Infectious Disease

Infectious Disease US Medical PG Question 1: An 18-month-old boy presents to the emergency department for malaise. The boy’s parents report worsening fatigue for 3 days with associated irritability and anorexia. The patient’s newborn screening revealed a point mutation in the beta-globin gene but the patient has otherwise been healthy since birth. On physical exam, his temperature is 102.4°F (39.1°C), blood pressure is 78/42 mmHg, pulse is 124/min, and respirations are 32/min. The child is tired-appearing and difficult to soothe. Laboratory testing is performed and reveals the following: Serum: Na+: 137 mEq/L Cl-: 100 mEq/L K+: 4.4 mEq/L HCO3-: 24 mEq/L Urea nitrogen: 16 mg/dL Creatinine: 0.9 mg/dL Glucose: 96 mg/dL Leukocyte count: 19,300/mm^3 with normal differential Hemoglobin: 7.8 g/dL Hematocrit: 21% Mean corpuscular volume: 82 um^3 Platelet count: 324,000/mm^3 Reticulocyte index: 3.6% Which of the following is the most likely causative organism for this patient's presentation?

• A. Streptococcus pneumoniae (Correct Answer)
• B. Listeria monocytogenes
• C. Haemophilus influenzae
• D. Neisseria meningitidis
• E. Salmonella

Infectious Disease Explanation: ***Streptococcus pneumoniae*** - Patients with **sickle cell disease** (indicated by the beta-globin gene mutation) are functionally **asplenic** and highly susceptible to encapsulated bacteria, with *S. pneumoniae* being the most common cause of **sepsis** in this population. - The patient's presentation with **fever**, **hypotension**, **tachycardia**, and **leukocytosis** is consistent with **sepsis**, and the elevated reticulocyte index suggests a hemolytic process or bone marrow response, common in sickle cell crises exacerbated by infection. *Listeria monocytogenes* - This pathogen primarily affects **neonates**, **immunocompromised individuals**, and **elderly** patients, often presenting as meningitis or sepsis. - While it can cause sepsis, it is a less common cause of severe infection in a non-neonatal toddler with sickle cell disease compared to *S. pneumoniae*. *Haemophilus influenzae* - Although *H. influenzae* is an encapsulated bacterium that can cause severe infections in functionally asplenic patients, routine childhood vaccinations have significantly reduced its incidence. - While possible, it is less likely than *S. pneumoniae* in an 18-month-old, especially if vaccinated, and *S. pneumoniae* remains the leading cause of sepsis in sickle cell patients. *Neisseria meningitidis* - *N. meningitidis* is another encapsulated bacterium that can cause serious infections, including **meningitis** and **sepsis**, particularly in immunocompromised individuals like those with sickle cell disease. - However, the incidence of **meningococcal disease** is generally lower than **pneumococcal disease** in this age group, and the absence of classic meningeal signs or petechial rash makes it a less probable primary suspect compared to *S. pneumoniae*. *Salmonella* - *Salmonella* species can cause **osteomyelitis** and **sepsis** in patients with sickle cell disease, often presenting with gastrointestinal symptoms. - While a known pathogen in this population, the clinical picture of **rapidly progressive sepsis** without clear GI focus makes *S. pneumoniae* a more immediate and common concern.

Infectious Disease US Medical PG Question 2: A 13-month-old boy is referred to an immunologist with recurrent otitis media, bacterial sinus infections, and pneumonia, which began several months earlier. He is healthy now, but the recurrent nature of these infections are troubling to his parents and they are hoping to find a definitive cause. 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. The patient has five older siblings, but none of them had similar recurrent illnesses. Clinical pathology results suggest very low levels of serum immunoglobulin. As you discuss options for diagnosis with the patient’s family, which of the following tests should be performed next?

