Infectious Diseases Practice Questions

Q: Which bacterial infection is characterized by a 'strawberry tongue'?

Scarlet fever. ***Scarlet fever*** - **Scarlet fever**, caused by **Group A Streptococcus**, is classically associated with a **strawberry tongue** due to inflamed papillae [1]. - Other characteristic symptoms include a **diffuse red rash** that feels like sandpaper, a sore throat, and fever [1]. *Impetigo* - **Impetigo** is a superficial skin infection characterized by **honey-colored crusted lesions**, typically on the face. - It does not involve systemic symptoms like fever or have oral manifestations such as a strawberry tongue. *Cellulitis* - **Cellulitis** is a deeper skin infection affecting the dermis and subcutaneous tissue, presenting as a **red, swollen, warm, and tender area of skin** [2]. - It does not cause a rash or a strawberry tongue; its manifestations are localized to the affected skin area [2]. *Erysipelas* - **Erysipelas** is a superficial form of cellulitis, characterized by a **sharply demarcated, raised, red, and warm rash**, often on the face or legs [2]. - While it's a skin infection, it does not involve the characteristic oral findings of a strawberry tongue.

Q: A 6-year-old boy presents with fever, sore throat, and a sandpaper-like rash. The rapid strep test is positive. What is the most appropriate treatment?

Amoxicillin. ***Amoxicillin*** - **Amoxicillin** is the **first-line treatment** for **Group A streptococcal pharyngitis** (strep throat) according to **AAP and IDSA guidelines**. - It is equally effective as penicillin V in eradicating *Streptococcus pyogenes* and preventing **rheumatic fever** and **post-streptococcal glomerulonephritis**. - Amoxicillin is preferred over penicillin V due to **better palatability**, **improved compliance** in children, and **convenient once-daily dosing option**. - The patient's presentation with fever, sore throat, and sandpaper rash (classic for **scarlet fever**) plus positive rapid strep test confirms the diagnosis. *Penicillin V* - **Penicillin V** is an acceptable alternative first-line treatment for strep throat with equal efficacy. - However, amoxicillin is generally preferred in pediatric practice due to better taste and compliance. - Both antibiotics have similarly low resistance rates for Group A Streptococcus. *Ceftriaxone* - **Ceftriaxone** is a third-generation cephalosporin reserved for severe infections, suspected complications, or patients unable to tolerate oral medications. - It is not indicated as first-line treatment for uncomplicated **streptococcal pharyngitis**. - May be used in cases of treatment failure or penicillin allergy. *Erythromycin* - **Erythromycin** is a macrolide antibiotic reserved for patients with **penicillin allergy**. - However, **azithromycin** or **clarithromycin** are now preferred over erythromycin due to better tolerability and dosing convenience. - Not indicated as first-line therapy when penicillin or amoxicillin can be used.

Q: A child with severe COVID-19 developed persistent fever and elevated inflammatory markers 3 weeks after initial infection. What is the next step in management?

Begin IVIG therapy. ***Begin IVIG therapy*** - **Intravenous immunoglobulin (IVIG)** is a cornerstone treatment for **Multisystem Inflammatory Syndrome in Children (MIS-C)**, which presents with persistent fever and elevated inflammatory markers post-COVID-19. - IVIG helps modulate the **immune response** and reduce systemic inflammation, crucial for preventing organ damage in MIS-C. *Administer antiviral therapy* - **Antiviral therapy** is most effective when given early in the course of **acute viral infection**, typically within days of symptom onset. - In severe COVID-19 with persistent fever and elevated inflammatory markers, the primary concern shifts from active viral replication to **post-infectious inflammatory complications** like MIS-C. *Consider transfer to intensive care unit* - While a child with severe COVID-19 might eventually require **ICU admission**, it is usually indicated for **respiratory failure**, **hemodynamic instability**, or other signs of severe organ dysfunction. - The initial step for persistent fever and inflammatory markers post-COVID-19 is to target the underlying **hyperinflammatory state** with specific immunotherapy, rather than immediately presuming ICU-level organ failure. *Start high-dose corticosteroids* - **High-dose corticosteroids** are often used in conjunction with IVIG for MIS-C, especially in more severe cases or those unresponsive to IVIG alone. - However, **IVIG** is generally considered the **first-line specific immunomodulatory therapy** for MIS-C, as it has a broader immunomodulatory effect.

Q: A 7-year-old child presents with persistent fever, abdominal pain, and a 'rose spots' rash on the abdomen. What is the most likely diagnosis?

