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Journal of Clinical Microbiology, Oct 1997, 2496-2502, Vol 35, No. 10
CD Paddock, JW Sumner, GM Shore, DC Bartley, RC Elie, JG McQuade, CR Martin, CS Goldsmith and JE Childs
Two new isolates of Ehrlichia chaffeensis (designated Jax and St. Vincent)
were obtained from patients with fatal ehrlichial infections. Patients
developed characteristic manifestations of severe disease due to E.
chaffeensis, including marked thrombocytopenia, pulmonary insufficiency,
and encephalopathy. Primary isolation was achieved in DH82 cells; the Jax
and St. Vincent isolates were detected within 19 and 8 days
postinoculation, respectively. The isolates were characterized by molecular
evaluation of the 16S rRNA gene, the groESL heat shock operon, a 120-kDa
immunodominant protein gene, and an incompletely characterized
repetitive-motif sequence (variable-length PCR target [VLPT]). The
sequences were compared with those of the corresponding molecular regions
in the type isolate (Arkansas). St. Vincent contained one fewer repeat unit
in both the 120-kDa protein gene and the VLPT compared with corresponding
sequences of the Jax and Arkansas isolates. 16S rRNA gene sequences from
the two new isolates had 100% identity to the corresponding sequences of
the 91HE17 and Sapulpa isolates of E. chaffeensis, and to the corrected 16S
rRNA gene sequence of the Arkansas isolate. The Jax isolate grew more
slowly than the St. Vincent isolate in DH82 cells, and both of the new
isolates grew more slowly than the extensively passaged Arkansas isolate.
Although specific associations between ehrlichial pathogenicity and
genotype were not identified from these comparisons, recovery of this
organism from a spectrum of clinical presentations remains an integral step
in understanding mechanisms of disease caused by E. chaffeensis.
Copyright © 1997 by the American Society for Microbiology. All rights reserved.
Isolation and characterization of Ehrlichia chaffeensis strains from patients with fatal ehrlichiosis
Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. cdp9@cdc.gov
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