Infectious Diseases Practice Questions

Q: Which vaccination schedule is correct for PCV (Pneumococcal Conjugate Vaccine)?

6, 10, 14 weeks, booster at 12 months. ***6, 10, 14 weeks, booster at 12 months*** - This is the **standard recommended schedule** for PCV (3+1 schedule) as per **IAP (Indian Academy of Pediatrics) guidelines**. - The initial three doses at 6, 10, and 14 weeks provide **primary immunity**, while the booster at 12 months significantly **enhances and extends protection** against invasive pneumococcal disease. - This schedule is included in the **Universal Immunization Programme (UIP)** in India. *2, 4, 6 months* - This schedule follows the **US CDC** pattern primarily used for DTaP, Hib, and PCV in the United States. - It **lacks the critical booster dose** at 12 months as per Indian guidelines and uses months instead of weeks for the primary series. - Not the standard schedule tested in **Indian Medical PG exams**. *6, 10, 14 weeks* - This provides the **primary series** but omits the crucial **booster dose** typically given at 12 months. - Without the booster, **long-term protection against pneumococcal disease** may be insufficient, leading to waning immunity. - An incomplete vaccination schedule. *2, 4, 6 months, booster at 15 months* - This follows the **US CDC schedule** with a delayed booster. - Indian guidelines recommend the primary series at **6, 10, 14 weeks** (not months) with booster at **12 months** (not 15 months). - Not aligned with **IAP/NTAGI recommendations** for India.

Q: An 8-year-old child presents with high-grade fever, restlessness and is found to have neck rigidity. On lab diagnosis, CSF glucose levels were decreased. What is the diagnosis?

A. Bacterial meningitis. ***Bacterial meningitis*** - The key indicators for bacterial meningitis are **high-grade fever**, **neck rigidity**, **restlessness**, and most importantly, **decreased glucose levels in CSF**. - **Bacterial meningitis** is a severe infection of the meninges and CSF, it rapidly progresses, requiring prompt antibiotic treatment. *Fungal meningitis* - While fungal meningitis can present with similar symptoms, it typically has a **more subacute or chronic course** and is more common in **immunocompromised individuals**. - CSF findings in fungal meningitis often show **decreased glucose** but may also have **lymphocytic pleocytosis**, which is not specified here. *Viral meningitis* - **Viral meningitis** is characterized by normal or **slightly decreased glucose levels** in CSF, usually with **lymphocytic predominance**. - Although it presents with similar symptoms, it is almost always **self-limiting** and typically runs a mild course. *TB meningitis* - **TB meningitis** usually has a **more insidious onset** and a **subacute to chronic course**, not the acute presentation described. - While CSF glucose can be decreased, a key feature is typically **lymphocytic pleocytosis** and evidence of **tuberculosis infection** elsewhere.

Q: A 5-year-old presents with high fever, strawberry tongue, bilateral cervical lymphadenopathy, and a fine sandpaper-like rash that blanches on pressure. What is the diagnosis?

Scarlet fever. ***Scarlet fever*** - The combination of **high fever**, **strawberry tongue**, **bilateral cervical lymphadenopathy**, and a **fine sandpaper-like rash that blanches on pressure** is pathognomonic for scarlet fever. - Scarlet fever is caused by **Group A Streptococcus** (Streptococcus pyogenes) producing erythrogenic toxin. - The rash typically spares the perioral area (circumoral pallor) and desquamates after 1-2 weeks. *Measles* - While measles causes high fever, it presents with a **maculopapular rash** (not sandpaper-like), **Koplik spots** on buccal mucosa, and the **three Cs: cough, coryza, and conjunctivitis**. - The strawberry tongue and blanching sandpaper rash are not features of measles. *Kawasaki disease* - Kawasaki disease presents with **prolonged fever (≥5 days)**, **bilateral non-exudative conjunctivitis**, **strawberry tongue**, **polymorphous rash**, **extremity changes** (erythema/edema of hands/feet, later desquamation), and **unilateral cervical lymphadenopathy >1.5 cm**. - The **sandpaper-like blanching rash** is characteristic of scarlet fever, not Kawasaki disease, which has a polymorphous (variable) rash. - Kawasaki disease lacks the pharyngeal exudate and specific rash pattern seen in scarlet fever. *Strep throat* - **Strep throat** (streptococcal pharyngitis) is the underlying pharyngeal infection that can progress to scarlet fever when the streptococcal strain produces erythrogenic toxin. - Strep throat alone presents with **sore throat**, **fever**, **pharyngeal exudate**, and **tender cervical lymphadenopathy**, but does **not** produce the characteristic **strawberry tongue** and **sandpaper rash** that define scarlet fever. - The question describes scarlet fever specifically, not just uncomplicated strep throat.

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 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 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 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.

Question 1

Which vaccination schedule is correct for PCV (Pneumococcal Conjugate Vaccine)?

Accepted Answer

6, 10, 14 weeks, booster at 12 months

Answer

2, 4, 6 months

Answer

6, 10, 14 weeks

Answer

2, 4, 6 months, booster at 15 months

Question 2

An 8-year-old child presents with high-grade fever, restlessness and is found to have neck rigidity. On lab diagnosis, CSF glucose levels were decreased. What is the diagnosis?

Accepted Answer

A. Bacterial meningitis

Answer

B. Fungal meningitis

Answer

D. Viral meningitis

Answer

C. TB meningitis

Question 3

A 5-year-old presents with high fever, strawberry tongue, bilateral cervical lymphadenopathy, and a fine sandpaper-like rash that blanches on pressure. What is the diagnosis?

Accepted Answer

Scarlet fever

Answer

Measles

Answer

Kawasaki disease

Answer

Strep throat

Question 4

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

Accepted Answer

Scarlet fever

Answer

Impetigo

Answer

Cellulitis

Answer

Erysipelas

Question 5

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 6

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 7

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 8

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 9

At what age should children begin receiving the influenza vaccine?

Accepted Answer

6 months

Answer

2 years

Answer

At birth

Answer

12 months

Question 10

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

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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