INFECTIOUS DISEASES Flashcards
Diarrhea and turtle at home
Nontyphoidal Salmonella
Childcare center, fever, vomiting, bloody diarrhea, new-onset seizure, leukocytosis, bandemia, and
rectal prolapse
Shigella
Diarrhea, high BUN/creatinine, thrombocytopenia, and hemolytic anemia
Hemolytic uremic syndrome E. coli O157: H7
Child with his family to the Bahamas on a cruise ship, all of them have diarrhea, and a large number of people on the ship have the same
Norovirus outbreak
Child had rice in a restaurant, presents with vomiting and diarrhea
Bacillus cereus
Child ate potato salad 3 h ago, presents with sudden onset of nausea, vomiting, severe abdominal cramps and diarrhea
Staphylococcus aureus (preformed enterotoxin)
Adolescent recently had grilled rare pork meat presents with acute right lower quadrant (RLQ) abdominal pain, normal appendix on abdominal US
Yersinia enterocolitica
Child living in a farm and has been drinking unpasteurized cow milk, presenting with fever, bloody diarrhea, and vomiting. What is the most likely cause?
Campylobacter jejuni
Campylobacter is associated with which of the following neurological conditions?
Guillain–Barré syndrome
A 6-month-old infant presents with constipation, and poor feeding (mother tried honey for the first time)
Botulism
What is the best test to confirm the diagnosis in the previous case with suspected botulism?
Detection of botulism toxins or spores in stool
Community outbreak of diarrhea, news reports that the drinking water has been contaminated with acid-fast protozoa
Cryptosporidium
What are the common pathogens causing recreational water-associated
outbreaks of acute gastroenteritis
Cryptosporidium, Shigella, Giardia, norovirus, and E. coli O157: H7
Traveled to Mexico; foul smelling diarrhea, with burping and flatulence
Giardiasis
Traveled to Mexico; bloody diarrhea, tenesmus, and without fever
Amebiasis (Entamoeba histolytica)
Patient with bloody diarrhea with mucus, fever, abdominal pain, liver abscess and recent travel to
Mexico
What is the best diagnostic test in cases with suspected invasive amebiasis?
Entamoeba histolytica
Treatment: metronidazole plus paromomycin
Serum antibodies to Entamoeba histolytica
Unimmunized and buccal cellulitis
Haemophilus influenzae type b (Hib)
Adolescent presents with, pneumonia, diarrhea, headache, and confusion
Legionella pneumophila
Adolescent presents with, cough, low-grade fever, headache, wheezing, and negative cold agglutinins
Chlamydia pneumoniae
A 3-day-old newborn, copious purulent eye discharge, and eyelid edema
Gonococcal conjunctivitis
Erythromycin ointment is considered the best regimen for prophylaxis against neonatal conjunctivitis because of its efficacy against
Gonococcal, and nongonococcal nonchlamydial pathogens (does not prevent
Chlamydia trachomatis transmission from mother to infant)
A 6-week-old, staccato cough, and eye discharge
Chlamydia trachomatis
A 3-month-old presents with a staccato cough, no fever, and chest radiograph positive for pneumonia
Chlamydia trachomatis
A 16-year-old with fever, recurrent non-productive cough, and malaise; patient was exposed to exotic birds in South America
Chlamydia psittaci
Breeds turkey, high fever, pneumonia, muscle pain, and splenomegaly
Chlamydia psittaci
Fever of unknown origin with elevated liver enzymes, lives on a farm, the most likely cause
Brucella, blood culture is the best test and treat with doxycycline + rifampin
Tick bite, fever, rash, myalgia, headache,
pancytopenia, elevated liver enzymes, and hyponatremia
Ehrlichiosis
Tick bite, fever, rash on palms and soles, headache, joint pain, low platelet, and hyponatremia
Rocky Mountain spotted fever (RMSF)
Rickettsia rickettsii
A 4-year-old with RMSF. What is the drug of choice?
Doxycycline
Connecticut, target skin lesion (erythema migrans), next step
Treat (Lyme disease); do not order serology
Child was camping in a park in New York, developed Bell’s palsy, no rash, no other symptoms
Order Lyme serology and treat if positive
A mother found a tick attached to her child’s thigh
Ticks should be removed by using forceps or tweezers without twisting or crushing
Child visited Oklahoma with family, they hunted and skinned rabbits, the child presented with a large lymph node in the groin, and fever
Tularemia (Francisella tularensis)
Neonate, peripherally inserted central catheter (PICC) line is positive for Candida albicans
Remove the catheter and start IV antifungal
Most common electrolyte disturbances associated with amphotericin B therapy
Hypokalemia
Hypomagnesemia
Infant presents with 3 days of high fever, febrile seizure, develops a rash when fever resolves
Human herpesvirus 6 infection (roseola
infantum)
Fever, headache, runny nose, rash on the cheeks (looks like slapped), lacy rash on both arms
Erythema infectiosum (parvovirus B19)
Very high fever, cough, coryza, conjunctivitis, bluish-gray specks on the buccal mucosa, the maculopapular rash spreading from the head down, splenomegaly, and lymphadenopathy
Measles
Child with mumps. For how long should children with mumps be excluded from school?
