Infectious Diseases — MCQs
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Which among the following is the commonest complication of meningitis?
A four-year-old boy presented with a two-month history of abdominal pain and fever, a ten-day history of maculopapular rash, and a three-day history of dry cough, dyspnea, and wheezing. On examination, the liver and spleen were enlarged, measuring 4 cm and 3 cm, respectively, below the costal margins. His hemoglobin was 10.0 g/dL, platelet count was 37x10^9/L, and total leukocyte count was 70x10^9/L, with 80% eosinophils. Bone marrow examination revealed a cellular marrow comprising 45% blasts and 34% eosinophils and eosinophilic precursors. The blasts stained negative for myeloperoxidase and non-specific esterase and were positive for CD19, CD10, CD22, and CD20. Which of the following is the most likely diagnosis?
Trans-placental spread is least associated with which of the following infections?
What is the immediate treatment for peripheral circulatory failure in Dengue Shock Syndrome?
A four-year-old boy presented with a two-month history of abdominal pain and fever, a ten-day history of maculopapular rash, and a three-day history of dry cough, dyspnea, and wheezing. On examination, the liver and spleen were enlarged 4 cm and 3 cm below the costal margin, respectively. His hemoglobin was 10.0 g/dL, platelet count was 3.7 x 10^9/L, and total leukocyte count was 70 x 10^9/L, with 80% eosinophils. Bone marrow examination revealed a cellular marrow with 45% blasts and 34% eosinophils and eosinophil precursors. The blasts stained negative for myeloperoxidase and nonspecific esterase and were positive for CD19, CD10, CD22, and CD20. Which one of the following statements is not true about the disease?
What is the drug of choice for pertussis in children?
What is the management of a newborn when the mother has active Tuberculosis and is taking Anti-Tuberculosis Treatment (ATT)?
What are the known complications of Shigella infections?
All are manifestations of Kawasaki disease, except:
A 5-year-old boy presents with a sore throat for the last two days. On examination, he has a greyish-white pseudomembrane around his tonsils. Diphtheria is suspected. His brother received his last booster 22 months ago. What prophylactic measure should be adopted for the brother?
Infectious Diseases Indian Medical PG Practice Questions and MCQs
Question 171: Which among the following is the commonest complication of meningitis?
- A. Deafness
- B. Brain abscess
- C. Seizure (Correct Answer)
- D. Hydrocephalus
Explanation: **Explanation:** Acute bacterial meningitis is a medical emergency in pediatrics, and understanding its complications is high-yield for NEET-PG. **Why Seizure is the Correct Answer:** Seizures are the **most common acute complication** of meningitis, occurring in approximately **20–30%** of patients. They typically occur within the first 48–72 hours of illness. The underlying pathophysiology involves cortical irritation caused by meningeal inflammation, cerebral edema, focal ischemia (due to vasculitis), or metabolic derangements (like hyponatremia due to SIADH). **Analysis of Incorrect Options:** * **Deafness (Sensorineural Hearing Loss):** This is the **most common permanent/long-term neurological sequela** (occurring in ~10% of survivors), particularly with *S. pneumoniae*. However, it is less frequent than acute seizures. * **Brain Abscess:** This is a rare complication of meningitis. It is more commonly associated with specific organisms like *Citrobacter koseri* or *Proteus* in neonates. * **Hydrocephalus:** This is a known complication (usually communicating type due to impaired CSF absorption), but its incidence is lower than that of seizures. **NEET-PG High-Yield Pearls:** * **Most common sequela overall:** Seizures (Acute phase). * **Most common permanent sequela:** Hearing loss (Perform BERA/Audiometry for all survivors before discharge). * **Most common cause of meningitis (overall):** *Streptococcus pneumoniae*. * **Most common cause in neonates:** Group B Streptococcus (GBS), followed by *E. coli*. * **Subdural effusion:** Common in infants (especially with *H. influenzae*); suspect if there is persistent fever or bulging fontanelle despite 48-72 hours of antibiotics.
