ID Flashcards
You have diagnosed a patient with active tuberculosis.
What comorbid conditions should you consider before prescribing isoniazid as part of your treatment regimen?
Acute liver disease (of any etiology) and alcohol use
Explanation
Isoniazid (a.k.a. isonicotinic acid hydrazide [INH]) is metabolized in the liver. It induces components of the cytochrome P-450 system when combined with alcohol, thus increasing toxicity, and is contraindicated in patients with acute liver disease. In all patients on INH, regardless of age, monitor monthly for signs and symptoms of liver toxicity. Laboratory testing is indicated if signs or symptoms develop. INH carries an FDA boxed warning regarding the risk of hepatitis.
A 5-year-old boy from rural Arkansas presents with:
Fever to 102.0° F (38.9° C)
Swollen lymph node in his right inguinal area
What is the most likely diagnosis?
Tularemia (a.k.a. rabbit fever)
Explanation
On exams, if you see a child from Arkansas (or Missouri/Oklahoma) with a swollen lymph node and fever, think tularemia, which is caused by Francisella tularensis. This is especially true if the patient is someone who hunts, traps, or handles rabbits. Treat with gentamicin or streptomycin for 10 days.
A 15-year-old boy who lives and works on a sheep farm presents with a painless papule that vesiculates and forms a painless ulcer, then a painless black eschar with nonpitting, painless induration and swelling.
What is the likely diagnosis?
Anthrax
Explanation
Anthrax inoculation occurs from handling contaminated hides/wool. It can progress to septicemia and meningoencephalitis if left untreated. The cutaneous form (95% of cases) presents as described. Associated symptoms can include fever, headache, and painful lymphadenopathy.
A 6-year-old girl who has been attending summer camp presents with:
Fever Pharyngitis Conjunctivitis Rhinitis Cervical adenitis What is the likely etiology for her signs and symptoms?
Adenovirus
Explanation
Adenovirus can cause a pharyngoconjunctival fever (particularly during the summer months) and is commonly associated with outbreaks at swimming pools in summer camps. It can also cause epidemic keratoconjunctivitis—this occurs with conjunctivitis, painful corneal involvement, and preauricular lymph node enlargement.
A girl presents with chickenpox.
When are patients with chickenpox contagious?
1–2 days prior to onset of the rash until all lesions are crusted over
Explanation
Children may return to school or day care when all the lesions are crusted over. Hospitalized patients who are exposed to chickenpox need to be placed in a negative-pressure isolation room if their hospitalization falls within the time frame of days 8−21 after exposure (up to 28 days after exposure if VariZIG was administered).
A 3-year-old presents with:
Fever
“Slapped cheek” rash on the face
A “lattice-like” rash on the arms and legs that is more prominent in sunlight or after a warm bath
What is the likely etiology of these signs and symptoms?
Parvovirus B19
Explanation
Parvovirus B19 is responsible for this classic presentation of erythema infectiosum (fifth disease). Once the rash appears, the child is no longer infectious. Adults (especially women) commonly get polyarthritis affecting small joints, particularly of the hand. Children less often develop arthritis (usually of the knee joint).
A 17-year-old presents with:
Pneumonia
Diarrhea
CNS symptoms (headache, delirium, and confusion)
What is the most likely etiology of this triad?
Legionella pneumophila
Explanation
L. pneumophila causes 80–90% of human Legionellae infections. L. pneumophila infection (legionellosis) is a multisysytem disease, with the 3 findings listed here being the classic triad. It is commonly associated with outbreaks related to contaminated water towers or air-conditioning water units in buildings, hotels, cruise ships, and hospitals. Legionellae infections are rarely seen in children.
A 2-year-old African child from rural Chad presents with:
Fever
Paralysis that began in the proximal muscles of the thigh and has progressively involved more distal muscle groups
What is the most likely diagnosis?
Polio
Explanation
Polio has essentially been eliminated from the Western Hemisphere and developed countries; however, Afghanistan, Pakistan, and Nigeria have never interrupted its transmission. Polio can be differentiated from Guillain-Barré syndrome by the patterns of the spread of paralysis; with Guillain-Barré, the paralysis begins distally and spreads proximally in an ascending manner, the opposite of polio (descending paralysis).
