccus** that grows in grape-like clusters and can cause severe CVC-related bloodstream infections, often leading to **endocarditis** or widespread dissemination. - Like *S. epidermidis*, it is a bacterium and does not exhibit ovoid budding.

Q: A farmer presents with a subcutaneous wound on his foot with discharge. Microscopy of a white granule from the wound shows Gram-positive filamentous rods. What is the most likely organism?

Nocardia. ***Nocardia*** - The presence of **white granules** in the discharge, along with **Gram-positive, filamentous rods**, is highly characteristic of *Nocardia* infection, often forming **sulfur granules** (though not always yellow). - *Nocardia* is a common soil bacterium, making it a likely pathogen in a **farmer with a subcutaneous wound** related to environmental exposure. *Staphylococcus aureus* - While *Staphylococcus aureus* can cause skin infections and abscesses, it presents as **Gram-positive cocci in clusters**, not filamentous rods. - It does not typically form **granules** in the discharge in the same manner as *Nocardia*. *Histoplasma* - *Histoplasma* is a **dimorphic fungus** that causes systemic infections, often acquired by inhaling spores. - It would appear as **yeast forms** in tissue or cultures, not Gram-positive filamentous rods, and is not typically associated with subcutaneous wounds forming granules. *Sporothrix* - *Sporothrix schenckii* causes **sporotrichosis**, characterized by a **subcutaneous nodule** that progresses along lymphatic channels. - It is a **dimorphic fungus** (yeast in tissue, mold in culture) and would not appear as Gram-positive filamentous rods on microscopy.

Q: A 2 year old child came with watery diarrhea. Electron Microscopy (EM) Image is shown here. Choose the correct pathogen.

Rota virus. ***Rota virus*** - The electron micrograph shows **double-layered viral particles** with a distinct wheel-like appearance, characteristic of **Rotavirus**, a major cause of severe watery diarrhea in young children. - Rotavirus is the most common cause of **severe dehydrating diarrhea** in infants and young children worldwide. *Norwalk virus* - Norwalk virus (now commonly referred to as **Norovirus**) particles are typically **smaller** and have an **amorphous** or indistinct surface morphology compared to the clearly structured Rotavirus. - Norovirus causes acute gastroenteritis but its electron microscopic appearance is less distinct and lacks the double-shelled structure seen here. *Adenovirus* - Adenoviruses are **larger, non-enveloped DNA viruses** with a distinct **icosahedral capsid** structure, often appearing hexagonal or pentagonal with prominent 'spikes' at the vertices. - While adenoviruses can cause gastroenteritis, their EM appearance is easily distinguishable from the image provided. *Astrovirus* - Astroviruses are **small, non-enveloped RNA viruses** that appear as **smooth-surfaced, star-shaped particles** on electron microscopy (hence the name "astro"). - They cause gastroenteritis in young children but lack the characteristic double-layered wheel-like structure of rotavirus. *ECHO virus* - ECHO viruses (Enteric Cytopathic Human Orphan viruses) are **picornaviruses**, which are very **small, non-enveloped RNA viruses** with an icosahedral shape. - Their EM image would show much smaller, less complex particles without the characteristic double-layered structure of rotavirus.

Q: Which of the following cardioselective betablockers has been shown to decrease mortality in patients with congestive heart failure?

