A 4-year-old boy presents with low-grade fever, inspiratory stridor, and barking cough for the past 5 days. Examination reveals a hoarse voice, a moderately inflamed pharynx, and a slightly increased respiratory rate. His chest x-ray showed subglottic narrowing appearing like a steeple. Which among the following is not indicated in the treatment of this condition?
Q2
A child presents with recurrent infections. Mediastinal imaging reveals an absent thymus gland, and further investigations show low ADA (adenosine deaminase) levels. What is the most likely diagnosis?
Q3
A 6-year-old child presents to the emergency department with sudden onset of palpitations, shortness of breath, and dizziness. The child has no significant past medical history. On examination, the heart rate is 220 beats per minute, blood pressure is $90 / 60 \mathrm{mmHg}$, and the child appears anxious but is otherwise stable. An ECG confirms the diagnosis of paroxysmal supraventricular tachycardia (PSVT). What is the initial recommended dose of adenosine for this child?
Q4
A 2 year old child came with watery diarrhea. Electron Microscopy (EM) Image is shown here. Choose the correct pathogen.
Q5
An unimmunized 5 -year-old child presents to the OPD with a white membranous layer on the throat upon inspection. The child's brother is immunized. What is the first step in management?
Q6
A 2-year-old male is brought to your office by his mother for evaluation. The patient develops a skin presentation similar to Image A on his cheeks and chin when exposed to certain food products. This patient is most likely predisposed to develop which of the following?
Q7
A 4-year-old boy who otherwise has no significant past medical history presents to the pediatric clinic accompanied by his father for a 2-day history of high fever, sore throat, nausea, vomiting, and bloody diarrhea. The patient’s father endorses that these symptoms began approximately 3 weeks after the family got a new dog. His father also states that several other children at the patient’s preschool have been sick with similar symptoms. He denies any other recent changes to his diet or lifestyle. The patient's blood pressure is 123/81 mm Hg, pulse is 91/min, respiratory rate is 15/min, and temperature is 39.2°C (102.5°F). Which of the following is the most likely cause for this patient’s presentation?
Q8
A 4-year-old girl presents to a pediatrician for a scheduled follow-up visit. She was diagnosed with her first episode of acute otitis media 10 days ago and had been prescribed oral amoxicillin. Her clinical features at the time of the initial presentation included pain in the ear, fever, and nasal congestion. The tympanic membrane in the left ear was markedly red in color. Today, after completing 10 days of antibiotic therapy, her parents report that she is asymptomatic, except for mild fullness in the left ear. There is no history of chronic nasal obstruction or chronic/recurrent rhinosinusitis. On physical examination, the girl's vital signs are stable. Otoscopic examination of the left ear shows the presence of an air-fluid interface behind the translucent tympanic membrane and decreased mobility of the tympanic membrane. Which of the following is the next best step in the management of this patient?
Q9
A 3-year-old girl is brought to the emergency room because of a 5-day history of high fever and fatigue. During this time she has been crying more than usual and eating less. Her mother says that the child has also complained about pain in her arms and legs for the past 3 days. She was born at term and has been otherwise healthy. She appears ill. Her temperature is 39.5°C (103.1°F), pulse is 128/min, and blood pressure is 96/52 mm Hg. The lungs are clear to auscultation. A grade 3/6 systolic murmur is heard at the apex. There is mild tenderness to palpation of the left upper quadrant with no guarding or rebound. The spleen is palpated 3 cm below the left costal margin. There is no redness or swelling of the joints. Laboratory studies show:
Hemoglobin 11.8 g/dL
Leukocyte count 16,300/mm3
Platelet count 220,000/mm3
Erythrocyte sedimentation rate 50 mm/h
Serum
Glucose 96 mg/dL
Creatinine 1.7 mg/dL
Total bilirubin 0.4 mg/dL
AST 18 U/L
ALT 20 U/L
Urine
Protein 2+
RBC casts rare
RBC 10/hpf
WBC 1–2/hpf
Which of the following is the most appropriate next step in management?
