Infectious Diseases — MCQs

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 401: A child with fever with abdominal cramps & pus in stools, causative organism is ?

A. EHEC
B. ETEC
C. EAEC (Correct Answer)
D. EPEC

Explanation: ***EAEC (Enteroaggregative E. coli)*** - Among the E. coli strains listed, EAEC is the answer for this question, though **this is an atypical presentation**. - EAEC classically causes **persistent watery diarrhea** (>14 days) in children, often with **low-grade fever** and **abdominal pain**. - While EAEC primarily causes non-bloody diarrhea, it can occasionally produce **mucoid stools** with inflammatory cells due to mucosal inflammation from biofilm formation. - **Note:** The classic organism for fever + cramps + pus in stools would be **Shigella**, **Campylobacter**, or **EIEC (Enteroinvasive E. coli)** - not listed here. *EHEC (Enterohemorrhagic E. coli)* - EHEC (O157:H7) causes **hemorrhagic colitis** with bloody diarrhea due to **Shiga toxins**. - Can lead to **hemolytic uremic syndrome (HUS)** in children. - Characterized by **blood** rather than pus in stools, distinguishing it from typical dysentery. *ETEC (Enterotoxigenic E. coli)* - Most common cause of **traveler's diarrhea** and watery diarrhea in developing countries. - Produces **heat-labile (LT)** and **heat-stable (ST)** enterotoxins causing secretory diarrhea. - Results in profuse **watery stools without inflammation, blood, or pus**. *EPEC (Enteropathogenic E. coli)* - Leading cause of infantile diarrhea in developing countries. - Causes **attaching and effacing** lesions on intestinal mucosa. - Results in **watery diarrhea without significant inflammatory cells or pus** in stools.

Question 402: Possibility of vertical transfer of HIV infection if no prophylaxis is given:

A. 25% (Correct Answer)
B. 75%
C. 100%
D. 50%

Explanation: ***25%*** - Without **antiretroviral prophylaxis**, the risk of vertical transmission of HIV from mother to child is approximately **15-45%**, with 25% being a commonly cited average. - This risk is significantly reduced to less than **1%** with effective **antiretroviral therapy (ART)** during pregnancy, labor, and delivery, and ART for the infant. *75%* - A 75% risk of vertical transmission is **too high** and not consistent with current understanding of HIV mother-to-child transmission rates without intervention. - The risk is influenced by many factors including **maternal viral load**, **mode of delivery**, and **breastfeeding practices**. *100%* - A 100% chance of vertical transmission without prophylaxis is **incorrect**; many HIV-positive mothers, even without intervention, do not transmit the virus to their infants. - While the risk is substantial, it is not guaranteed for every pregnancy. *50%* - A 50% risk is **higher than the average** reported rates for vertical HIV transmission in the absence of prophylaxis. - While some individual circumstances might lead to a higher risk, it is not the general range.

Question 403: Which micro–organism is responsible for classical presentation of hydrocephalus, chorioretinitis, intracerebral calcification ?

A. Toxoplasmosis (Correct Answer)
B. CMV
C. Measles
D. Rubella

Explanation: ***Toxoplasmosis*** - This classic triad of **hydrocephalus**, **chorioretinitis**, and **intracerebral calcifications** is highly indicative of congenital toxoplasmosis. - *Toxoplasma gondii* is an intracellular parasite acquired transplacentally, leading to these severe neurological and ocular manifestations in the fetus. *CMV* - While congenital CMV can cause **intracerebral calcifications** (often periventricular), it typically presents with **microcephaly** rather than hydrocephalus. - CMV is also commonly associated with **sensorineural hearing loss** and hepatosplenomegaly. *Measles* - Congenital measles is extremely rare and can lead to **miscarriage** or **premature birth**, but not the classic triad described. - Measles is known for causing **subacute sclerosing panencephalitis (SSPE)** much later in life, an entirely different clinical picture. *Rubella* - Congenital rubella syndrome (CRS) is characterized by a different constellation of symptoms, including a **PDA (patent ductus arteriosus)**, **cataracts**, and **sensorineural hearing loss**. - While it can cause some central nervous system abnormalities, it does not typically present with hydrocephalus or chorioretinitis with intracerebral calcifications.

