Infectious Diseases Practice Questions

Q: Which among the following statements about congenital toxoplasmosis is false?

IgG is diagnostic. ***IgG is diagnostic*** - **IgG antibodies** against *Toxoplasma gondii* cross the placenta from mother to fetus, so their presence in a neonate merely reflects maternal immunity rather than confirming congenital infection. - Therefore, the presence of IgG alone in a neonate is **NOT diagnostic** of congenital toxoplasmosis; specific tests like **IgG avidity testing** or demonstrating rising IgG titers over months are needed. - **This statement is FALSE.** *IgA is better than IgM for detection in neonates* - This statement is **TRUE** because **IgA antibodies** have superior sensitivity and specificity compared to IgM for diagnosing congenital toxoplasmosis. - IgA testing has fewer false positives and better diagnostic accuracy in neonates. - Both IgA and IgM can be used, but IgA is generally more reliable. *Congenital toxoplasmosis is diagnosed using serological tests* - This statement is **TRUE** as **serological testing** (IgM, IgA, IgG avidity) forms the cornerstone of diagnosis. - Combined with **PCR testing** of amniotic fluid or other specimens and clinical/radiological findings, serology provides crucial diagnostic information. *IgM detection in cord blood is not diagnostic* - This statement is **TRUE** because while **IgM antibodies** don't cross the placenta (making their presence suggestive of infection), they have significant limitations. - IgM can give **false positives** (rheumatoid factor, maternal blood contamination) and **false negatives** (up to 25% of infected infants may be IgM-negative at birth). - Therefore, IgM alone cannot be relied upon as a standalone diagnostic marker.

Q: What is the most appropriate antibiotic choice for a 4-year-old unvaccinated child with epiglottitis?

Ceftriaxone or cefotaxime. ***Ceftriaxone or cefotaxime*** - **Third-generation cephalosporins** are the **first-line antibiotics** for epiglottitis in children - Provide excellent coverage against ***Haemophilus influenzae* type b (Hib)**, the most common causative organism in unvaccinated children - Effective against **both beta-lactamase producing and non-producing strains**, addressing the widespread ampicillin resistance (20-40%) - **Ceftriaxone** (50-100 mg/kg/day) or **cefotaxime** (150-200 mg/kg/day divided) are standard of care - Treatment duration is typically **7-10 days** *Immediate airway assessment and management* - While this is the **most critical priority** in epiglottitis management (life-threatening airway obstruction risk), the question specifically asks for **antibiotic choice** - Airway management is a procedural intervention, not antimicrobial therapy - In clinical practice, airway assessment comes first, but this doesn't answer the question asked *Administering a vaccine* - **Hib vaccine** is a **preventive measure**, not a treatment for active infection - Vaccination during acute epiglottitis has no therapeutic benefit - The vaccine prevents future disease but does not treat current infection *Doxycycline for 4 days* - **Not first-line therapy** for epiglottitis in any age group - **Contraindicated in children under 8 years** due to risk of permanent **tooth discoloration** and enamel hypoplasia - Poor coverage against *H. influenzae* type b - Tetracyclines are not recommended for typical bacterial causes of epiglottitis

Q: What is the treatment for a baby brought to the clinic with a history of hair fall and a boggy scalp with easily pluckable hair, with a similar history occurring six months prior?

Oral griseofulvin. **Oral griseofulvin** - This presentation describes **tinea capitis**, a fungal infection of the scalp, characterized by **hair fall**, a **boggy scalp** (kerion), and **easily pluckable hair**. - **Oral griseofulvin** is the first-line and most effective systemic antifungal treatment for tinea capitis, particularly in children, due to its fungistatic action and accumulation in keratinized tissues. *Oral ketoconazole* - While an antifungal, **oral ketoconazole** is generally not recommended as the first-line treatment for tinea capitis in children due to concerns about **hepatotoxicity** and potential drug interactions. - **Griseofulvin** has a better safety profile and established efficacy for this condition. *Topical cotrimoxazole* - **Cotrimoxazole** is an antibiotic, not an antifungal, and thus would be ineffective against a fungal infection like tinea capitis. - Topical treatments alone are generally insufficient for tinea capitis because the infection is deep within the hair follicles. *Intralesional steroid* - **Intralesional steroids** are used to reduce inflammation in certain dermatological conditions, but they do not treat primary fungal infections. - Their use in tinea capitis, especially in the absence of an antifungal, could worsen the infection or lead to secondary complications due to immunosuppression.

Q: Treatment for meningitis caused by Streptococcus pneumoniae in children is typically given for how many days?