A 14-year-old boy from Hawaii presents with the following:
History of swimming in fresh-water lagoons Fever Conjunctival redness without exudates Myalgias and headaches Jaundice Laboratory:
Creatinine 1.9 mg/dL
Bilirubin is disproportionately high compared to AST/ALT, which are each mildly elevated.
What is the most likely diagnosis?
Leptospirosis
Explanation
Leptospirosis is a spirochetal disease that is transferred by contact with contaminated water or infected animals. Rats, dogs, and livestock are the most common vectors. Many patients have a biphasic illness (2 phases separated by 3–4 days of no fever). Diagnose with blood (acute phase) or urine cultures (immune phase), along with serum antibodies.
A bat is found in the room of a sleeping 2-year-old boy. His parents like to keep the windows cracked open to allow the cool Hawaiian breeze in.
Should he be given rabies prophylaxis?
No
Explanation
In areas where rabies is found, you would always provide rabies postexposure prophylaxis if you found a bat in the room of a sleeping child; however, Hawaii is the only state in the U.S. that is rabies free!
A newborn presents with:
IUGR Hepatosplenomegaly Jaundice Thrombocytopenia Petechia/purpura Microcephaly Cerebral atrophy Chorioretinitis Periventricular intracerebral calcifications What is the most likely etiology of these signs and symptoms?
Congenital cytomegalovirus (CMV) infection Explanation Congenital CMV infection occurs in ~ 1% of all newborns in the U.S. What determines the severity of the infection is whether or not the mother has IgG antibodies to CMV. In the case of maternal primary CMV infection during pregnancy, there is an increased risk of this congenital syndrome occurring with dire consequences. This child has the most severe form of congenital CMV infection, cytomegalic inclusion disease. It can resemble toxoplasmosis, but remember that the cerebral calcifications are periventricular (they CircuMVent the ventricles) in CMV. In toxoplasmosis, they are scattered throughout the cerebrum. Congenital rubella can present similarly, with the petechial/purpuric “blueberry muffin” rash.
A newborn of a mother who recently immigrated from Albania presents at birth with:
Petechiae and purpura on the face, trunk, and extremities
Hepatosplenomegaly
Hemolytic anemia
Patent ductus arteriosus (PDA) without pulmonary artery stenosis
Cataracts with microphthalmia
Radiolucencies in the metaphyseal long bones
What is the most likely diagnosis?
Congenital rubella syndrome
Explanation
Rubella was declared eliminated from the U.S. by 2004. By 2015, it was eliminated from the Americas. Since elimination, < 10 people in the U.S. are reported as having rubella each year. Since 2012, all rubella cases had evidence that they were infected while outside the U.S. It continues to be endemic in many areas of the world.
This infant has petechiae and purpura consistent with the “blueberry muffin” baby (as seen in congenital CMV), but she also has a PDA and cataracts, which are classically seen in congenital rubella syndrome. Most likely, the mother was infected in the 1st trimester.
A 5-year-old presents for her first influenza vaccine.
How many should she receive?
2 doses, 1 month apart
Explanation
For children < 9 years of age who have never been vaccinated for the flu, this vaccination schedule will produce adequate antibody levels. Thereafter, they receive 1 annual vaccine.
A 5-year-old girl presents with a 1-week history of a tender, left axillary lymph node after receiving a cat scratch to her left hand.
What is the name of the organism most likely responsible for her disease?
Bartonella henselae
Explanation
This is catscratch disease (CSD) which is caused by Bartonella henselae. Treatment is supportive; the key is to avoid needing to incise and drain the lymph node because a persistent sinus tract will likely develop. Azithromycin has been shown to reduce the time for lymph node swelling to resolve, but spontaneous resolution usually occurs in 2–4 months without antibiotics.
A 4-year-old presents with presumed bacterial meningitis.
What are the drugs of choice for empiric therapy?
Ceftriaxone (or cefotaxime) and vancomycin
Explanation
Because of the increased penicillin resistance rates of Streptococcus pneumoniae, vancomycin has been added to the standard therapy of 3rd generation cephalosporins (ceftriaxone or cefotaxime) for children > 3 months of age suspected of having bacterial meningitis. This combination should be used empirically in all such patients; antibiotics can be modified once you get the results of susceptibility