Question 404: Indication for lumbar puncture in child with febrile seizures are all except?

A. Severely ill infants with clinical signs and symptoms
B. Children 6 to 12 months with no Hib & pneumococcal vaccination
C. Infants pretreated with antibiotics
D. All infants <6 months (Correct Answer)

Explanation: ***All infants <6 months*** - While lumbar puncture should be **strongly considered** in infants under 6 months with febrile seizures, the **American Academy of Pediatrics (AAP)** guidelines do not mandate **routine lumbar puncture for ALL** infants in this age group as an absolute rule. - The current approach emphasizes **clinical assessment**: well-appearing infants without signs of meningitis (e.g., no **lethargy**, **irritability**, or **bulging fontanelle**) may be managed without immediate LP, especially if close observation is possible. - This distinguishes "strongly considered" from "absolute indication," making this the correct answer to the EXCEPT question. *Severely ill infants with clinical signs and symptoms* - **Severely ill infants** with febrile seizures and signs suggestive of meningitis (e.g., **lethargy**, **neck stiffness**, **bulging fontanelle**, **poor perfusion**) are a **strong absolute indication** for lumbar puncture. - The high risk of **bacterial meningitis** in this clinical presentation overrides age or vaccination status, as delayed diagnosis can be life-threatening. *Children 6 to 12 months with no Hib & pneumococcal vaccination* - In children aged 6 to 12 months who are **unvaccinated** or **incompletely vaccinated** against *Haemophilus influenzae type b* (**Hib**) and *Streptococcus pneumoniae*, lumbar puncture is **strongly indicated**. - Lack of immunization against these common causes of **bacterial meningitis** significantly increases risk, making diagnostic LP crucial when febrile seizures occur. *Infants pretreated with antibiotics* - **Antibiotic pretreatment** can mask the clinical signs and symptoms of meningitis, creating a falsely reassuring picture (**partially treated meningitis**). - In such cases, lumbar puncture is **necessary** to confirm or rule out central nervous system infection, as CSF analysis remains the gold standard despite prior antibiotic exposure.

Question 405: The most characteristic manifestation of congenital toxoplasmosis is:

A. Intracranial calcifications (Correct Answer)
B. Deafness
C. Thrombocytopenia
D. Hepatosplenomegaly

Explanation: ***Intracranial calcifications*** - **Intracranial calcifications**, particularly scattered and diffuse throughout the brain parenchyma, are the most **characteristic and pathognomonic** finding of congenital toxoplasmosis - These calcifications result from the parasite's predilection for **neural tissue** and subsequent inflammatory necrosis - Along with **hydrocephalus** and **chorioretinitis**, they form the **classic triad** of congenital toxoplasmosis - The scattered pattern of calcifications helps differentiate toxoplasmosis from CMV (which causes periventricular calcifications) *Deafness* - **Sensorineural hearing loss** can occur but is not a characteristic feature of congenital toxoplasmosis - Deafness is more commonly associated with congenital **cytomegalovirus (CMV)** or **rubella** infection - When present in toxoplasmosis, it is typically a late sequela rather than a primary manifestation *Thrombocytopenia* - **Thrombocytopenia** may occur as part of generalized systemic involvement but is a **non-specific finding** - It can be seen in many congenital infections (TORCH complex) - Not diagnostically useful for distinguishing toxoplasmosis from other congenital infections *Hepatosplenomegaly* - **Hepatosplenomegaly** indicates systemic infection and may reflect **extramedullary hematopoiesis** - Common in many congenital infections, making it non-specific - The most **diagnostically valuable** findings in congenital toxoplasmosis are the neurological (intracranial calcifications, hydrocephalus) and ocular (chorioretinitis) manifestations

Question 406: Which of the following is NOT a feature of HIV infection in childhood -

