Community Medicine
1 questionsVaccines are available against which types of meningococcus?
NEET-PG 2013 - Community Medicine NEET-PG Practice Questions and MCQs
Question 481: Vaccines are available against which types of meningococcus?
- A. Type A
- B. Type B
- C. Type A, B, and C
- D. Type A, B, C, W, and Y (Correct Answer)
Explanation: ***Type A, B, C, W, and Y*** - Vaccines are currently available against **all five major meningococcal serogroups**: A, B, C, W-135, and Y. - **Meningococcal conjugate vaccines (MenACWY)** provide protection against serogroups A, C, W-135, and Y, and are widely used globally. - **Meningococcal B vaccines (MenB)** such as Bexsero and Trumenba specifically target serogroup B, which is a leading cause of meningococcal disease in developed countries. - Combined, these vaccines provide comprehensive coverage against the most epidemiologically important meningococcal serogroups worldwide. *Type A* - While vaccines against **meningococcus type A** do exist (as part of conjugate vaccines), this option is incomplete as it excludes the other important serogroups (B, C, W, Y) for which vaccines are also available. *Type B* - **Type B vaccines** are available and important, particularly in developed countries where serogroup B causes significant disease burden. - However, this option alone is insufficient because vaccines also effectively target other serogroups (A, C, W, Y). *Type A, B, and C* - This option is incomplete because it omits **serogroups W and Y**, for which conjugate vaccines (MenACWY) are readily available and widely used. - The question asks which types vaccines are *available* against, not which are most common, making this an incorrect answer.
ENT
2 questionsWhat causes the cart-wheel appearance of the tympanic membrane in acute suppurative otitis media (ASOM)?
What is the most common cause of ASOM?
NEET-PG 2013 - ENT NEET-PG Practice Questions and MCQs
Question 481: What causes the cart-wheel appearance of the tympanic membrane in acute suppurative otitis media (ASOM)?
- A. Perforation of the tympanic membrane
- B. Edema of the tympanic membrane
- C. Congested blood vessels along the malleus (Correct Answer)
- D. Granulation tissue on the tympanic membrane
Explanation: ***Congested blood vessels along the malleus*** - The **cart-wheel appearance** in **acute suppurative otitis media (ASOM)** is a characteristic sign caused by the significant **engorgement of blood vessels** radiating out from the **malleus handle**. - This vascular congestion gives the tympanic membrane a distinct spoke-like pattern, resembling the spokes of a **cart wheel**. *Perforation of the tympanic membrane* - While **tympanic membrane perforation** can occur in ASOM, it typically signals a later stage of the disease, often leading to relief of pain and discharge, not the cart-wheel appearance. - Perforation appears as a **hole or defect** in the tympanic membrane, altering its integrity rather than its vascular pattern. *Edema of the tympanic membrane* - **Edema** (swelling) of the tympanic membrane does occur in ASOM due to inflammation, giving it a **dull, thickened, or bulging appearance**. - However, edema alone does not create the specific spoke-like pattern seen in the cart-wheel appearance; this pattern is primarily vascular. *Granulation tissue on the tympanic membrane* - **Granulation tissue** formation is more commonly associated with **chronic inflammatory processes** or healing after injury, and it would present as a **red, friable mass** on the tympanic membrane. - It is not a feature of early or established ASOM leading to the cart-wheel sign, which is an acute vascular phenomenon.
Question 482: What is the most common cause of ASOM?
- A. Meningococci
- B. Pneumococci (Correct Answer)
- C. H. influenzae
- D. Moraxella catarrhalis
Explanation: ***Pneumococci*** - **_Streptococcus pneumoniae_ (Pneumococci)** is the **most common bacterial cause** of Acute Suppurative Otitis Media (ASOM) in all age groups, particularly in young children. - It accounts for an estimated 25-50% of all ASOM cases, often leading to significant inflammation and **purulent discharge**. *Meningococci* - **_Neisseria meningitidis_ (Meningococci)** is rarely a cause of ASOM. - It is primarily known for causing **meningitis** and **sepsis**, not typically middle ear infections. *H. influenzae* - **_Haemophilus influenzae_ (non-typable)** is the **second most common cause** of ASOM, accounting for 20-40% of cases. - While significant, it is generally less prevalent than _Streptococcus pneumoniae_. *Moraxella catarrhalis* - **_Moraxella catarrhalis_** is another common causative agent of ASOM, responsible for 10-20% of cases. - It is frequently seen in conjunction with other pathogens but is not the most common on its own.
Microbiology
3 questionsWhich of the following statements about Corynebacterium diphtheriae is NOT true?
Pneumococcal vaccine is prepared from ?
What is the most common genetic factor associated with increased susceptibility to Neisseria infections?
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 481: Which of the following statements about Corynebacterium diphtheriae is NOT true?
