Infectious Flashcards
A 5-year-old boy is seen for evaluation of a rash. He has a history of atopic dermatitis that is typically well controlled. He reports falling on the playground and skinning his knee 4 days ago. This morning, he awoke to find redness, swelling, and tenderness surrounding the abrasion. The boy’s mother is a physician, and his younger sister has been treated for several skin abscesses in the past. The boy appears well and has age-appropriate vital signs with no fever. He has a 2×1–cm shallow abrasion overlying his left patella with approximately 3 cm of surrounding erythema and edema. The area is tender, with no focal fluctuance. He has full range of motion of his knee. He has several enlarged, nontender lymph nodes at the left inguinal canal. The remainder of his physical examination findings are normal.
Of the following, the MOST appropriate treatment is
A. amoxicillin
B. cephalexin
C. clindamycin D. doxycycline
Clindamycin
For hemodynamically stable children with cellulitis and risk factors for methicillin-resistant Staphylococcus aureus, initial antibiotic choice should include coverage for methicillin-resistant Staphylococcus aureus and β-hemolytic Streptococcus. Clindamycin is the preferred first-line agent.
For hemodynamically stable children with cellulitis and no risk factors for methicillin-resistant Staphylococcus aureus, coverage should include methicillin-sensitive Staphylococcus aureus and β-hemolytic Streptococcus. Cephalexin, cefadroxil, and cefuroxime are options for this clinical situation.
Risk factors for methicillin-resistant Staphylococcus aureus infection include skin trauma, frequent exposure to antibiotics, chronic disease, recent surgery or hospitalization, sharing of potentially contaminated items such as razors or towels, history of abscesses or other skin infections in patient or household contact, and history of methicillin-resistant Staphylococcus aureus infection in patient or household contact.
A 35 4/7-week-gestation neonate is admitted to the neonatal intensive care unit with respiratory distress. Maternal group B Streptococcus status is negative. The mother’s pregnancy was complicated by mild gestational hypertension. A primary cesarean delivery was performed after failed induction of labor. Meconium was noted in the amniotic fluid. The Apgar score was 8 at 1 and 5 minutes. Maternal temperature was 38°C for 1 hour after delivery. The neonate is placed on continuous positive airway pressure. Ampicillin and gentamicin are started after a blood culture specimen is drawn. Early-onset sepsis is a concern.
Of the following, the factor in this neonate’s history MOST closely associated with this diagnosis is
A. cesarean delivery
B. maternal gestational hypertension
C. meconium-stained amniotic fluid
D. preterm gestational age
Preterm GA
Risk of early-onset sepsis due to group B Streptococcus is higher among neonates born at less than 36 weeks’ or greater than 41 weeks’ gestation.
Highest maternal temperature greater than 38°C and prolonged rupture of membranes are associated with increased risk of early-onset sepsis.
Intrapartum prophylaxis for mothers positive for group B Streptococcus (GBS) has decreased overall rates of neonatal GBS sepsis.
https://neonatalsepsiscalculator.kaiserpermanente.org/
A 7-year-old previously healthy boy is seen in the emergency department for concern about black stools for 1 day. For 2 days before the onset of the black stool, he had multiple episodes of brown, watery, nonbloody diarrhea and nonbloody, nonbilious emesis. He complains of abdominal pain only when he has a bowel movement or vomits. He has had no fever. He has had no known sick contacts and has not traveled. On the day of presentation, the boy had a large black stool with no visible blood. His vital signs and physical examination findings are normal. His mother reports giving the boy several over-the-counter medications for his diarrhea and vomiting.
Of the following, the medication MOST likely responsible for the boy’s stool finding is
A. aluminum hydroxide
B. bismuth subsalicylate C. calcium carbonate D. magnesium hydroxide
bismuth salicylate
The bismuth component of bismuth subsalicylate may react with small amounts of sulfur in the gastrointestinal tract and result in black stools.
Ingestion of bismuth subsalicylate can result in salicylism, especially with chronic ingestions, and children with varicella may be at risk for Reye syndrome.
Over-the-counter cough and cold medications have not been shown to be effective in young children, and can pose a significant risk to children younger than 6 years.