Q10
A 7-year-old boy is brought to his pediatrician for evaluation of a sore throat. The sore throat began 4 days ago and has progressively worsened. Associated symptoms include subjective fever, pain with swallowing, and fatigue. The patient denies any cough or rhinorrhea. Vital signs are as follows: T 38.6 C, HR 88, BP 115/67, RR 14, and SpO2 99%. Physical examination is significant for purulent tonsillar exudate; no cervical lymphadenopathy is noted. Which of the following is the best next step in the management of this patient?
Infectious Disease US Medical PG Practice Questions and MCQs
Question 1: A 4-year-old boy presents with low-grade fever, inspiratory stridor, and barking cough for the past 5 days. Examination reveals a hoarse voice, a moderately inflamed pharynx, and a slightly increased respiratory rate. His chest x-ray showed subglottic narrowing appearing like a steeple. Which among the following is not indicated in the treatment of this condition?
A. Nebulized racemic epinephrine
B. Intramuscular dexamethasone
C. Helium oxygen mixture
D. Parenteral cefotaxime (Correct Answer)
E. Nebulized budesonide
Explanation: ***Parenteral cefotaxime***
- The clinical presentation (low-grade fever, inspiratory stridor, barking cough, hoarse voice) and the **steeple sign** on chest X-ray are classic for **croup (laryngotracheobronchitis)**, which is predominantly caused by **viral infections**, not bacterial. Therefore, antibiotics like parenteral cefotaxime are generally **not indicated**.
- **Cefotaxime** is a broad-spectrum antibiotic used for serious bacterial infections; its use in viral croup would be inappropriate and could contribute to antibiotic resistance.
*Nebulized racemic epinephrine*
- **Nebulized racemic epinephrine** is a common and effective treatment for moderate to severe croup, as it helps to **vasoconstrict** the subglottic mucosa, reducing edema and improving airflow.
- It provides temporary relief from symptoms, especially stridor, by reducing swelling in the airway.
*Intramuscular dexamethasone*
- **Dexamethasone**, a corticosteroid, is a cornerstone of croup treatment as it reduces inflammation and edema in the airway, improving respiratory symptoms.
- It can be administered orally, intravenously, or intramuscularly, and provides sustained relief, typically for 24-48 hours.
*Nebulized budesonide*
- **Nebulized budesonide** is an alternative corticosteroid treatment for croup that delivers anti-inflammatory medication directly to the airway.
- Studies show it is equally effective to dexamethasone for mild to moderate croup, though dexamethasone is often preferred due to ease of administration and longer duration of action.
*Helium oxygen mixture*
- A **helium-oxygen mixture (heliox)** is a therapeutic gas that is less dense than air, which can reduce the work of breathing in patients with severe airway obstruction, such as refractory croup.
- By decreasing airway turbulence, heliox can temporarily improve air movement past the narrowed subglottic area.
Question 2: A child presents with recurrent infections. Mediastinal imaging reveals an absent thymus gland, and further investigations show low ADA (adenosine deaminase) levels. What is the most likely diagnosis?
A. Severe Combined Immunodeficiency (SCID) (Correct Answer)
B. DiGeorge syndrome
C. X-linked agammaglobulinemia
D. Hyper-IgM syndrome
E. Wiskott-Aldrich syndrome
Explanation: ***Severe Combined Immunodeficiency (SCID)***
- **Recurrent infections**, an **absent thymus gland** (indicating severe T-cell deficiency), and **low ADA levels** are classic features of SCID, specifically **ADA deficiency-SCID**.
- ADA deficiency leads to the accumulation of toxic metabolites that destroy **B and T lymphocytes**, severely compromising both humoral and cellular immunity.
*DiGeorge syndrome*
- Characterized by **thymic hypoplasia or aplasia**, leading to T-cell deficiencies and recurrent infections, similar to the absent thymus.
