A 5-year-old boy is brought to the emergency department for evaluation of a progressive rash that started 2 days ago. The rash began on the face and progressed to the trunk and extremities. Over the past week, he has had a runny nose, a cough, and red, crusty eyes. He immigrated with his family from Turkey 3 months ago. His father and his older brother have Behcet disease. Immunization records are unavailable. The patient appears irritable and cries during the examination. His temperature is 40.0°C (104°F). Examination shows general lymphadenopathy and dry mucous membranes. Skin turgor is decreased. There is a blanching, partially confluent erythematous maculopapular exanthema. Examination of the oral cavity shows small white spots with erythematous halos on the buccal mucosa. His hemoglobin concentration is 11.5 g/dL, leukocyte count is 6,000/mm3, and platelet count is 215,000/mm3. Serology confirms the diagnosis. Which of the following is the most appropriate next step in management?
Q172
A 3-year-old boy is brought to the emergency department with abdominal pain. His father tells the attending physician that his son has been experiencing severe stomach aches over the past week. They are intermittent in nature, but whenever they occur he cries and draws up his knees to his chest. This usually provides some relief. The parents have also observed mucousy stools and occasional bloody stools that are bright red with blood clots. They tell the physician that their child has never experienced this type of abdominal pain up to the present. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is up to date on all vaccines and is meeting all developmental milestones. On physical exam, his vitals are generally normal with a slight fever and mild tachycardia. The boy appears uncomfortable. An abdominal exam reveals a sausage-shaped mass in the right upper abdomen. Which of the following is the LEAST likely cause of these symptoms?
Q173
An 11-year-old girl is brought to the physician by her parents because of a mildly pruritic rash on her trunk and extremities for 2 days. One week ago, she developed a low-grade fever, rhinorrhea, and headache, followed by a facial rash 4 days later. The facial rash did not involve the perioral skin. Her temperature is 37.4°C (99.3°F). A photograph of the rash on her lower arms is shown. Which of the following is the most likely diagnosis?
Q174
A 4-year-old boy is brought to the clinic by his mother with fever and a rash. The patient’s mother says his symptoms started 1 week ago with the acute onset of fever and a runny nose, which resolved over the next 3 days. Then, 4 days later, she noted a rash on his face, which, after a day, spread to his neck, torso, and extremities. The patient denies any pruritus or pain associated with the rash. No recent history of sore throat, chills, or upper respiratory infection. The patient has no significant past medical history and takes no medications. The vital signs include: temperature 37.2°C (99.9°F) and pulse 88/min. On physical examination, there is a maculopapular rash on his face, torso, and extremities, which spares the palms and soles. The appearance of the rash is shown in the exhibit (see image below). Which of the following would most likely confirm the diagnosis in this patient?
Q175
A 7-year-old boy comes to the physician because of a generalized rash for 3 days. Over the past 5 days, he has also had a high fever and a sore throat. His 16-year-old sister was treated for infectious mononucleosis 2 weeks ago. He returned from a summer camp a week ago. His immunizations are up-to-date. Three years ago, he required intubation after an allergic reaction to dicloxacillin. The patient appears ill. His temperature is 38.2°C (100.8°F). Examination shows circumferential oral pallor. Cervical lymphadenopathy is present. There is tonsillar erythema and exudate. A confluent, blanching, punctate erythematous rash with a rough texture is spread over his trunk and extremities. His hemoglobin concentration is 13.3 g/dL, leukocyte count is 12,000/mm3, and erythrocyte sedimentation rate is 43 mm/h. Which of the following is the most appropriate next step in management?
Infectious Disease US Medical PG Practice Questions and MCQs
Question 171: A 5-year-old boy is brought to the emergency department for evaluation of a progressive rash that started 2 days ago. The rash began on the face and progressed to the trunk and extremities. Over the past week, he has had a runny nose, a cough, and red, crusty eyes. He immigrated with his family from Turkey 3 months ago. His father and his older brother have Behcet disease. Immunization records are unavailable. The patient appears irritable and cries during the examination. His temperature is 40.0°C (104°F). Examination shows general lymphadenopathy and dry mucous membranes. Skin turgor is decreased. There is a blanching, partially confluent erythematous maculopapular exanthema. Examination of the oral cavity shows small white spots with erythematous halos on the buccal mucosa. His hemoglobin concentration is 11.5 g/dL, leukocyte count is 6,000/mm3, and platelet count is 215,000/mm3. Serology confirms the diagnosis. Which of the following is the most appropriate next step in management?
