Respiratory Tract Infections — MCQs
A 6-year-old boy presents with fever and chills, cough, rapid breathing, difficulty breathing, and chest pain. A culture from a respiratory sample shows Gram-positive bacteria. What is the most likely organism causing this infection?
Which is the most common organism causing acute epiglottitis among the following options?
Which one of the following conditions does not typically present with inspiratory stridor in children?
Which of the following statements regarding Pertussis is INCORRECT?
A 3-month-old infant with no chest indrawing and a respiratory rate of 52/minute. The diagnosis is:
A child presents with complaints of cough. Characteristic inspiratory whoop present. He is not immunised. Sample for investigation is:
A 4-year-old child with barking cough is diagnosed with croup. Which virus is most likely responsible?
An 8-year-old boy from an impoverished inner-city area has never been vaccinated appropriately. He develops fever, cough, and coryza. The next day, blue white spots develop on the buccal mucosa. On the third day, an erythematous, nonpruritic maculopapular rash develops on the face and spreads over the entire body. Which of the following is the most likely complication?
Most common cause of bacterial meningitis in post-neonatal period:
What is the most common presentation for IgA nephropathy?
Respiratory Tract Infections Indian Medical PG Practice Questions and MCQs
Question 1: A 6-year-old boy presents with fever and chills, cough, rapid breathing, difficulty breathing, and chest pain. A culture from a respiratory sample shows Gram-positive bacteria. What is the most likely organism causing this infection?
- A. Streptococcus pyogenes
- B. Streptococcus pneumoniae (Correct Answer)
- C. Staphylococcus aureus
- D. Propionibacterium acnes
Explanation: ***Streptococcus pneumoniae*** - This clinical picture describes typical symptoms of **pneumonia** in a child, including fever, cough, rapid and difficult breathing, and chest pain. - **_Streptococcus pneumoniae_** is the most common bacterial cause of community-acquired pneumonia in children. The respiratory sample showing gram-positive bacteria further supports this. *Staphylococcus aureus* - While **_Staphylococcus aureus_** can cause pneumonia, it is less common than _Streptococcus pneumoniae_ in community-acquired cases in healthy children and often associated with more severe, necrotizing forms or post-viral infections. - While it is a **Gram-positive bacterium**, its clinical presentation would not be the most likely first choice for typical pneumonia symptoms in this age group. *Propionibacterium acnes* - **_Propionibacterium acnes_** (now *Cutibacterium acnes*) is primarily associated with **acne vulgaris** and, less commonly, opportunistic infections related to implanted devices or some rare soft tissue infections. - It is not a typical cause of primary respiratory infections like pneumonia. *Streptococcus pyogenes* - **_Streptococcus pyogenes_** (Group A Streptococcus) is known for causing **pharyngitis** (strep throat), skin infections (impetigo, cellulitis), and scarlet fever. - While it can rarely cause pneumonia, it is not a common cause, and the constellation of symptoms points more strongly to _Streptococcus pneumoniae_.
Question 2: Which is the most common organism causing acute epiglottitis among the following options?
- A. N. Meningitidis
- B. H. influenzae (Correct Answer)
- C. S. pyogenes
- D. S. Pneumoniae
Explanation: ***H. influenzae*** - **_Haemophilus influenzae_ type b (Hib)** was historically the **most common cause** of acute epiglottitis, particularly in children before widespread Hib vaccination. - This remains the **classically taught answer** in medical education and is still relevant in **unvaccinated populations** or areas with low vaccination coverage. - **Important note:** In the **post-vaccine era** with widespread Hib vaccination, the incidence has decreased by >95%, and other organisms (particularly _Streptococcus_ species) have become relatively more common, especially in adults. - However, H. influenzae remains the organism most associated with acute epiglottitis in traditional medical teaching. *N. meningitidis* - **_Neisseria meningitidis_** primarily causes **meningococcal meningitis** and **meningococcemia** (fulminant septicemia). - While it can cause various invasive infections, it is **not a common cause** of acute epiglottitis. - Characteristic features include petechial/purpuric rash in septicemia. *S. pyogenes* - **_Streptococcus pyogenes_** (Group A Streptococcus) is the leading cause of **acute bacterial pharyngitis** ("strep throat"). - It causes complications like **acute rheumatic fever** and **acute post-streptococcal glomerulonephritis**. - In the post-Hib vaccine era, it has emerged as an **increasingly common cause** of epiglottitis, especially in adults, but is still less classically associated than H. influenzae in traditional teaching. *S. pneumoniae* - **_Streptococcus pneumoniae_** is a major cause of **community-acquired pneumonia, acute otitis media, bacterial meningitis**, and **bacteremia**. - While it can cause **supraglottitis/epiglottitis** (particularly in adults in the modern era), it is **less classically associated** with acute epiglottitis compared to the traditional pathogen H. influenzae type b.