- However, DiGeorge syndrome is typically associated with **hypocalcemia** due to parathyroid hypoplasia, and **cardiac defects**, which are not mentioned, and **low ADA levels** are not a feature.
*X-linked agammaglobulinemia*
- Primarily affects **B-cell development**, leading to a severe deficiency of antibodies, resulting in recurrent bacterial infections.
- **T-cell function** and the **thymus gland** are typically normal in this condition, and low ADA levels are not observed.
*Hyper-IgM syndrome*
- Characterized by normal or elevated levels of **IgM** but very low levels of **IgG, IgA, and IgE** due to defects in B-cell class switching.
- The thymus gland is generally normal, and the primary defect lies in antibody production, not T-cell development or ADA deficiency.
*Wiskott-Aldrich syndrome*
- An X-linked immunodeficiency presenting with recurrent infections, but classically features the triad of **thrombocytopenia with small platelets**, **eczema**, and **immunodeficiency**.
- The thymus is typically present, and **low ADA levels** are not characteristic of this syndrome.
Question 3: A 6-year-old child presents to the emergency department with sudden onset of palpitations, shortness of breath, and dizziness. The child has no significant past medical history. On examination, the heart rate is 220 beats per minute, blood pressure is $90 / 60 \mathrm{mmHg}$, and the child appears anxious but is otherwise stable. An ECG confirms the diagnosis of paroxysmal supraventricular tachycardia (PSVT). What is the initial recommended dose of adenosine for this child?
A. $0.1 \mathrm{mg} / \mathrm{kg}$ (Correct Answer)
B. $0.2 \mathrm{mg} / \mathrm{kg}$
C. $0.5 \mathrm{mg} / \mathrm{kg}$
D. $1.0 \mathrm{mg} / \mathrm{kg}$
E. $0.05 \mathrm{mg} / \mathrm{kg}$
Explanation: ***0.1 mg/kg***
- The initial recommended dose of **adenosine** for children with **PSVT** is **0.1 mg/kg** given as a rapid intravenous bolus.
- This dose is typically followed by a saline flush to ensure rapid delivery to the heart and minimize peripheral metabolism.
*0.05 mg/kg*
- This dose is **too low** and is below the recommended initial dose for pediatric PSVT.
- While it may be safer, it is unlikely to be effective in terminating the arrhythmia and would delay definitive treatment.
- The standard starting dose of 0.1 mg/kg has been established to balance efficacy with safety.
*0.2 mg/kg*
- This dose is typically used as a **second dose** of adenosine if the initial 0.1 mg/kg dose is ineffective in converting PSVT.
- The second dose can be **doubled** (e.g., from 0.1 mg/kg to 0.2 mg/kg), with a maximum single dose of 12 mg.
*0.5 mg/kg*
- This dose is **too high** for the initial administration of adenosine in a pediatric patient and could lead to significant side effects like profound bradycardia or asystole.
- Gradual dose escalation is crucial to balance efficacy with safety in children.
*1.0 mg/kg*
- This dose is **excessively high** for pediatric adenosine administration and is not recommended as an initial or even subsequent dose.
- Such a dose would greatly increase the risk of adverse cardiovascular effects.
Question 4: A 2 year old child came with watery diarrhea. Electron Microscopy (EM) Image is shown here. Choose the correct pathogen.
A. Norwalk virus
B. Adenovirus
C. ECHO virus
D. Rota virus (Correct Answer)
E. Astrovirus
Explanation: ***Rota virus***
- The electron micrograph shows **double-layered viral particles** with a distinct wheel-like appearance, characteristic of **Rotavirus**, a major cause of severe watery diarrhea in young children.
- Rotavirus is the most common cause of **severe dehydrating diarrhea** in infants and young children worldwide.
*Norwalk virus*
- Norwalk virus (now commonly referred to as **Norovirus**) particles are typically **smaller** and have an **amorphous** or indistinct surface morphology compared to the clearly structured Rotavirus.