Bisoprolol. ***Bisoprolol*** - **Bisoprolol** is a highly cardioselective beta-1 blocker that has been extensively studied and proven to reduce mortality and morbidity in patients with **systolic congestive heart failure**. - It is one of the **"big three" beta-blockers** (along with **carvedilol** and **metoprolol succinate**) recommended for chronic heart failure management by major cardiology guidelines, supported by the **CIBIS-II trial**. *Atenolol* - **Atenolol** is a cardioselective beta-1 blocker commonly used for hypertension and angina. - Despite being cardioselective, it has **not been shown to reduce mortality** in patients with chronic heart failure and is generally **not recommended** for this indication due to lack of supportive clinical trial evidence. *Propranolol* - **Propranolol** is a non-selective beta-blocker that blocks both beta-1 and beta-2 receptors. - While effective for conditions like angina and arrhythmias, it is generally **not recommended** for chronic heart failure due to its non-selectivity and lack of evidence for mortality reduction in this specific patient population. *Labetalol* - **Labetalol** is an alpha- and beta-adrenergic blocker, often used in hypertensive emergencies and for managing hypertension in pregnancy. - It is **not indicated** for mortality reduction in chronic heart failure due to its different pharmacological profile and lack of clinical trial evidence supporting its use for this purpose. *Pindolol* - **Pindolol** is a non-selective beta-blocker with **intrinsic sympathomimetic activity (ISA)**, meaning it partially stimulates beta-receptors while blocking the effects of norepinephrine and epinephrine. - Beta-blockers with ISA are generally **contraindicated** in heart failure because their partial agonist activity can potentially worsen myocardial function, and they have not shown any mortality benefit.

Question 1

What is the primary function of IL-8?

Accepted Answer

Chemotaxis

Answer

Lymphocyte proliferation

Answer

TH1 activation

Answer

Fever

Answer

B cell activation

Question 2

Which PCR technique is best suited for identifying a syndrome with multiple causative agents?

Accepted Answer

Multiplex PCR

Answer

RT-PCR

Answer

Nested PCR

Answer

Conventional PCR

Question 3

A patient from Bihar is admitted with splenomegaly and clinical features suggestive of leishmaniasis. What is the vector responsible for transmitting this disease?

Accepted Answer

Phlebotomus

Answer

Rat flea

Answer

Black fly

Answer

Chrysops fly

Question 4

A woman presents with a chronic history of fever and lower limb swelling. The microscopic image of a parasite in her blood smear is shown. Identify the pathogen responsible for her condition.

Accepted Answer

Brugia

Answer

Mansonella

Answer

Wuchereria bancrofti

Answer

Loa loa

Question 5

A man presents with dysuria and urethral discharge after a history of unprotected sex. The Gram stain of his discharge is shown. What is the best culture medium for isolating the organism responsible?

Accepted Answer

Thayer-Martin agar

Answer

MacConkey agar

Answer

Chocolate agar

Answer

TCBS agar

Question 6

A young boy who used to wash his contact lenses in tap water or with unhygienic lens fluid developed keratitis. Microscopy revealed an organism with spiked or star-shaped structures. Identify the correct organism responsible.

Accepted Answer

Acanthamoeba

Answer

Balantidium

Answer

Pseudomonas

Answer

Staphylococcus aureus

Question 7

A patient in the ICU with a central venous catheter (CVC) develops an infection. Microscopy reveals ovoid budding yeast cells. What is the most likely organism?

Accepted Answer

Candida

Answer

Staphylococcus epidermidis

Answer

Escherichia coli

Answer

Staphylococcus aureus

Question 8

A farmer presents with a subcutaneous wound on his foot with discharge. Microscopy of a white granule from the wound shows Gram-positive filamentous rods. What is the most likely organism?

Accepted Answer

Nocardia

Answer

Staphylococcus aureus

Answer

Histoplasma

Answer

Sporothrix

Question 9

A 2 year old child came with watery diarrhea. Electron Microscopy (EM) Image is shown here. Choose the correct pathogen.

Accepted Answer

Rota virus

Answer

Norwalk virus

Answer

Adenovirus

Answer

ECHO virus

Answer

Astrovirus

Question 10

Which of the following cardioselective betablockers has been shown to decrease mortality in patients with congestive heart failure?

Accepted Answer

Bisoprolol

Answer

Propranolol

Answer

Labetalol

Answer

Pindolol

Answer

Atenolol

NEET-PG 2024

Biochemistry

Community Medicine

Microbiology

Pediatrics

Pharmacology