Question 3: Which one of the following conditions does not typically present with inspiratory stridor in children?
- A. Laryngomalacia
- B. Acute epiglottitis
- C. Bronchiolitis (Correct Answer)
- D. Croup
Explanation: ***Bronchiolitis*** - This condition primarily affects the **small airways** (bronchioles) and is caused by inflammation and swelling, leading to **expiratory wheezing** and difficulty breathing, rather than inspiratory stridor. - While it can cause respiratory distress, the narrowing of the lower airways typically manifests as **wheezing and crackles**, not the harsh, high-pitched sound of inspiratory stridor associated with upper airway obstruction. *Laryngomalacia* - This is a common congenital condition characterized by the collapse of **supraglottic structures** during inspiration, leading to intermittent **inspiratory stridor** that is often worse when the infant is feeding, agitated, or supine. - The stridor is typically **soft and musical**, and usually improves spontaneously as the child grows. *Acute epiglottitis* - This is a severe and rapidly progressive bacterial infection of the **epiglottis**, which can cause significant **upper airway obstruction** and life-threatening inspiratory stridor. - Children with epiglottitis often present with a **sudden onset of high fever**, sore throat, **drooling**, and a **"tripod" position** (leaning forward with neck extended). *Croup* - This condition, typically caused by a viral infection, leads to **subglottic inflammation** and swelling, resulting in the characteristic **"barking" cough** and **inspiratory stridor**. - The stridor is due to the narrowing of the trachea below the vocal cords.
Question 4: Which of the following statements regarding Pertussis is INCORRECT?
- A. The drug of choice is Erythromycin.
- B. Cerebellar ataxia is a known complication. (Correct Answer)
- C. Some infections may be subclinical.
- D. The most infective stage is the catarrhal stage.
Explanation: ***Cerebellar ataxia is a known complication.*** - **Cerebellar ataxia** is not a typical or known complication of pertussis. Complications usually involve the respiratory, neurological (e.g., seizures, encephalopathy due to hypoxia), and nutritional systems due to severe coughing. - While neurological complications can occur, **ataxia** specifically is not frequently sighted in the context of pertussis. *Some infections may be subclinical.* - Some individuals, especially those partially immunized or older, can experience **subclinical or atypical infections** with pertussis, often presenting as a mild cough. - This characteristic makes it difficult to control the spread of the disease as infected individuals may not be recognized. *The most infective stage is the catarrhal stage.* - The **catarrhal stage**, characterized by non-specific cold-like symptoms, is the most contagious phase because bacterial shedding is highest. - During this stage, symptoms are mild and often indistinguishable from a common cold, leading to widespread transmission before diagnosis. *The drug of choice is Erythromycin.* - **Erythromycin**, or other macrolides like azithromycin or clarithromycin, are the drugs of choice for treating pertussis. - These antibiotics are most effective when administered early in the **catarrhal stage** to reduce disease severity and prevent transmission.