5 days from onset of parotid gland swelling
During school outbreak of mumps. For how long unimmunized children should be excluded from school?
At least 26 days after the onset of parotitis in the last person with mumps in the affected school
Posterior auricular and suboccipital
lymphadenopathy, headache, eye pain, sore throat, maculopapular rash, low-grade fever, and chills
German measles (rubella)
Newborn with microcephaly, chorioretinitis, periventricular calcification and a major cause of
sensorineural hearing loss
Cytomegalovirus (CMV)
Newborn with microcephaly, subcortical
intracranial calcifications, eye anomalies, and hyperreflexia. Mother immigrated from Brazil 2 months before giving birth in the USA. She
recalls having a fever in the first trimester
Congenital Zika syndrome
A fully immunized 6-year-old presented with malaise, low-grade fever, and a mild vesicular rash that resembles “dew drops on a rose petal”
Varicella zoster—may have mild episode even if vaccinated
Child is born to a mother who is diagnosed with varicella. When should the varicella zoster immunoglobulin (VZIG) be given?
If the mother is diagnosed from 5 days before birth to 2 days after birth
A 5-year-old male with sudden onset of high fever during the month of March; he has body aches, chills, sore throat, and generalized fatigue
Influenza
A 20-month-old boy with sudden onset of high fever 105 °F during the month of January. He has a runny nose, cough, and malaise. O/E: he has nasal flaring and retractions, bilateral rhonchi. Rapid
influenza and respiratory syncytial virus (RSV) tests are negative. What is the next best step?
Start oseltamivir and order influenza molecular assays (no need to wait for the result in highrisk children before starting the medicine)
Who is at risk of hospitalization and development of complications caused by influenza infection?
Children younger than 2 years or who have underlying medical conditions
What is the sensitivity of rapid diagnostic influenza assays test?
Ranges from 10% to 70% (negative test result does not rule out influenza)
What is the sensitivity of influenza molecular assay?
Ranges from 86% to 100%
A 3-year-old male never vaccinated against influenza should receive how many doses?
From 6 months to 8 years, if never received a previous influenza vaccine, 2 doses separated by 1 month are needed, then annually afterward
What is the most common cause of croup in children?
Parainfluenza virus
A 4-month-old unvaccinated child with profuse foul-smelling diarrhea, dehydration, and electrolyte abnormalities
Rotavirus
An 8-year-old female with recurrent cold sore on her lower lip
Herpes labialis (HSV-1)
A 16-year-old sexually active male is complaining of painful vesicles noted on the penis
HSV-1 or HSV-2
A 14-year-old with a history of severe eczema presents with diffuse clusters and vesicles noted on the affected area
Eczema herpeticum
Treatment: acyclovir
A 16-year-old sexually active female presents with cauliflower-like lesions in the genital region
HPV—strains 6 and 11 are commonly
associated with anogenital warts
Which strains of HPV are more commonly associated with cervical cancer?
HPV—strains 16 and 18
Adolescent male present with mumps (parents are asking about the possible complications)
Epididymo orchitis, arthritis, encephalitis
Chickenpox rash is infectious for how long?
1–2 days before the rash, and until all lesions are crusted over
Limping, after stepping on a nail with a shoe on
Pseudomonas aeruginosa
Kitten at home, large axillary and cervical lymph nodes
Bartonella henselae (cat scratch disease)
What is the best laboratory test to establish the diagnosis of cat scratch disease
Serologic test (indirect immunofluorescent assay)
Dog bite, 12 h later presents with swelling of the hand, tenderness, and erythema
Pasteurella species
Dog bite, 5 days later presents with swelling of the hand, tenderness, and erythema
S. aureus
Dog bite with severe complications, the patient is hospitalized
Ampicillin/sulbactam IV
Dog, cat, and human bite drug of choice
Amoxicillin/clavulanate
Dog bite and allergic to penicillin
Clindamycin and TMP-SMX
Dead bat found in the same room as the patient
Give rabies vaccine and immunoglobulin
Bitten by a fox
Give rabies vaccine and immunoglobulin
Bitten by a domestic dog during aggressive play
Give amoxicillin/clavulanate
The most common organism that causes infection in cat bite
Pasteurella multocida
Cochlear implants are associated with an increased risk of which bacterial infection?
Streptococcus pneumoniae
What is the best empiric treatment in cases of perianal bacterial dermatitis?
