Community Medicine
1 questionsThe primary reservoir for leptospirosis transmission is:
NEET-PG 2012 - Community Medicine NEET-PG Practice Questions and MCQs
Question 741: The primary reservoir for leptospirosis transmission is:
- A. Rat (Correct Answer)
- B. Cat
- C. Dog
- D. Fish
Explanation: ***Correct Answer: Rat*** - **Rats** (and other rodents) are considered the primary natural reservoir for *Leptospira* bacteria worldwide and are **asymptomatic carriers**. - They excrete the bacteria in their urine, contaminating water and soil, which serves as the main source of human infection. *Incorrect: Cat* - While cats can become infected with *Leptospira*, they are **not typically considered significant reservoirs** for human transmission. - Their role in the epidemiologic cycle of leptospirosis is generally minor compared to rodents and some other mammals. *Incorrect: Dog* - **Dogs** can contract leptospirosis and excrete the bacteria in their urine, posing a risk to humans, but they are generally considered **incidental hosts or secondary reservoirs**, not the primary one. - Vaccination in dogs helps reduce their role in transmission. *Incorrect: Fish* - **Fish are not known to be reservoirs** for *Leptospira* bacteria. - Leptospirosis is primarily transmitted through contact with infected animal urine, not aquatic life like fish.
Forensic Medicine
1 questionsWhich of the following sources provides the highest yield and most reliable samples for DNA fingerprinting?
NEET-PG 2012 - Forensic Medicine NEET-PG Practice Questions and MCQs
Question 741: Which of the following sources provides the highest yield and most reliable samples for DNA fingerprinting?
- A. Saliva
- B. Tooth
- C. Buccal mucosa
- D. Blood (Correct Answer)
Explanation: ***Blood*** - **Blood** provides a high concentration of **nucleated cells** (e.g., white blood cells), yielding abundant and high-quality DNA. - The DNA obtained from blood is typically well-preserved and less prone to degradation or contamination compared to other sources. *Saliva* - While saliva contains DNA from **buccal epithelial cells** and white blood cells, its DNA yield can be lower and more variable due to mucous and bacterial contamination. - DNA from saliva may be more subject to degradation, especially if not collected and stored properly. *Tooth* - **Teeth** can be a good source of DNA, particularly from the **pulp**, but extraction can be challenging and destructive. - The DNA yield varies depending on the tooth's condition and the extraction method, and it is generally reserved for situations where other sources are unavailable or severely degraded. *Buccal mucosa* - **Buccal mucosa** swabs are a common and non-invasive source of DNA from **epithelial cells**. - While suitable for many applications, the DNA yield can be lower than blood, and the sample may be more susceptible to surface contamination.
Internal Medicine
2 questionsTabes dorsalis is seen in -
Meningitis with rash is seen in -
NEET-PG 2012 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 741: Tabes dorsalis is seen in -
- A. Tertiary syphilis (Correct Answer)
- B. Primary syphilis
- C. Latent syphilis
- D. Secondary syphilis
Explanation: ***Tertiary syphilis*** - **Tabes dorsalis** is a neurological manifestation of **tertiary syphilis**, characterized by demyelination and degeneration of the posterior columns of the spinal cord [1]. - This leads to symptoms such as **ataxia**, **loss of proprioception**, **lightning pains**, and **Argyll-Robertson pupils**. *Primary syphilis* - Characterized by the presence of a **chancre**, a painless ulcer, at the site of infection [1]. - This stage typically occurs 3-90 days after exposure and is not associated with neurological complications of tabes dorsalis. *Latent syphilis* - This is a period during which there are **no clinical signs or symptoms** of syphilis, although the infection persists. - It can be early or late, but it is not the stage where overt neurological complications like tabes dorsalis arise [1]. *Secondary syphilis* - This stage typically presents with a **generalized mucocutaneous rash**, **lymphadenopathy**, and **condylomata lata** [1]. - While it can involve various organ systems, it does not typically include the severe neurological degeneration seen in tabes dorsalis.
Question 742: Meningitis with rash is seen in -
- A. Neisseria meningitidis (Correct Answer)
- B. H. influenzae
- C. Strepto. agalactae
- D. Pneumococcus
Explanation: **Neisseria meningitidis** - **Meningococcal meningitis** is classically associated with an acute onset of fever, headache, stiff neck, and a characteristic **petechial or purpuric rash** [1]. - The rash is due to widespread **vasculitis** and disseminated intravascular coagulation (DIC) caused by the bacteria. *H. influenzae* - While *H. influenzae* type b (Hib) was a major cause of bacterial meningitis before vaccination, it typically does not cause a *rash*. - Meningitis caused by *H. influenzae* presents with fever, headache, stiff neck, and altered mental status without dermatological manifestations. *Strepto. agalactiae* - *Streptococcus agalactiae* (Group B Strep) is a common cause of meningitis in **neonates** and infants. - It usually presents with non-specific symptoms like fever, lethargy, and poor feeding, and a rash is not a typical feature of GBS meningitis. *Pneumococcus* - *Streptococcus pneumoniae* (Pneumococcus) is another leading cause of bacterial meningitis in adults and children [1]. - Symptoms include fever, headache, stiff neck, and altered mental status, but a cutaneous rash is not characteristic of pneumococcal meningitis [1].