- Norovirus causes acute gastroenteritis but its electron microscopic appearance is less distinct and lacks the double-shelled structure seen here.
*Adenovirus*
- Adenoviruses are **larger, non-enveloped DNA viruses** with a distinct **icosahedral capsid** structure, often appearing hexagonal or pentagonal with prominent 'spikes' at the vertices.
- While adenoviruses can cause gastroenteritis, their EM appearance is easily distinguishable from the image provided.
*Astrovirus*
- Astroviruses are **small, non-enveloped RNA viruses** that appear as **smooth-surfaced, star-shaped particles** on electron microscopy (hence the name "astro").
- They cause gastroenteritis in young children but lack the characteristic double-layered wheel-like structure of rotavirus.
*ECHO virus*
- ECHO viruses (Enteric Cytopathic Human Orphan viruses) are **picornaviruses**, which are very **small, non-enveloped RNA viruses** with an icosahedral shape.
- Their EM image would show much smaller, less complex particles without the characteristic double-layered structure of rotavirus.
Question 5: An unimmunized 5 -year-old child presents to the OPD with a white membranous layer on the throat upon inspection. The child's brother is immunized. What is the first step in management?
A. Diphtheria antitoxin (Correct Answer)
B. Diphtheria toxoid
C. Penicillin
D. Isolation and supportive care
E. Tracheostomy
Explanation: ***Diphtheria antitoxin***
- The presence of a **white membranous layer** on the **throat** in an **unimmunized child**, along with the high contagiousness (brother's immunization is relevant to exposure), strongly suggests **diphtheria**.
- **Diphtheria antitoxin (DAT)** is the crucial first-line treatment to neutralize the **exotoxin** produced by *Corynebacterium diphtheriae*, which is responsible for the severe systemic effects.
- Antitoxin must be administered **immediately** without waiting for culture confirmation, as it only neutralizes unbound toxin.
*Diphtheria toxoid*
- **Diphtheria toxoid** is used for **active immunization** (vaccination) to prevent diphtheria, not for emergency treatment of an active infection.
- Administering toxoid during an acute infection would not rapidly neutralize the circulating toxin.
*Penicillin*
- **Penicillin** (or erythromycin) is used to **eradicate the bacteria** (*Corynebacterium diphtheriae*) from the patient's throat and prevent further toxin production and transmission.
- While important for source control, it does not neutralize the pre-formed toxin, which is the immediate threat to life.
- Antibiotics should be given **after** antitoxin administration.
*Isolation and supportive care*
- **Isolation** is essential to prevent transmission, but it does not treat the patient's infection.
- **Supportive care** is also crucial, but it addresses symptoms rather than the underlying cause or the effects of the toxin.
*Tracheostomy*
- **Tracheostomy** may be required later for airway obstruction if the membrane extends to the larynx or causes significant respiratory compromise.
- However, it is **not the first step** in management; securing airway patency comes after antitoxin administration unless there is immediate life-threatening airway obstruction.
- The priority is neutralizing the toxin to prevent further membrane formation and systemic complications.
Question 6: A 2-year-old male is brought to your office by his mother for evaluation. The patient develops a skin presentation similar to Image A on his cheeks and chin when exposed to certain food products. This patient is most likely predisposed to develop which of the following?
A. Fingernail pitting
B. Gluten hypersensitivity
C. Wheezing (Correct Answer)
D. Cyanosis
E. Arthralgias
Explanation: ***Wheezing***
- The skin presentation described (similar to Image A, on cheeks and chin, triggered by food products) is highly suggestive of **atopic dermatitis** or **eczema**.
- Individuals with atopic dermatitis are prone to developing other atopic conditions, collectively known as the **atopic march**, which includes **allergic asthma** (manifesting as wheezing) and **allergic rhinitis**.