A. Oral acyclovir
B. Oral penicillin V
C. Reassurance and follow-up in 3 days
D. Vitamin A supplementation (Correct Answer)
E. Intravenous immunoglobulin (IVIG)
Explanation: ***Vitamin A supplementation***
- The patient's symptoms (fever, rash, cough, conjunctivitis, oral ulcers, progressive rash starting on face) coupled with a history of recent immigration and unconfirmed immunization status are highly suggestive of **measles**.
- **Vitamin A supplementation** is recommended for all children with measles, especially in settings with a high prevalence of vitamin A deficiency or in patients with complicated measles, as it reduces morbidity and mortality.
*Oral acyclovir*
- **Acyclovir** is an antiviral medication used primarily for **herpes simplex virus (HSV)** or **varicella-zoster virus (VZV)** infections.
- The clinical presentation with a **maculopapular rash** and lack of vesicular lesions makes HSV or VZV unlikely.
*Oral penicillin V*
- **Penicillin V** is an antibiotic used to treat bacterial infections, such as streptococcal pharyngitis.
- The patient's symptoms are consistent with a viral illness (**measles**), making antibiotic treatment inappropriate.
*Reassurance and follow-up in 3 days*
- Given the high fever, dehydration, irritability, and the potential for serious complications of **measles** (e.g., pneumonia, encephalitis), simple reassurance and delayed follow-up are insufficient.
- The patient requires immediate medical intervention and supportive care.
*Intravenous immunoglobulin (IVIG)*
- **IVIG** is used for certain severe infections or autoimmune conditions, or to provide passive immunity (e.g., post-exposure prophylaxis for measles in susceptible high-risk individuals).
- While IVIG might be considered for measles post-exposure prophylaxis in unimmunized, immunocompromised individuals, it is not the primary treatment for active measles infection, nor is it a standard supportive measure like Vitamin A.
Question 172: A 3-year-old boy is brought to the emergency department with abdominal pain. His father tells the attending physician that his son has been experiencing severe stomach aches over the past week. They are intermittent in nature, but whenever they occur he cries and draws up his knees to his chest. This usually provides some relief. The parents have also observed mucousy stools and occasional bloody stools that are bright red with blood clots. They tell the physician that their child has never experienced this type of abdominal pain up to the present. The boy was born at 39 weeks gestation via spontaneous vaginal delivery. He is up to date on all vaccines and is meeting all developmental milestones. On physical exam, his vitals are generally normal with a slight fever and mild tachycardia. The boy appears uncomfortable. An abdominal exam reveals a sausage-shaped mass in the right upper abdomen. Which of the following is the LEAST likely cause of these symptoms?
A. Henoch-Schonlein purpura (Correct Answer)
B. Meckel's diverticulum
C. Enlarged mesenteric lymph node
D. Gastrointestinal infection
E. Idiopathic
Explanation: ***Henoch-Schonlein purpura***
- While Henoch-Schonlein purpura (HSP) can cause **abdominal pain** and **gastrointestinal bleeding**, it is primarily characterized by a **palpable purpuric rash**, renal involvement, and arthritis, which are not described in the classic presentation of **intussusception** in this child.
- The classic presentation of intense, episodic abdominal pain with **currant jelly stools** and a **sausage-shaped abdominal mass** is highly indicative of intussusception, which is less directly associated with HSP as a primary cause compared to other etiologies.
*Meckel's diverticulum*
- A Meckel's diverticulum containing **ectopic gastric or pancreatic tissue** can be a **lead point for intussusception** and can also cause **painless rectal bleeding**, although the pain described here is severe and intermittent.
- While it can be a cause of bleeding, the presence of a **sausage-shaped mass** and intermittent, colicky pain with knee-chest posturing points more specifically to intussusception, where Meckel's could be the lead point.
*Enlarged mesenteric lymph node*
- **Enlarged mesenteric lymph nodes**, often following a **viral infection**, are a common **lead point for intussusception** in children.
- They can serve as a physical obstruction that initiates the telescoping of the bowel, consistent with the described symptoms of acute, severe abdominal pain and a palpable mass.