• A. CSF gram staining
• B. Urine protein screening
• C. Stool cultures
• D. Flow cytometry (Correct Answer)
• E. Genetic analysis

Infectious Disease Explanation: ***Flow cytometry*** - Flow cytometry is essential for evaluating **lymphocyte subsets** (B cells, T cells, NK cells) and their maturation, which is crucial for diagnosing **primary immunodeficiencies** like X-linked agammaglobulinemia (XLA). - Given the history of recurrent bacterial infections and **very low serum immunoglobulin levels**, assessing B cell numbers and T cell populations would directly help identify defects in humoral immunity. *CSF gram staining* - **CSF gram staining** is used to diagnose **bacterial meningitis** at the time of an active infection. - The patient is currently healthy, and the test would not identify the underlying cause of recurrent infections or low immunoglobulin levels. *Urine protein screening* - **Urine protein screening** is used to detect **kidney disease** or other conditions causing proteinuria. - It is not relevant to investigating recurrent bacterial infections or low serum immunoglobulin levels, which point towards an immune system defect. *Stool cultures* - **Stool cultures** are performed to identify **gastrointestinal infections** (e.g., bacterial, parasitic). - While infections can occur in immunodeficient patients, this test is not a primary diagnostic tool for the underlying **immunodeficiency** causing recurrent otitis media, sinus infections, and pneumonia. *Genetic analysis* - **Genetic analysis** can confirm certain **primary immunodeficiency diagnoses** once specific defects are suspected (e.g., mutations in *BTK* for XLA). - However, flow cytometry is typically the next step to broadly characterize the immune cell populations and narrowed down differential diagnoses before proceeding with targeted genetic testing.

Infectious Disease US Medical PG Question 3: A 12-month-old girl is brought to her pediatrician for a checkup and vaccines. The patient’s mother wants to send her to daycare but is worried about exposure to unvaccinated children and other potential sources of infection. The toddler was born at 39 weeks gestation via spontaneous vaginal delivery. She is up to date on all vaccines. She does not walk yet but stands in place and can say a few words. The toddler drinks formula and eats a mixture of soft vegetables and pureed meals. She has no current medications. On physical exam, the vital signs include: temperature 37.0°C (98.6°F), blood pressure 95/50 mm Hg, pulse 130/min, and respiratory rate 28/min. The patient is alert and responsive. The remainder of the exam is unremarkable. Which of the following is most appropriate for this patient at this visit?

• A. Meningococcal vaccine
• B. Gross motor workup and evaluation
• C. Rotavirus vaccine
• D. Referral for speech pathology
• E. MMR vaccine (Correct Answer)

Infectious Disease Explanation: ***MMR vaccine*** - The **measles, mumps, and rubella (MMR) vaccine** is recommended for administration at **12-15 months of age**. - This timing offers protection against these common childhood diseases, which is especially important for children attending **daycare**. *Meningococcal vaccine* - The routine **meningococcal vaccine (MenACWY)** is typically recommended for adolescents at **11-12 years of age**, with a booster at 16 years. - While there are specific circumstances for earlier vaccination (e.g., high-risk conditions), it is **not routine** for a 12-month-old. *Gross motor workup and evaluation* - The patient's motor development, standing in place but not yet walking, is **within the normal range** for a 12-month-old. - A definitive **gross motor workup** would generally be considered if there were more significant delays or regressions. *Rotavirus vaccine* - The **rotavirus vaccine** series is typically given at **2, 4, and 6 months of age**, with the final dose administered no later than **8 months of age**. - A 12-month-old is **outside the recommended age range** for initiating or completing this vaccine series. *Referral for speech pathology* - Saying "a few words" at 12 months is **within the normal developmental milestone** for expressive language at this age. - A referral for **speech pathology** would generally be indicated for more significant language delays.

Infectious Disease US Medical PG Question 4: A father brings his 3-year-old son to the pediatrician because he is concerned about his health. He states that throughout his son's life he has had recurrent infections despite proper treatment and hygiene. Upon reviewing the patient's chart, the pediatrician notices that the child has been infected multiple times with S. aureus, Aspergillus, and E. coli. Which of the following would confirm the most likely cause of this patient's symptoms?