*Fingernail pitting*
- **Fingernail pitting** is more characteristic of **psoriasis**, an autoimmune skin condition that is not directly linked to food-triggered eczema in this manner.
- While psoriasis can have an immune component, it is distinct from the **Type I hypersensitivity reaction** underlying atopic dermatitis.
*Gluten hypersensitivity*
- **Gluten hypersensitivity** (celiac disease) primarily affects the gastrointestinal tract and can present with various symptoms including skin manifestations (like **dermatitis herpetiformis**), but this is distinct from food-triggered eczema on the face.
- The skin lesions described are typical of eczema, not the specific papulovesicular rash of dermatitis herpetiformis.
*Cyanosis*
- **Cyanosis** is a bluish discoloration of the skin and mucous membranes due to inadequate oxygenation of the blood.
- It is typically caused by **cardiac or respiratory failure** and is not a direct predisposition or complication of food-triggered eczema.
*Arthralgias*
- **Arthralgias** (joint pain) can be associated with various inflammatory and autoimmune conditions, but it is not a common or direct complication of food-triggered eczema in young children.
- While systemic inflammation can occur, the primary predisposition for eczema patients is towards other atopic conditions.
Question 7: A 4-year-old boy who otherwise has no significant past medical history presents to the pediatric clinic accompanied by his father for a 2-day history of high fever, sore throat, nausea, vomiting, and bloody diarrhea. The patient’s father endorses that these symptoms began approximately 3 weeks after the family got a new dog. His father also states that several other children at the patient’s preschool have been sick with similar symptoms. He denies any other recent changes to his diet or lifestyle. The patient's blood pressure is 123/81 mm Hg, pulse is 91/min, respiratory rate is 15/min, and temperature is 39.2°C (102.5°F). Which of the following is the most likely cause for this patient’s presentation?
A. Exposure to bacteria at school (Correct Answer)
B. A recent antibiotic prescription
C. Reheated fried rice
D. The new dog
E. Failure to appropriately immunize the patient
Explanation: ***Exposure to bacteria at school***
- The combination of **bloody diarrhea**, high fever, vomiting, and **similar symptoms in other children at preschool** strongly suggests an outbreak of bacterial gastroenteritis, with **Shiga toxin-producing *E. coli* (STEC)** often implicated in such settings.
- This scenario points to a **common source of infection** within the preschool environment, facilitating person-to-person transmission or exposure to contaminated food/water.
*A recent antibiotic prescription*
- While antibiotics can cause diarrhea, especially **Clostridioides difficile (C. diff)**, the absence of prior antibiotic use in this patient weakens this possibility.
- Antibiotic-associated diarrhea typically does not spread to multiple children in a preschool unless there is a common source of toxin or organism.
*Reheated fried rice*
- **Reheated fried rice** is primarily associated with **Bacillus cereus** food poisoning, which typically causes rapid onset vomiting or diarrhea without a prolonged incubation period.
- This type of food poisoning is less likely to result in bloody diarrhea or widespread outbreaks in a preschool.
*The new dog*
- **Zoonotic infections** from dogs, such as **Campylobacter** or **Salmonella**, can cause similar symptoms but typically have a shorter incubation period than 3 weeks.
- The **widespread illness** at preschool makes exposure within the school a more likely primary cause for the outbreak.
*Failure to appropriately immunize the patient*
- While vaccinations prevent many infectious diseases, **no routine vaccine** specifically prevents the common bacterial causes of bloody diarrhea outbreaks in this age group, such as **Shiga toxin-producing *E. coli***.
- Immunization status is generally not directly linked to a sudden outbreak of infectious gastroenteritis of this specific type.