10 days. ***10 days*** - The standard duration for treating **bacterial meningitis** caused by *Streptococcus pneumoniae* in children is **10 days**. - This duration is crucial to ensure complete eradication of the bacteria and prevent relapse or long-term neurological sequelae. *5 days* - A 5-day course is generally **too short** for *Streptococcus pneumoniae* meningitis; it might lead to treatment failure or recurrence. - Shorter courses, such as 5-7 days, are sometimes used for less resistant organisms or in specific cases of **meningococcal meningitis**. *7 days* - While 7 days might be sufficient for some causes of bacterial meningitis, such as **meningococcal meningitis** or particular strains of *Haemophilus influenzae*, it is generally considered insufficient for **pneumococcal meningitis**. - *Streptococcus pneumoniae* often requires a longer course due to its potential for resistance and the severity of the infection. *21 days* - A 21-day course is typically reserved for more difficult-to-treat or **intracranial infections** like **tuberculous meningitis** or certain fungal meningitis cases. - It is generally **unnecessary** and could increase the risk of antibiotic-related side effects for uncomplicated *Streptococcus pneumoniae* meningitis.

Q: Koplik spots are characteristic of which viral infection?

Pathognomonic sign of measles. ***Correct Answer: Pathognomonic sign of measles*** - **Koplik spots** are considered an **enanthem** (a rash on mucous membranes) and are **pathognomonic** for **measles (rubeola)**, meaning their presence is diagnostic of the disease. - These spots typically appear on the **buccal mucosa** opposite the molars as small white spots with red halos, preceding the characteristic skin rash. - They serve as an important early clinical marker for the diagnosis of measles. *Incorrect: Not typically seen in measles* - This statement is completely incorrect; **Koplik spots are highly characteristic** and pathognomonic for measles. - Their presence is virtually diagnostic of measles infection. *Incorrect: Seen 2-3 days after cutaneous rashes* - This is incorrect regarding timing; Koplik spots typically **appear 1-3 days BEFORE the onset of the generalized maculopapular rash**. - Their presence helps in the **early diagnosis** of measles, before the widespread skin eruption develops. *Incorrect: Seen in the incubation period of measles* - This is incorrect. The **incubation period** (typically **10-12 days** after exposure) is asymptomatic - no signs or symptoms are present. - Koplik spots appear during the **prodromal stage**, which follows the incubation period and is characterized by fever, cough, coryza, and conjunctivitis (the 3 C's). - The prodromal stage precedes the full-blown maculopapular rash by 1-3 days.

Q: Which vaccine is recommended at 2 years of age according to the latest Indian Academy of Pediatrics (IAP) guidelines?

Booster of Typhoid Conjugate Vaccine. ***Booster of Typhoid Conjugate Vaccine*** - As per the latest IAP immunization guidelines, a **booster dose** of the **Typhoid Conjugate Vaccine** is recommended at **2 years of age** after the primary series given during infancy. - This booster provides continued protection against **typhoid fever**, which remains a significant health concern in India. *MMR* - The first dose of **MMR (Measles, Mumps, Rubella)** vaccine is typically given at **9 months**, with a second dose around **15-18 months** of age. - While important, it is usually completed before or at 18 months, not specifically at 2 years. *Pneumococcal conjugate* - The primary series of **Pneumococcal Conjugate Vaccine (PCV)** is administered in infancy, with doses typically at 6 weeks, 14 weeks, and a booster at 9 months. - While it protects against **pneumococcal infections**, a specific dose at 2 years is not a standard recommendation per IAP guidelines. *Varicella* - The first dose of **Varicella vaccine** is recommended around **15 months** of age, with a second dose typically given between **4 and 6 years**. - Therefore, 2 years of age falls between the usual schedule for the primary and booster doses of Varicella vaccine.

Q: Which vaccine is associated with complications such as osteomyelitis?

BCG vaccine. ***BCG vaccine*** - The BCG vaccine, particularly when given to immunocompromised individuals or sometimes due to improper administration, can lead to disseminated infection, including **BCG osteitis** or **osteomyelitis**. - This complication, though rare, involves the infection of **bone tissue** by the attenuated *Mycobacterium bovis* strain used in the vaccine. *Hepatitis B vaccine* - The Hepatitis B vaccine is generally safe, with common side effects limited to **local reactions** at the injection site. - It is not associated with an increased risk of developing **osteomyelitis**. *Measles vaccine* - The measles vaccine (MMR) is a live attenuated vaccine, and side effects usually include **fever** or a mild rash. - There is no established link between the measles vaccine and the development of **osteomyelitis**. *IPV* - Inactivated Poliovirus Vaccine (IPV) is a safe vaccine, and its serious complications are exceedingly rare, primarily involving **severe allergic reactions**. - It does not contain live virus and is not known to cause **osteomyelitis**.

Q: What is the most common presentation of tuberculosis (TB) in children?