• A. Increased IgM, Decreased IgG, IgA, and IgE
• B. Negative nitroblue-tetrazolium test (Correct Answer)
• C. Positive nitroblue-tetrazolium test
• D. Normal dihydrorhodamine (DHR) flow cytometry test
• E. Increased IgE and IgA, Decreased IgM

Infectious Disease Explanation: ***Negative nitroblue-tetrazolium test*** - A **negative nitroblue-tetrazolium (NBT) test** indicates an inability of phagocytes to produce a respiratory burst, which is characteristic of **Chronic Granulomatous Disease (CGD)**. - CGD patients suffer from recurrent infections with catalase-positive organisms such as *Staphylococcus aureus*, *Aspergillus*, and *E. coli*, consistent with the patient's history. *Increased IgM, Decreased IgG, IgA, and IgE* - This pattern of immunoglobulin levels is characteristic of **X-linked hyper-IgM syndrome**, where there is a defect in CD40L on T cells. - While it also causes recurrent infections, the typical pathogens differ from those stated in the question, often including *Pneumocystis jirovecii*. *Positive nitroblue-tetrazolium test* - A **positive NBT test** indicates that phagocytes are capable of producing a respiratory burst and forming superoxide, thus ruling out CGD. - This result would be expected in a healthy individual or someone with an immunodeficiency not affecting the phagocytic oxidative burst. *Normal dihydrorhodamine (DHR) flow cytometry test* - A **normal DHR flow cytometry test** indicates that neutrophils can produce reactive oxygen species (ROS) effectively, meaning the respiratory burst is intact. - This result would rule out CGD, as CGD patients have an abnormal (decreased) DHR test. *Increased IgE and IgA, Decreased IgM* - This specific pattern of immunoglobulin abnormalities is not typically associated with a single, well-defined primary immunodeficiency that would present with the described infections. - **Hyper-IgE syndrome (Job's syndrome)**, for example, features very high IgE levels but usually a normal IgM.

Infectious Disease US Medical PG Question 5: You are treating a neonate with meningitis using ampicillin and a second antibiotic, X, that is known to cause ototoxicity. What is the mechanism of antibiotic X?

• A. It binds the 50S ribosomal subunit and inhibits formation of the initiation complex
• B. It binds the 30S ribosomal subunit and inhibits formation of the initiation complex (Correct Answer)
• C. It binds the 30S ribosomal subunit and reversibly inhibits translocation
• D. It binds the 50S ribosomal subunit and inhibits peptidyltransferase
• E. It binds the 50S ribosomal subunit and reversibly inhibits translocation

Infectious Disease Explanation: ***It binds the 30s ribosomal subunit and inhibits formation of the initiation complex*** - The second antibiotic, X, is likely an **aminoglycoside**, such as **gentamicin** or **amikacin**, which are commonly used in combination with ampicillin for neonatal meningitis and are known to cause ototoxicity. - Aminoglycosides exert their bactericidal effect by **irreversibly binding to the 30S ribosomal subunit**, thereby **inhibiting the formation of the initiation complex** and leading to misreading of mRNA. *It binds the 50S ribosomal subunit and inhibits formation of the initiation complex* - This mechanism is characteristic of **linezolid**, which targets the 50S ribosomal subunit to prevent the formation of the initiation complex. - While linezolid can cause side effects, **ototoxicity** is less commonly associated with it compared to aminoglycosides, and it is not a primary drug for neonatal meningitis alongside ampicillin. *It binds the 50S ribosomal subunit and inhibits peptidyltransferase* - This is the mechanism of action for **chloramphenicol**, which inhibits **peptidyltransferase** activity on the 50S ribosomal subunit, preventing peptide bond formation. - Although chloramphenicol can cause **ototoxicity** and **aplastic anemia**, its use in neonates is limited due to the risk of **Gray Baby Syndrome**. *It binds the 30s ribosomal subunit and reversibly inhibits translocation* - This describes the mechanism of action of **tetracyclines**, which reversibly bind to the 30S ribosomal subunit and prevent the attachment of aminoacyl-tRNA, thereby inhibiting protein synthesis. - Tetracyclines are **contraindicated in neonates** due to their potential to cause **tooth discoloration** and **bone growth inhibition**, and ototoxicity is not their primary adverse effect. *It binds the 50s ribosomal subunit and reversibly inhibits translocation* - This mechanism of reversibly inhibiting translocation by binding to the 50S ribosomal subunit is characteristic of **macrolides** (e.g., erythromycin, azithromycin) and **clindamycin**. - While some macrolides can cause **transient ototoxicity**, they are not typically the second antibiotic of choice for neonatal meningitis in combination with ampicillin, and clindamycin's side effect profile is different.

