Infectious Diseases — MCQs

A mother brings her 1-year-old daughter to the physician. She says that for the last 2 days her daughter has been fussy and crying more than usual. She also refuses formula. The patient has a fever of 39.4degC (102.9degF). Meningitis is suspected, and a lumbar puncture is performed. Analysis of the cerebrospinal fluid shows an opening pressure of 98 mm H2O, a leukocyte count of 1256/mm3, a protein level of 210 mg/dL, and a glucose level of 31 mg/dL.. The mother says that the patient has received no immunizations. Which of the following organisms is most likely responsible for this patient's illness?

Infectious Diseases Indian Medical PG Practice Questions and MCQs

Question 461: A 4-year-old child presented with fever for 6 days, generalized rash and cervical lymphadenopathy with strawberry tongue. What could be the diagnosis?

A. Kimura disease
B. Scarlet fever
C. Kawasaki disease (Correct Answer)
D. Rosai-Dorfman disease

Explanation: ***Kawasaki disease*** * Kawasaki disease is a **vasculitis** affecting medium-sized arteries, predominantly in children. * **Persistent fever** for more than 5 days, **generalized rash**, **cervical lymphadenopathy**, and **strawberry tongue** are key diagnostic criteria. * The child's age (4 years) is also consistent with the typical presentation of Kawasaki disease. *Kimura disease* * Kimura disease is a **rare chronic inflammatory condition** primarily affecting the head and neck, characterized by subcutaneous nodules and enlarged lymph nodes. * It typically presents with **painless subcutaneous masses**, often in young adults of Asian descent, and does not commonly include a generalized rash or strawberry tongue. *Scarlet fever* * Scarlet fever is caused by **Group A Streptococcus** and typically presents with a **fine, sandpaper-like rash**, **strawberry tongue**, and fever. * While a strawberry tongue and rash are present, the rash of Kawasaki disease is more polymorphous, and cervical lymphadenopathy is often more pronounced and less generalized than in scarlet fever. *Rosai Dorfman disease* * Rosai-Dorfman disease, also known as **sinus histiocytosis with massive lymphadenopathy**, is characterized by striking, often **painless and massive lymph node enlargement**, predominantly in the cervical region. * Systemic symptoms like fever and rash can occur, but the classic presentation does not typically include a "strawberry tongue" or the specific constellation of symptoms seen in Kawasaki disease.

Question 462: The following age group is most severely affected by Rubella infection -

A. Unborn child (Correct Answer)
B. Young girls
C. Adolescent girls
D. Females aged 25-35 years

Explanation: ***Unborn child*** - Rubella infection during pregnancy, especially in the **first trimester**, can lead to **Congenital Rubella Syndrome (CRS)**, causing severe birth defects. - CRS can manifest as **cardiac malformations**, **cataracts**, **deafness**, and neurological disorders, making it the most severely affected group. *Young girls* - While susceptible to rubella, young girls typically experience a **mild, self-limiting disease** with a rash, low-grade fever, and lymphadenopathy. - The risk of severe complications as seen in CRS is significantly lower in this age group compared to an unborn child. *Adolescent girls* - Rubella infection in adolescent girls is generally a **mild illness**, similar to young girls, characterized by a rash and mild constitutional symptoms. - The main concern for this group is if they become pregnant, as **maternal infection** then poses a severe risk to the fetus, not the adolescent herself. *Females aged 25 -- 35 Year* - In this age group, rubella infection is typically **mild and self-limiting**, similar to younger females. - The primary concern is if the woman is pregnant or becomes pregnant, as the **teratogenic effects** on the fetus are devastating, not the severity of the disease in the mother.

Question 463: Most common organism causing bacterial meningitis between 6 months and 2 years in vaccinated populations.