An 8-year-old girl is referred to her primary care provider by her dentist for evaluation of tongue and mouth lesions (Item Q7A and Item Q7B). Her mother recalls the lesions as being present for at least the past 3 years. They have not changed and are asymptomatic. The girl has no known medical problems. A review of systems is significant for intermittent constipation and diarrhea. No one in her family has similar lesions. Her weight is at the 25th percentile, and her height is at the 90th percentile. Her face is long and thin, and she has full lips. Her joints are hyperextensible, and pes planus is present. The remainder of her physical examination findings are unremarkable.
Of the following, the BEST next step is to evaluate for
A. an insulinoma
B. a medullary thyroid carcinoma C. an optic glioma D. a pheochromocytoma
Phenotypic features of multiple endocrine neoplasia type 2B include mucosal neuromas; a tall, thin body habitus; full lips; joint laxity; and alacrima. Gastrointestinal tract ganglioneuromas may cause intermittent constipation and diarrhea.
Multiple endocrine neoplasia type 2B is associated with early-onset and aggressive medullary thyroid carcinoma, in addition to pheochromocytoma and the physical phenotype.
It is important to recognize the clinical features of multiple endocrine neoplasia type 2B for timely prevention (prophylactic thyroidectomy), detection, and treatment of the associated medullary thyroid carcinoma.
MEN2A/B RET proto onco gene Autosomal Dominant
MEN2A hyperparathyroidism, MTC, and pheochromocytoma
A 30-week-gestation pregnant woman is seen at the obstetrician’s office for a febrile illness. Her symptoms include headache and joint pain. She has had routine prenatal care and no complications of pregnancy. Physical examination reveals the rash shown in Item Q8. She asks how this illness may affect her newborn.
Of the following, the MOST accurate response is that a likely sequela is
A. central nervous system calcification
B. chorioretinitis C. generalized edema D. hearing loss
generalized edema
Maternal infection with parvovirus B19 can lead to fetal hydrops, intrauterine growth restriction, and fetal death.
Clinical manifestations of parvovirus B19 infections include erythema infectiosum, arthropathy, severe anemia caused by pure red cell aplasia in immunodeficient patients and aplastic crises in patients with hemoglobinopathies.
Parvovirus B19 infection during pregnancy is not a cause of congenital anomalies.
Maternal infection with parvovirus B19 is suggested by arthralgia and a lacy rash.
An 11-year-old boy is being evaluated for bilateral anterior knee pain. He reports gradual onset of pain after beginning training with a local soccer development program. He denies any acute injury. The pain is progressive, and over the past several weeks he has developed focal swelling several inches below his kneecaps. His medical history is remarkable for multiple episodes of chronic heel and lower leg pain over the past several years. He is otherwise healthy with normal growth and development. The boy began training year round with a soccer travel league last year. In addition, he enjoys participating in basketball and baseball. His soccer coach recently recommended that the boy focus more on soccer and give up other sports activities.
On physical examination, the boy has a significant limp. There is focal swelling and tenderness bilaterally over the tibial tuberosities and pain with resisted extension of the knees. His examination findings are otherwise unremarkable. The boy is counseled on ways to address his current knee pain and minimize his risk of future injury.
Of the following, the BEST recommendation for this boy would be to
A. comply with his coach’s recommendation regarding sports participation
B. obtain cushioned orthotics for use with his cleats
C. seek additional training with a certified fitness specialist
D. spend at least 2-3 months per year away from structured sports participation
spend at least 2-3 months per year away from structured sports participation
Overuse occurs when periods of recovery are insufficient to support the volume and intensity of physical training.
Young athletes need 1 to 2 days per week and 2 to 3 months per year of recovery time away from structured sports participation.
Osgood-Schlatter disease is an overuse syndrome that occurs with repetitive traction of the patellar tendon on the open apophysis. Overuse occurs when periods of recovery are insufficient to support the volume and intensity of physical training. Rigorous physical activity results in microtrauma of bones and soft tissue, and at the end of a given training session, overall strength and tissue integrity are compromised.
When recovery periods are inadequate, overuse injuries typically follow this 4-step progression as microtrauma accumulates:
Pain after activity
Pain during activity that does not interfere with performance
Pain during activity that results in decreased performance or participation
Persistent pain, even during periods of rest.
An expectant mother is seen for a prenatal visit. Prenatal genetic testing performed on her fetus showed karyotype 45,X. She will be meeting with a genetic counselor in the coming days.