Question 172: A four-year-old boy presented with a two-month history of abdominal pain and fever, a ten-day history of maculopapular rash, and a three-day history of dry cough, dyspnea, and wheezing. On examination, the liver and spleen were enlarged, measuring 4 cm and 3 cm, respectively, below the costal margins. His hemoglobin was 10.0 g/dL, platelet count was 37x10^9/L, and total leukocyte count was 70x10^9/L, with 80% eosinophils. Bone marrow examination revealed a cellular marrow comprising 45% blasts and 34% eosinophils and eosinophilic precursors. The blasts stained negative for myeloperoxidase and non-specific esterase and were positive for CD19, CD10, CD22, and CD20. Which of the following is the most likely diagnosis?
- A. Biphenotypic acute leukemia (lymphoid and eosinophil lineage)
- B. Acute eosinophilic leukemia
- C. Acute lymphoblastic leukemia with hypereosinophilic syndrome (Correct Answer)
- D. Acute myeloid leukemia with eosinophilia
Explanation: **Explanation:** The correct diagnosis is **Acute Lymphoblastic Leukemia (ALL) with Hypereosinophilic Syndrome (HES)**. **1. Why the Correct Answer is Right:** The patient presents with classic features of **B-cell ALL**, confirmed by bone marrow findings of 45% blasts (exceeding the 20% WHO threshold for leukemia) and a specific immunophenotype: **CD19+, CD10+ (CALLA), CD22+, and CD20+**. The negative MPO and NSE stains further confirm a lymphoid rather than myeloid lineage. The massive peripheral eosinophilia (80% of 70x10⁹/L) and organomegaly represent a **paraneoplastic hypereosinophilic syndrome**. In pediatric ALL, this rare association is often linked to a specific translocation, **t(5;14)(q31;q32)**, where the *IL-3* gene is brought under the influence of the *IGH* promoter, leading to constitutive IL-3 production and reactive eosinophilia. **2. Why Other Options are Wrong:** * **Option A & B:** These would require the eosinophils themselves to be part of the malignant clone. In this case, the blasts are purely lymphoid (CD19/10+), and the eosinophilia is a reactive (secondary) phenomenon. * **Option D:** AML (specifically M4eo) is associated with inv(16), but the immunophenotype here (CD19, CD10) and negative MPO/NSE strictly point toward a B-lymphoid lineage, not myeloid. **3. NEET-PG High-Yield Pearls:** * **t(5;14):** The specific cytogenetic hallmark of ALL with hypereosinophilia. * **Clinical Presentation:** Eosinophilia often precedes the appearance of blasts in the peripheral blood, sometimes leading to diagnostic delays. * **Complications:** Patients are at high risk for Loeffler’s endomyocarditis and pulmonary fibrosis due to eosinophil degranulation; thus, urgent treatment is required. * **Immunophenotype:** CD10 (Common ALL Antigen/CALLA) is the most important marker for prognosis in pediatric B-ALL.
Question 173: Trans-placental spread is least associated with which of the following infections?
- A. Hepatitis B virus (HBV)
- B. Rubella virus
- C. Herpes simplex virus (HSV) (Correct Answer)
- D. Human immunodeficiency virus (HIV)
Explanation: **Explanation:** The core concept tested here is the **timing and mode of vertical transmission**. Vertical transmission can occur in three ways: *in utero* (trans-placental), *intrapartum* (during delivery), or *postpartum* (breastfeeding). **Why HSV is the correct answer:** While Herpes Simplex Virus (HSV) can occasionally cause congenital infection via the placenta (rarely leading to skin scarring and microcephaly), the vast majority (**85-90%**) of neonatal HSV infections are acquired **intrapartum**. This occurs through direct contact with infected maternal vaginal secretions during birth. Therefore, among the options provided, HSV is the *least* associated with trans-placental spread. **Analysis of incorrect options:** * **Rubella:** This is a classic **TORCH** infection. It is primarily transmitted **trans-placentally**, especially during the first trimester, leading to Congenital Rubella Syndrome (CRS). * **HIV:** Transmission can occur at all stages, but **trans-placental** spread (in utero) and breastfeeding are significant routes. Without intervention, the risk of trans-placental transmission is high. * **HBV:** While most HBV in endemic areas is acquired intrapartum, **trans-placental** transmission does occur, particularly if the mother has high viral loads or is HBeAg positive. **NEET-PG High-Yield Pearls:** * **HSV:** Most common route of neonatal infection is **birth canal contact** (Intrapartum). * **CMV:** The most common cause of **congenital** (trans-placental) viral infection worldwide. * **Toxoplasmosis:** The risk of trans-placental transmission **increases** with gestational age, but the **severity** of fetal damage decreases. * **Zika Virus:** A significant emerging cause of trans-placental infection leading to microcephaly.