A. E. coli
B. Pneumococcus (Correct Answer)
C. H. influenzae
D. N. meningitidis

Explanation: ***Pneumococcus*** - **Pneumococcus (Streptococcus pneumoniae)** is now the most common cause of bacterial meningitis in children aged 6 months to 2 years in countries with high vaccination rates for *H. influenzae type b (Hib)* and *N. meningitidis*. - The introduction of the **pneumococcal conjugate vaccine (PCV)** has significantly reduced the incidence of pneumococcal meningitis, but it still remains the leading cause among the remaining cases in this age group. *E. coli* - **E. coli meningitis** is primarily a concern in **neonates** (birth to 1 month of age), often acquired during passage through the birth canal. - Its incidence significantly decreases after the neonatal period, making it a much less common cause in children aged 6 months to 2 years. *H. influenzae* - Before routine vaccination, **Haemophilus influenzae type b (Hib)** was the leading cause of bacterial meningitis in children under 5 years old. - The widespread use of the **Hib vaccine** has drastically reduced its incidence, making it a rare cause in vaccinated populations. *N. meningitidis* - **Neisseria meningitidis** (meningococcus) is a significant cause of bacterial meningitis, especially in older children, adolescents, and young adults. - While it can occur in children aged 6 months to 2 years, widespread **meningococcal vaccination** in many regions has reduced its overall prevalence, making *Pneumococcus* a more frequent cause in this specific vaccinated age group.

Question 464: Which vaccine formulation is NOT recommended for use in adults?

A. Pneumococcal
B. Hep A
C. MMR
D. DPT (Correct Answer)

Explanation: ***DPT (Pediatric Formulation)*** - The **pediatric DPT vaccine** contains whole-cell pertussis antigen and higher doses of diphtheria toxoid, which cause significantly more **adverse reactions** (fever, local reactions) in adolescents and adults. - Adults should receive **Td (Tetanus-diphtheria)** or **Tdap (Tetanus-diphtheria-acellular pertussis)** instead, which contain: - Reduced diphtheria toxoid (lowercase 'd') - Acellular pertussis component (in Tdap) with fewer side effects - The pediatric formulation is **not recommended** (though not absolutely contraindicated) due to increased reactogenicity in older individuals. *Pneumococcal* - **Pneumococcal vaccines** (PCV13, PCV20, and PPSV23) are routinely recommended for adults, especially those over 65 years or with chronic medical conditions. - They protect against **_Streptococcus pneumoniae_**, preventing pneumonia, meningitis, and invasive pneumococcal disease. *Hepatitis A* - The **Hepatitis A vaccine** is recommended for adults at risk: travelers to endemic areas, individuals with chronic liver disease, MSM, healthcare workers, and food handlers. - Provides active immunity against **Hepatitis A virus**, preventing acute liver infection. *MMR* - The **MMR vaccine** (Measles, Mumps, Rubella) is given to adults without evidence of immunity, particularly healthcare workers, students, and international travelers. - This **live attenuated vaccine** is safe and effective in adults for preventing these highly contagious viral diseases.

Question 465: Most common manifestation of HPV infection in children :

A. Common skin warts (verruca vulgaris) (Correct Answer)
B. Condyloma acuminatum (genital warts)
C. Sarcoma
D. Osteoma

Explanation: ***Common skin warts (verruca vulgaris)*** - **Verruca vulgaris**, or common skin warts, are the most frequent cutaneous manifestation of **human papillomavirus (HPV)** infection in children. - These warts are typically caused by **HPV types 2, 4, and 7** and are often found on the hands, fingers, and feet. - They account for the majority of HPV-related lesions in the pediatric population. *Condyloma acuminatum (genital warts)* - While **condyloma acuminatum** (genital warts) are caused by HPV (usually types 6 and 11), they are **much less common** in children compared to common skin warts. - In children, their presence may raise concerns about sexual abuse or vertical transmission from mother to child. - Common skin warts remain the predominant manifestation in the pediatric age group. *Sarcoma* - **Sarcomas** are malignant tumors of connective tissue and are not directly caused by HPV infection. - HPV is associated with **carcinomas** (epithelial cancers) like cervical, anal, and oropharyngeal cancers, but not sarcomas. *Osteoma* - An **osteoma** is a benign tumor composed of bone tissue, usually found on the skull or facial bones. - It is not associated with HPV infection and is typically a slow-growing, asymptomatic lesion.