A. Failure to thrive
B. Hepatomegaly
C. Kaposi sarcoma (Correct Answer)
D. Lymphoid interstitial pneumonitis

Explanation: ***Kaposi sarcoma*** - While Kaposi's sarcoma is a common HIV-associated malignancy in adults, it is **very rare in HIV-infected children**. - Its presence in children with HIV usually suggests a **more aggressive and rapidly progressing disease course**, but it is not a typical or common feature. *Failure to thrive* - **Failure to thrive** is a very common manifestation of HIV infection in children, often due to **poor nutrient absorption**, increased metabolic demands, and chronic infections. - It leads to **poor weight gain and growth faltering**, negatively impacting overall development. *Hepatomegaly* - **Hepatomegaly**, or an enlarged liver, is a frequent finding in HIV-infected children due to various causes such as **opportunistic infections**, drug side effects, and direct HIV involvement of the liver. - It can be a clinical sign indicating **inflammation or dysfunction** of the liver. *Lymphoid interstitial pneumonitis* - **Lymphoid interstitial pneumonitis (LIP)** is a prevalent pulmonary complication specific to HIV infection in children, characterized by **lymphocytic infiltration of the alveolar septa and peribronchial spaces**. - It often leads to **chronic cough**, hypoxemia, and is considered an **AIDS-defining condition** in pediatric HIV.

Question 407: A 10-year-old girl presented with fever, convulsions, and neck rigidity. CSF findings are protein 150 mg/dL, sugar 40 mg/dL with lymphocytic pleocytosis –

A. Viral meningitis
B. Pyogenic meningitis
C. Tuberculous meningitis (Correct Answer)
D. Cryptococcal meningitis

Explanation: ***Tuberculous meningitis*** - The combination of **fever, convulsions, neck rigidity** (suggesting meningitis), elevated **CSF protein (150 mg/dL)**, **low CSF sugar (40 mg/dL)**, and **lymphocytic pleocytosis** is highly characteristic of tuberculous meningitis. - Tuberculous meningitis typically presents with a **subacute** or **chronic** course and CSF analysis reveals **elevated protein**, **low glucose**, and a **lymphocytic pleocytosis**. *Viral meningitis* - While viral meningitis presents with fever and meningeal signs, the **CSF protein** is usually mildly elevated (<100 mg/dL), and **CSF glucose** is typically normal. - Often has a **benign and self-limiting course** with predominantly lymphocytic pleocytosis. *Pyogenic meningitis* - Characterized by very high **CSF protein (>100 mg/dL)**, very low **CSF glucose (<40 mg/dL)**, and a predominant **neutrophilic pleocytosis**. - Symptoms are usually **acute and severe**, rapidly progressing over hours to days. *Cryptococcal meningitis* - This is more common in **immunocompromised individuals**, such as those with HIV/AIDS, and the clinical picture in a 10-year-old girl without immune compromise makes it less likely. - While it can cause elevated CSF protein and low glucose, the presence of **lymphocytic pleocytosis** is less specific for cryptococcal infection compared to tuberculous meningitis in this clinical context.

Question 408: A child who was treated for H. influenzae meningitis is being discharged. Most important investigation to be done before discharge is:

A. Brainstem evoked auditory response (Correct Answer)
B. Growth screening test
C. Psychotherapy
D. MRI

Explanation: ***Brainstem evoked auditory response*** - **Sensorineural hearing loss** is a common and severe complication of *H. influenzae* meningitis, occurring in about 5-30% of cases due to damage to the auditory nerve or cochlea. - **Brainstem Evoked Auditory Response (BAER)** is an objective test that measures the electrical activity in the auditory pathway from the cochlea to the brainstem, making it the most reliable method for detecting hearing impairment in infants and children. *Growth screening test* - While chronic illness can affect growth, **growth faltering** is not specific to *H. influenzae* meningitis or its sequelae in the acute or subacute phase. - Growth checks are part of routine pediatric care and would be performed but are not the *most important* specific investigation for meningitis complications before discharge. *Psychotherapy* - **Psychotherapy** is a treatment modality for psychological and behavioral issues, not a diagnostic test. - It would only be considered if the child developed significant emotional or behavioral problems after meningitis, and these are typically assessed through clinical observation and neurodevelopmental screening, not a direct "psychotherapy" investigation. *MRI* - **MRI** is primarily used to detect structural brain abnormalities such as **hydrocephalus**, **subdural effusions**, **cerebral edema**, or **infarcts** that may result from meningitis. - While important for assessing neurological damage, **hearing loss** is a distinct and prevalent complication that requires a specific functional assessment (BAER), which MRI does not provide.

Question 409: Most serious characteristic finding of HIV in children is?

A. Kaposi sarcoma is common
B. Cryptococcal diarrhoea is common
C. Recurrent chest infection (Correct Answer)
D. Recurrent candidiasis

Explanation: ***Recurrent chest infection*** - **Recurrent chest infections**, particularly with common bacterial pathogens, are a hallmark of HIV in children due to their underdeveloped immune systems being further compromised. - Children with HIV are highly susceptible to respiratory infections such as **pneumonia** and **bronchiolitis**, leading to frequent hospitalizations and poor outcomes. *Kaposi sarcoma is common* - **Kaposi sarcoma** is a well-known HIV-associated malignancy, but it is much more prevalent in **HIV-positive adults**, especially men who have sex with men, rather than in children. - While it can occur in children, it is not considered a *characteristic* or common presenting feature, as other opportunistic infections and non-specific symptoms are far more frequent. *Cryptococcal diarrhoea is common* - **Cryptococcal infection** primarily manifests as **meningitis** or disseminated disease, particularly in adults with advanced HIV. - While gastrointestinal symptoms can occur, **Cryptococcal diarrhea** is not a common or characteristic presentation of HIV in children. *Recurrent candidiasis* - While **recurrent oral candidiasis** (thrush) is common in HIV-infected children, it is often one of the **earliest indicators** and can be present even in less advanced disease. - However, **recurrent chest infections** generally represent a more significant and debilitating manifestation of immune compromise in pediatric HIV.

Question 410: The most common site of involvement of spinal TB in children is at which of the following level?

A. Cervical vertebra
B. Upper thoracic vertebra
C. Mid thoracic vertebra
D. Lower thoracic vertebra (Correct Answer)

Explanation: ***Lower thoracic vertebra*** - The **lower thoracic spine (T8–T12)** is the most common site for spinal tuberculosis (Pott's disease) in children and adults due to its high vascularity and mechanical stress. - Involvement at this level often leads to severe **kyphosis** and neurological deficits like **paraplegia** as the disease progresses. *Cervical vertebra* - While cervical spinal TB can occur, it is relatively **less common** than thoracic involvement. - Lesions here are more likely to cause **neurological symptoms** with upper limb involvement or respiratory compromise due to phrenic nerve irritation. *Upper thoracic vertebra* - Involvement of the upper thoracic spine is **less frequent** compared to the lower thoracic segments. - Though possible, the upper thoracic region is not considered the **predominant site** for initial lesion development. *Mid thoracic vertebra* - The mid-thoracic region (e.g., T4-T7) is less frequently affected by spinal TB compared to the **thoracolumbar junction** or lower thoracic area. - This area has a relatively **stable mechanical load** compared to the junctional segments.

Practice by Chapter

Vaccine-Preventable Diseases

Practice Questions

Immunization Schedule

Practice Questions

Common Childhood Infections

Practice Questions

Pediatric HIV

Practice Questions

Congenital Infections

Practice Questions

Fever in Infants and Children

Practice Questions

Meningitis and Encephalitis

Practice Questions

Respiratory Tract Infections

Practice Questions

Gastrointestinal Infections

Practice Questions

Parasitic Infections

Practice Questions

Tuberculosis in Children

Practice Questions

Opportunistic Infections

Practice Questions

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