Infectious Diseases — MCQs
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A child presents with a painful swelling below the ear, fever, and difficulty opening the mouth. What is the most likely diagnosis?
A child with acute otitis media who fails initial antibiotic therapy, what is the next step in management?
A 5-year-old boy presents with a rash that began on his face and has spread to his trunk and limbs. The rash consists of red patches that give a 'slapped cheek' appearance on the face, followed by a lacy, net-like rash on the trunk and limbs, and he also has a low-grade fever. What is the most likely diagnosis?
A 6-month-old infant is brought to the clinic with a history of severe cough. Upon examination, the child exhibits severe respiratory distress and is diagnosed with pertussis. Which vaccine is recommended for prevention?
What is the next best step in managing a child presenting with fever and metaphyseal bone pain, suspected of having acute osteomyelitis?
Which of the following is the most common cause of pneumonia in a 2-year-old child?
A 7-year-old girl presents with a sore throat, fever, and a strawberry tongue. Which of the following conditions is most likely?
A 3-year-old child presents with a history of high fever, irritability, and refusal to move the right hip. What is the most likely diagnosis?
A 2-month-old infant presents with poor feeding, irritability, and a bulging anterior fontanelle. What is the most likely diagnosis?
A 7-year-old boy presents with fever, sore throat, and painful swelling of the parotid glands. What is the most likely diagnosis?
Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 521: A child presents with a painful swelling below the ear, fever, and difficulty opening the mouth. What is the most likely diagnosis?
- A. Bacterial parotitis
- B. Mumps (Correct Answer)
- C. Branchial cyst
- D. Lymphadenitis
Explanation: ***Mumps*** - The classic presentation of **mumps** includes **parotitis** (painful swelling below the ear), fever, and sometimes difficulty opening the mouth due to pain, especially in a child. - Mumps is a **viral infection** that primarily affects the parotid glands. *Bacterial parotitis* - While it causes painful swelling and fever, **bacterial parotitis** is more common in **dehydrated** or **immunocompromised individuals**, or those with salivary duct obstruction. - It often presents with **purulent discharge** from Stensen's duct, which is not mentioned in this case. *Branchial cyst* - A **branchial cyst** is a congenital anomaly that presents as a **painless, soft swelling**, usually located on the side of the neck, not typically associated with acute fever or difficulty opening the mouth. - It is typically **non-inflammatory** unless secondarily infected. *Lymphadenitis* - **Lymphadenitis** involves swelling of the **lymph nodes**, which are usually more generalized in the neck or can be tender and inflamed, but typically do not cause the prominent, diffuse swelling below the ear characteristic of parotid involvement. - While it can cause fever, the primary swelling location and nature differ from parotitis.
Question 522: A child with acute otitis media who fails initial antibiotic therapy, what is the next step in management?
- A. Repeat the initial antibiotic
- B. Switch to a broader spectrum antibiotic (Correct Answer)
- C. Add a second antibiotic to the regimen
- D. Schedule for myringotomy
Explanation: ***Switch to a broader spectrum antibiotic*** - Failure of initial antibiotic therapy for **acute otitis media** suggests that the causative pathogen may be resistant to the initial drug or is a different organism requiring broader coverage. - Switching to an antibiotic with a **wider spectrum of activity** or one known to be effective against common resistant strains (e.g., high-dose amoxicillin-clavulanate) is generally the next appropriate step. *Repeat the initial antibiotic* - Repeating the same antibiotic without clinical improvement is unlikely to be effective, as it implies the initial drug failed to eradicate the infection, possibly due to **resistance** or an **incorrect diagnosis**. - This approach delays appropriate treatment and may contribute to **antibiotic resistance**. *Add a second antibiotic to the regimen* - While combination therapy is sometimes used for severe infections, simply adding a second antibiotic without considering the spectrum of the initial drug or the most likely resistant pathogens is not typically the first empirical step. - It increases the risk of side effects and can lead to unnecessary **polypharmacy**. *Schedule for myringotomy* - Myringotomy, with or without tympanostomy tube placement, is typically reserved for **recurrent acute otitis media**, persistent middle ear effusion, or complications, not immediately after the failure of an initial antibiotic course. - It is an invasive procedure and should only be considered after medical management options have been exhausted or if there are specific indications such as severe pain or complications (e.g., mastoiditis).
Question 523: A 5-year-old boy presents with a rash that began on his face and has spread to his trunk and limbs. The rash consists of red patches that give a 'slapped cheek' appearance on the face, followed by a lacy, net-like rash on the trunk and limbs, and he also has a low-grade fever. What is the most likely diagnosis?