Infectious Disease US Medical PG Question 6: You are seeing a 4-year-old boy in clinic who is presenting with concern for a primary immune deficiency. He has an unremarkable birth history, but since the age of 6 months he has had recurrent otitis media, bacterial pneumonia, as well as two episodes of sinusitis, and four episodes of conjunctivitis. He has a maternal uncle who died from sepsis secondary to H. influenza pneumonia. If you drew blood work for diagnostic testing, which of the following would you expect to find?

• A. Abnormally low number of T cells
• B. Abnormally high number of B cells
• C. Elevated immunoglobulin levels
• D. Abnormally low number of B cells (Correct Answer)
• E. Abnormally high number of T cells

Infectious Disease Explanation: ***Abnormally low number of B cells*** - The recurrent bacterial infections (otitis media, pneumonia, sinusitis, conjunctivitis) and the family history of death from *H. influenza* pneumonia suggest a **primary B-cell immunodeficiency**, such as **X-linked agammaglobulinemia (XLA)**. - In XLA, there is a block in B-cell development, leading to a profound absence of mature B cells and immunoglobulins. *Abnormally low number of T cells* - This would point towards a **T-cell immunodeficiency** or a **combined immunodeficiency**, typically presenting with opportunistic infections, viral, or fungal infections, rather than predominantly bacterial infections. - Examples include **Severe Combined Immunodeficiency (SCID)**, which often presents earlier and more severely. *Abnormally high number of B cells* - This is not characteristic of a primary immunodeficiency with recurrent bacterial infections; rather, it might be seen in certain autoimmune conditions or lymphoproliferative disorders. - **High B cell counts** generally imply a functioning humoral immune system, which contradicts the infectious history. *Elevated immunoglobulin levels* - This finding would generally indicate a **functioning humoral immune response**, possibly due to chronic infection or an inflammatory process, but not a primary B-cell immunodeficiency causing recurrent bacterial infections. - In conditions like **Common Variable Immunodeficiency (CVID)**, some immunoglobulin levels might be normal, but often key classes (like IgG, IgA, or IgM) are low. *Abnormally high number of T cells* - This finding is generally not associated with the pattern of recurrent bacterial infections described, which strongly points to a **humoral (antibody) deficiency**. - **Elevated T cells** could be seen in some autoimmune conditions or certain viral infections, but not typically in a primary immunodeficiency characterized by recurrent bacterial infections.

Infectious Disease US Medical PG Question 7: A 4-year-old boy is brought to the emergency department by his parents. He is lethargic and confused and has a severe headache, vomiting, and a high-grade fever since earlier that day. His mother reports that the child was doing well until 2 days ago when he developed a fever and green nasal discharge. The patient has a history of neonatal sepsis, meningococcemia at 18 months of age, and pneumococcal pneumonia at 2 and 3 years of age. His scheduled vaccinations are up to date. His blood pressure is 70/50 mm Hg, heart rate is 120/min, respiratory rate is 22/min, and temperature is 39.3°C (102.4°F). On examination, the child is lethargic and his skin is pale, with several petechiae over his buttocks. There is a purulent nasal discharge from both nostrils. The lungs are clear to auscultation bilaterally. Heart sounds are normal. There is marked neck rigidity. Cerebrospinal fluid analysis shows the following results: Opening pressure 100 mm H2O Appearance cloudy Protein 500 mg/dL (5 g/L) White blood cells 2500/μL (polymorphonuclear predominance) Glucose 31 mg/dL (1.7 mmol/L) Culture positive for N. meningitidis Which of the following immunological processes is most likely to be impaired in this child?

• A. Formation of C5-9 complex (Correct Answer)
• B. Production of IL-2 by Th1 cells
• C. Oxidative burst in macrophages
• D. Activation of TCRs by MHC-II
• E. Cleavage of C2 component of complement into C2a and C2b