Question 466: Prophylaxis with Cotrimoxazole is recommended in the following situation EXCEPT:

A. All symptomatic HIV infected children > 5 years of age irrespective of CD4
B. All HIV infected infants less than 1 year age irrespective of symptoms or CD4 counts
C. All HIV exposed infants till HIV infection can be ruled out
D. Should be started only after the diagnosis of HIV is confirmed (Correct Answer)

Explanation: ***Should be started only after the diagnosis of HIV is confirmed*** - Cotrimoxazole prophylaxis can be initiated in **HIV-exposed infants** even before a definitive HIV diagnosis is confirmed, especially in high-prevalence settings, to prevent opportunistic infections. - The decision to start prophylaxis is often based on exposure risk and age, not strictly requiring a confirmed positive HIV test, especially for conditions where early intervention significantly reduces morbidity and mortality. *All symptomatic HIV infected children > 5 years of age irrespective of CD4* - **Symptomatic HIV infection** in children older than 5 years indicates a compromised immune system, making them highly susceptible to opportunistic infections. - Cotrimoxazole provides broad-spectrum protection against common pathogens like *Pneumocystis jirovecii* pneumonia (PCP) and bacterial infections, which are prevalent in this vulnerable group. *All HIV infected infants less than 1 year age irrespective of symptoms or CD4 counts* - Infants under 1 year of age with HIV are at an extremely **high risk for developing PCP** and other serious bacterial infections due to their immature immune systems. - Prophylaxis is crucial in this age group regardless of CD4 counts or symptoms because the risk of life-threatening infections is substantial and rapid. *All HIV exposed infants till HIV infection can be ruled out* - **HIV-exposed infants** are at risk of acquiring HIV through mother-to-child transmission, and early immune compromise can occur even before a confirmed diagnosis. - Providing cotrimoxazole prophylaxis until HIV infection can be definitively ruled out protects these vulnerable infants during a critical period of potential exposure and immune immaturity.

Question 467: Oral Thrush develops in infants at

A. 18 months
B. 6 days
C. 10-12 weeks
D. 2-6 weeks (Correct Answer)

Explanation: **2-6 weeks (Correct)** - **Oral thrush** commonly appears in infants between **2 to 6 weeks of age**, as their immune systems are still developing and they are exposed to *Candida albicans* during birth or from their environment. - This period aligns with the typical onset of symptoms like **white patches** on the tongue and buccal mucosa, which cannot be easily wiped away. - This is the **most common age** for initial presentation of oral thrush in otherwise healthy infants. *18 months (Incorrect)* - While toddlers can get **oral thrush**, it's less common for the initial development to occur as late as **18 months** in an otherwise healthy child. - By this age, the infant's immune system is generally more robust, making primary oral thrush less likely unless there are predisposing factors like antibiotic use or immunodeficiency. *6 days (Incorrect)* - **Oral thrush** can sometimes manifest in the first few days of life, particularly with **birth canal transmission** of *Candida*. - While possible, the classic full-blown presentation is more common at **2-6 weeks** when maternal antibody protection begins to wane. *10-12 weeks (Incorrect)* - Though still possible, **oral thrush** is less typical to first develop around **10-12 weeks** in healthy infants. - If it appears at this age, it might suggest ongoing exposure, recurrence, or other contributing factors rather than the most common timeframe for initial presentation.

Question 468: Which of the following methods is NOT recommended for the diagnosis of HIV infection in a 2-month-old child?

A. Viral culture
B. DNA-PCR
C. P24 antigen assay
D. HIV ELISA (Correct Answer)

Explanation: ***HIV ELISA*** - **HIV ELISA** (Enzyme-linked Immunosorbent Assay) detects **HIV antibodies**, which are maternally derived and can persist in newborns for up to 18 months, leading to **false positive** results. - Therefore, antibody-based tests are **not suitable** for diagnosing HIV infection in infants under 18 months of age. *Viral culture* - **HIV viral culture** can directly detect the presence of replication-competent virus in an infant's blood. - While sensitive, it is **expensive**, labor-intensive, and takes a long time (several weeks) to obtain results, making it less practical for routine diagnosis. *DNA-PCR* - **DNA PCR (Polymerase Chain Reaction)** directly detects **HIV proviral DNA** within infected cells, making it highly specific and sensitive for early infant diagnosis. - It is currently the **recommended method** for HIV diagnosis in infants and young children, especially in the first few months of life. *P24 antigen assay* - The **P24 antigen assay** detects the **core protein of the HIV virus**, indicating active viral replication. - It can be used for early diagnosis in infants but may be less sensitive than DNA PCR, particularly in the presence of maternal antibodies or during early infection.

