ENT
5 questionsWhat causes the cart-wheel appearance of the tympanic membrane in acute suppurative otitis media (ASOM)?
Retraction of tympanic membrane touching the promontory. What is the classification according to Sade's grading system?
What is the most common cause of ASOM?
Bullous myringitis is caused by?
What are the potential causes of myringosclerosis?
NEET-PG 2013 - ENT NEET-PG Practice Questions and MCQs
Question 501: 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 502: Retraction of tympanic membrane touching the promontory. What is the classification according to Sade's grading system?
- A. Grade 1
- B. Grade 2
- C. Grade 3 (Correct Answer)
- D. Grade 4
Explanation: ***Grade 3*** - **Grade 3** retraction involves the tympanic membrane making contact with the **promontory** of the middle ear. - This contact indicates significant retraction, often with loss of definition of the malleus handle. *Grade 1* - **Grade 1** retraction is characterized by mild retraction with an **intact cone of light** and good mobility. - The tympanic membrane does not touch any middle ear structures. *Grade 2* - **Grade 2** retraction shows the tympanic membrane touching the **incudostapedial joint** or posterior wall of the middle ear. - The handle of the malleus may appear significantly foreshortened. *Grade 4* - **Grade 4** retraction involves **adhesive otitis media**, where the tympanic membrane is severely retracted and fully adherent to the middle ear structures. - This often results in a nearly complete obliteration of the middle ear space.
Question 503: 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.
Question 504: Bullous myringitis is caused by?
- A. Haemophilus influenzae
- B. Candida
- C. Mycoplasma pneumoniae (Correct Answer)
- D. Streptococcus pneumoniae
Explanation: ***Mycoplasma pneumoniae*** - **Bullous myringitis** is characterized by the formation of **blisters** (bullae) on the **tympanic membrane**, which is a classic presentation associated with *Mycoplasma pneumoniae* infection. - While other bacteria can cause otitis media, *Mycoplasma pneumoniae* has a strong association with the development of **hemorrhagic bullae** on the eardrum. *Streptococcus pneumoniae* - This bacterium is the **most common cause** of **acute otitis media (AOM)**, but it typically presents with inflammation and bulging of the tympanic membrane **without** the characteristic bullae. - While it can cause severe ear infections, its typical presentation does not involve the **blister formation** seen in bullous myringitis. *Haemophilus influenzae* - This is another **common bacterial cause** of **acute otitis media**, especially in children, often leading to bulging and redness of the eardrum. - Similar to *Streptococcus pneumoniae*, it is not typically associated with the development of **bullae** on the tympanic membrane. *Candida* - **Candida** species are **fungi** and are a cause of **otitis externa** (ear canal infection) or, less commonly, **chronic otitis media**, particularly in immunocompromised individuals. - Fungal infections of the ear, including Candida, do **not** typically cause the characteristic **bullous myringitis** presentation.
Question 505: What are the potential causes of myringosclerosis?
- A. Genetic predisposition
- B. Chronic inflammation from recurrent infections (Correct Answer)
- C. Otosclerosis
- D. None of the options
Explanation: ***Chronic inflammation from recurrent infections*** - **Myringosclerosis** is often a consequence of **chronic inflammation** and repair processes in the tympanic membrane (eardrum), commonly triggered by **recurrent otitis media** (middle ear infections). - The inflammatory exudates and subsequent healing lead to the deposition of **calcium and phosphate crystals** within the fibrous layer of the tympanic membrane, causing it to become stiff and opaque. *Genetic predisposition* - While genetics can play a role in some ear conditions, **myringosclerosis** is primarily an **acquired condition** rather than one solely determined by genetic factors. - No specific strong genetic link has been identified as a primary cause compared to environmental triggers. *Otosclerosis* - **Otosclerosis** is a condition affecting the **ossicles** (typically the stapes) in the middle ear, leading to conductive hearing loss due to abnormal bone growth, not directly affecting the tympanic membrane. - Myringosclerosis involves the eardrum itself, characterized by **calcification of the tympanic membrane**, which is distinct from the pathology of otosclerosis. *None of the options* - This option is incorrect because **chronic inflammation from recurrent infections** is a well-established cause of myringosclerosis. - The presence of a correct answer negates this choice.
Microbiology
5 questionsWhich of the following is a saccharolytic species of Clostridium?
'String of pearl' colonies on penicillin-containing nutrient agar are produced by:
JSB stain is used for which parasite?
In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?
Pneumococcal vaccine is prepared from ?
NEET-PG 2013 - Microbiology NEET-PG Practice Questions and MCQs
Question 501: Which of the following is a saccharolytic species of Clostridium?