Oral cephalexin or another antistaphylococcal antibiotic depends on the local pattern of antibiotic resistance and sensitivity
Child with perianal painful rash and rectal pain for 3 days. O.E: bright red, sharply demarcated rash around the anal area
Perianal bacterial dermatitis (caused by
Streptococcus pyogenes or S. aureus),
A 5-year-old, fever, headache, pharyngeal erythema, palatal petechiae, abdominal pain, nausea
S. pyogenes (group A streptococcus)
A 5-year-old presents with fever, headache, pharyngeal exudates, and diffuse sandpaper-like rash. Gram-positive beta-hemolytic streptococci
isolated from throat culture
Scarlet fever
A 2-year-old child presents with low-grade fever, thick nasal discharge, and anterior cervical lymphadenopathy
Streptococcosis (Streptococcus)
A 12-year-old, throat pain with exudates, fever, headache, large cervical lymph node, and splenomegaly
Epstein–Barr virus (EBV) infectious
mononucleosis
A 3-year-old, fever, runny nose, hoarse voice, cough, and pharyngeal exudates
Viral pharyngitis
Best screening test for suspected EBV infection in ≥ 5-year-old
Monospot test
A football player is diagnosed with EBV without splenomegaly. How soon can he return to contact sports?
No contact sports for at least 4–6 weeks— increased risk of splenic rupture
Prodromal high fever and irritability, followed by painful vesicles that ulcerate on the anterior palate,
tongue, and buccal mucosa, with intensely inflamed gingivae
Primary herpetic gingivostomatitis
Abrupt onset of pharyngitis, palpebral
conjunctivitis, fever, a moderate degree of illness, and preauricular lymphadenopathy, mild cough, and nasal congestion, rhinorrhea, abdominal pain
Adenovirus infection (pharyngoconjunctival fever)
A 6-year-old child with fever, headache, throat pain and abdominal pain. O/E: pharyngeal erythema, palatal petechiae, and positive cervical lymphadenopathy. What is the next best step?
Rapid antigen Streptococcus testing (RAST). If RAST is negative, obtain a throat culture. Prescribing antibiotics for presumed group A
Streptococcus (GAS) without testing is not appropriate
Poor feeding, drooling, tiny vesicles, and
erythematous ulcers occur on the posterior pharynx, involving the soft palate, uvula, and tonsillar pillars, and resolve spontaneously within 1 week.
With or without fever
Herpangina (enteroviral stomatitis)
A painful 1- to 3-mm vesicles on an erythematous base involving the buccal mucosa, palate, tongue, uvula, and anterior tonsillar pillars. A gray-white
vesicle surrounded by erythema primarily on the palms and soles, also on the buttocks and distal extremities
Hand-foot-mouth disease (enteroviral stomatitis with exanthem)
Throat pain, fever, grayish-white membrane on the pharynx; the child is not immunized and looks toxic
Diphtheria
Child with a persistent tooth abscess developed multiple sinuses drainage on the cheeks with sulfur granules seen in the exudates
Actinomycosis
A 12-year-old boy with a history of swimming in freshwater lagoons, developed headaches, myalgia,
and fever; 7 days later he became jaundiced, with elevated creatinine level, high bilirubin level, mild elevation of AST and ALT
Leptospirosis
Unimmunized, dirty wound, and fracture of the femur
Tetanus vaccine and tetanus immunoglobulin (TIG)
Immunizations up to date, last tetanus vaccine was 3 years ago, dirty wounds, and multiple compound fractures in a car accident
No tetanus vaccine nor TIG
A 12-year-old boy stepped on a dirty rusty nail, the last DTaP immunization was 8 years ago (received 5 doses of DTaP by the age 4 years of age)
Tdap immunization
A 12-year-old boy stepped on a clean object at home, presents with a minor, clean wound (received 5 doses of DTaP by the age 4 years of age)
Needs booster dose for pertussis component at 11–12 years (Tdap). Tetanus booster required every 10 years
A 2-month-old developed bronchiolitis and negative RSV
Human metapneumovirus
Young adolescent works on an animal farm developed skin papule on the arm that eventually ulcerates and forms black eschar with non-pitting, painless induration and swelling
Anthrax
Unimmunized, presents with fever, muscle weakness and paralysis involving the proximal muscles first. History of foreign travel
Poliomyelitis
Child sustained significant burn a few days ago, starts having a fever, tachypnea, tachycardia and new discoloration of wound edges. What is the next best step?
Start IV antibiotics
Central line, methicillin-resistant S. aureus (MRSA) infection. What is the drug of choice?
Vancomycin
IV vancomycin, suddenly develop a rash, itchiness, flushing, and tachycardia
Red man syndrome (reduce IV infusion rate)
Recently traveled to Africa, seizure, decreased level of consciousness, retinal hemorrhage, and hypoglycemia. What is the most likely cause?
