Pediatric Examination and Board Review (170 page)

3.
While hospitalized the child develops prominent respiratory symptoms, including cough, rhinorrhea, and wheezing, which is noted on physical examination. You now suspect that the child has RSV infection. The diagnostic test of choice for diagnosing RSV is

(A) enzyme immunoassay of nasal wash specimen

(B) enzyme immunoassay of nasal swab specimen

(C) virus isolation of nasopharyngeal aspirate specimen

(D) immunofluorescent assay of throat specimen

(E) PCR of nasopharyngeal aspirate

4.
You ask the clinical microbiologist about antimicrobial susceptibility testing of bacteria isolated from clinical specimens of children at the children’s hospital where you practice. You are told there are difficulties in detecting which organism in the microbiology laboratory?

(A) penicillin-resistant
Streptococcus pneumoniae

(B) vancomycin-resistant
Enterococcus faecium

(C) clindamycin-resistant methicillin-susceptible
S aureus

(D) Extended-spectrum beta-lactamase (ESBL) producing
Escherichia coli

(E) none of the above; all these choices have become easy to detect

5.
A 15-month-old boy presents with a 3-day history of fever to 103°F (39.4°C) followed by refusal to walk. On physical examination he is found to have swelling of the left knee. Arthrocentesis of the left knee reveals purulent fluid that grows
S pneumoniae
. The minimum inhibitory concentration (MIC) of the organism is 1.0 μg/mL. The organism is nonsusceptible to penicillin with intermediate resistance. The MIC for the
S pneumoniae
isolate to be considered susceptible to ceftriaxone would be

(A) 0.5 μg/mL or less

(B) 1.0 μg/mL or less

(C) more than 1.0 ug/mL

(D) 2.0 μg/mL

(E) 4.0 μg/mL or more

6.
A 2-year-old previously healthy boy develops orbital cellulitis with a positive blood culture for methicillin-resistant
S aureus
(MRSA). The child is treated with vancomycin at an initial dose of 40 mg/kg per day in 3 divided doses, and serum concentrations of vancomycin are monitored. Adverse reactions to vancomycin include all but

(A) renal toxicity

(B) red-man syndrome

(C) hypotension

(D) dose-related anemia with reticulocytopenia

(E) A and C

7.
All but one of the following antibiotics are best monitored by both peak and trough measurements of serum concentrations

(A) amikacin

(B) linezolid

(C) tobramycin

(D) gentamicin

(E) none of the above

8.
An 18-month-old boy with recurrent otitis media develops fever, rhinorrhea, and fussiness. At your office he has purulent drainage from the left ear, which you send to the children’s hospital microbiology laboratory for bacterial culture. Amoxicillin is prescribed, and 2 days later you receive a call from the microbiology laboratory that the culture is positive for
H influenzae
. The method to determine whether or not the isolate is susceptible to amoxicillin is to

(A) perform a test for detection of beta-lactamase production

(B) perform a disk diffusion (Kirby-Bauer) antibiotic susceptibility test

(C) perform the oxacillin disk diffusion test

(D) perform susceptibility testing by the antibiotic gradient method (E-test)

(E) measure the MIC of amoxicillin

9.
A 14-year-old adolescent boy who works on a dairy farm presents with a 4-day history of fever, headache, myalgias of the calf, and abdominal pain. On physical examination he is febrile to 102°F (38.8°C) and also has a conjunctival effusion without purulent drainage. You suspect leptospirosis. The most appropriate diagnostic test to perform to confirm the diagnosis is

(A) blood culture

(B) urine culture

(C) anaerobic swab culture of the conjunctiva

(D) PCR test on blood

(E) serology for
Leptospira
species

10.
An 8-year-old girl develops monoarticular arthritis of the left knee 3 months after traveling with her family in Wisconsin. You suspect late disseminated disease manifesting as Lyme arthritis. Of the following, the most accurate statement about the diagnosis of Lyme disease is

(A) the EIA is usually positive in patients with erythema migrans

(B) a positive EIA in a patient with chronic fatigue syndrome is indicative of late disseminated Lyme disease

(C) virtually all patients with late disseminated Lyme disease have IgG antibodies to
Borrelia burgdorferi

(D) the EIA if positive should be confirmed by the PCR assay

(E) the diagnosis of early localized disease in the form of erythema migrans is best made by culture of a skin biopsy specimen

11.
A 24-year-old woman has a pregnancy complicated by fever, headache, and lymphadenopathy during the first trimester. The mother reports that a number of stray cats live in the neighborhood. The infant is born at 38 weeks’ gestation and weighs 2.5 kg. On physical examination the infant has jaundice, hepatomegaly, chorioretinitis, and scattered punctate calcifications throughout the brain on computed tomography (CT) scan. The diagnostic test to determine the etiology of this infant’s infection is

