Pediatric Examination and Board Review (228 page)

(D) zidovudine

(E) no effective therapy known

12.
In utero herpes simplex viral infection can cause which of the following clinical features?

(A) intrauterine growth retardation

(B) microcephaly

(C) intracranial calcifications

(D) cataracts

(E) all of the above

13.
All of the following are causes of arthropodtransmitted encephalitis except

(A) lymphocytic choriomeningitis virus

(B) West Nile virus

(C) Japanese encephalitis virus

(D) St. Louis encephalitis virus

(E) eastern equine encephalitis virus

14.
A 6-year-old boy presents to your clinic with the chief complaint of new-onset headache, fever, and neck stiffness on returning from a camping trip. He has also had a sore throat for 3 days. On physical examination, he has an erythematous rash over the palms of his hands and vesicular lesions and ulcers over the oropharynx. The most likely cause of this child’s symptoms is which of the following?

(A) echovirus

(B) HSV type 1

(C) HIV

(D) Chikungunya virus

(E) West Nile virus

15.
Which of the following parasites is responsible for cysticercosis?

(A)
Diphyllobothrium latum

(B)
Taenia multiceps

(C)
Taenia solium

(D)
Angiostrongylus cantonensis

(E)
Plasmodium falciparum

16.
Which of the following anaerobic organisms have been isolated from brain abscesses?

(A)
Actinomyces

(B)
Bacteroides

(C)
Peptostreptococcus

(D)
Propionibacterium

(E) all of the above

MATCH EACH OF THE FOLLOWING BACTERIA WITH THE CORRESPONDING NEUROLOGIC DISEASE

17.
Treponema pallidum
              (A) Cat-scratch disease

18.
Borrelia burgdorferi
               (B) Lyme disease

19.
Bartonella henselae
                (C) Syphilis

20.
Mycoplasma pneumoniae
       (D) Acute disseminated encephalomyelitis

ANSWERS

1.
(A)
This patient most likely has
S pneumoniae
or
N meningitidis. H influenzae
type b disease has virtually disappeared with the advent of effective immunization, and pneumococcal meningitis has become less frequent as well. The recent introduction of a 13-valent pneumococcal conjugate vaccine should further decrease the prevalence of pneumococcal meningitis.
S pneumoniae
is a gram-positive diplococci. Group B streptococci (
Streptococcus agalactiae
) are also gram-positive cocci usually configured in chains.
N meningitidis
is a gram-negative diplococcus.
Escherichia coli
is a gram-negative rod;
L monocytogenes
is a gram-positive bacillus. Staphylococci are gram-positive cocci appearing in “grape-like” clusters. Mixed bacterial flora rarely cause meningitis.

2.
(E)
Recent concern has been raised regarding the increased prevalence of penicillin-resistant
S pneumoniae
. As a result, children older than 1 month of age who are suspected of having bacterial meningitis should be treated with vancomycin and ceftriaxone or cefotaxime. The therapy is especially indicated if the Gram stain reveals gram-positive diplococci (see answer 1). Of course, susceptibility testing should be performed, and the antimicrobial therapy should be altered based on that laboratory testing.

3.
(E)
As a result of
H influenzae
and now
S pneumoniae
vaccination programs, the epidemiology of meningitis has changed with
H influenzae
, type b disease virtually absent in the United States and the incidence of pneumococcal meningitis drastically reduced. Importantly, these vaccines are not yet in the routine immunization programs of many nations.

4.
(E)
The differential diagnosis includes all of the diseases listed. Other possibilities include febrile seizures, encephalitis, and other unusual infectious agents, such as fungi or tuberculosis.

5.
(E)
Sensorineural hearing loss, hydrocephalus, SIADH, and extra-axial fluid collections are all complications of bacterial meningitis. In addition, seizures, cranial nerve involvement (as seen in this case), infarction, and disseminated intravascular coagulation can also occur.

6.
(D)
Bacterial meningitis is an important cause of acquired sensorineural deafness that can be caused by the infectious agent, especially
S pneumoniae
, or the use of ototoxic antibiotics. Before discharge, each child should have audiometry or brainstem auditory-evoked potentials in a younger child. If total deafness is observed, cochlear implants should be considered.

7.
(A)
Group B streptococcus and
L monocytogenes
can both cause bacterial meningitis in the neonate.
L monocytogenes
, however, although often considered, does so quite rarely.

8.
(E)
Listeria monocytogenes
is best treated with ampicillin and gentamicin. The gentamicin is added to provide synergy.

9.
(B)
This infant most likely has a neonatal HSV2 infection acquired during passage through an infected birth canal. Although the mother denied a history of vaginal or vesicular lesions, in most cases, infection occurs in children of asymptomatic mothers. Outside the neonatal period, HSV2 is a relatively rare cause of viral encephalitis. In older individuals, HSV1 is more likely to cause encephalitis with an estimated annual occurrence of 1 in 250,000-500,000 individuals. Most individuals acquire HSV1 from oral transmission.