Hilar adenopathy. ***Hilar adenopathy*** - **Hilar adenopathy** is the most common radiographic finding in children with **primary tuberculosis**, reflecting lymph node involvement. - This is often accompanied by a small parenchymal lesion, forming the **Ghon complex**. *Abscess* - While TB can cause abscesses (e.g., cold abscesses in bone or soft tissue), it's not the **most common initial presentation** of primary childhood TB. - Abscess formation suggests a more **advanced or extrapulmonary** manifestation. *Consolidation* - **Consolidation** can be seen in adult-type or progressive primary TB, but it is less frequent than hilar adenopathy as the **initial presentation** in children. - It indicates **pneumonia-like changes** due to parenchymal inflammation. *CNS tuberculosis* - **Central Nervous System (CNS) tuberculosis** (e.g., tuberculous meningitis or tuberculoma) is a severe, extrapulmonary form of TB. - It is a **serious complication** rather than the most common initial presentation in children.

Q: What is the most common cause of infantile diarrhea?

Rotavirus. ***Rotavirus*** - **Rotavirus** is the **classic and most common cause** of severe, dehydrating **diarrhea** in infants and young children worldwide, especially in unvaccinated populations. - It remains the **standard answer** in medical examinations and textbooks. - While **rotavirus vaccine introduction** (Universal Immunization Program in India) has significantly reduced its prevalence in vaccinated populations, it continues to be a major pathogen in areas with incomplete vaccine coverage. - Presents with **watery diarrhea, vomiting, fever**, and can lead to severe dehydration. *Adenovirus* - **Adenovirus** (especially serotypes 40 and 41) can cause **gastroenteritis**, but it is a **less common cause** of infantile diarrhea compared to rotavirus. - It often presents with **respiratory symptoms** in addition to diarrhea. - Accounts for approximately **5-10%** of viral gastroenteritis cases. *Reovirus* - **Reovirus** is a family of viruses, and while some members can infect humans, they are **rarely associated** with significant or widespread diarrheal disease. - It is **not considered a common cause** of infantile diarrhea in clinical practice. *Norovirus* - **Norovirus** is a **very common cause of gastroenteritis** in older children and adults, often in outbreak settings (schools, cruise ships). - While it can affect infants and has increased in relative frequency in highly vaccinated populations, **rotavirus historically and classically predominated** as the leading cause of severe infantile diarrhea. - Norovirus causes more **sporadic cases** in infancy compared to rotavirus.

Question 1

Which among the following statements about congenital toxoplasmosis is false?

Accepted Answer

IgG is diagnostic

Answer

Congenital toxoplasmosis is diagnosed using serological tests.

Answer

IgM detection in cord blood is not diagnostic

Answer

IgA is better than IgM for detection in neonates

Question 2

What is the most appropriate antibiotic choice for a 4-year-old unvaccinated child with epiglottitis?

Accepted Answer

Ceftriaxone or cefotaxime

Answer

Administering a vaccine

Answer

Doxycycline for 4 days

Answer

Immediate airway assessment and management

Question 3

What is the treatment for a baby brought to the clinic with a history of hair fall and a boggy scalp with easily pluckable hair, with a similar history occurring six months prior?

Accepted Answer

Oral griseofulvin

Answer

Oral ketoconazole

Answer

Intralesional steroid

Answer

Topical cotrimoxazole

Question 4

Treatment for meningitis caused by Streptococcus pneumoniae in children is typically given for how many days?

Accepted Answer

10 days

Answer

5 days

Answer

7 days

Answer

21 days

Question 5

Prophylaxis with cotrimoxazole is recommended in all situations except for which of the following?

Accepted Answer

All symptomatic HIV infected children > 5 years of age irrespective of CD4

Answer

All HIV infected infants less than 1 year age irrespective of symptoms or CD4 counts

Answer

All HIV exposed infants till HIV infection can be ruled out

Answer

As secondary prophylaxis after initial treatment for Pneumocystis jirovecii pneumonia

Question 6

Koplik spots are characteristic of which viral infection?

Accepted Answer

Pathognomonic sign of measles

Answer

Seen in the incubation period of measles

Answer

Seen 2-3 days after cutaneous rashes

Answer

Not typically seen in measles

Question 7

Which vaccine is recommended at 2 years of age according to the latest Indian Academy of Pediatrics (IAP) guidelines?

Accepted Answer

Booster of Typhoid Conjugate Vaccine

Answer

MMR

Answer

Pneumococcal conjugate

Answer

Varicella

Question 8

Which vaccine is associated with complications such as osteomyelitis?

Accepted Answer

BCG vaccine

Answer

Hepatitis B vaccine

Answer

Measles vaccine

Answer

IPV

Question 9

What is the most common presentation of tuberculosis (TB) in children?

Accepted Answer

Hilar adenopathy

Answer

Abscess

Answer

Consolidation

Answer

CNS tuberculosis

Question 10

What is the most common cause of infantile diarrhea?

Accepted Answer

Rotavirus

Answer

Adenovirus

Answer

Reovirus

Answer

Norovirus

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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