Question 469: In children commonest organ involved in nocardiosis is

A. Brain
B. Skin
C. Lungs (Correct Answer)
D. Renal

Explanation: ***Lungs*** - The **lungs** are the primary site of infection for **Nocardia** in both adults and children, as the pathogen is typically acquired via **inhalation**. - **Pulmonary nocardiosis** can manifest as pneumonia, nodules, or cavitary lesions, especially in immunocompromised individuals. *Brain* - While the **brain** can be involved in nocardiosis, leading to **abscesses**, it is usually a result of **hematogenous dissemination** from a primary pulmonary infection, making it a secondary rather than the commonest primary site. - **Cerebral nocardia** is a serious complication, but it does not represent the initial presentation in most cases. *Skin* - **Cutaneous nocardiosis** can occur through direct inoculation into the skin following trauma, but it is less common than pulmonary involvement in children. - Such infections may present as pustules, cellulitis, or subcutaneous abscesses, usually localized to the site of injury. *Renal* - **Renal involvement** in nocardiosis is rare and typically occurs via **hematogenous spread** from a primary site, often the lungs. - It can lead to **renal abscesses** but is not considered a common initial presentation or primary site of infection.

Question 470: A mother brings her 1-year-old daughter to the physician. She says that for the last 2 days her daughter has been fussy and crying more than usual. She also refuses formula. The patient has a fever of 39.4degC (102.9degF). Meningitis is suspected, and a lumbar puncture is performed. Analysis of the cerebrospinal fluid shows an opening pressure of 98 mm H2O, a leukocyte count of 1256/mm3, a protein level of 210 mg/dL, and a glucose level of 31 mg/dL.. The mother says that the patient has received no immunizations. Which of the following organisms is most likely responsible for this patient's illness?

A. Haemophilus influenzae (Correct Answer)
B. Group B Streptococcus
C. Neisseria meningitidis
D. Streptococcus pneumoniae

Explanation: ***Haemophilus influenzae*** - *H. influenzae* type b (Hib) is the **most common cause of bacterial meningitis** in unvaccinated children aged 6 months to 5 years. - Before the introduction of the Hib vaccine, this organism was the **leading cause** of bacterial meningitis in this age group. - The CSF profile (high leukocyte count with **neutrophil predominance**, elevated protein >100 mg/dL, and low glucose <40 mg/dL) is classic for **bacterial meningitis**. - In an **unimmunized 1-year-old**, Hib remains the most likely pathogen. *Streptococcus pneumoniae* - *S. pneumoniae* is a common cause of bacterial meningitis across all age groups and is now the **most common cause in vaccinated populations** where Hib has been eliminated. - However, in an **unvaccinated child** of this age, *H. influenzae* type b is statistically more likely. - The CSF findings would be identical and cannot distinguish between these two organisms. *Group B Streptococcus* - **Group B Streptococcus** (*Streptococcus agalactiae*) primarily causes **early-onset neonatal meningitis** (first week of life) and **late-onset neonatal meningitis** (up to 3 months of age). - While late-late onset can occur beyond 3 months, it is uncommon at 1 year of age. - This organism is not a typical cause of meningitis in this age group. *Neisseria meningitidis* - *N. meningitidis* causes bacterial meningitis primarily in **older children, adolescents, and young adults**, often associated with outbreaks. - While possible in a 1-year-old, it is less common than Hib in unvaccinated children of this age. - Meningococcal meningitis is often associated with a **petechial or purpuric rash**, which is not mentioned in this case.

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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