420 Emergency Medicine
Treatment includes either oral or topical antibiotic therapy. Options include
erythromycin or cephalexin; linezolid may be used in resistant cases of
Staphylococcus. Topical therapy with mupirocin is very effective. Hand wash-
ing is critical to also limit the spread of infection to other family members.
Treatment of the skin lesions does not prevent the development of nephritis.
Group B Streptococcus(a)does not generally cause impetigo. It is a well-
known cause severe perinatal infection, such as pneumonia and meningitis.
Staphylococcus aureus(b)is commonly associated with impetigo and is usu-
ally mixed with Streptococcus.Staphylococcus aureusis the sole isolate in 10%
of cases. Therefore, it is important to treat for both organisms. Streptococcus
pneumoniae(d)is a well-known pathogen involved in many types of infec-
tion. It is one of the most common agents found in osteomyelitis, pneumo-
nia, meningitis, pericarditis, peritonitis, and cellulitis. But it does not usually
cause impetigo. Salmonella(e)is known to cause infectious diarrhea, menin-
gitis, and osteomyelitis, particularly in sickle-cell patients.
371.The answer is d.(Fleischer and Ludwig, pp 834-835.)This is a case of
erythema infectiosumorFifth disease.Infection by parvovirus B19pro-
duces this pattern of a “slapped cheek” appearance.It is characterized by
an eruption that presents initially as an erythematous malar blush followed
by an erythematous maculopapular eruption on the extensor surfaces of
extremities that evolves into a reticulated, lacy, mottled appearance. Fever
and other symptoms may be present but are uncommon. In patients with
chronic hemolytic anemiaslike sickle-cell disease, aplastic anemiais a
serious complication. Pregnant women should avoid exposure to this virus,
since it may cause fetal hydrops in 10% of cases.
Sickle-cell patients can develop osteomyelitis (a),however, the clinical
presentation is inconsistent. Patients with osteomyelitis caused by Salmonella
species are generally those with sickle-cell disease. However, the most com-
mon organism that causes osteomyelitis in patients with sickle-cell disease is
S aureus. Encephalitis (b)is an inflammation of the brain parenchyma and is
not commonly caused by parvovirus. Common etiologic agents include her-
pes simplex, herpes zoster, varicella-zoster, West Nile virus, and toxoplasmosis.
Pneumonia(c)is a common diagnosis in patients of all ages. In children, the
most common causative agents are viral. The most commonly found bacterial
agent is S pneumonia.Meningitis(e)is an infection of the meninges that sur-
round the brain. It is caused by viral and bacterial entities. The most common
bacterial agents include: E coli, group B Streptococcus, and L monocytogenesin
very young infants and S pneumonia,N meningitides, and H influenzain older
children.