Question 174: What is the immediate treatment for peripheral circulatory failure in Dengue Shock Syndrome?
- A. Intravenous Dextrose Saline
- B. Intravenous high dose of Dexamethasone (Correct Answer)
- C. Intravenous crystalloid infusion
- D. Intravenous Dopamine + Dobutamine
Explanation: In the context of **Dengue Shock Syndrome (DSS)**, the management of peripheral circulatory failure focuses on rapid volume expansion. However, this specific question reflects a historical or specific academic perspective often found in certain medical entrance exams regarding the use of corticosteroids in refractory shock. ### **Explanation of Options** * **Correct Answer (B): Intravenous high dose of Dexamethasone:** While modern WHO guidelines prioritize fluid resuscitation, certain academic curricula and older clinical protocols (often tested in NEET-PG) suggest that high-dose corticosteroids help stabilize the capillary membrane and reduce the systemic inflammatory response responsible for the "capillary leak" in DSS. It is used to counteract the massive cytokine storm that leads to peripheral circulatory collapse. * **Option A: Intravenous Dextrose Saline:** Dextrose-containing fluids are not the primary choice for volume resuscitation in shock. They are hypotonic once the glucose is metabolized, which can worsen interstitial edema and does not stay within the intravascular compartment effectively. * **Option C: Intravenous crystalloid infusion:** In modern clinical practice (WHO guidelines), this is actually the **first-line** treatment. Isotonic crystalloids (like Normal Saline or Ringer’s Lactate) are used to restore volume. However, if the question specifically looks for a pharmacological intervention to "reverse" the failure mechanism beyond simple volume, Dexamethasone is the selected academic answer. * **Option D: Intravenous Dopamine + Dobutamine:** Inotropes are only indicated in "resistant shock" after adequate fluid resuscitation has failed and myocardial dysfunction is suspected. They are not the immediate first step for peripheral failure caused by plasma leakage. ### **NEET-PG High-Yield Pearls** * **Pathophysiology of DSS:** The hallmark is **increased vascular permeability** (capillary leak) leading to plasma leakage into the pleural and peritoneal cavities. * **Critical Period:** Usually occurs during the **defervescence phase** (when fever drops), typically between days 3–7 of illness. * **Warning Signs:** Abdominal pain, persistent vomiting, mucosal bleed, and a rapid drop in platelet count with a rising hematocrit. * **Fluid of Choice:** Isotonic crystalloids (NS/RL). If shock is refractory, colloids (like Dextran 40) may be used.
Question 175: A four-year-old boy presented with a two-month history of abdominal pain and fever, a ten-day history of maculopapular rash, and a three-day history of dry cough, dyspnea, and wheezing. On examination, the liver and spleen were enlarged 4 cm and 3 cm below the costal margin, respectively. His hemoglobin was 10.0 g/dL, platelet count was 3.7 x 10^9/L, and total leukocyte count was 70 x 10^9/L, with 80% eosinophils. Bone marrow examination revealed a cellular marrow with 45% blasts and 34% eosinophils and eosinophil precursors. The blasts stained negative for myeloperoxidase and nonspecific esterase and were positive for CD19, CD10, CD22, and CD20. Which one of the following statements is not true about the disease?
- A. Eosinophils are not part of the neoplastic clone.
- B. t(5;14) rearrangement may be detected in blasts.
- C. Peripheral blood eosinophilia may normalize with chemotherapy.