- A. Scarlet Fever
- B. Measles
- C. Erythema Infectiosum (Correct Answer)
- D. Roseola
Explanation: ***Erythema Infectiosum*** - The distinctive **'slapped cheek' rash** on the face, followed by a **lacy, reticular (net-like) rash** spreading to the trunk and limbs, is characteristic of Erythema Infectiosum, also known as Fifth Disease, caused by **Parvovirus B19**. - It often presents with a **low-grade fever** and is more common in school-aged children. *Scarlet Fever* - Characterized by a **fine, sandpaper-like rash** that blanches with pressure and often starts on the neck and chest before spreading. - Typically accompanied by a **high fever**, sore throat, and swollen lymph nodes, due to a **Group A Streptococcus** infection. *Measles* - Measles rash typically presents as **maculopapular, erythematous lesions** that start behind the ears and on the face, spreading downwards. - It is preceded by **Koplik spots** (small white spots on the buccal mucosa) and a prodrome of high fever, cough, conjunctivitis, and coryza. *Roseola* - Roseola is characterized by a **high fever** (often >103°F) that lasts for 3-5 days, followed by the sudden appearance of a **rose-pink maculopapular rash** once the fever breaks. - The rash usually starts on the trunk and spreads to the neck and extremities, but does not present with a "slapped cheek" or lacy appearance.
Question 524: A 6-month-old infant is brought to the clinic with a history of severe cough. Upon examination, the child exhibits severe respiratory distress and is diagnosed with pertussis. Which vaccine is recommended for prevention?
- A. Live attenuated
- B. Conjugate
- C. Inactivated
- D. Subunit (Correct Answer)
Explanation: ***Subunit*** - The **pertussis vaccine** (DTaP for infants/children and Tdap for adolescents/adults) is a **subunit vaccine**, meaning it contains only specific purified antigens from the *Bordetella pertussis* bacterium, such as pertussis toxin, filamentous hemagglutinin, and pertactin. - This type of vaccine is used because the whole-cell pertussis vaccine (DTP) was associated with a higher rate of adverse effects, leading to the development of safer acellular subunit formulations. *Live attenuated* - **Live attenuated vaccines** contain a weakened form of the pathogen that can replicate in the host without causing severe disease, providing a strong immune response (e.g., MMR, varicella, rotavirus). - While effective, live attenuated vaccines are generally not used for pertussis due to concerns about safety and potential for reversion to virulence in some cases. *Inactivated* - **Inactivated vaccines** contain whole pathogens that have been killed or inactivated, preventing them from replicating but retaining their antigenicity (e.g., inactivated polio vaccine, influenza vaccine). - While one of the older pertussis vaccines (DTP) was a **whole-cell inactivated vaccine**, the current recommended DTaP/Tdap vaccines are **acellular subunit vaccines**, which are safer due to fewer adverse reactions. *Conjugate* - **Conjugate vaccines** are created by chemically linking a polysaccharide antigen (which is T-cell independent) to a protein carrier (which is T-cell dependent), thereby eliciting a more robust and long-lasting immune response, especially in infants (e.g., Hib, pneumococcal, meningococcal vaccines). - The pertussis vaccine is not a conjugate vaccine; its antigens are primarily proteins (e.g., pertussis toxin), not polysaccharides conjugated to a carrier protein.
Question 525: What is the next best step in managing a child presenting with fever and metaphyseal bone pain, suspected of having acute osteomyelitis?
- A. Wait for MRI results before starting treatment
- B. Conduct a bone biopsy immediately
- C. Obtain a blood culture and perform imaging
- D. Start empirical antibiotics immediately (Correct Answer)
Explanation: ***Start empirical antibiotics immediately*** - In a child with suspected **acute osteomyelitis**, prompt initiation of empirical antibiotics is crucial to prevent further bone destruction and systemic spread of infection. - Waiting for culture results or extensive imaging can delay treatment, leading to worse outcomes, including **septic arthritis** or chronic osteomyelitis. *Obtain a blood culture and perform imaging* - While **blood cultures** and **imaging** (such as X-rays, ultrasound, or MRI) are essential diagnostic steps, they should be performed concurrently with, or immediately after, the initiation of empirical antibiotics. - Imaging confirms the diagnosis and extent, while cultures identify the causative organism, but neither should delay the initial therapeutic intervention. *Wait for MRI results before starting treatment* - **Magnetic Resonance Imaging (MRI)** is highly sensitive for diagnosing osteomyelitis, but waiting for MRI results can cause a significant delay in treatment, especially in an acute setting. - This delay increases the risk of complications such as **bone damage** or spread of infection. *Conduct a bone biopsy immediately* - A **bone biopsy** provides definitive diagnosis and allows for targeted antibiotic therapy based on culture results, but it is an invasive procedure and not the immediate first step. - It is typically reserved for cases where initial empirical antibiotic therapy fails or the diagnosis remains uncertain despite other diagnostic tests.