Typhoid fever. ***Typhoid fever*** - **Persistent fever**, **abdominal pain**, and characteristic **'rose spots' rash** on the abdomen are classic clinical features of typhoid fever, caused by *Salmonella typhi*. - This illness can progress to involve multiple organs and requires prompt antibiotic treatment. *Scarlet fever* - Characterized by a **fine, sandpaper-like rash** that blanches with pressure, predominantly on the trunk and extremities, often accompanied by a **strawberry tongue**. - It is caused by *Streptococcus pyogenes* and typically follows a streptococcal pharyngitis, which is not suggested by the symptoms provided. *Measles* - Presents with a **maculopapular rash** that begins on the face and spreads downwards, often preceded by a **prodrome of fever**, **cough**, **coryza**, and **conjunctivitis**, with characteristic **Koplik spots** in the mouth. - The rash is not described as "rose spots" nor is it limited to the abdomen initially. *Rubella* - Characterized by a milder **maculopapular rash** that starts on the face and spreads to the trunk and extremities, often accompanied by **postauricular** and **occipital lymphadenopathy**. - The rash is less distinct than measles and does not typically present as "rose spots" or with severe abdominal pain.

Q: A 7-year-old girl presents with a sore throat, fever, and a red, swollen throat with white patches. A rapid strep test is positive. What is the most likely diagnosis?

Streptococcal pharyngitis. ***Streptococcal pharyngitis*** - The combination of **sore throat, fever, red and swollen throat with white patches**, and a **positive rapid strep test** is highly indicative of streptococcal pharyngitis (strep throat). - This bacterial infection, typically caused by *Streptococcus pyogenes* (Group A Strep), requires antibiotic treatment to prevent complications like **rheumatic fever**. *Viral pharyngitis* - While viral pharyngitis can cause a sore throat and fever, it generally does not present with **white exudates** to the extent described. - A **rapid strep test would be negative** in viral pharyngitis, differentiating it from this case. *Infectious mononucleosis* - Infectious mononucleosis, caused by the **Epstein-Barr virus**, can cause exudative tonsillitis, but it's often accompanied by **lymphadenopathy** (especially in the posterior cervical chain) and **splenomegaly**, which are not mentioned here. - Critically, a **rapid strep test would be negative**, ruling out strep as the primary cause. *Diphtheria* - Diphtheria is characterized by the formation of a **thick, gray pseudomembrane** that can obstruct the airway and is difficult to dislodge. - While it causes a sore throat and fever, it is rare in vaccinated populations and a **rapid strep test would be negative**.

Q: At what age should children begin receiving the influenza vaccine?

6 months. ***6 months*** - The **influenza vaccine** is recommended annually for all individuals aged **6 months and older**. This age is chosen because infants younger than 6 months are at higher risk for severe influenza complications but cannot directly receive the vaccine. - For children aged 6 months to 8 years receiving the vaccine for the first time, **two doses** administered at least four weeks apart are recommended. *At birth* - Influenza vaccines are **not approved or recommended for infants younger than 6 months** due to lack of efficacy and safety data in this age group. - Protection for infants under 6 months relies on **maternal vaccination** during pregnancy and cocooning strategies (vaccinating household contacts). *12 months* - Waiting until 12 months means the child misses out on a full season or more of potential protection during their first year of life when they are particularly vulnerable if not vaccinated. - The recommendation is to start at 6 months, not to delay until 12 months, to provide timely protection against influenza. *2 years* - Delaying vaccination until 2 years old would leave a child unprotected through several high-risk influenza seasons. - Current guidelines uniformly recommend vaccination starting at 6 months, highlighting the importance of early protection against influenza.

Q: A 4-year-old with fever, neck stiffness, and petechial rash presents with a positive Kernig sign, positive Brudzinski sign, heart rate of 140, respiratory rate of 30, and blood pressure of 90/50. CSF analysis shows increased white blood cells, decreased glucose, and increased protein. Analyze the situation and initiate the most appropriate treatment.

IV antibiotics + IV dexamethasone. ***IV antibiotics + IV dexamethasone*** - The clinical picture of **fever**, **neck stiffness**, **petechial rash**, and positive **Kernig** and **Brudzinski** signs strongly indicates **bacterial meningitis**, which is a medical emergency. The CSF analysis with **increased WBCs**, **decreased glucose**, and **increased protein** further confirms bacterial meningitis. - **IV antibiotics** are crucial for killing the bacteria, while **IV dexamethasone** reduces inflammation in the brain, helping to prevent neurological complications such as hearing loss. *IV antivirals + fluid resuscitation* - While fluid resuscitation might be necessary for hemodynamic stability, **IV antivirals** are not the primary treatment for **bacterial meningitis**. - **Antivirals** are used for **viral meningitis** or encephalitis, but the CSF profile (especially **low glucose**) is more consistent with a bacterial infection. *Lumbar puncture + observation without antibiotics* - Performing a **lumbar puncture** is appropriate for diagnosis, but **observation without immediate antibiotics** in a case of suspected bacterial meningitis is extremely dangerous and can lead to rapid deterioration and death. - The patient's critical condition warrants urgent treatment, not just observation after diagnosis. *Supportive care and observation only* - **Supportive care** (e.g., fever reduction, fluid management) is necessary but not sufficient for **bacterial meningitis**. - **Observation only** without specific antimicrobial therapy would result in severe morbidity or mortality in a patient with confirmed bacterial meningitis.

