Infections withEhrlichia chaffeensisandEhrlichia ewingiiin Persons Coinfected with Human Immunodeficiency Virus

Abstract

The clinical course and laboratory evaluation of 21 patients coinfected with human immunodeficiency virus (HIV) and Ehrlichia chaffeensis or Ehrlichia ewingii are reviewed and summarized, including 13 cases of ehrlichiosis caused by E. chaffeensis, 4 caused by E. ewingii, and 4 caused by either E. chaffeensis or E. ewingii. Twenty patients were male, and the median CD4(+) T lymphocyte count was 137 cells/microL. Exposures to infecting ticks were linked to recreational pursuits, occupations, and peridomestic activities. For 8 patients, a diagnosis of ehrlichiosis was not considered until > or =4 days after presentation. Severe manifestations occurred more frequently among patients infected with E. chaffeensis than they did among patients infected with E. ewingii, and all 6 deaths were caused by E. chaffeensis. Ehrlichiosis may be a life-threatening illness in HIV-infected persons, and the influence of multiple factors, including recent changes in the epidemiology and medical management of HIV infection, may increase the frequency with which ehrlichioses occur in this patient cohort.

Detection of Medically Important Ehrlichia by Quantitative Multicolor TaqMan Real-Time Polymerase Chain Reaction of the dsb Gene

“…11 Two studies have demonstrated the high clinical sensitivity of PCR in patients when the organism was concurrently isolated from the blood or in patients co-infected with human immunodeficiency virus. 11,15,24 However, in another study, a substantial number of confirmed cases of HME had undetectable ehrlichial DNA by PCR. 25 Because of the limited data available and lack of a standard PCR protocol, current recommendations for the diagnosis of HME suggest that PCR is a valuable adjunct to IFA.…”

“…15,19 E. canis-infected dogs were experimentally inoculated and monitored for ehrlichiae in peripheral blood by PCR amplification of the p28 gene. PCR of E. canis p28 was conducted by the Louisiana State University Veterinary Medical Diagnostic Laboratory using primers ECa282F239, 5Ј-CAA GCA GCA GCC ACA CAA T-3Ј (forward), and ECa28R701, 5Ј-GAT GCT TCT GGG CTT ATG GAG TA-3Ј (reverse), with thermal cycling protocol of 10 minutes at 95°C, 40 cycles of 95°C for 30 seconds, 50°C for 1 minute, and 72°C for 1 minute and finished with 10 minutes at 72°C as previously described.…”

“…The specificity of the dsb real-time assay matched previous results obtained using a nested 16S rRNA assay. 15 One sample was negative by dsb real-time PCR (three independent DNA extractions). These DNA templates (three) were subsequently retested by the laboratory of origin, and E. ewingii was detected in one of the samples.…”

“…A limited number of gene targets have been available for genus-and species-specific detection of Ehrlichia infections because of the inability to culture some Ehrlichia species and the lack of genomic sequence information. PCR and reverse transcriptase PCRbased assays for E. chaffeensis, E. ewingii, and E. canis have most commonly targeted the 16S rRNA gene, 3,[12][13][14][15] but other genes including the variable-length PCR target, groESL, and p28 have been used for detection of these ehrlichiae. 11,16 -18 Because of increased analytical sensitivity, nested PCR has been used routinely for detection of ehrlichemia, 3,10,11,19,20 but it involves additional cost and labor and can be more susceptible to false positives as a result of exogenous contamination.…”

Characteristic peripheral blood findings in human ehrlichiosis

“…A rapid and inexpensive method to diagnose ehrlichiosis is by identification of morulae on Wright's-stained peripheral blood films. The literature regarding the prevalence of and morphologic descriptions of peripheral blood films containing infected white blood cells in confirmed cases of ehrlichiosis is limited, 21 so the detection rate and Figure 1 Atypical lymphocytes were more commonly seen in Ehrlichia-infected cases. They were typically large, with hyperchromatic nuclei, abundant basophilic cytoplasm, and contained prominent cytoplasmic granules (Wright's-stained blood film, patient 6, original magnification  300).…”