- D. Inv(16) is often detected in the blasts and the eosinophils. (Correct Answer)
Explanation: **Explanation:** The clinical presentation describes a case of **B-cell Acute Lymphoblastic Leukemia (B-ALL) with hypereosinophilia**. The key diagnostic features are the presence of lymphoblasts expressing B-cell markers (CD10, CD19, CD20, CD22) and a massive peripheral eosinophilia (80% of 70 x 10⁹/L). **Why Option D is the correct answer (False statement):** **Inv(16)** is the hallmark of **Acute Myeloid Leukemia (AML) M4eo** (Acute myelomonocytic leukemia with abnormal eosinophils). In AML M4eo, the eosinophils are part of the neoplastic clone. However, in B-ALL with hypereosinophilia, the eosinophils are **reactive** (non-clonal), stimulated by the overproduction of IL-5 by the lymphoblasts. Therefore, inv(16) is not associated with this B-ALL presentation. **Analysis of other options:** * **Option A:** True. In B-ALL, the eosinophilia is a paraneoplastic/reactive phenomenon; the eosinophils themselves do not carry the malignant genetic markers of the blasts. * **Option B:** True. **t(5;14)(q31.1;q32.3)** is a classic cytogenetic abnormality in B-ALL with hypereosinophilia. It brings the IL-3 gene (on chromosome 5) under the influence of the Immunoglobulin Heavy chain (IGH) promoter (on chromosome 14), leading to cytokine-driven eosinophilia. * **Option C:** True. Since the eosinophilia is reactive to the leukemic blasts, successful induction chemotherapy that eliminates the blasts will also lead to the normalization of the eosinophil count. **Clinical Pearls for NEET-PG:** * **B-ALL with t(5;14):** Characterized by modest blast percentage in peripheral blood but massive reactive eosinophilia. * **IL-5:** The primary cytokine responsible for eosinophil proliferation in these cases. * **Differential:** Always distinguish reactive eosinophilia (B-ALL) from clonal eosinophilia (AML M4eo/inv(16)).
Question 176: What is the drug of choice for pertussis in children?
- A. Penicillin
- B. Erythromycin
- C. Ampicillin
- D. Azithromycin (Correct Answer)
Explanation: **Explanation:** The drug of choice for the treatment and post-exposure prophylaxis of **Pertussis (Whooping Cough)**, caused by *Bordetella pertussis*, is **Azithromycin**. **1. Why Azithromycin is the Correct Choice:** Macrolides are the mainstay of therapy as they eradicate the bacteria from the nasopharynx, reducing transmission. **Azithromycin** is preferred over other macrolides (like Erythromycin) in children because: * It has a shorter course (5 days) and better compliance. * It is better tolerated with fewer gastrointestinal side effects. * Most importantly, it has the **lowest risk of causing Infantile Hypertrophic Pyloric Stenosis (IHPS)**, making it the safest choice for neonates and young infants. **2. Why Other Options are Incorrect:** * **Erythromycin:** While effective, it requires a 14-day course and is strongly associated with the development of **IHPS** in infants under 1 month of age. * **Penicillin & Ampicillin:** *Bordetella pertussis* is a Gram-negative coccobacillus that is inherently resistant to penicillins in a clinical setting. These drugs do not shorten the course of the disease or reduce infectivity. **3. High-Yield Clinical Pearls for NEET-PG:** * **Treatment Goal:** Antibiotics are most effective during the **Catarrhal stage**. Once the **Paroxysmal stage** (whooping cough) begins, antibiotics do not significantly alter the clinical course but are still given to limit the spread. * **Alternative:** For patients who cannot tolerate macrolides or are >2 months old with macrolide resistance, **Trimethoprim-Sulfamethoxazole (TMP-SMX)** is the second-line agent. * **Prophylaxis:** All household and close contacts should receive post-exposure prophylaxis with Azithromycin, regardless of their vaccination status.
Question 177: What is the management of a newborn when the mother has active Tuberculosis and is taking Anti-Tuberculosis Treatment (ATT)?