*Gastrointestinal infection*
- **Gastrointestinal infections** can lead to **mesenteric adenitis** (enlarged mesenteric lymph nodes) due to lymphoid hyperplasia, which can then act as a **lead point for intussusception**.
- The systemic symptoms such as a slight fever and mild tachycardia could also be consistent with an infectious process preceding intussusception.
*Idiopathic*
- A significant proportion of intussusception cases, particularly in younger children, are considered **idiopathic**, meaning no clear lead point is identified.
- This diagnosis reflects the common presentation where the bowel telescopes without an obvious anatomical anomaly, aligning with the general profile of the described symptoms.
Question 173: An 11-year-old girl is brought to the physician by her parents because of a mildly pruritic rash on her trunk and extremities for 2 days. One week ago, she developed a low-grade fever, rhinorrhea, and headache, followed by a facial rash 4 days later. The facial rash did not involve the perioral skin. Her temperature is 37.4°C (99.3°F). A photograph of the rash on her lower arms is shown. Which of the following is the most likely diagnosis?
A. Exanthem subitum
B. Hand, foot, and mouth disease
C. Scarlet fever
D. Erythema infectiosum (Correct Answer)
E. Rubella
Explanation: ***Erythema infectiosum***
- The combination of a prodromal illness (low-grade fever, rhinorrhea, headache) followed by a **facial rash that spares the perioral skin** (classically described as "slapped cheek" appearance) and a subsequent **body rash** (lacy, reticular pattern on the trunk and extremities) is pathognomonic for **erythema infectiosum**, caused by **Parvovirus B19**.
- The description of a **mildly pruritic rash on the trunk and extremities** appearing after the facial rash is consistent with the typical progression of the rash in erythema infectiosum.
*Exanthem subitum*
- Characterized by a **high fever** (often >39.5°C) for several days, followed by the sudden appearance of a **rose-pink maculopapular rash** once the fever breaks.
- The rash in exanthem subitum typically starts on the trunk and spreads outwards, and there is no characteristic "slapped cheek" facial rash.
*Hand, foot, and mouth disease*
- Presents with fever, malaise, sore throat, and a characteristic **vesicular rash on the hands, feet, and oral mucosa**.
- The rash described in the patient does not match the typical presentation or distribution of hand, foot, and mouth disease.
*Scarlet fever*
- Caused by **Group A Streptococcus** and typically presents with a **fine, sandpaper-like rash** that starts on the neck and chest and spreads to the trunk and extremities, often with circumoral pallor and a "strawberry tongue."
- The described rash pattern and facial involvement are not consistent with scarlet fever.
*Rubella*
- Features include a maculopapular rash that starts on the face and spreads rapidly downwards, and may be accompanied by **postauricular and occipital lymphadenopathy**.
- While it involves a facial rash, the characteristic "slapped cheek" appearance and the specific reticular body rash are not typical for rubella.
Question 174: A 4-year-old boy is brought to the clinic by his mother with fever and a rash. The patient’s mother says his symptoms started 1 week ago with the acute onset of fever and a runny nose, which resolved over the next 3 days. Then, 4 days later, she noted a rash on his face, which, after a day, spread to his neck, torso, and extremities. The patient denies any pruritus or pain associated with the rash. No recent history of sore throat, chills, or upper respiratory infection. The patient has no significant past medical history and takes no medications. The vital signs include: temperature 37.2°C (99.9°F) and pulse 88/min. On physical examination, there is a maculopapular rash on his face, torso, and extremities, which spares the palms and soles. The appearance of the rash is shown in the exhibit (see image below). Which of the following would most likely confirm the diagnosis in this patient?
A. Assay for IgM and IgG against measles virus
B. Serology for human herpesvirus-6 IgM antibodies
C. Throat culture
D. ELISA for parvovirus B-19 IgM and IgG antibodies (Correct Answer)
E. ELISA for IgM antibodies against Rubella virus
Explanation: ***ELISA for parvovirus B-19 IgM and IgG antibodies***
- The presentation of a child with a prodrome of fever and runny nose followed a few days later by a **maculopapular rash** that started on the face and spread to the torso and extremities, sparing the palms and soles, is highly suggestive of **Erythema Infectiosum** (Fifth Disease) caused by **Parvovirus B19**.
- An **ELISA for parvovirus B-19 IgM antibodies**, indicating a recent infection, would confirm the diagnosis, with IgG antibodies suggesting past exposure and immunity.