(A) herpes simplex virus serology on the infant

(B)
Toxoplasma gondii
serology on the maternal and infant sera

(C) culture of blood and cerebrospinal fluid for lymphocytic choriomeningitis virus

(D) cytomegalovirus (CMV) serology on maternal and infant sera

(E) serologic testing for HIV

12.
A 3-month-old female infant is brought to your office by her mother for evaluation of fever, nasal congestion, and poor feeding. On physical examination the infant has a temperature of 101°F, a maculopapular rash, and hepatosplenomegaly. The mother’s obstetric record is not available. You suspect congenital syphilis. The following diagnostic test result would be most useful in confirming infection with
Treponema pallidum

(A) a positive
Treponema pallidum
particle agglutination (TP-PA) test or positive fluorescent treponemal antibody absorption (FTA-ABS) test

(B) a titer of 1:2 on a rapid plasma reagin (RPR) test

(C) a hemoglobin concentration of 7.5 g/dL

(D) the presence of intracranial calcifications

(E) an elevated immunoglobulin M (IgM) level

13.
A 4-year-old boy has a 3-day history of mild headache and decreased activity. This is followed by fever to 103°F (39.4°C), mild cough, and sore throat. On physical examination the child has anterior and posterior cervical lymphadenopathy and splenomegaly. The white blood cell count is 5000/mm
³
with a normal differential. The alanine aminotransferase level is increased at 280 U/L. Of the following, the most diagnostic study is

(A) IgM for hepatitis A in serum

(B) IgM for the viral capsid antigen (VCA) of Epstein-Barr virus

(C) rapid heterophil slide test (monospot)

(D) isolation of HHV-6 from peripheral blood lymphocytes

(E) urine “shell vial” culture for CMV

14.
A 14-day-old term infant develops fever to 100.8°F (38.2°C), poor feeding, and two vesicular-appearing skin lesions on the right arm. You suspect neonatal herpes simplex virus (HSV) infection. The most appropriate diagnostic test to perform is

(A) direct fluorescence antibody (DFA) test of skin lesions

(B) Tzanck test of the skin lesions

(C) PCR of skin lesions

(D) serum for type-specific HSV-2 IgG antibody

(E) serum for HSV immunoglobulin M (IgM) antibody

15.
Of the following viruses, the one(s) that can be identified by culture is (are)

(A) calicivirus

(B) measles

(C) parvovirus B19

(D) hepatitis E

(E) A and C

16.
An 8-year-old girl who has received Bacille Calmette-Guérin (BCG) vaccine at age 5 years now has a positive tuberculin skin test measured using 5 tuberculin (TU) of purified protein derivative. Which of the following would most support that the positive tuberculin skin test (TST) is caused by BCG?

(A) TST of 16 mm induration

(B) known contact with a person with contagious tuberculosis

(C) chest radiographic findings of hilar adenopathy

(D) child’s mother known to have HIV infection

(E) identification of the BCG immunization scar

17.
A previously healthy 5-year-old boy has been exposed to
Mycobacterium tuberculosis
by his aunt who is now hospitalized with cavitary pulmonary tuberculosis. You place a Mantoux test and order a chest radiograph. The Mantoux test is nonreactive, but the chest radiograph is abnormal showing mediastinal adenopathy with a left upper lobe segmental lesion. The most likely explanation for the negative Mantoux skin test is

(A) receipt of measles vaccine 16 weeks earlier

(B) malnutrition

(C) selective anergy to PPD

(D) the child’s young age

(E) underlying immunodeficiency

18.
A 3-year-old girl has a large left minimally tender, anterior cervical triangle lymph node that has been present for approximately 5 weeks. All but one of the following factors would suggest a nontuberculosis mycobacterium (NTM) infection

(A) bilateral location of lymphadenopathy

(B) Mantoux test smaller than 12 mm in induration

(C) normal chest radiograph

(D) age younger than 6 years

(E) lack of systemic symptoms, such as fever and weight loss

ANSWERS

1.
(C)
The rapid antigen tests commercially available for identification of influenza A or B have variable sensitivity and specificity compared with viral culture. The DFA is more sensitive than the rapid antigen tests and its sensitivity is high (90%) when compared with culture. Serologic testing with acute and convalescent serum can identify children with influenza not detected by other methods but is not helpful for rapid diagnosis.

2.
(A)
The so-called “shell vial” culture is the preferred method of diagnosis of adenovirus infection and can detect virus in culture as early as 2 days. The DFA of nasopharyngeal secretions lacks sensitivity (<70%) as does measurement of complement fixation antibodies. The one exception to viral culture is the detection of the enteric adenovirus types 40 and 41 that cannot be isolated in standard cell cultures. An enzyme immunoassay as well as PCR can be used to detect these enteric adenoviruses in fecal specimens. PCR to diagnose adenovirus from respiratory specimens also has recently been developed.