Infectious Disease Explanation: ***Formation of C5-9 complex*** - The recurrent infections with **encapsulated bacteria** like *N. meningitidis* and *S. pneumoniae*, along with recurrent **meningococcemia**, strongly suggest a deficiency in the **terminal complement pathway (C5-C9)**, which is crucial for forming the **membrane attack complex (MAC)**. - The MAC is essential for **lysing gram-negative bacteria** such as *N. meningitidis*, and a defect here increases susceptibility to recurrent infections by this pathogen. *Production of IL-2 by Th1 cells* - **Interleukin-2 (IL-2)** is vital for **T-cell proliferation** and differentiation, particularly of **cytotoxic T lymphocytes (CTLs)**, important for viral and intracellular bacterial infections. - While important for overall immune function, a deficiency in IL-2 production does not specifically or primarily explain recurrent encapsulated bacterial infections and meningococcemia. *Oxidative burst in macrophages* - The **oxidative burst** is critical for phagocytic cells (neutrophils and macrophages) to kill ingested pathogens, especially **catalase-positive bacteria** and fungi. - A defect here (e.g., in **chronic granulomatous disease**) leads to recurrent severe bacterial and fungal infections, typically forming granulomas, which is not the specific pattern observed with recurrent meningococcal disease. *Activation of TCRs by MHC-II* - **T-cell receptor (TCR)** activation by **MHC-II** is central to **CD4+ helper T cell** function, essential for coordinating immune responses and antibody production. - While critical for adaptive immunity, a defect here would lead to broader immune deficiencies, including impaired antibody responses and susceptibility to various pathogens, but does not preferentially predispose to recurrent *N. meningitidis* infections like terminal complement deficiency. *Cleavage of C2 component of complement into C2a and C2b* - The cleavage of **C2** is part of the **classical and lectin complement pathways**, which are important for opsonization and inflammation. - **C2 deficiency** is often associated with recurrent pyogenic infections and autoimmune diseases (e.g., SLE), but not specifically with recurrent infections by *N. meningitidis*, which is more characteristic of **terminal complement component deficiencies**.

Infectious Disease US Medical PG Question 8: A 10-year-old boy is brought to the emergency department by his parents because of a dull persistent headache beginning that morning. He has nausea and has vomited twice. During the past four days, the patient has had left-sided ear pain and fever, but his parents did not seek medical attention. He is from Thailand and is visiting his relatives in the United States for the summer. There is no personal or family history of serious illness. He is at the 45th percentile for height and 40th percentile for weight. He appears irritable. His temperature is 38.5°C (101.3°F), pulse is 110/min, and blood pressure is 98/58 mm Hg. The pupils are equal and reactive to light. Lateral gaze of the left eye is limited. The left tympanic membrane is erythematous with purulent discharge. There is no nuchal rigidity. Which of the following is the most appropriate next step in management?

• A. Intravenous ceftriaxone and clindamycin therapy
• B. Lumbar puncture
• C. MRI of the brain (Correct Answer)
• D. Intravenous cefazolin and metronidazole therapy
• E. Cranial burr hole evacuation

Infectious Disease Explanation: ***MRI of the brain*** - The patient's presentation with **headache**, **nausea**, **vomiting**, recent **ear infection** (otitis media), **fever**, and **abducens nerve palsy** (limited lateral gaze of the left eye) is highly suggestive of an intracranial complication, such as a **brain abscess** or **epidural abscess**, secondary to the uncontrolled otitis media. - An MRI of the brain is the **most sensitive and specific imaging modality** for detecting intracranial abscesses, which are critical to diagnose promptly due to their potential for surgical drainage and targeted antibiotic therapy. *Intravenous ceftriaxone and clindamycin therapy* - While broad-spectrum antibiotics are necessary, they should be initiated **after establishing a definitive diagnosis and ruling out conditions requiring immediate surgical intervention**. - Without imaging, there's a risk of delaying crucial surgical management for a contained abscess or empyema. *Lumbar puncture* - A lumbar puncture is **contraindicated** in the presence of focal neurological deficits (like **abducens nerve palsy**) and symptoms of **increased intracranial pressure** (headache, nausea, vomiting), as it carries a significant risk of **herniation** if there's a mass lesion. - Imaging should always precede LP in such cases. *Intravenous cefazolin and metronidazole therapy* - Cefazolin has **poor penetration into the CNS**, making it an inadequate choice for suspected intracranial infection. - While metronidazole targets anaerobes common in brain abscesses, the overall regimen is not optimal, and imaging is still the priority. *Cranial burr hole evacuation* - This is a definitive surgical treatment for a brain abscess but should only be performed **after the abscess has been localized and characterized by imaging**. - Performing a burr hole without prior imaging would be a blind procedure and is not the appropriate next step in diagnosis and management.

