morbidity and mortality over the second-line drug, chloramphenicol, and doxycycline also treats ehrlichiosis, which can present with symptoms similar to RMSF Doxycycline is the preferred treatment for RMSF in children of all ages, unless a child has a severe doxycycline allergy Babesiosis Babesiosis is caused by Babesia microti, an intraerythrocytic parasite whose symptoms mimic those of malaria in persons who lack a travel history to a malarial-endemic region Babesiosis is seen in the northeastern and upper Midwestern United States; it is transmitted by the same Ixodes ticks that transmit Lyme disease and has also been transmitted via blood transfusion Symptoms include fever and influenza-like illness; signs can be minimal, but in more severe cases, tachypnea, hypotension, icterus, and mild hepatosplenomegaly can be seen Disease can be severe in asplenic patients, who have very high parasite burdens The diagnosis is made by thick and thin blood smears demonstrating the organism’s classic Maltese cross form within erythrocytes Treatment is azithromycin with atovaquone or clindamycin with quinine for to 10 days Exchange transfusion may be needed for patients with parasitemia above 10% CNS INFECTIOUS EMERGENCIES Meningitis, Bacterial CLINICAL PEARLS AND PITFALLS The most common causes of meningitis in the first month of life are GBS and gram-negative rods; beyond the first month of life, the most common etiologies are pneumococcus and meningococcus The “classic” signs and symptoms of meningitis, including nuchal rigidity, are insensitive in infancy The Gram stain of the cerebrospinal fluid (CSF) should be used to broaden, but not to narrow, empiric antibiotic selection Empiric antibiotic therapy should comprise bactericidal agents that cross the blood–brain barrier For neonates, ampicillin and either cefotaxime or ceftriaxone can be used For infants and older children, vancomycin (for enhanced pneumococcal coverage) and either cefotaxime or ceftriaxone (for meningococcal coverage) should be utilized In neonates and young infants with a CSF pleocytosis, addition of acyclovir (20 mg/kg every hours) is reasonable until herpes simplex virus (HSV) is excluded Current Evidence The most common causes of bacterial meningitis by age are listed in Table 94.3 In the first month of life, Escherichia coli and GBS are usually isolated; Listeria monocytogenes, a gram-positive rod, accounts for 1% to 3% of the cases Between 30 and 60 days of age, GBS continues to be recovered frequently, followed by S pneumoniae and Neisseria meningitidis; Hib occurs rarely After the first months of life, S pneumoniae and N meningitidis cause the majority of meningeal infections; Haemophilus influenzae remains a consideration primarily among children not immunized with conjugated Hib vaccine Salmonella, an uncommon etiologic agent in the United States, should be suspected in the first few months of life if meningitis occurs in association with gastroenteritis The incidence of acute bacterial meningitis has declined in the last three decades due to widespread use of the Hib and polyvalent pneumococcal conjugate vaccines