Microbiology
5 questionsWhich of the following statements is true regarding T cell independent antigens?
Which of the following is an enrichment medium for cholera?
A patient with sore throat has a positive Paul Bunnell test, indicating infectious mononucleosis. The causative organism is?
Which of the following statements is true regarding Diphyllobothrium?
Cercariae are the infective form of which of the following parasites?
NEET-PG 2012 - Microbiology NEET-PG Practice Questions and MCQs
Question 741: Which of the following statements is true regarding T cell independent antigens?
- A. They primarily activate T-cells.
- B. They primarily activate B-cells. (Correct Answer)
- C. They primarily activate macrophages.
- D. They primarily activate CD8+ T cells.
Explanation: ***Correct: They primarily activate B-cells*** - T-cell independent antigens are typically **polysaccharides** (TI-2) or **lipopolysaccharides** (TI-1) with repeating epitopes that can directly cross-link B cell receptors (BCRs) - This direct binding and cross-linking provide a strong enough signal to activate B cells and induce **antibody production** (mainly IgM) without the need for T cell help - They induce a rapid but limited immune response with minimal memory formation *Incorrect: They primarily activate T-cells* - T-cell independent antigens do not require processing and presentation by **MHC molecules**, which is essential for T cell activation - T cells recognize processed peptides presented by MHC, a mechanism not utilized by T-cell independent antigens - By definition, these antigens activate B cells **without** T cell involvement *Incorrect: They primarily activate macrophages* - While macrophages are antigen-presenting cells, their primary role in adaptive immunity is to process and present antigens to T cells - Macrophages are involved in **phagocytosis** and antigen processing, but are not the primary target cells for T-independent antigens - The key feature of TI antigens is direct B cell activation, not macrophage activation *Incorrect: They primarily activate CD8+ T cells* - **CD8+ T cells** are activated by processed antigens presented on **MHC class I molecules**, typically derived from intracellular pathogens - T-cell independent antigens do not utilize this pathway and are primarily involved in **humoral immunity** through direct B cell activation - TI antigens cannot activate CD8+ T cells as they bypass the T cell-dependent pathway entirely
Question 742: Which of the following is an enrichment medium for cholera?
- A. TCBS medium
- B. Cary-Blair medium
- C. Alkaline peptone water (Correct Answer)
- D. MacConkey agar
Explanation: ***Alkaline peptone water*** - This is a commonly used **enrichment broth** for *Vibrio cholerae* due to its **high pH (around 8.6)**, which selectively suppresses the growth of most other intestinal flora. - The alkaline environment provides a favorable condition for the rapid multiplication of *Vibrio cholerae* before subculturing onto selective media. *TCBS medium* - **Thiosulfate citrate bile salts sucrose (TCBS) agar** is a **selective and differential medium** used for the isolation of *Vibrio cholerae*, not an enrichment medium. - It differentiates *Vibrio cholerae* (yellow colonies) from most other *Vibrio* species (blue-green colonies) and inhibits the growth of most non-Vibrio bacteria. *Cary-Blair medium* - This is a **transport medium** designed to maintain the viability of enteric bacterial pathogens, including *Vibrio cholerae*, for extended periods at ambient temperatures. - It prevents overgrowth of commensals and helps preserve the pathogen's concentration, but it does not promote growth. *MacConkey agar* - **MacConkey agar** is a **selective and differential medium** primarily used for the isolation and differentiation of gram-negative enteric bacilli. - It is not specifically designed for *Vibrio cholerae* and its selective properties (bile salts and crystal violet) and differential properties (lactose fermentation) are less optimal for *Vibrio* isolation compared to specialized media.
Question 743: A patient with sore throat has a positive Paul Bunnell test, indicating infectious mononucleosis. The causative organism is?