Question 5: A 3-month-old infant with no chest indrawing and a respiratory rate of 52/minute. The diagnosis is:
- A. Severe pneumonia
- B. Pneumonia (Correct Answer)
- C. No pneumonia
- D. Very severe disease
Explanation: ***Pneumonia*** - A respiratory rate of 52/minute in a 3-month-old infant **meets the age-specific threshold for tachypnea** (respiratory rate ≥ 50 breaths/minute for infants 2-12 months according to IMCI guidelines). - In the **absence of chest indrawing**, the presence of fast breathing (tachypnea) alone classifies this as **pneumonia** per IMCI classification. - This requires **outpatient management with oral antibiotics** and close follow-up. *No pneumonia* - This diagnosis would apply if the respiratory rate was **< 50 breaths/minute** for this age group with no chest indrawing. - Since the respiratory rate is 52/minute (≥ 50/minute), this rules out "no pneumonia." *Severe pneumonia* - This diagnosis requires the presence of **chest indrawing** in addition to fast breathing. - The question explicitly states **"no chest indrawing,"** which excludes severe pneumonia. - Severe pneumonia would require **hospitalization and parenteral antibiotics**. *Very severe disease* - This diagnosis involves **danger signs** such as inability to drink or breastfeed, persistent vomiting, convulsions, lethargy, unconsciousness, or severe malnutrition. - None of these critical signs are mentioned in the clinical scenario. - Very severe disease requires **urgent hospitalization and injectable antibiotics**.
Question 6: A child presents with complaints of cough. Characteristic inspiratory whoop present. He is not immunised. Sample for investigation is:
- A. Nasopharyngeal swab (Correct Answer)
- B. Sputum culture
- C. Tracheal aspiration
- D. Cough plate culture
Explanation: ***Nasopharyngeal swab*** - A **nasopharyngeal swab** is the preferred sample for diagnosing **whooping cough** (pertussis) caused by *Bordetella pertussis*, especially for PCR testing. - This method provides the best yield for detecting the bacterium which colonizes the **nasopharynx**. *Sputum culture* - **Sputum culture** is generally not recommended for diagnosing pertussis as *Bordetella pertussis* is a fastidious organism and less likely to be found in sputum. - Sputum collection can also be challenging and less effective in young children. *Tracheal aspiration* - **Tracheal aspiration** is an invasive procedure and is generally reserved for critically ill patients or those with specific indications like ventilator-associated pneumonia, not routine pertussis diagnosis. - The primary site for *Bordetella pertussis* colonization is the nasopharynx, not typically deep within the trachea for initial sampling. *Cough plate culture* - **Cough plate culture** involves exposing a culture medium directly to a patient's cough, but it is an older technique with lower sensitivity and specificity compared to nasopharyngeal swabs and PCR. - Modern diagnostic methods, such as PCR from nasopharyngeal samples, offer faster and more accurate results for pertussis.
Question 7: A 4-year-old child with barking cough is diagnosed with croup. Which virus is most likely responsible?
- A. Parainfluenza virus (Correct Answer)
- B. Rhinovirus
- C. Adenovirus
- D. Respiratory syncytial virus
Explanation: ***Parainfluenza virus*** - **Parainfluenza viruses (PIV)** are the most common cause of **croup**, characterized by a **barking cough**, hoarseness, and inspiratory stridor. - PIV types 1 and 2 are particularly associated with acute laryngotracheobronchitis (croup) in young children. *Rhinovirus* - **Rhinoviruses** are the primary cause of the **common cold** and typically result in upper respiratory tract symptoms like runny nose, sneezing, and sore throat. - They are generally not associated with the severe laryngeal inflammation that causes the characteristic barking cough of croup. *Adenovirus* - **Adenoviruses** can cause a variety of respiratory illnesses, including pharyngitis and pneumonia, and sometimes mimic croup. - However, they are a less frequent cause of croup compared to parainfluenza viruses. *Respiratory syncytial virus* - **Respiratory syncytial virus (RSV)** is the leading cause of **bronchiolitis** and pneumonia in infants and young children. - While RSV can cause upper respiratory symptoms, it typically leads to wheezing and crackles rather than the barking cough of croup.
Question 8: An 8-year-old boy from an impoverished inner-city area has never been vaccinated appropriately. He develops fever, cough, and coryza. The next day, blue white spots develop on the buccal mucosa. On the third day, an erythematous, nonpruritic maculopapular rash develops on the face and spreads over the entire body. Which of the following is the most likely complication?