Plasmodium falciparum (cerebral malaria)
A 3-year-old developed osteomyelitis, culture is negative, not responding to vancomycin. What is the most likely cause?
Kingella kingae (aerobic CO2 enhanced culture)
For travel to Africa, the prophylactic antimicrobial therapy of choice for malaria is
Atovaquone-proguanil or doxycycline
(mefloquine has black box warning)
The best study for neonates presenting with fever and Citrobacter bacteremia
Brain CT or MRI
Neonate presents with fever, and blood culture grows Citrobacter. What is the most common complication?
Brain abscess
Late-onset (7 days to 3 months of life) group B streptococcal infection presents with
Bacteremia (more common), meningitis, or osteomyelitis
Stiff neck, fever, CSF WBC < 1000, 80%
neutrophil, negative CSF gram stain. What is the best CSF study?
Enterovirus PCR
Empiric antibiotic therapy in a newborn with presumed bacterial meningitis
Ampicillin plus aminoglycoside or ampicillin plus cefotaxime
Empiric antibiotic therapy in infants and children with presumed bacterial meningitis
Vancomycin plus ceftriaxone or cefotaxime
What is the duration of therapy in most of the cases of meningitis?
14–21 days
What are the long-term neurologic complications of bacterial meningitis in children?
Developmental delay, intellectual disability, hearing impairment, epilepsy, spasticity, and hemiparesis
Child with tetralogy of Fallot presents with a headache, seizure and brain abscess
S. aureus
A 17-year-old female with a history of IV drug abuse presents with fever, dyspnea, cough, chest pain, tender subcutaneous nodules in the distal nail pads, positive blood culture for S. aureus
Endocarditis
Adolescent with high-risk behavior and IV drug
abuse presents with fever, lymphadenopathy,
pharyngitis, muscle and joint pain, mouth and
genital ulcers, skin rash including the palms and
soles, rapid strep and monospot tests are negative
Acute retroviral (HIV) syndrome
The best initial test for the diagnosis of acute
retroviral (HIV) syndrome
HIV DNA PCR
Confirm with ELISA/Western blot and HIV
RNA PCR (viral load)
Main side effect of zidovudine (ZDV)
Bone marrow suppression
A pregnant adolescent with HIV, her CD4 count is 800
Start anti-HIV therapy immediately
Patient with HIV infection, diarrhea for 3 weeks
and not resolving
Cryptosporidium
Child lives with his father who was in jail,
developed cough, weight loss, night sweats, chest radiograph shows hilar adenopathy and pneumonia
Tuberculosis
Developed large matted cervical lymph node,
persistent for 6 weeks, and not responding to
antibiotic; you notice the overlying skin is
violaceous. Most likely diagnosis
Mycobacterium avium
Child presents with large anterior cervical lymph
node measure 7 × 4 cm, matted, painless, PPD is 9 mm induration, not responding to antibiotics for 9 weeks
Surgical removal of the node with complete
excision (atypical mycobacteria, including M.
avium)
First-line treatment for head lice
Pyrethrin and 1% permethrin
When can children with head lice infestation return to school or daycare?
Should be allowed to complete the school day
(no exclusion from school or daycare because
of head lice or nits in healthy children)
Head lice resistant after the treatment with
permethrin
Give malathion (ovicidal)
A 1-month-old with scabies. What is the drug of
choice?
Precipitated sulfur 6% in petrolatum
A young girl with malodorous vaginal discharge.
She has a vaginal discharge visible at the introitus. Mother denied sexual abuse or trauma. What is the most likely cause?
Retained foreign body
Adolescent girl presents with severe rash and
desquamation in the hands and feet, hypotension, and fever. The vaginal examination reveals a tampon
Toxic shock syndrome due to Staphylococcus
Treatment: IV vancomycin + clindamycin)
A 7-year-old presents with fever, malaise, skin rash with bullae, and positive Nikolsky sign
Staphylococcal scalded skin syndrome
A 2-week-old neonate with a history of a PICC
line, with fever, bacteremia, and positive culture
showing gram-positive cocci
Enterococcus faecium—resistant to vancomycin
(VRE) and cephalosporins
Treatment: linezolid
A 13-year-old presents with bloody diarrhea,
abdominal pain and cramps; patient recently treated with clindamycin
Clostridium difficile—initial treatment choice
for first, and a non-severe episode is oral
metronidazole
Patient does not respond to metronidazole and is diagnosed with another episode of C. difficile. What antibiotic should be used?
Oral vancomycin
Child with a fever, cervical lymphadenopathy.
Child ingested undercooked meat. CT scan shows ring enhanced lesion
Toxoplasmosis
