Infectious Diseases Practice Questions

Q: Most common organism causing meningitis in a 1 year old child -

Streptococcus pneumoniae. ***Streptococcus pneumoniae*** - **_Streptococcus pneumoniae_** is currently the most prevalent cause of bacterial meningitis in children over **3 months of age**, including 1-year-olds, largely due to successful vaccination programs reducing other common pathogens. - Though **meningococcal disease** often presents with a fulminant course, **pneumococcal meningitis** is more frequently encountered among pathogens overall in this age group due to its widespread carriage and diverse serotypes. *Listeria* - **_Listeria monocytogenes_** is a significant cause of meningitis in **neonates** (under 1 month of age) and **immunocompromised individuals**, but less common in a healthy 1-year-old. - Transmission typically occurs vertically from mother to child or through contaminated food products. *H. influenzae* - **_Haemophilus influenzae_ type B (Hib)** was historically a major cause of meningitis in young children, but its incidence has dramatically decreased due to widespread **Hib vaccination**. - While other non-typeable strains or unvaccinated individuals can still be affected, it is no longer the most common cause in vaccinated populations. *Neisseria meningitidis* - **_Neisseria meningitidis_** is a significant cause of bacterial meningitis, particularly in children and young adults, often associated with epidemics and a **petechial rash**. - Although it can cause severe disease and outbreaks, **_Streptococcus pneumoniae_** tends to have a higher overall incidence in 1-year-olds in the post-Hib vaccine era.

Q: True about childhood tuberculosis:

Diagnosis by sputum is difficult. ***Diagnosis by sputum is difficult*** - Children often have **pauci-bacillary disease**, meaning fewer bacteria are present in their sputum, making microbiological confirmation challenging. - Young children typically **cannot produce adequate sputum samples** voluntarily, unlike adults. - **Gastric aspirates** or induced sputum may be needed, but even these have lower diagnostic yield. - This is a hallmark feature distinguishing pediatric TB from adult TB. *Highly contagious* - Childhood tuberculosis, especially **extrapulmonary forms** or **pauci-bacillary disease**, is generally considered **less contagious** than adult pulmonary TB. - The reduced bacterial load and less forceful cough in children make transmission less efficient. - Children are more commonly victims than vectors of TB transmission. *5% prevalence* - The global prevalence of tuberculosis in children is highly variable and depends on specific regional epidemiology. - This figure is not a generally accepted statistic for childhood TB prevalence. *Common in 5-8 years age* - While TB can occur at any age, **children under 5 years old** are at highest risk for **severe and disseminated disease** (including TB meningitis and miliary TB). - Older children and adolescents might have clinical presentations more akin to adult TB, but the 5-8 year age range is not specifically highlighted as the peak age for childhood TB.

Q: Which of the following is the most common cause of Meningoencephalitis in children?

Enterovirus. ***Enterovirus*** - **Enteroviruses** are the most frequent cause of **aseptic meningitis** and **meningoencephalitis** in children, particularly during summer and fall. - They can cause a wide range of neurological manifestations, from mild meningitis to severe encephalitis. *Mumps* - While mumps can cause **meningitis** and **encephalitis**, its incidence has significantly decreased due to widespread **MMR vaccination**. - It is less common than enteroviral infections as a cause of meningoencephalitis in the vaccinated population. *HSV* - **Herpes Simplex Virus (HSV)** is a significant cause of **viral encephalitis**, especially **temporal lobe encephalitis**, which can be severe and life-threatening. - However, HSV encephalitis is **rarer** than meningoencephalitis caused by enteroviruses in the general pediatric population. *Arbovirus* - **Arboviruses** (e.g., West Nile virus, La Crosse encephalitis virus) can cause severe meningitis and encephalitis, and their prevalence is **geographically dependent** and often associated with seasonal outbreaks. - While important in specific regions, they are not the most common overall cause of meningoencephalitis in children compared to enteroviruses.

Q: Which of the following is true regarding tuberculosis in children?

All of the options. ***All of the options*** - All statements — **commonly sputum negative**, **incidence 10-15% of all TB cases**, and **clinically children do not show signs of florid TB** — are generally true for tuberculosis in children. - Children often have **paucibacillary disease** and less severe clinical presentations compared to adults, making diagnosis challenging. *Commonly sputum negative* - Children often have **paucibacillary disease**, meaning fewer bacteria are present in their sputum, making cultures negative or difficult to obtain. - Their smaller airways and inability to effectively expectorate sputum contribute to the **common finding of sputum negativity**. *Incidence 10-15% of all TB cases* - Tuberculosis in children accounts for a significant but smaller proportion of the global TB burden compared to adults. - This statistic reflects that a substantial number of TB cases still occur in the pediatric population, often as contacts of adult cases. *Clinically child does not show sign of florid TB.* - Pediatric TB often presents with **non-specific symptoms** like fever, weight loss, and failure to thrive, rather than the classic severe respiratory symptoms seen in adults. - This makes clinical diagnosis challenging as **florid (severe, overt) TB signs** are less common in children due to their developing immune systems and smaller bacterial loads.