HSV2 infection in neonates can be classified into 3 categories.

1. Encephalitis (localized CNS disease)

2. Skin, eye, mouth disease

3. Disseminated disease

In the case of localized disease, symptoms typically occur 2-3 weeks after birth. HSV2 seems to have a predilection for the insula, temporal cortex, and cingulate gyrus; however, focal abnormalities may be seen in other cortical regions. Unilateral and bilateral lesions can be observed on neuroimaging. In the past, HSV2 infection was more commonly thought of as a hemorrhagic encephalitis. This perception was based on postmortem studies before the widespread use of PCR as a diagnostic tool. As a result, it is now known that HSV encephalitis can occur without the presence of red blood cells in the CSF. In severe cases (those that resulted in the postmortem studies), red blood cells in the CSF are observed. CMV is the most frequent cause of intrauterine viral infection. Affected infants may be asymptomatic or have a petechial skin rash, intrauterine growth retardation, sensorineural hearing loss, hepatosplenomegaly, microcephaly, seizures, and/or retinitis. Periventricular calcifications can be observed on head CT. Although the clinical manifestations of HIV are highly variable, infants who acquire HIV vertically typically become symptomatic around 3 months of age. These children may present with failure to thrive, lymphadenopathy, neurologic disease, hepatomegaly, or with an opportunistic infection. Some children do not manifest symptoms for several years. Human herpes virus 6 causes roseola in children. It has been linked to encephalitis and myelitis in young children and adults. Incidentally, acyclovir seems to be an ineffective treatment, despite the fact that this virus is a member of the Herpesviridae family.

10.
(A)
Although HSV can be isolated by culture from CSF, the yield is relatively low (25-35%). As a result of this low yield, the use of PCR to detect HSV DNA has become routine in laboratory investigation. The sensitivity and specificity of this test are greater than 90%. An MRI of the brain or head CT may reveal destruction of the insular and temporal areas but is not specific for HSV. A head CT may be helpful in detecting intracranial calcifications seen following CMV infection, toxoplasmosis, or in utero HSV infection.

11.
(C)
The dose of acyclovir for treatment of neonatal herpes infection involving the CNS is 60 mg/kg per day in 3 divided doses given for 21 days, assuming normal renal function.

12.
(E)
HSV is acquired in utero in approximately 5% of cases. Under these circumstances, infants experience intrauterine growth retardation, cataracts, microcephaly, and vesicular rash. Intracranial calcifications are also observed.

13.
(A)
Lymphocytic choriomeningitis virus (LCMV) is acquired by inhalation of aerosolized virus or by direct contact with contaminated fomites. The natural host and reservoir is the common house mouse. The virus can be transmitted vertically if a pregnant woman acquires the virus and develops viremia. The virus can also be transmitted to the infant during delivery. Although a third of patients are asymptomatic and many develop a self-limited febrile illness, others may experience symptoms of an aseptic meningitis: fever, headache, nuchal rigidity, photophobia, and malaise. Most patients recover fully, although on rare occasions, LCMV can be fatal.

14.
(A)
This patient has an aseptic meningitis due to enterovirus (non-poliovirus) infection, most likely caused by echovirus. Other members of the enterovirus (non-poliovirus) family include group A coxsackie viruses, group B coxsackie viruses, echoviruses, and other unclassified enteroviruses. The illness is more common in children, and often the patients have a mild pharyngitis or other respiratory symptoms. A rash commonly occurs that varies in distribution. Treatment is primarily supportive.

15.
(C)
Cysticercosis is caused by
Taenia solium
, the pork tapeworm. It is the most common parasitic infection of the CNS. Headache, seizures, meningeal signs, neuropsychiatric symptoms, visual loss, and ataxia are common symptoms.
D latum
is a fish tapeworm, which causes vitamin B
₁₂
deficiency. The neurologic symptoms of this parasite are caused by the vitamin deficiency.
T multiceps
is a canine tapeworm that results in symptoms similar to cysticercosis with more pronounced ophthalmic involvement. This condition is extremely rare.
A cantonensis
is a nematode responsible for eosinophilic meningitis. Humans are infected by eating snails or shrimp.
P falciparum
is a parasite responsible for one kind of malaria.

16.
(E)
All of these anaerobic organisms have been isolated from brain abscesses. In addition, aerobic organisms, such as members of the genera
Staphylococcus, Streptococcus,
and
Haemophilus,
have been isolated as have Gram-negative enterics. Brain abscesses frequently contain more than one organism. Fungal brain abscesses can occur, primarily in immunocompromised hosts. The causal organism depends on the underlying condition: head injury, postoperative infection, chronic otitis media, and cardiac disease.

17.
(C)

18.
(B)
(See
Figure 133-1
.)

FIGURE 133-1
.
Erythema migrans due to
Borrelia burgdorferi
(Lyme Disease). (Reproduced, with permission, from McPhee SJ, Papadakis MA. Current Medical Diagnosis and Treatment 2010, 49th ed. New York: McGraw-Hill; 2010: Plate 32.)