Q: A 1-year-old child is brought in for routine vaccination. Which of the following vaccines is typically administered at this age to provide immunity against multiple diseases?

MMR vaccine. ***MMR vaccine*** - The **Measles, Mumps, and Rubella (MMR) vaccine** is typically recommended for administration at **9-12 months of age** (first dose at 9 months as per IAP schedule, or 12-15 months as per WHO/CDC) as part of routine childhood immunizations. - It provides protection against **three common childhood diseases** (measles, mumps, and rubella) with a single shot. - This is the **primary multi-disease vaccine** given at this age. *BCG vaccine* - The **Bacillus Calmette-Guérin (BCG) vaccine** primarily protects against **tuberculosis** and is typically given **at birth** as per the Indian immunization schedule. - It is not a multi-disease vaccine and is not administered at 1 year of age. *Hepatitis B vaccine* - The **Hepatitis B vaccine** is administered in a **series**, with the first dose given at **birth**, followed by doses at 6, 10, and 14 weeks of age. - It specifically targets the **Hepatitis B virus** only and is not a multi-disease vaccine given at 1 year. *Influenza vaccine* - The **influenza vaccine** is recommended **annually** starting at **6 months of age**, but it targets **seasonal influenza strains** only. - It is not considered a routine multi-disease vaccine like MMR for childhood immunization.

Q: 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?

Erythema Infectiosum. ***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 1

Which bacterial infection is characterized by a 'strawberry tongue'?

Accepted Answer

Scarlet fever

Answer

Impetigo

Answer

Cellulitis

Answer

Erysipelas

Question 2

A 6-year-old boy presents with fever, sore throat, and a sandpaper-like rash. The rapid strep test is positive. What is the most appropriate treatment?

Accepted Answer

Amoxicillin

Answer

Ceftriaxone

Answer

Penicillin V

Answer

Erythromycin

Question 3

A child with severe COVID-19 developed persistent fever and elevated inflammatory markers 3 weeks after initial infection. What is the next step in management?

Accepted Answer

Begin IVIG therapy

Answer

Administer antiviral therapy

Answer

Consider transfer to intensive care unit

Answer

Start high-dose corticosteroids

Question 4

A 7-year-old child presents with persistent fever, abdominal pain, and a 'rose spots' rash on the abdomen. What is the most likely diagnosis?

Accepted Answer

Typhoid fever

Answer

Scarlet fever

Answer

Measles

Answer

Rubella

Question 5

A 7-year-old girl presents with a sore throat, fever, and a red, swollen throat with white patches. A rapid strep test is positive. What is the most likely diagnosis?

Accepted Answer

Streptococcal pharyngitis

Answer

Viral pharyngitis

Answer

Infectious mononucleosis

Answer

Diphtheria

Question 6

At what age should children begin receiving the influenza vaccine?

Accepted Answer

6 months

Answer

2 years

Answer

At birth

Answer

12 months

Question 7

A 6-month-old infant presents with a high fever, irritability, and a bulging fontanelle. Which immediate intervention is the most appropriate?

Accepted Answer

Administer intravenous antibiotics immediately and perform lumbar puncture after stabilization

Answer

Lumbar puncture to evaluate for meningitis

Answer

Oral antipyretics and outpatient follow-up

Answer

CT scan of the head to evaluate for intracranial pressure

Question 8

A 4-year-old with fever, neck stiffness, and petechial rash presents with a positive Kernig sign, positive Brudzinski sign, heart rate of 140, respiratory rate of 30, and blood pressure of 90/50. CSF analysis shows increased white blood cells, decreased glucose, and increased protein. Analyze the situation and initiate the most appropriate treatment.

Accepted Answer

IV antibiotics + IV dexamethasone

Answer

IV antivirals + fluid resuscitation

Answer

Lumbar puncture + observation without antibiotics

Answer

Supportive care and observation only

Question 9

A 1-year-old child is brought in for routine vaccination. Which of the following vaccines is typically administered at this age to provide immunity against multiple diseases?

Accepted Answer

MMR vaccine

Answer

BCG vaccine

Answer

Hepatitis B vaccine

Answer

Influenza vaccine

Question 10

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?

Accepted Answer

Erythema Infectiosum

Answer

Scarlet Fever

Answer

Measles

Answer

Roseola

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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