*Assay for IgM and IgG against measles virus*
- Measles (Rubeola) typically presents with a prodrome of **cough, coryza, conjunctivitis, and Koplik spots** before the rash appears, which are not described in this patient.
- The rash of measles is usually **more confluent** and starts behind the ears, spreading downwards, and is often accompanied by a higher fever.
*Serology for human herpesvirus-6 IgM antibodies*
- Human herpesvirus-6 (HHV-6) causes **Roseola Infantum** (Sixth Disease), which is characterized by a **high fever** for 3-5 days that resolves abruptly, followed by the appearance of a **rose-colored maculopapular rash** on the trunk that spreads to the extremities.
- Though there is a rash after fever, the rash in this patient started on the face and the fever was mild, which is atypical for Roseola.
*ELISA for IgG antibodies against Rubella virus*
- A positive IgM antibody test would suggest an acute infection with Rubella (German Measles), which presents with a rash that often starts on the face and spreads downwards, similar to this case.
- However, Rubella is typically associated with **posterior auricular and suboccipital lymphadenopathy**, which is not mentioned in the patient's history or physical exam.
*Throat culture*
- A throat culture is primarily used to diagnose **bacterial infections** like Streptococcus pyogenes (strep throat), which can cause a rash such as scarlet fever.
- The rash of scarlet fever characteristically feels like sandpaper and is associated with a "strawberry tongue" and perioral pallor, which are not seen here.
Question 175: A 7-year-old boy comes to the physician because of a generalized rash for 3 days. Over the past 5 days, he has also had a high fever and a sore throat. His 16-year-old sister was treated for infectious mononucleosis 2 weeks ago. He returned from a summer camp a week ago. His immunizations are up-to-date. Three years ago, he required intubation after an allergic reaction to dicloxacillin. The patient appears ill. His temperature is 38.2°C (100.8°F). Examination shows circumferential oral pallor. Cervical lymphadenopathy is present. There is tonsillar erythema and exudate. A confluent, blanching, punctate erythematous rash with a rough texture is spread over his trunk and extremities. His hemoglobin concentration is 13.3 g/dL, leukocyte count is 12,000/mm3, and erythrocyte sedimentation rate is 43 mm/h. Which of the following is the most appropriate next step in management?
A. Amoxicillin therapy
B. Doxycycline therapy
C. Azithromycin therapy (Correct Answer)
D. Cephalexin therapy
E. Acyclovir therapy
Explanation: ***Azithromycin therapy***
- This patient presents with symptoms highly suggestive of **streptococcal pharyngitis** (sore throat, fever, tonsillar exudates, cervical lymphadenopathy) complicated by **scarlet fever** (confluent, blanching, punctate erythematous rash with a rough texture, circumferential oral pallor).
- Given his **history of severe allergic reaction (intubation) to dicloxacillin**, a penicillin-class antibiotic, azithromycin (a macrolide) is the appropriate choice for treating **Group A Streptococcus** (GAS) infection in a penicillin-allergic patient.
*Amoxicillin therapy*
- **Amoxicillin** is a penicillin-class antibiotic and is **contraindicated** due to the patient's severe allergic reaction (intubation) to dicloxacillin, another penicillin.
- Cross-reactivity between penicillins, especially in severe allergic reactions, is a significant concern, making this an unsafe choice.
*Doxycycline therapy*
- **Doxycycline**, a tetracycline, is not a first-line treatment for **streptococcal pharyngitis** and is primarily used for atypical bacterial infections or in specific cases of penicillin allergy where other agents are not suitable.
- While it has some activity against GAS, macrolides like azithromycin are preferred alternatives for penicillin-allergic patients.
*Cephalexin therapy*
- **Cephalexin** is a first-generation cephalosporin, and while it can be used for GAS, roughly 5-10% of patients with a penicillin allergy may have a **cross-reaction** to cephalosporins, especially with a history of severe reactions.
- Therefore, it is generally avoided in patients with a history of anaphylaxis or other severe reactions to penicillin.
*Acyclovir therapy*
- **Acyclovir** is an antiviral medication used to treat herpes simplex and varicella-zoster virus infections.
- The patient's symptoms (pharyngitis, rash consistent with scarlet fever) are indicative of a **bacterial infection (GAS)**, not a viral infection that would respond to acyclovir.