Of the following, the MOST likely cardiac disorder to be seen in this fetus is
A. aortopulmonary window
B. coarctation of the aorta C. tetralogy of Fallot D. truncus arteriosus
coarctation of the aorta
Individuals with Turner syndrome can have congenital heart disease in the form of coarctation of the aorta, bicuspid aortic valve, aortic dilation, anomalous pulmonary venous drainage, persistent left superior vena cava, sinus tachycardia, and prolonged QT.
Although the occurrence is rare, individuals with Turner syndrome can have aortic dissection, which typically is fatal.
Individuals with Turner syndrome can have involvement of multiple organ systems, including renal, endocrine, skeletal, auditory, and visual.
Individuals with Turner syndrome typically do not have intellectual or motor delays.
A 4-year-old girl with short bowel syndrome and on long-term total parenteral nutrition is seen in the emergency department for evaluation of fever, chills, redness, and swelling within 2 cm of her central venous catheter site. She appears ill and has a temperature of 39.1°C, tachycardia, and hypotension. There is marked erythema and induration surrounding the exit site of the central venous catheter. Blood cultures are obtained from the catheter and a peripheral site, and antibiotic therapy with vancomycin and ceftazidime is initiated. Within 12 hours, both central and peripheral blood cultures grow gram-positive cocci in clusters.
Of the following, the BEST next step in management is
A. addition of gentamicin and rifampin
B. antibiotic lock therapy
C. echocardiography
D. removal of the central venous catheter
removal of the central venous catheter
Catheter-related bloodstream infection is defined as bacteremia or fungemia in which the catheter is identified as the source of infection. Several types of catheter-related infection may occur including exit site, subcutaneous tunnel or pocket, or in the bloodstream.
The common pathogens causing intravascular catheter-related infections include Staphylococcus species, enterococci, gram-negative bacilli, and Candida spp.
In patients with catheter-related infection, removal of the central venous catheter is recommended in patients who are critically ill (eg, hypotension).
Removal of the CVC is recommended if
-the catheter is no longer needed
-exit site, tunnel, or pocket infection is found
the patient is critically ill (eg, hypotension)
-infection caused by certain microorganisms (eg, candida, atypical mycobacteria, S aureus) is present
-Bacteremia fails to clear in 48 to 72 hours
-underlying valvular heart disease (eg, increased risk of developing endocarditis) is present
-known endocarditis
-development of metastatic infection
the finding of septic thrombophlebitis
Complications of catheter-related bloodstream infection include sepsis, endocarditis, thrombosis and thrombophlebitis, and metastatic infection involving many organs.
A male neonate, born at 34 weeks’ gestation, is being evaluated for respiratory distress shortly after delivery. The mother reports no medical problems during the pregnancy; prenatal care records are not available. Maternal group B Streptococcus status is unknown. The mother was febrile, with a maximum temperature of 39°C, for 6 hours before delivery. The neonate was delivered vaginally through green amniotic fluid. On physical examination, he is noted to have grunting and tachypnea. The remainder of his examination findings are unremarkable. He is started on continuous positive airway pressure +5 cm H2O and 30% oxygen in the delivery room. Chest radiography shows bilateral streaky infiltrates.
Of the following, the pathogen MOST likely to be responsible for this neonate’s findings is
A. Chlamydia trachomatis
B. Escherichia coli
C. Listeria monocytogenes
D. Streptococcus agalactiae
Listeria monocytogenes
Neonates born to mothers with Listeria infection are often delivered prematurely with brown- or green-stained amniotic fluid. Among premature infants, meconium-stained amniotic fluid is uncommon.
Early-onset neonatal Listeria is uncommon, with a high rate of mortality. These neonates may present with respiratory distress and an erythematous papular rash.
Late-onset neonatal Listeria typically presents with nonspecific findings among term infants at 14 days after birth. Meningitis is more common with late-onset neonatal Listeria.
Pregnant women acquire Listeria via contaminated food such as ready-to-eat deli meat, unpasteurized milk, soft cheese, ice cream, or frozen fruits and vegetables. Affected pregnant women may report a flu-like illness with fever before delivery.
Listeria crosses the placenta into the fetal circulation. More than 70% of women with Listeria deliver before 35 weeks’ gestation.
chest radiographic findings show bilateral streaky infiltrates or a miliary pattern.