- A. encephalitis
- B. bronchitis
- C. otitis media
- D. pneumonia (Correct Answer)
Explanation: ***Pneumonia*** - This scenario describes **measles** (rubeola) with the classic triad of fever, cough, and coryza (the **3 Cs**), along with pathognomonic **Koplik spots** (blue-white spots on buccal mucosa) and the characteristic **maculopapular rash** spreading cephalocaudally from the face. - **Pneumonia** is the **most common serious complication** of measles, occurring in approximately **1-6% of cases**, and is the **leading cause of measles-related mortality** in children. - It can be either **viral pneumonia** (direct measles virus infection) or **secondary bacterial pneumonia** (especially *Streptococcus pneumoniae*, *Staphylococcus aureus*, *Haemophilus influenzae*). - This is particularly common in **unvaccinated, malnourished, and immunocompromised children** from impoverished areas, as described in this case. *Otitis media* - **Otitis media** is a common complication of measles, occurring in approximately **5-9% of cases**. - While frequent, it is **less common than pneumonia** and is generally less severe in terms of mortality risk. - It typically presents with ear pain and can lead to hearing complications if untreated. *Encephalitis* - **Measles encephalitis** is a rare but severe complication, occurring in approximately **1 in 1000 cases** (0.1%). - It typically develops **1-2 weeks after rash onset**, presenting with fever, headache, seizures, altered consciousness, and neurological deficits. - While serious with significant mortality and morbidity, it is **much less common** than pneumonia. *Bronchitis* - **Bronchitis** (cough, chest congestion) is typically part of the **initial prodromal phase** of measles itself rather than a distinct complication. - The respiratory symptoms (cough, coryza) are manifestations of the primary measles infection, not secondary complications.
Question 9: Most common cause of bacterial meningitis in post-neonatal period:
- A. Mycobacterium tuberculosis
- B. Staphylococcus aureus
- C. Streptococcus pneumoniae (Correct Answer)
- D. Klebsiella
Explanation: ***Streptococcus pneumoniae*** - *S. pneumoniae* is the most common cause of **bacterial meningitis** in the post-neonatal period (1 month to 1 year of age), particularly in regions with high vaccination rates against Hib. - Its polysaccharide capsule and ability to evade the immune system contribute to its virulence in causing **central nervous system infections**. - Accounts for approximately 40-50% of bacterial meningitis cases in this age group. *Mycobacterium tuberculosis* - While it can cause **tuberculous meningitis**, this is a less common form of meningitis, typically with a more **insidious onset** and often associated with immunosuppression or endemic areas. - Represents a chronic form of meningitis rather than acute bacterial meningitis. *Staphylococcus aureus* - *S. aureus* meningitis typically occurs in specific contexts such as **post-neurosurgery**, following head trauma, or in patients with indwelling catheters or bacteremia. - It is not the most frequent pathogen in community-acquired meningitis in infants. *Klebsiella* - **Klebsiella pneumoniae** can cause meningitis, especially in **neonates** (first 28 days of life), immunocompromised individuals, or patients with healthcare-associated infections. - However, it is not the most common cause of meningitis in the post-neonatal period.
Question 10: What is the most common presentation for IgA nephropathy?
- A. Nephritic syndrome
- B. Nephrotic syndrome
- C. Microscopic hematuria
- D. Repeated gross hematuria (Correct Answer)
Explanation: ***Repeated gross hematuria*** - The hallmark of **IgA nephropathy** is recurrent episodes of **gross hematuria**, particularly following **respiratory infections** [1]. - It is often associated with **renal impairment** but can present initially with **visible blood** in the urine [1]. *Nephritic syndrome* - While IgA nephropathy can lead to nephritic features, it does not commonly present primarily as **nephritic syndrome**, which includes hypertension and edema. - Nephritic syndrome is characterized by significant **proteinuria** and acute renal failure, rather than the classic presentation of hematuria [2]. *Microscopic hematuria* - Although **microscopic hematuria** can occur in IgA nephropathy, it is not the most common and noticeable presentation; **gross hematuria** is more characteristic [1]. - Microscopic hematuria lacks the acute visual symptoms seen in cases proving the diagnosis. *Nephritic syndrome* - This option is a repetition of and does not provide any additional unique characteristics specific to **IgA nephropathy**. - It shares the same clinical features discussed previously and is thus not representative of the most common presentation.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free