Question 8: A 4-year-old girl presents to a pediatrician for a scheduled follow-up visit. She was diagnosed with her first episode of acute otitis media 10 days ago and had been prescribed oral amoxicillin. Her clinical features at the time of the initial presentation included pain in the ear, fever, and nasal congestion. The tympanic membrane in the left ear was markedly red in color. Today, after completing 10 days of antibiotic therapy, her parents report that she is asymptomatic, except for mild fullness in the left ear. There is no history of chronic nasal obstruction or chronic/recurrent rhinosinusitis. On physical examination, the girl's vital signs are stable. Otoscopic examination of the left ear shows the presence of an air-fluid interface behind the translucent tympanic membrane and decreased mobility of the tympanic membrane. Which of the following is the next best step in the management of this patient?
A. Prescribe oral prednisolone for 7 days
B. Observation and regular follow-up (Correct Answer)
C. Prescribe oral antihistamine and decongestant for 7 days
D. Prescribe amoxicillin-clavulanate for 14 days
E. Continue oral amoxicillin for a total of 21 days
Explanation: ***Observation and regular follow-up***
- The presence of an **air-fluid interface** and **decreased tympanic membrane mobility** after a completed course of antibiotics for acute otitis media (AOM) suggests **otitis media with effusion (OME)**.
- In most cases, OME is **self-limiting** and resolves spontaneously within **3 months**, especially when the child is asymptomatic apart from mild ear fullness. Therefore, observation is the appropriate initial step.
*Prescribe oral prednisolone for 7 days*
- **Corticosteroids** are **not recommended** for the routine treatment of OME due to limited efficacy and potential side effects.
- While they might temporarily reduce inflammation, they do not significantly alter the long-term course of effusion resolution.
*Prescribe oral antihistamine and decongestant for 7 days*
- **Antihistamines and decongestants** have **not been shown to be effective** in resolving OME and are often associated with side effects in children.
- Their use is generally discouraged for this condition.
*Prescribe amoxicillin-clavulanate for 14 days*
- The patient has already completed a course of antibiotics and is largely asymptomatic, indicating the **resolution of the acute bacterial infection**.
- There is **no evidence of persistent bacterial infection**, and extending antibiotic therapy with a broader spectrum agent like amoxicillin-clavulanate is unnecessary and contributes to antibiotic resistance.
*Continue oral amoxicillin for a total of 21 days*
- Continuing antibiotics for **OME** (which is typically sterile) is **not effective** and does not improve the resolution rate of the effusion.
- The initial acute infection has resolved, and prolonged antibiotic exposure carries risks without benefit in this scenario.
Question 9: A 3-year-old girl is brought to the emergency room because of a 5-day history of high fever and fatigue. During this time she has been crying more than usual and eating less. Her mother says that the child has also complained about pain in her arms and legs for the past 3 days. She was born at term and has been otherwise healthy. She appears ill. Her temperature is 39.5°C (103.1°F), pulse is 128/min, and blood pressure is 96/52 mm Hg. The lungs are clear to auscultation. A grade 3/6 systolic murmur is heard at the apex. There is mild tenderness to palpation of the left upper quadrant with no guarding or rebound. The spleen is palpated 3 cm below the left costal margin. There is no redness or swelling of the joints. Laboratory studies show:
Hemoglobin 11.8 g/dL
Leukocyte count 16,300/mm3
Platelet count 220,000/mm3
Erythrocyte sedimentation rate 50 mm/h
Serum
Glucose 96 mg/dL
Creatinine 1.7 mg/dL
Total bilirubin 0.4 mg/dL
AST 18 U/L
ALT 20 U/L
Urine
Protein 2+
RBC casts rare
RBC 10/hpf
WBC 1–2/hpf
Which of the following is the most appropriate next step in management?
A. Obtain a transesophageal echocardiography
B. Administer intravenous vancomycin
C. Obtain a renal biopsy
D. Measure rheumatoid factors
E. Obtain 3 sets of blood cultures (Correct Answer)
Explanation: ***Obtain 3 sets of blood cultures***
- The patient presents with **fever, new murmur**, and **splenomegaly**, in addition to elevated ESR and proteinuria. These findings are highly suggestive of **infective endocarditis**, which requires urgent diagnosis via blood cultures.
