Sm. Standaert et al., Primary isolation of Ehrlichia chaffeensis from patients with febrile illnesses: Clinical and molecular characteristics, J INFEC DIS, 181(3), 2000, pp. 1082-1088
Ehrlichia chaffeensis was sought among patients with a history of tick expo
sure and fever, and the accuracy of other diagnostic tests was compared wit
h that of primary isolation. Among the 38 patients enrolled, E. chaffeensis
was isolated from the blood of 7 (18%) and from cerebrospinal fluid specim
ens of 2 of these 7. All 7 patients also were positive by polymerase chain
reaction (PCR) of blood, and 6 patients developed diagnostic titers of anti
body to E. chaffeensis. The isolates were characterized by molecular analys
is of the 16S rRNA gene, the 120-kDa protein gene, and the variable-length
PCR target (VLPT) of E. chaffeensis. On the basis of the 120-kDa and VLPT g
enotypes, the cerebrospinal fluid and blood isolates from the same patients
were identical. This study demonstrates that both PCR and culture of blood
for E. chaffeensis have high diagnostic yields. More frequent isolation of
E. chaffeensis from patients with infection should further our understandi
ng of the pathogenesis of this infection.