- A. Clostridium tetani
- B. Clostridium septicum (Correct Answer)
- C. Clostridium cochlearium
- D. None of the options
Explanation: ***Clostridium septicum*** - *Clostridium septicum* is a **saccharolytic** species, meaning it ferments carbohydrates to produce gas, which contributes to the rapid tissue destruction seen in **gas gangrene**. - Its ability to rapidly consume sugars in tissues fuels its invasive growth and toxin production, which is characteristic of its pathogenic mechanism. *Clostridium tetani* - *Clostridium tetani* is a **proteolytic** species, primarily deriving its energy from **protein degradation**. - It does not ferment carbohydrates, and its pathogenicity is mainly due to the production of **tetanospasmin**, a neurotoxin. *Clostridium cochlearium* - *Clostridium cochlearium* is a **proteolytic** species that metabolizes proteins and amino acids. - It is not known for significant saccharolytic activity and is typically found in environments rich in protein. *None of the options* - This option is incorrect because *Clostridium septicum* is indeed a saccharolytic species, as detailed above.
Question 502: 'String of pearl' colonies on penicillin-containing nutrient agar are produced by:
- A. Salmonella
- B. Bacillus (Correct Answer)
- C. Proteus
- D. Klebsiella
Explanation: ***Bacillus*** - The "string of pearls" morphology is a classic characteristic of *Bacillus anthracis* when grown on a nutrient agar containing penicillin. - This appearance is due to the bacterium's cell wall being weakened by penicillin, leading to swollen, elongated cells that remain attached in a chain. *Proteus* - *Proteus* species are known for their characteristic **swarming motility** on agar, not a "string of pearls" appearance. - They are typically **resistant to penicillin** and would not show this inhibited growth pattern. *Salmonella* - *Salmonella* typically forms **smooth, round colonies** on agar and does not exhibit a "string of pearls" morphology. - While some species can be inhibited by penicillin, they do not develop this specific appearance. *Klebsiella* - *Klebsiella* species are typically **mucoid** due to their polysaccharide capsule, forming large, glistening colonies. - They are also often **resistant to penicillin** and would not show the "string of pearls" effect.
Question 503: JSB stain is used for which parasite?
- A. Kala azar
- B. Sleeping sickness
- C. Malaria
- D. Filaria (Correct Answer)
Explanation: ***Filaria*** - The **JSB stain (Jaswant Singh Battacharya stain)** is a rapid Romanowsky-type stain specifically developed for the diagnosis of **microfilariae** in blood films. - It allows for clear visualization of the sheaths and nuclei of microfilariae, which is crucial for species identification and diagnosis of **filariasis**. *Malaria* - **Giemsa stain** is the gold standard for identifying malaria parasites in thick and thin blood smears, not JSB stain. - Giemsa allows for detailed morphological differentiation of malaria species and stages within **red blood cells**. *Kala azar* - **Kala-azar (visceral leishmaniasis)** is diagnosed by detecting **Leishman bodies (amastigotes)** in bone marrow, splenic, or lymph node aspirates. - Stains like **Giemsa** or **Leishman stain** are traditionally used for visualizing these amastigotes. *Sleeping sickness* - **Sleeping sickness (African trypanosomiasis)** is diagnosed by identifying **trypomastigotes** in blood smears, lymph node aspirates, or cerebrospinal fluid. - **Giemsa stain** is commonly used for the microscopic examination of these specimens to detect the parasites.
Question 504: In a patient presenting with respiratory symptoms, acute angled septate hyphae are seen in which of the following fungi?
- A. Aspergillus (Correct Answer)
- B. Mucor
- C. Penicillium
- D. Candida
Explanation: ***Aspergillus*** - *Aspergillus* species are characterized by their distinctive **acute-angled (dichotomous) septate hyphae** when observed microscopically in tissue sections or clinical samples. - This morphological feature is crucial for differentiating *Aspergillus* infections, such as **aspergillosis**, from other fungal infections. *Mucor* - *Mucor* (along with *Rhizopus* and *Lichtheimia*) belongs to the Zygomycetes class, which are characterized by **broad, non-septate, ribbon-like hyphae** with irregular branching, not acute-angled septate hyphae. - These fungi are associated with **mucormycosis**, often seen in immunocompromised patients, particularly those with diabetes. *Penicillium* - *Penicillium* is a common mold known for producing penicillin and typically appears as **septate hyphae** but is more often recognized by its branching, brush-like conidiophores (penicilli) in culture rather than a distinct acute-angled septate hyphal morphology in clinical samples causing invasive disease. - While it can cause opportunistic infections, its hyphae are less commonly described as having uniquely acute angles compared to *Aspergillus*. *Candida* - *Candida* species are typically observed as **yeast cells (oval budding forms)**, often forming **pseudohyphae** (elongated yeast cells that remain attached) or true hyphae under specific conditions, but not as acute-angled septate hyphae. - *Candida* is a common cause of superficial and invasive candidiasis, and its microscopic appearance is distinct from filamentous fungi.
Question 505: 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.