- Blood cultures are essential to identify the causative organism for targeted antibiotic therapy and confirm the diagnosis of endocarditis.
*Obtain a transesophageal echocardiography*
- While echocardiography is crucial for diagnosing endocarditis, **blood cultures should be obtained first** to identify the pathogen before initiating empiric antibiotics.
- Transesophageal echocardiography (TEE) provides superior visualization of vegetations compared to transthoracic echo (TTE) but is usually performed after positive blood cultures or if TTE is inconclusive.
*Administer intravenous vancomycin*
- Administering antibiotics prior to obtaining blood cultures can **sterilize the blood**, making it difficult to identify the causative organism and select effective definitive treatment.
- Empiric antibiotic therapy, such as vancomycin, is typically initiated after blood cultures are drawn, especially if the patient is severely ill and infective endocarditis is highly suspected.
*Obtain a renal biopsy*
- The patient has elevated creatinine and proteinuria with RBC casts, suggesting **glomerulonephritis**, which can be a complication of infective endocarditis or other systemic diseases.
- However, a renal biopsy is an invasive procedure and generally not the initial step in management for a sick child with suspected endocarditis, as the primary concern is the cardiac infection.
*Measure rheumatoid factors*
- Rheumatoid factors are associated with **rheumatoid arthritis** and other autoimmune conditions, which do not fully explain the constellation of symptoms (fever, new murmur, splenomegaly, elevated ESR, renal involvement) seen in this patient.
- While some autoimmune conditions can cause similar symptoms, the acute presentation with fever and a new murmur points more strongly towards an infectious etiology like endocarditis.
Question 10: A 7-year-old boy is brought to his pediatrician for evaluation of a sore throat. The sore throat began 4 days ago and has progressively worsened. Associated symptoms include subjective fever, pain with swallowing, and fatigue. The patient denies any cough or rhinorrhea. Vital signs are as follows: T 38.6 C, HR 88, BP 115/67, RR 14, and SpO2 99%. Physical examination is significant for purulent tonsillar exudate; no cervical lymphadenopathy is noted. Which of the following is the best next step in the management of this patient?
A. Perform rapid antigen detection test (Correct Answer)
B. Recommend acetaminophen for symptomatic relief
C. Prescribe acyclovir
D. Perform throat culture
E. Prescribe 10-day course of penicillin
Explanation: ***Perform rapid antigen detection test***
- The patient presents with symptoms highly suggestive of **streptococcal pharyngitis** (sore throat, fever, purulent tonsillar exudates, absence of cough/rhinorrhea), making a rapid antigen detection test (RADT) the appropriate immediate diagnostic step.
- A positive RADT allows for prompt initiation of antibiotics, preventing complications like **acute rheumatic fever**.
*Recommend acetaminophen for symptomatic relief*
- While symptomatic relief is important, treating only symptoms without ruling out **Group A Streptococcus (GAS)** infection in a child with these clinical features can lead to serious complications.
- This approach delays specific treatment for bacterial infection which is crucial in preventing sequelae such as **acute rheumatic fever**.
*Prescribe acyclovir*
- Acyclovir is an antiviral medication used for herpes simplex virus infections, which typically present with **vesicular lesions** and ulcers, not purulent tonsillar exudates.
- The clinical picture provided is not consistent with a **viral etiology** requiring antiviral treatment.
*Perform throat culture*
- A throat culture is a **gold standard** for diagnosing strep throat, but it takes 24-48 hours for results.
- A **RADT** provides quicker results, allowing for earlier treatment and is sufficient for initial diagnosis, especially in areas with good sensitivity/specificity of RADT.
*Prescribe 10-day course of penicillin*
- Prescribing antibiotics without confirming a bacterial infection can contribute to **antibiotic resistance** and is not recommended as a first step.
- While penicillin would be the appropriate treatment if strep throat is confirmed, diagnosis should precede treatment to avoid unnecessary antibiotic use.