A previously healthy 2-year-old boy is seen in the office for a worsening cough. The illness started 2 days ago with cough, rhinorrhea, and a fever of 38.3°C. His mother describes the cough as having a harsh, seal-like quality. The boy’s temperature is 38°C, heart rate is 110 beats/min, respiratory rate is 25 breaths/min, oxygen saturation is 99% on room air, and blood pressure is 90/60 mm Hg. At rest, he has a frequent seal-like cough; he is not in respiratory distress and has no stridor. His lungs are clear to auscultation bilaterally with good aeration, and he has no chest wall retractions. When he becomes more active, the boy has mild stridor and mild retractions.
Of the following, the BEST next step in management of the boy’s symptoms is to
A. administer dexamethasone
B. continue supportive care C. prescribe azithromycin D. refer for laryngoscopy
administer dexamethasone
Children with worsening mild croup and children with moderate or severe croup should be treated with oral glucocorticoids.
Nebulized epinephrine may be considered for treatment of children with moderate croup and should be administered to those with severe croup.
Bacterial tracheitis and epiglottitis must be considered in the differential diagnosis of viral croup.
An 11-month-old girl is seen by her primary care provider for evaluation after a daycare exposure. Two and a half weeks ago, her room teacher developed fever, nausea, and vomiting, and 1 week later developed jaundice. She was subsequently diagnosed with hepatitis A infection. The teacher has been out of work since the onset of this illness. Yesterday, the daycare program notified families of the possible exposure and recommended medical evaluation. The girl has been eating, voiding, and sleeping well. She has no underlying medical conditions and is scheduled for her 12-month health supervision visit in a few weeks. Her vital signs include a temperature of 37.1°C, heart rate of 110 beats/min, respiratory rate of 28 breaths/min, and blood pressure of 88/46 mm Hg. Physical examination findings reveal a well-appearing child with no jaundice, abdominal tenderness, or hepatomegaly.
Of the following, the BEST next management step for this child is to administer
A. hepatitis A vaccine B. immune globulin C. interferon D. no prophylaxis
no prophylaxis
Hepatitis A vaccine or immune globulin can be used for hepatitis A postexposure prophylaxis and should be administered within 14 days of the exposure.
Hepatitis A vaccine can be used in individuals who are vaccine eligible between the ages of 1 and 40 years, and is preferred over immune globulin because it provides active and more durable immunity.
Immune globulin should be used for hepatitis A postexposure prophylaxis in individuals younger than 12 months, older than 40 years, those who have vaccine contraindications, immunocompromised individuals, and individuals with chronic liver disease.
Hepatitis A infection in children is often asymptomatic; only 30% of young children develop symptoms, which can include fever, malaise, nausea, vomiting, and jaundice. In contrast, approximately 70% of adults with hepatitis A develop jaundice and 80% develop hepatomegaly
average incubation 28 days
A 5-year-old boy who is otherwise healthy is brought to the emergency department after 7 days of fever and fatigue. He has not had cough, congestion, rhinorrhea, vomiting, or diarrhea. He appears ill but is not in distress. He has a temperature of 39°C, a heart rate of 140 beats/min, a blood pressure of 90/60 mm Hg, a respiratory rate of 40 breaths/min, and oxygen saturation of 95%. He has clear bilateral breath sounds. His heart rate and rhythm are regular. He has a grade 2/4 diastolic murmur that is not indicated in prior clinic notes. He has petechiae on his distal extremities. Blood cultures and an echocardiogram are obtained. A vegetation is noted on his mitral valve.
Of the following, the pathogen that is MOST likely to be the cause of this child’s infection is
A. Eikenella corrodens
B. Kingella kingae
C. Staphylococcus aureus D. Streptococcus pneumoniae
S. aureus
The most common pathogens associated with infective endocarditis are streptococcus viridans group and Staphylococcus aureus.
The clinical presentation of infective endocarditis can be subacute or acute and is often nonspecific. A high index of suspicion is needed.
The modified Duke criteria can aid in the diagnosis of infective endocarditis.
major criteria needed to make the diagnosis include evidence of bloodstream infection and of endocardial involvement.
Treatment initially includes broad-spectrum antibiotics that can then be tailored to the clinical situation.
An 8-year-old boy with a 3-day history of low-grade fever, sore throat, nasal discharge, cough, and malaise is seen in the office. He recently returned to school after summer break. He appears well and has a temperature of 38.2°C, a heart rate of 102 beats/min, a respiratory rate of 18 breaths/min, and a blood pressure of 108/67 mm Hg. There is redness of the pharyngeal mucosa without exudate. There is nontender, shotty, anterior cervical adenopathy. His right tympanic membrane is erythematous. The remainder of his physical examination findings are normal.