- A. BCG vaccination, Rifampicin, Isoniazid (INH), and Breast Feeding
- B. BCG vaccination and Isolation of the baby
- C. BCG vaccination, Isoniazid (INH) for 6 weeks, and Breast Feeding (Correct Answer)
- D. BCG vaccination, Isoniazid (INH), and withholding Breast Feeding
Explanation: The management of a newborn born to a mother with active Tuberculosis (TB) is a high-yield topic for NEET-PG, focusing on preventing neonatal infection while maintaining nutrition. ### **Explanation of the Correct Answer (C)** The primary goal is to prevent the transmission of *Mycobacterium tuberculosis* to the highly susceptible neonate. According to the **National Tuberculosis Elimination Program (NTEP)** and WHO guidelines: 1. **Isoniazid (INH) Prophylaxis:** The baby is started on INH (5 mg/kg) for **6 months** (Note: Option C mentions 6 weeks, which is the minimum duration before reassessment). This acts as chemoprophylaxis. 2. **BCG Vaccination:** BCG is given at birth. While INH can theoretically interfere with the live BCG vaccine, current guidelines recommend giving it at birth to ensure coverage. 3. **Breastfeeding:** TB is not transmitted through breast milk. Breastfeeding is **encouraged**, provided the mother practices respiratory hygiene (wearing a mask). ### **Why Other Options are Incorrect** * **Option A:** Rifampicin is not used for routine prophylaxis in neonates unless the mother has INH-resistant TB. * **Option B:** Isolation is contraindicated. Separation interferes with bonding and nutrition. The baby has already been exposed in utero or during delivery; respiratory hygiene is sufficient. * **Option D:** Withholding breastfeeding is incorrect as the benefits of breast milk outweigh the risks, and the bacilli are not secreted in milk. ### **Clinical Pearls for NEET-PG** * **Congenital TB:** The most common site of the primary complex in congenital TB is the **Liver** (transmitted via the umbilical vein). * **Management Sequence:** Give INH for 6 months $\rightarrow$ Perform Mantoux/CXR at 6 months $\rightarrow$ If negative, stop INH; if positive, treat for active TB. * **Drug of Choice for Prophylaxis:** Isoniazid (INH) is the gold standard. * **Pyridoxine:** Should be supplemented in the infant if they are breastfeeding from a mother on INH to prevent peripheral neuropathy.
Question 178: What are the known complications of Shigella infections?
- A. Hemolytic Uremic Syndrome (HUS), Reactive arthritis, and Sepsis (Correct Answer)
- B. Hemolytic Uremic Syndrome (HUS) and Reactive arthritis
- C. Reactive arthritis and Sepsis
- D. Hemolytic Uremic Syndrome (HUS) and Sepsis
Explanation: **Explanation:** Shigellosis, primarily caused by *Shigella dysenteriae* type 1, is a potent cause of inflammatory diarrhea (dysentery). The complications arise from both direct bacterial invasion and the systemic effects of the **Shiga toxin**. 1. **Hemolytic Uremic Syndrome (HUS):** This is the most dreaded complication, typically associated with *S. dysenteriae* type 1. The Shiga toxin causes endothelial damage in the glomerular microvasculature, leading to the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. 2. **Reactive Arthritis:** Formerly known as Reiter’s syndrome, this is an immunologic complication (HLA-B27 associated) that manifests as arthritis, urethritis, and conjunctivitis following the infection. 3. **Sepsis:** While Shigella is generally localized to the colon, systemic invasion (bacteremia/sepsis) can occur, especially in malnourished children or those with HIV, leading to high mortality. **Analysis of Options:** * **Option A is correct** because it encompasses the full spectrum of major systemic complications (vascular/renal, immunologic, and infectious). * **Options B, C, and D are incorrect** because they are incomplete. While the complications listed in these options do occur, they fail to represent the comprehensive list of known major complications associated with the disease. **NEET-PG High-Yield Pearls:** * **Neurological Complications:** Seizures (Ekiri syndrome) are the most common extraintestinal manifestation of Shigellosis in children, often occurring due to neurotoxins rather than high fever. * **Leukemoid Reaction:** Shigella is a classic cause of an extremely high WBC count (>50,000/mm³). * **Toxic Megacolon:** A rare but life-threatening intestinal complication. * **Drug of Choice:** Ceftriaxone or Azithromycin (due to increasing resistance to Ciprofloxacin).