- A. EBV (Correct Answer)
- B. Adenovirus
- C. CMV
- D. HSV (Herpes Simplex Virus)
Explanation: ***Correct: EBV*** - The **Paul-Bunnell test** (monospot test) detects **heterophile antibodies**, which are characteristic of acute **Epstein-Barr virus (EBV)** infection. - **EBV** is the primary causative agent of **infectious mononucleosis**, commonly known as "mono." *Incorrect: Adenovirus* - **Adenoviruses** can cause various infections, including **pharyngitis** and **conjunctivitis**, but are not associated with a positive **Paul-Bunnell test** or heterophile antibodies. - While it can cause sore throat, the presence of a **positive Paul-Bunnell test** differentiates it from EBV. *Incorrect: CMV* - **Cytomegalovirus (CMV)** can cause a mononucleosis-like syndrome, but it typically results in a **negative Paul-Bunnell test** (i.e., it is heterophile antibody-negative). - CMV mononucleosis is often seen in individuals who are **immunocompromised** or in infants as a congenital infection. *Incorrect: HSV (Herpes Simplex Virus)* - **Herpes simplex virus (HSV)** causes infections such as **oral herpes (cold sores)** and **genital herpes**, and in some cases, **pharyngitis**. - HSV infection is not associated with a positive **Paul-Bunnell test** or the production of heterophile antibodies.
Question 744: Which of the following statements is true regarding Diphyllobothrium?
- A. Humans are the only definitive host
- B. Vitamin B12 deficiency always occurs in infection
- C. Fish are definitive hosts
- D. The operculated egg is a diagnostic feature (Correct Answer)
Explanation: ***The operculated egg is a diagnostic feature*** - *Diphyllobothrium latum*, also known as the **fish tapeworm**, produces characteristic **operculated eggs** that are oval-shaped with an operculum (cap) at one end and a small knob at the other. - The presence of these **unembryonated eggs** in stool samples is the primary diagnostic method for diphyllobothriasis. *Humans are the only definitive host* - While humans are common definitive hosts, other **fish-eating mammals** such as bears, dogs, and cats can also serve as definitive hosts for *Diphyllobothrium latum*. - The definitive host is where the **adult worm resides** and reproduces sexually. *Vitamin B12 deficiency always occurs in infection* - **Vitamin B12 deficiency (megaloblastic anemia)** is a known complication of *Diphyllobothrium latum* infection, as the worm competes for B12 in the host's intestine. - However, it does **not occur in all infected individuals**; it is estimated to affect a significant minority, typically those with heavy worm burdens or prolonged infection, and can be influenced by dietary intake. *Fish are definitive hosts* - Fish (specifically freshwater fish like pike, perch, and salmon) act as **second intermediate hosts** for *Diphyllobothrium latum*, carrying the **plerocercoid larvae**. - **Humans and other fish-eating mammals** are the definitive hosts, where the plerocercoid larvae mature into adult tapeworms in the small intestine.
Question 745: Cercariae are the infective form of which of the following parasites?
- A. Schistosoma hematobium (Correct Answer)
- B. Paragonimus westermani
- C. Fasciola hepatica
- D. Taenia solium
Explanation: ***Schistosoma hematobium*** - **Cercariae** are the motile, free-swimming larval stage of **Schistosoma** species, including *S. hematobium* - They **actively penetrate human skin** to initiate infection, making cercariae the infective form for humans *Paragonimus westermani* - The infective form for humans is **metacercariae**, which are ingested by consuming insufficiently cooked **crabs or crayfish** - Cercariae develop into metacercariae in secondary intermediate hosts (crustaceans) *Fasciola hepatica* - Humans are infected by ingesting **metacercariae** present on aquatic vegetation, such as **watercress** - Cercariae encyst on plants to form metacercariae, not directly infective *Taenia solium* - The infective forms are **cysticerci** in undercooked pork (for adult tapeworm) or **embryonated eggs** (causing cysticercosis) - This cestode has a different life cycle and does **not** involve cercariae
Pharmacology
1 questionsAll are true about ciprofloxacin except?
NEET-PG 2012 - Pharmacology NEET-PG Practice Questions and MCQs
Question 741: All are true about ciprofloxacin except?
- A. More active at acidic pH (Correct Answer)
- B. DNA gyrase inhibition
- C. Contraindicated in pregnancy
- D. Second generation fluoroquinolone
Explanation: ***More active at acidic pH*** - Fluoroquinolones, including ciprofloxacin, exhibit **reduced antibacterial activity in acidic environments**. Their efficacy is generally better at **neutral or alkaline pH**. - This is clinically relevant as fluoroquinolones may have **reduced effectiveness in acidic sites** like the stomach or acidic urine. - The optimal antibacterial activity occurs at physiological or slightly alkaline pH. *DNA gyrase inhibition* - Ciprofloxacin, like other fluoroquinolones, exerts its antibacterial effect by inhibiting **bacterial DNA gyrase (topoisomerase II)** and **topoisomerase IV**. - This inhibition prevents DNA replication and repair, leading to bacterial cell death. *Contraindicated in pregnancy* - Ciprofloxacin is generally **contraindicated in pregnancy** due to concerns about potential harm to the developing fetus, particularly effects on **cartilage development**. - However, it may be used in specific, life-threatening situations if the benefit outweighs the potential risk. *Second generation fluoroquinolone* - Ciprofloxacin is classified as a **second-generation fluoroquinolone**. - This class includes agents with improved activity against Gram-negative bacteria and some atypical organisms.