Q: A HIV-positive mother delivers a baby. All are true, except:

Risk of HIV in the baby is up to 90%.. ***Risk of HIV in the baby is up to 90%.*** - Without intervention, the risk of mother-to-child transmission (MTCT) of HIV ranges from **15-45%**, not 90%. - This risk can be reduced to **less than 1%** with effective interventions like antiretroviral therapy (ART) during pregnancy, elective cesarean section, and avoiding breastfeeding. *HIV infection cannot be diagnosed in the baby with available methods.* - **HIV infection CAN be diagnosed in infants** using virological tests such as **HIV DNA PCR** or **HIV RNA PCR**. - These tests detect the actual virus, unlike antibody tests which would detect maternal antibodies that crossed the placenta and can persist up to 18 months. *Breast feeding can transmit HIV.* - **Breastfeeding is a known route of HIV transmission** from an infected mother to her child. - The risk of transmission through breastfeeding is estimated to be **5-20%** and varies with viral load and duration of breastfeeding. *HIV can be transmitted from mother to child during delivery.* - **Peripartum transmission** (during labor and delivery) is the most common route of MTCT of HIV. - This occurs through exposure to maternal blood and genital secretions during the birthing process.

Q: Which of the following is not a common manifestation of congenital Rubella -

Aortic stenosis. ***Aortic stenosis*** - While **congenital heart defects** are characteristic of congenital rubella syndrome, **aortic stenosis** is NOT typically associated. - The most common cardiac anomalies in **congenital rubella syndrome** are **patent ductus arteriosus (PDA)** and **peripheral pulmonary artery stenosis**. *PDA* - **Patent ductus arteriosus** is one of the most common and classic cardiac manifestations of **congenital rubella syndrome**, occurring in 50-75% of cases. - The rubella virus interferes with normal closure of the **ductus arteriosus** during fetal development. *Deafness* - **Sensorineural deafness** is the most common manifestation of **congenital rubella syndrome**, occurring in up to 80% of cases. - The virus damages the developing **cochlea** and auditory structures, often resulting in bilateral profound hearing loss. *Intellectual disability* - **Neurological complications**, including **intellectual disability** and developmental delays, are frequent in infants with **congenital rubella syndrome**. - The virus directly infects the developing brain, leading to various degrees of **cognitive and neurological impairment**.

Q: Most common cause of Pyogenic Meningitis in 6 month to 2 years of age is

Streptococcus pneumoniae. ***Streptococcus pneumoniae*** - *Streptococcus pneumoniae* is currently the most common cause of **bacterial meningitis** in children aged 6 months to 2 years, especially after the widespread use of the *H. influenzae* type b (Hib) vaccine. - The **pneumococcal conjugate vaccine (PCV)** has significantly reduced, but not eliminated, the incidence of pneumococcal meningitis. *H. influenzae* - Before the introduction of the Hib vaccine, *H. influenzae* type b was the most common cause of **bacterial meningitis** in this age group. - Due to successful vaccination programs, its incidence has drastically declined, making **pneumococcus** more common. *Staphylococcus aureus* - *Staphylococcus aureus* is a common cause of **meningitis** associated with neurosurgical procedures, trauma, or intravenous drug use. - It is not typically the leading cause of community-acquired pyogenic meningitis in otherwise healthy children aged 6 months to 2 years. *Neisseria meningitidis* - *Neisseria meningitidis* is a significant cause of **bacterial meningitis**, especially in older children, adolescents, and young adults. - While it can occur in infants, it is generally less common than *Streptococcus pneumoniae* in the 6-month to 2-year age group.

Q: Which of the following statements regarding Congenital Rubella Syndrome (CRS) is FALSE?