- A. Has metachromatic granules
- B. Toxin mediated by chromosomal gene (Correct Answer)
- C. Toxigenicity demonstrated by elek's test
- D. Does not invade deeper tissues
Explanation: ***Toxin mediated by chromosomal gene*** - The **diphtheria toxin** is encoded by the **tox gene**, which is a lysogenic bacteriophage (cornyphage) gene, not a chromosomal gene. - This **bacteriophage** integrates into the bacterial chromosome, making toxigenic *C. diphtheriae* strains lysogenized. *Has metachromatic granules* - *Corynebacterium diphtheriae* is known for possessing **metachromatic granules** (also called Babes-Ernst bodies), which are inclusions that stain differently from the rest of the cell. - These granules are composed of **polyphosphate reserves** and are important for identification. *Does not invade deeper tissues* - *Corynebacterium diphtheriae* remains **localized** to the mucosal surface of the upper respiratory tract or skin, forming a **pseudomembrane**. - Its pathogenicity is primarily due to the **exotoxin** it produces, which then disseminates systemically. *Toxigenicity demonstrated by elek's test* - The **Elek test** is a standard laboratory assay used to determine the **toxigenicity** of *Corynebacterium diphtheriae* strains by detecting the production of diphtheria toxin. - It works by identifying the **immunoprecipitation lines** formed between antitoxin and toxin in an agar medium.
Question 482: Pneumococcal vaccine is prepared from ?
- A. Cell surface antigen
- B. Capsular polysaccharide (Correct Answer)
- C. Exotoxin
- D. M protein
Explanation: ***Capsular polysaccharide*** - The **polysaccharide capsule** of *Streptococcus pneumoniae* is the primary virulence factor, protecting the bacteria from phagocytosis. - Vaccines, such as **PCV13** (pneumococcal conjugate vaccine) and **PPSV23** (pneumococcal polysaccharide vaccine), are designed targeting these capsular polysaccharides to elicit a protective immune response. *Cell surface antigen* - While bacteria possess various **cell surface antigens**, not all are immunogenic or provide protective immunity as effectively as the capsular polysaccharides for *S. pneumoniae*. - For pneumococcus, the **capsule** is the most critical surface component for vaccine development due to its role in virulence and serotype specificity. *From exotoxin* - *S. pneumoniae* primarily causes disease through its **polysaccharide capsule** and other bacterial components, not through the production of an **exotoxin** that would be targeted by a vaccine. - Vaccines developed from exotoxins (e.g., diphtheria or tetanus toxoids) target specific toxins, which is not the mechanism for pneumococcal vaccines. *From M protein* - **M protein** is a major virulence factor for *Streptococcus pyogenes* (Group A Strep), not *Streptococcus pneumoniae*. - Vaccines targeting M protein are associated with **Group A Streptococcus** infections, for protection against diseases like rheumatic fever.
Question 483: What is the most common genetic factor associated with increased susceptibility to Neisseria infections?
- A. HLA-B27
- B. Complement deficiency (Correct Answer)
- C. IgA deficiency
- D. Factor H deficiency
Explanation: ***Complement deficiency*** - Deficiencies in the **terminal complement pathway (C5-C9)**, particularly C5b-C9 (membrane attack complex, MAC), significantly increase susceptibility to disseminated *Neisseria* infections. - The MAC is crucial for lysing Gram-negative bacteria like *Neisseria meningitidis* and *Neisseria gonorrhoeae*, and its absence allows for uncontrolled bacterial proliferation. *Factor H deficiency* - **Factor H** is a regulatory protein of the alternative complement pathway, preventing its overactivation on host cells. - Its deficiency typically leads to conditions like **atypical hemolytic uremic syndrome (aHUS)** and **dense deposit disease**, not primarily increased susceptibility to *Neisseria* infections. *HLA B27* - **HLA-B27** is a human leukocyte antigen strongly associated with a group of autoimmune inflammatory diseases called **spondyloarthropathies**, such as ankylosing spondylitis. - It does not directly impact the immune response to *Neisseria* infections or increase susceptibility to them. *IgA deficiency* - **Selective IgA deficiency** is the most common primary immunodeficiency, characterized by low or absent IgA levels. - Individuals with IgA deficiency are more prone to **recurrent respiratory and gastrointestinal infections**, but not specifically disseminated *Neisseria* infections.
Pharmacology
4 questionsWhat is Hydroxyethyl starch?
Aminophylline inhibits which of the following enzymes?
Which of the following is NOT an advantage of amoxicillin over ampicillin?
Which of the following is a metabolite of hydroxyzine?
NEET-PG 2013 - Pharmacology NEET-PG Practice Questions and MCQs
Question 481: What is Hydroxyethyl starch?