Infectious Disease US Medical PG Question 9: A 6-year-old girl is brought to the clinic for evaluation of malaise and low-grade fever over the past 3 days. In the last 24 hours, she developed sores and pain in her mouth. She also had vesicles on her hands and feet. Her past medical history was benign and the immunization history was up-to-date. The oral temperature was 38.1°C (100.6°F). The physical examination revealed several erythematous macules in the oropharynx and small oval vesicles with an erythematous base on the palms. What is the next best step in the management of this patient?

• A. Supportive care (Correct Answer)
• B. Corticosteroids
• C. Penicillin
• D. Ribavirin
• E. Aspirin

Infectious Disease Explanation: ***Supportive care*** - This presentation is consistent with **hand-foot-and-mouth disease (HFMD)**, a common viral illness caused by **Coxsackievirus** or **Enterovirus 71**. - HFMD is typically **self-limiting**, and management focuses on **symptomatic relief** with antipyretics, analgesics, and hydration. *Corticosteroids* - Corticosteroids are generally **contraindicated** in uncomplicated viral infections like HFMD, as they can **suppress the immune response** and potentially prolong the illness or lead to secondary infections. - They are primarily used for inflammatory conditions or severe allergic reactions. *Penicillin* - Penicillin is an **antibiotic** and is ineffective against viral infections such as HFMD. - Using antibiotics inappropriately can contribute to **antibiotic resistance** and may cause adverse effects. *Ribavirin* - Ribavirin is an **antiviral agent** used for specific viral infections like **Hepatitis C** and **RSV**. - It is **not indicated** for the treatment of HFMD, as HFMD is typically mild and self-resolving. *Aspirin* - Aspirin is generally **contraindicated in children** due to the risk of **Reye's syndrome**, especially after viral infections. - While it has antipyretic and analgesic properties, safer alternatives like acetaminophen or ibuprofen are preferred for fever and pain in children.

Infectious Disease US Medical PG Question 10: 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)

Infectious Disease 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.

Infectious Disease Flashcard 1 of 9

Question: Which RNA virus presents with rash of 3-days duration?_____

Answer: Rubella

Infectious Disease Flashcard 2 of 9

Question: When does common variable immunodeficiency typically present? _____

Answer: After age 2

Infectious Disease Flashcard 3 of 9

Question: Which childhood exanthem is known as second disease?_____

Answer: Scarlet fever (Step pyogenes - GAS)

Infectious Disease Flashcard 4 of 9

Question: What is the most common cause of pneumonia in infants?_____

Answer: Respiratory synctial virus (RSV)

Infectious Disease Flashcard 5 of 9

Question: What is the treatment of Haemophilus influenzae meningitis?_____

Answer: Ceftriaxone

Infectious Disease Flashcard 6 of 9

Question: What is the likely diagnosis in a child that presents with fever and signs of heart failure ~1 week after an URI? _____

Answer: Viral myocarditis

Extra Information:  * preceded by ~1 week of flu-like symptoms Watch Myocarditis [https://dashboard.sketchy.com/study/medical/courses/medical-pathophysiology/units/medical-pathophysiology-cardiac/videos/medical-pathophysiology-cardiac-myocardial-and-pericardial-disorders-myocarditis?utm_source=anki&utm_medium=partnership&utm_campaign=february_update&utm_content=medical] https://onlinemeded.org/spa/cardiac?ref=anki 

Infectious Disease Flashcard 7 of 9

Question: What is the treatment for Roseola?_____

Answer: Supportive (infection is self-limiting)

Infectious Disease Flashcard 8 of 9

Question: The measles rash starts on the _____ and moves _____-wards

Answer: face

Extra Information:    https://onlinemeded.org/spa/infectious-disease?ref=anki 

Infectious Disease Flashcard 9 of 9

Question: Narrowing of the _____ and _____ region produces the "steeple sign" on CXR of croup (parainfluenza virus)

Answer: trachea

Extra Information:   Watch associated Bootcamp video [https://app.bootcamp.com/med-school/pulmonology/videos/lung-pathology-fundamentals?index=4] https://onlinemeded.org/spa/infectious-disease?ref=anki