Question 526: Which of the following is the most common cause of pneumonia in a 2-year-old child?
- A. Haemophilus influenzae
- B. Mycoplasma pneumoniae
- C. RSV
- D. Streptococcus pneumoniae (Correct Answer)
Explanation: ***Streptococcus pneumoniae*** - **Streptococcus pneumoniae** is the **most common cause of bacterial pneumonia** in children aged 2 months to 5 years, including 2-year-olds. - Remains the leading bacterial pathogen causing community-acquired pneumonia in this age group despite pneumococcal vaccination. - Typically presents with **lobar pneumonia**, high fever, and may be associated with **pleural effusion** or empyema in severe cases. - The **13-valent pneumococcal conjugate vaccine (PCV13)** has reduced incidence but S. pneumoniae remains the predominant bacterial cause. *RSV* - **Respiratory Syncytial Virus (RSV)** is the most common cause of **bronchiolitis** and lower respiratory tract infections in **infants**, particularly those aged **2-8 months**. - By age 2 years, RSV remains a cause of viral pneumonia but is significantly less common than in infancy. - When it does occur at this age, it tends to be less severe than in younger infants. *Haemophilus influenzae* - **Non-typeable Haemophilus influenzae** can cause pneumonia but is less common than S. pneumoniae. - **Haemophilus influenzae type b (Hib)** vaccine has dramatically reduced invasive Hib disease, including pneumonia. - Now accounts for a much smaller proportion of childhood pneumonia cases in vaccinated populations. *Mycoplasma pneumoniae* - **Mycoplasma pneumoniae** is a common cause of **atypical pneumonia** in **school-aged children** (>5 years) and adolescents. - Uncommon in children under 5 years of age, though can occasionally occur. - Presents with gradual onset, dry cough, and extrapulmonary manifestations (rash, myalgias).
Question 527: A 7-year-old girl presents with a sore throat, fever, and a strawberry tongue. Which of the following conditions is most likely?
- A. Scarlet fever (Correct Answer)
- B. Kawasaki disease
- C. Infectious mononucleosis
- D. Hand-foot-and-mouth disease
Explanation: ***Scarlet fever*** - The classic triad of **sore throat**, **fever**, and **strawberry tongue** is highly characteristic of scarlet fever, a systemic illness caused by toxigenic strains of **Group A Streptococcus**. - Other common findings include a **scarlatiniform rash** (sandpaper-like texture) and **circumoral pallor**. *Kawasaki disease* - While it can present with fever and strawberry tongue, Kawasaki disease typically involves **bilateral conjunctival injection**, **polymorphous rash**, **cervical lymphadenopathy**, and changes in **extremities** (e.g., desquamation). - It usually occurs in children younger than 5 years and lacks the prominent pharyngitis associated with scarlet fever. *Infectious mononucleosis* - Caused by the **Epstein-Barr virus**, it is characterized by **fever**, **pharyngitis**, **lymphadenopathy**, and sometimes **splenomegaly**. - A strawberry tongue is not a typical feature, and the pharyngitis is often exudative. *Hand-foot-and-mouth disease* - This viral illness, often caused by **Coxsackievirus**, presents with **fever**, **oral lesions** (herpangina-like), and a characteristic rash on the **hands and feet** (vesicular or papular). - A strawberry tongue is not a typical or distinguishing feature of hand-foot-and-mouth disease.
Question 528: A 3-year-old child presents with a history of high fever, irritability, and refusal to move the right hip. What is the most likely diagnosis?
- A. Septic arthritis (Correct Answer)
- B. Transient synovitis
- C. Legg-Calvé-Perthes disease
- D. Slipped capital femoral epiphysis
Explanation: ***Septic arthritis*** - The combination of **high fever, irritability, and refusal to move the hip** in a 3-year-old child is highly suggestive of **septic arthritis**, a medical emergency [1]. - This condition involves an **infection within the joint space**, leading to severe pain and limited range of motion due to inflammation and pus accumulation [2]. *Transient synovitis* - While it causes hip pain and refusal to bear weight, **transient synovitis** typically presents with a **lower-grade or no fever** and less severe systemic symptoms [2]. - It is a self-limiting inflammation of the hip joint that usually follows a **viral infection**. *Legg-Calvé-Perthes disease* - This condition is characterized by **avascular necrosis of the femoral head** and typically presents with a **limp** and **insidious onset of hip pain**, usually without fever or acute irritability. - It usually affects children between 4 and 8 years old, and **fever is generally absent**. *Slipped capital femoral epiphysis* - This condition occurs when the **femoral head slips off the femoral neck** through the growth plate and is more common in **adolescents (typically 10-16 years)**, particularly during periods of rapid growth [1]. - It usually presents with **hip or knee pain and a limp** but generally **without fever**.
