Community Medicine
1 questionsVaccines are available against which types of meningococcus?
NEET-PG 2013 - Community Medicine NEET-PG Practice Questions and MCQs
Question 651: 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.
Internal Medicine
1 questionsWaterhouse-Friderichsen syndrome is seen in:
NEET-PG 2013 - Internal Medicine NEET-PG Practice Questions and MCQs
Question 651: Waterhouse-Friderichsen syndrome is seen in:
- A. Neisseria meningitidis (Correct Answer)
- B. Yersinia
- C. Pseudomonas
- D. Pneumococci
Explanation: ***Neisseria meningitidis*** - **Waterhouse-Friderichsen syndrome** is a severe complication of **meningococcal sepsis**, predominantly caused by *Neisseria meningitidis* [1]. - It is characterized by **adrenal gland hemorrhage**, leading to acute adrenal insufficiency, hemorrhagic skin rash, and shock [1]. *Pseudomonas* - While *Pseudomonas aeruginosa* can cause severe infections, including sepsis, it is **not typically associated** with Waterhouse-Friderichsen syndrome. - *Pseudomonas* infections often lead to **ecthyma gangrenosum** in immunocompromised patients, a different dermatological manifestation. *Yersinia* - *Yersinia* species can cause various infections, such as **yersiniosis** (gastroenteritis) and **plague** (*Yersinia pestis*). - These infections do not commonly present with the distinct features of **adrenal hemorrhage** and **fulminant sepsis** seen in Waterhouse-Friderichsen syndrome. *Pneumococci* - *Streptococcus pneumoniae* (**pneumococci**) is a common cause of **meningitis** and **sepsis**, especially in children and the elderly. - Although it can lead to severe bloodstream infections, it is **rarely specifically linked** to the adrenal hemorrhage syndrome known as Waterhouse-Friderichsen syndrome.
Microbiology
8 questionsWhat component is included in the vaccine against N-meningitidis?
What is the most common genetic factor associated with increased susceptibility to Neisseria infections?
Pneumococcal vaccine is prepared from ?
Which of the following statements about Corynebacterium diphtheriae is NOT true?
Milk ring test is done to detect which organism present in milk?
Which of the following Chlamydia species is primarily associated with respiratory infections?
Inclusion body containing glycogen is seen in which of the following organisms?
Boutonneuse fever is caused by which of the following?
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 651: What component is included in the vaccine against N-meningitidis?
- A. Killed whole-cell vaccine
- B. Capsular polysaccharide (polysaccharide vaccine) (Correct Answer)
- C. Outer membrane protein (OMP)
- D. Live attenuated vaccine
Explanation: ***Capsular polysaccharide (polysaccharide vaccine)*** - *Neisseria meningitidis* vaccines commonly include **capsular polysaccharides** from different serogroups (A, C, Y, W-135) to elicit a protective immune response. - These polysaccharides act as antigens, stimulating the production of **antibodies** that can neutralize the bacteria. - **Conjugate vaccines** combine polysaccharides with carrier proteins to improve immunogenicity, especially in infants and young children. *Killed whole-cell vaccine* - **Killed whole-cell vaccines** are not used for *N. meningitidis* due to potential reactogenicity and the availability of more effective targeted antigens. - **Polysaccharide and conjugate vaccines** are the established formulations for meningococcal disease prevention. *Outer membrane protein (OMP)* - **Outer membrane proteins (OMPs)** are specifically used in **serogroup B vaccines** (e.g., Bexsero, Trumenba) due to the poor immunogenicity of the serogroup B polysaccharide capsule. - However, for serogroups A, C, Y, and W-135, **capsular polysaccharide** remains the primary vaccine component. *Live attenuated vaccine* - **Live attenuated vaccines** are not used for *N. meningitidis* as they pose risks of reversion to virulence and are unnecessary given the effectiveness of polysaccharide-based vaccines. - Meningococcal vaccines rely on **subunit approaches** (polysaccharides, conjugates, OMPs) rather than live organisms.
Question 652: 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.
Question 653: 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 654: 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 655: Milk ring test is done to detect which organism present in milk?