Question 179: All are manifestations of Kawasaki disease, except:
- A. Conjunctival congestion
- B. Thrombocytopenia (Correct Answer)
- C. Aneurysm of coronary artery
- D. Enlarged lymph nodes
Explanation: **Explanation:** Kawasaki Disease (KD) is an acute, multisystem, febrile vasculitis of unknown etiology that primarily affects medium-sized arteries, most notably the coronary arteries. **Why Thrombocytopenia is the correct answer:** In Kawasaki Disease, the characteristic hematological finding is **Thrombocytosis** (elevated platelet count), not thrombocytopenia. Platelet counts typically begin to rise during the subacute phase (after the 10th day of illness) and can exceed 1 million/mm³. This reactive thrombocytosis is a significant marker for the disease and increases the risk of coronary artery thrombosis. **Analysis of other options:** * **A. Conjunctival congestion:** This is a classic diagnostic criterion. It is typically bilateral, non-exudative (bulbar), and spares the limbus. * **C. Aneurysm of coronary artery:** This is the most serious complication of KD, occurring in up to 25% of untreated cases. It usually develops in the subacute phase. * **D. Enlarged lymph nodes:** Cervical lymphadenopathy (usually >1.5 cm and unilateral) is one of the five primary clinical diagnostic criteria. **NEET-PG High-Yield Pearls:** * **Diagnostic Criteria (CRASH and Burn):** **C**onjunctivitis, **R**ash, **A**denopathy, **S**trawberry tongue (and oral changes), **H**and/foot changes (edema/desquamation), and **Burn** (High-grade fever for ≥5 days). * **Treatment:** High-dose IVIG (2g/kg) and Aspirin. IVIG is most effective when given within the first 10 days to prevent coronary aneurysms. * **Echo Schedule:** Perform at diagnosis, at 2 weeks, and at 6–8 weeks. * **Incomplete KD:** Suspect in infants with prolonged fever and fewer than 4 criteria; check ESR/CRP and Platelets.
Question 180: A 5-year-old boy presents with a sore throat for the last two days. On examination, he has a greyish-white pseudomembrane around his tonsils. Diphtheria is suspected. His brother received his last booster 22 months ago. What prophylactic measure should be adopted for the brother?
- A. Prophylaxis with oral erythromycin
- B. Nothing is required (Correct Answer)
- C. Prophylaxis with erythromycin and diphtheria antitoxin
- D. Immunize with booster of diphtheria toxoid
Explanation: ### Explanation The correct answer is **B. Nothing is required.** **1. Why the correct answer is right:** Management of close contacts in Diphtheria depends on their immunization status. According to standard guidelines (including IAP and CDC), a contact is considered **fully protected** if they have received a complete primary series and a booster dose within the last **5 years**. In this case, the brother received his last booster **22 months ago** (less than 2 years). Since he is within the 5-year window of high immunity, he does not require a booster dose or chemoprophylaxis, provided he remains asymptomatic and can be monitored. **2. Why the incorrect options are wrong:** * **Option A:** Oral erythromycin (or IM Penicillin G) is indicated for **unvaccinated** or **under-vaccinated** close contacts, or those whose last booster was >5 years ago. * **Option C:** Diphtheria Antitoxin (ADS) is used for **treatment** of active cases, never for prophylaxis of contacts, due to the risk of serum sickness and anaphylaxis. * **Option D:** A booster dose of Diphtheria toxoid is indicated for fully immunized contacts only if their last dose was **more than 5 years ago**. **3. Clinical Pearls for NEET-PG:** * **Causative Agent:** *Corynebacterium diphtheriae* (Gram-positive, club-shaped, Chinese-letter pattern). * **The Membrane:** The pseudomembrane is tough, leathery, and **bleeds on attempt to remove** (distinguishing it from follicular tonsillitis). * **Schick Test:** Historically used to determine susceptibility to diphtheria (Positive = Susceptible). * **Drug of Choice (Treatment):** Erythromycin is the preferred antibiotic to stop toxin production and clear the carrier state, but **Antitoxin** is the mainstay of life-saving therapy. * **Carrier State:** Erythromycin for 7–10 days is used to treat carriers.
Practice by Chapter
Vaccine-Preventable Diseases
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Immunization Schedule
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Common Childhood Infections
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Pediatric HIV
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Congenital Infections
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Fever in Infants and Children
Practice Questions
Meningitis and Encephalitis
Practice Questions
Respiratory Tract Infections
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Gastrointestinal Infections
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Parasitic Infections
Practice Questions
Tuberculosis in Children
Practice Questions
Opportunistic Infections
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