- A. Vasodilator
- B. Inotrope
- C. Plasma expander (Correct Answer)
- D. Diuretic
Explanation: ***Plasma expander*** - **Hydroxyethyl starch** is a **colloid solution** used intravenously to increase plasma volume and maintain oncotic pressure. - It is often used in situations of **hypovolemia** or shock to support circulation. *Vasodilator* - A **vasodilator** is a medication that widens blood vessels, typically used to lower blood pressure or improve blood flow. - Hydroxyethyl starch does not directly cause **vasodilation** as its primary mechanism of action. *Inotrope* - An **inotrope** is an agent that alters the force or energy of muscular contractions, mainly affecting the heart's contractility. - Hydroxyethyl starch has no direct effect on **myocardial contractility**. *Diuretic* - A **diuretic** is a substance that promotes increased production of urine, thereby increasing the excretion of water from the body. - While fluid administration can temporarily increase urine output, hydroxyethyl starch is not classified as a **diuretic agent** itself.
Question 482: Aminophylline inhibits which of the following enzymes?
- A. MAO
- B. Alcohol dehydrogenase
- C. Cytochrome P450
- D. Phosphodiesterase (Correct Answer)
Explanation: ***Phosphodiesterase*** - **Aminophylline** is a methylxanthine derivative that primarily acts as a **phosphodiesterase (PDE) inhibitor** [1], [2]. - By inhibiting PDE, aminophylline increases intracellular levels of **cAMP** and **cGMP**, leading to **bronchodilation** and other effects [2], [3]. *MAO* - **MAO (monoamine oxidase)** inhibitors are antidepressants that prevent the breakdown of neurotransmitters like serotonin, norepinephrine, and dopamine. - Aminophylline does not significantly inhibit MAO. *Alcohol dehydrogenase* - **Alcohol dehydrogenase** is an enzyme responsible for metabolizing alcohol (ethanol) in the liver. - Aminophylline has no direct inhibitory effect on alcohol dehydrogenase. *Cytochrome P450* - **Cytochrome P450 (CYP450)** enzymes are a group of enzymes primarily involved in the metabolism of drugs and other xenobiotics in the liver [4]. - While aminophylline (and its active metabolite theophylline) can be metabolized by and *affect* certain **CYP450** isoenzymes (e.g., CYP1A2), it does not act as a general inhibitor of the entire CYP450 system; its primary therapeutic action is not through CYP450 inhibition.
Question 483: Which of the following is NOT an advantage of amoxicillin over ampicillin?
- A. Spectrum includes H. influenzae & Shigella (Correct Answer)
- B. Incidence of diarrhea is lower
- C. Food does not interfere with its absorption
- D. Better bioavailability & faster action
Explanation: ***Spectrum includes H. influenzae & Shigella*** - Amoxicillin and ampicillin both have a similar spectrum of activity against *Haemophilus influenzae* and *Shigella* species. Neither drug possesses a distinct advantage over the other in this regard for these specific pathogens. - Therefore, stating that amoxicillin's spectrum *includes* these bacteria as an advantage over ampicillin implies a unique characteristic, which is incorrect. *Better bioavailability & faster action* - **Amoxicillin** has superior oral **bioavailability** compared to ampicillin, leading to higher and more consistent blood levels. - This improved absorption often translates to a **faster onset of action** and allows for less frequent dosing. *Incidence of diarrhea is lower* - **Amoxicillin** is associated with a **lower incidence of diarrhea** and other gastrointestinal side effects compared to ampicillin. - This is partly due to its better absorption, meaning less unabsorbed drug reaches the colon to disrupt normal flora. *Food does not interfere with its absorption* - The absorption of **amoxicillin is largely unaffected by food**, allowing it to be taken without regard to meals. - In contrast, ampicillin's absorption can be significantly reduced when taken with food, making amoxicillin more convenient.
Question 484: Which of the following is a metabolite of hydroxyzine?
- A. Fexofenadine
- B. Terfenadine
- C. Cetirizine (Correct Answer)
- D. Azelastine
Explanation: ***Cetirizine*** - **Cetirizine** is the principal active metabolite of **hydroxyzine**, formed through the oxidation of the primary alcohol group of hydroxyzine [2]. - Both hydroxyzine and cetirizine are **H1-receptor antagonists**, but cetirizine is a **second-generation antihistamine** known for being less sedating due to its limited ability to cross the blood-brain barrier [2]. *Fexofenadine* - **Fexofenadine** is an active metabolite of **terfenadine**, not hydroxyzine [2]. - **Fexofenadine** is a second-generation antihistamine used to treat allergies, known for its non-sedating properties [3]. *Terfenadine* - **Terfenadine** is a second-generation antihistamine that was withdrawn from the market due to its cardiotoxicity, particularly the risk of **QT prolongation** and **Torsades de Pointes**. - Its active metabolite is **fexofenadine**, which does not cause similar cardiac issues [2]. *Azelastine* - **Azelastine** is an antihistamine primarily available as a **nasal spray** for the treatment of allergic rhinitis and conjunctivitis [1], [3]. - It is not a metabolite of hydroxyzine but a distinct therapeutic compound.