Cataract in CRS is always bilateral.. ***Cataract in CRS is always bilateral.*** - While **cataracts** are a common manifestation of **Congenital Rubella Syndrome (CRS)**, they are **not always bilateral**; they can affect one or both eyes. - The severity and presentation of CRS features, including ocular defects, can vary. *Infants with Congenital Rubella Syndrome can shed virus in respiratory secretions for up to 1 year of age.* - Infants with **CRS** can indeed shed the rubella virus for an extended period, often up to a year or even longer, posing a risk of transmission to susceptible contacts. - This prolonged shedding highlights the importance of **infection control measures** when caring for affected infants. *Risk of congenital defects is high when fetus is infected during the first trimester.* - The risk of severe congenital defects is highest when the mother is infected with rubella during the **first trimester** of pregnancy, particularly in weeks 8-10. - This is due to the critical period of **organogenesis**, where viral infection can disrupt major developmental processes. *CRS is associated with increased risk of hearing loss and cardiac defects.* - **Sensorineural hearing loss** is one of the most common and significant sequelae of CRS, along with **cardiac defects** such as **patent ductus arteriosus (PDA)** and **pulmonary artery stenosis**. - These are considered part of the classic triad of CRS, which also includes eye abnormalities.

Q: What is the recommended duration of erythromycin prophylaxis for children exposed to pertussis?

14 days of prophylactic antibiotics. ***14 days of prophylactic antibiotics*** - For **post-exposure prophylaxis of pertussis** with **erythromycin**, the recommended duration is **14 days** (40-50 mg/kg/day in 4 divided doses, max 2 g/day). - This duration aims to **eradicate Bordetella pertussis** and prevent disease development or reduce severity in exposed contacts. - **Note:** Azithromycin (5 days) and clarithromycin (7 days) are shorter alternative regimens, but erythromycin specifically requires 14 days for adequate prophylaxis. *10 days of prophylactic antibiotics* - A 10-day course is **insufficient for erythromycin prophylaxis** against pertussis. - Premature discontinuation may lead to **treatment failure** and continued risk of disease transmission. *12 days of prophylactic antibiotics* - A 12-day course is **not the standard recommendation** for erythromycin-based pertussis prophylaxis. - The established CDC and AAP guidelines specify **14 days** for complete eradication. *11 days of prophylactic antibiotics* - An 11-day course is **inadequate** for erythromycin prophylaxis in pertussis-exposed children. - Adhering to the **full 14-day regimen** is crucial for optimal prevention and public health control.

Question 1

A 30 month old deaf boy whose development is slower than normal is being followed for congenital cytomegalovirus (CMV) infection in your clinic.The child's mother is pregnant again and is worried about her new baby. Which of the following is true?

Accepted Answer

The mother has antibodies to CMV that are passed to the fetus

Answer

The new infant should be isolated from the older child

Answer

Termination of pregnancy is advised

Answer

The mother's infection cannot become reactivated

Question 2

Most common organism causing meningitis in a 1 year old child -

Accepted Answer

Streptococcus pneumoniae

Answer

Listeria

Answer

H. influenzae

Answer

Neisseria meningitidis

Question 3

True about childhood tuberculosis:

Accepted Answer

Diagnosis by sputum is difficult

Answer

Highly contagious

Answer

5% prevalence

Answer

Common in 5-8 years age

Question 4

Which of the following is the most common cause of Meningoencephalitis in children?

Accepted Answer

Enterovirus

Answer

Mumps

Answer

HSV

Answer

Arbovirus

Question 5

Which of the following is true regarding tuberculosis in children?

Accepted Answer

All of the options

Answer

Commonly sputum negative

Answer

Incidence 10-15% of all TB cases

Answer

Clinically child does not show sign of florid TB.

Question 6

A HIV-positive mother delivers a baby. All are true, except:

Accepted Answer

Risk of HIV in the baby is up to 90%.

Answer

HIV infection cannot be diagnosed in the baby with available methods.

Answer

Breast feeding can transmit HIV.

Answer

HIV can be transmitted from mother to child during delivery.

Question 7

Which of the following is not a common manifestation of congenital Rubella -

Accepted Answer

Aortic stenosis

Answer

PDA

Answer

Deafness

Answer

Intellectual disability

Question 8

Most common cause of Pyogenic Meningitis in 6 month to 2 years of age is

Accepted Answer

Streptococcus pneumoniae

Answer

H. influenzae

Answer

Staphylococcus aureus

Answer

Neisseria meningitidis

Question 9

Which of the following statements regarding Congenital Rubella Syndrome (CRS) is FALSE?

Accepted Answer

Cataract in CRS is always bilateral.

Answer

Infants with Congenital Rubella Syndrome can shed virus in respiratory secretions for up to 1 year of age.

Answer

Risk of congenital defects is high when fetus is infected during the first trimester.

Answer

CRS is associated with increased risk of hearing loss and cardiac defects.

Question 10

What is the recommended duration of erythromycin prophylaxis for children exposed to pertussis?

Accepted Answer

14 days of prophylactic antibiotics

Answer

10 days of prophylactic antibiotics

Answer

12 days of prophylactic antibiotics

Answer

11 days of prophylactic antibiotics

Infectious Diseases — MCQs

Infectious Diseases — MCQs

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