- A. Mycobacterium
- B. Bordetella
- C. Bartonella
- D. Brucella (Correct Answer)
Explanation: ***Brucella*** - The **milk ring test (MRT)** is a rapid serological test used for the detection of **Brucella antibodies** in milk samples, indicating an infection in the herd. - This test is crucial for screening dairy cattle and helps in the control and eradication of **brucellosis**, a zoonotic disease. *Bordetella* - **Bordetella** species are primarily associated with **respiratory infections** in humans and animals, such as whooping cough (B. pertussis). - They are not typically detected in milk using serological tests like the milk ring test. *Bartonella* - **Bartonella** species are known to cause diseases like **cat scratch disease** and **trench fever**, often transmitted by vectors. - They are not commonly associated with milk contamination or detected by the milk ring test. *Mycobacterium* - **Mycobacterium** species, particularly **M. bovis**, can cause tuberculosis in cattle and be transmitted through milk. - While important for milk safety, their detection usually involves different methods like **tuberculin skin tests**, **culture**, or **PCR**, not the milk ring test.
Question 656: Which of the following Chlamydia species is primarily associated with respiratory infections?
- A. C psittaci
- B. C pneumoniae (Correct Answer)
- C. C trachomatis
- D. None of the options
Explanation: ***C pneumoniae*** - *C. pneumoniae* is the **primary Chlamydia species** associated with **respiratory infections** in humans - It is a common cause of **community-acquired pneumonia** (5-10% of cases), **atypical pneumonia**, **bronchitis**, **pharyngitis**, and **sinusitis** - Transmission occurs via **respiratory droplets** from person to person - Causes both **acute and chronic respiratory infections** and has been linked to exacerbations of asthma and COPD - It is the most frequently encountered Chlamydia species in respiratory tract infections *C psittaci* - Causes **psittacosis** (ornithosis), a specific type of **atypical pneumonia** transmitted from **birds** (parrots, pigeons, poultry) - While it does cause respiratory infection, it is much **less common** than C. pneumoniae and is associated with **occupational or recreational bird exposure** - Not the primary Chlamydia species for general respiratory infections *C trachomatis* - Primarily causes **genital tract infections** (urethritis, cervicitis, PID) and **ocular infections** (trachoma, inclusion conjunctivitis) - Can cause **neonatal pneumonia** in infants exposed during birth, presenting at 1-3 months of age with a staccato cough - NOT a primary respiratory pathogen in adults *None of the options* - This is incorrect because **C. pneumoniae** is definitively the Chlamydia species primarily associated with respiratory infections
Question 657: Inclusion body containing glycogen is seen in which of the following organisms?
- A. Chlamydia trachomatis (Correct Answer)
- B. Chlamydia pneumoniae
- C. Chlamydia psittaci
- D. None of the options
Explanation: ***Chlamydia trachomatis*** - This species is known to form **intracytoplasmic inclusion bodies** that contain **glycogen**. - The presence of this glycogen allows these inclusions to be stained by **iodine**, aiding in laboratory identification. *Chlamydia pneumoniae* - Inclusion bodies of *Chlamydia pneumoniae* are typically **round or pear-shaped** and **do not contain glycogen**. - They are often **vacuolated** and stain poorly with iodine, unlike those of *C. trachomatis*. *Chlamydia psittaci* - The inclusion bodies of *Chlamydia psittaci* are usually **dense and pleiomorphic**, but they **do not contain glycogen**. - They tend to be **larger** and are often found near the host cell nucleus. *None of the options* - This option is incorrect because *Chlamydia trachomatis* specifically forms **glycogen-containing inclusion bodies**. - The presence of glycogen within inclusions is a key distinguishing feature of this species.
Question 658: Boutonneuse fever is caused by which of the following?
- A. A. Rickettsia japonica
- B. B. Rickettsia conorii (Correct Answer)
- C. C. Rickettsia sibirica
- D. D. Rickettsia australis
Explanation: ***Rickettsia conorii*** - **Boutonneuse fever**, also known as Mediterranean spotted fever, is specifically caused by the bacterium **Rickettsia conorii**. - This zoonotic disease is transmitted to humans through the bite of infected ticks, primarily the **dog tick** (Rhipicephalus sanguineus). *Rickettsia japonica* - **Rickettsia japonica** is the causative agent of **oriental spotted fever**, a tick-borne illness primarily found in Japan. - This Rickettsial disease is distinct from Boutonneuse fever, having a different geographical distribution and primary vector. *Rickettsia sibirica* - **Rickettsia sibirica** is responsible for **Siberian tick typhus** (North Asian tick typhus), which is prevalent in Siberia, Mongolia, and Northern China. - While also a tick-borne Rickettsial infection, its clinical presentation and geographic range differ from Boutonneuse fever. *Rickettsia australis* - **Rickettsia australis** causes **Queensland tick typhus**, an indigenous Rickettsial disease found in Australia. - This pathogen is distinct from Rickettsia conorii and causes a localized form of tick typhus.