Of the following, the MOST likely etiology of this child’s illness is
A. adenovirus
B. influenza
C. respiratory syncytial virus
D. rhinovirus
Rhinovirus
Rhinovirus is the most frequently implicated community respiratory viral pathogen causing the common cold in children and adults.
Rhinovirus infection occurs throughout the year, with peak activity from autumn through spring.
In addition to the common cold, rhinoviruses can cause otitis media, bronchiolitis, and pneumonia in infants and children.
rhinovirus is the most frequently implicated pathogen in children and adults, accounting for almost 50% of cases of upper respiratory tract infections. Rhinovirus infection occurs throughout the year, with peak activity from autumn through spring. There are many serotypes (>150) of rhinovirus and although immunity is type-specific, the duration of protection is temporary and short-lived.
A 5-year-old girl is seen in the emergency department for acute onset of left arm weakness. Two weeks earlier she had a nonspecific viral illness that self-resolved. She awoke on the day of admission with inability to move her left arm. She denies pain, numbness, headache, bowel or bladder involvement, or prior trauma.
In the emergency department, the girl is alert, pleasant, and interactive with no evidence of encephalopathy. Her vital signs and general physical examination findings are normal. On neurologic examination, cranial nerve findings, fundoscopy, sensation, and gait are normal. Motor examination is notable for flaccid paralysis of the left upper extremity with areflexia; strength, reflexes, and coordination are preserved in her other extremities.
Brain magnetic resonance imaging (MRI) is normal. Spine MRI scans are shown (Item Q52A and Q52B). Lumbar puncture reveals clear cerebrospinal fluid with a lymphocytic pleocytosis. Cerebrospinal fluid is sent for viral testing and bacterial culture.
Of the following, the MOST likely diagnosis for this girl is
A. acute flaccid myelitis B. acute disseminated encephalomyelitis C. Guillain-Barré syndrome D. idiopathic transverse myelitis
acute flaccid myelitis
Acute flaccid myelitis is a rare neurologic disorder presenting with acute paralysis of 1 or more limbs, preserved sensation, and normal mental status, typically within a week of viral symptoms.
Treatment of acute flaccid myelitis is supportive; recovery is variable and often incomplete.
Suspected cases of acute flaccid myelitis should be reported to the Centers for Disease Control and Prevention with samples sent for viral testing.
Idiopathic transverse myelitis is a postinfectious inflammatory disorder of the spinal cord typically presenting with myelopathy symptoms over hours to days. Symptoms include bilateral motor and sensory deficits. Bowel and bladder dysfunction and autonomic dysregulation may also occur. Spinal MRI demonstrates a longitudinal lesion traversing multiple contiguous segments involving both the white and gray matter of the spinal cord
A 16-year-old adolescent boy diagnosed with acute myeloid leukemia 8 weeks ago has remained hospitalized for fever and neutropenia since his last chemotherapy course. He has had persistent fever and neutropenia for the last 5 days despite treatment with broad-spectrum antibiotics, including vancomycin and ceftazidime. He is febrile and has a heart rate of 110 beats/min, a respiratory rate of 24 breaths/min, a blood pressure of 110/86 mm Hg, and an oxygen saturation of 92% on room air. He has decreased breath sounds and dullness to percussion at the right lower lung field and in the right axillary area. Laboratory findings are notable for an absolute neutrophil count of 200/µL (0.2 × 109/L), anemia, and thrombocytopenia. Blood culture results have remained negative. Chest radiography and computed tomography with contrast (Item Q55) show diffuse nodular densities of various sizes in both lung fields.
Of the following, the organism MOST likely responsible for the patient’s findings is
A. Aspergillus B. mycoplasma C. Pneumocystis jirovecii D. Staphylococcus aureus
Aspergillus
Invasive aspergillosis may complicate the clinical course of immunocompromised patients.
Pulmonary infection is the most common manifestation of invasive aspergillosis, but other sites, including the sinus, skin, and brain, may be involved.
Voriconazole is the preferred drug of choice for primary treatment of invasive Aspergillus infection
invasive pulmonary aspergillosis is suggested by positive galactomannan assay finding in the serum or bronchoalveolar lavage fluid (BAL) and evidence of dichotomously branched and septate hyphae
presents with unremitting fever in high-risk patients who are immunocompromised; other early symptoms may include dry cough or chest pain