Question 529: A 2-month-old infant presents with poor feeding, irritability, and a bulging anterior fontanelle. What is the most likely diagnosis?
- A. Hydrocephalus
- B. Meningitis (Correct Answer)
- C. Intraventricular Hemorrhage
- D. Cerebral Palsy
Explanation: ***Meningitis*** - The **classic triad** of a **bulging anterior fontanelle**, **poor feeding**, and **irritability** in a 2-month-old infant is highly suggestive of **meningitis**. - A bulging fontanelle indicates **increased intracranial pressure**, which in the context of fever, poor feeding, and irritability points to **central nervous system infection**. - Infants with meningitis often present with **non-specific symptoms** due to an underdeveloped immune system, making this constellation of findings critical for diagnosis. - **Immediate lumbar puncture** and empirical antibiotics are warranted given the high morbidity and mortality of bacterial meningitis in this age group. *Hydrocephalus* - While hydrocephalus can cause a **bulging fontanelle** due to increased intracranial pressure, it typically presents with **progressive head circumference enlargement** over weeks to months. - The **acute presentation** with irritability and poor feeding, without mention of increasing head size or developmental concerns, makes an **infectious etiology more likely**. - Hydrocephalus would be a more chronic process rather than the acute presentation described. *Intraventricular Hemorrhage* - **Intraventricular hemorrhage (IVH)** primarily affects **premature infants** in the first few days of life, not typically term infants at 2 months of age. - IVH presents with **acute neurological deterioration**, **apnea**, **bradycardia**, and **seizures**, often with a sudden drop in hematocrit. - The absence of prematurity history and the subacute presentation make IVH much less likely than meningitis. *Cerebral Palsy* - **Cerebral palsy** is a **non-progressive motor disorder** resulting from perinatal brain injury, not an acute illness. - CP presents with **delayed motor milestones**, **abnormal muscle tone**, and **persistent primitive reflexes**, typically diagnosed after 6-12 months of age. - A bulging fontanelle and acute symptoms like poor feeding and irritability are **not features of cerebral palsy**.
Question 530: A 7-year-old boy presents with fever, sore throat, and painful swelling of the parotid glands. What is the most likely diagnosis?
- A. Tonsillitis
- B. Mumps (Correct Answer)
- C. Epiglottitis
- D. Lymphadenitis
Explanation: ***Correct Answer: Mumps*** - **Fever**, **sore throat**, and **painful swelling of the parotid glands** are classic symptoms of mumps, a viral infection caused by the mumps virus (paramyxovirus). - Mumps primarily targets the **salivary glands**, especially the parotid glands, leading to characteristic bilateral facial swelling. - The combination of constitutional symptoms with parotid involvement is pathognomonic for mumps. *Incorrect: Tonsillitis* - Characterized by **inflamed and swollen tonsils**, often with exudate, leading to severe sore throat and difficulty swallowing. - **Parotid gland swelling** is not a typical feature of tonsillitis. - Lymph node enlargement may occur but differs from parotid enlargement. *Incorrect: Epiglottitis* - A serious bacterial infection causing inflammation and swelling of the **epiglottis**, which can rapidly obstruct the airway. - Symptoms include **stridor**, **drooling**, **tripod positioning**, and **difficulty breathing**, not parotid swelling. - This is a medical emergency requiring immediate airway management. *Incorrect: Lymphadenitis* - Refers to inflammation of the **lymph nodes**, which can cause localized swelling and tenderness. - While cervical lymph nodes might be swollen with a sore throat, this presents as distinct nodular swelling along lymph node chains. - Does not involve the specific, bilateral swelling of the **parotid glands** as seen with mumps.
Practice by Chapter
Vaccine-Preventable Diseases
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Immunization Schedule
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Common Childhood Infections
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Pediatric HIV
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Congenital Infections
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Fever in Infants and Children
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Meningitis and Encephalitis
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Respiratory Tract Infections
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Gastrointestinal Infections
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Parasitic Infections
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Tuberculosis in Children
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Opportunistic Infections
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