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Volume 29, Number 1—January 2023
Dispatch

Using Serum Specimens for Real-Time PCR-Based Diagnosis of Human Granulocytic Anaplasmosis, Canada

Carl BoodmanComments to Author , Courtney Loomer, Antonia Dibernardo, Todd Hatchette, Jason J. LeBlanc, Brooks Waitt, and L. Robbin Lindsay
Author affiliations: University of Manitoba, Winnipeg, Manitoba, Canada (C. Boodman); National Microbiology Laboratory, Winnipeg (C. Loomer, A. Dibernardo, B. Waitt, L.R. Lindsay); Dalhousie University and Nova Scotia Health, Halifax, Nova Scotia, Canada (T. Hatchette, J.J. LeBlanc)

Main Article

Table 2

Comparison between PCR-positive acute serum samples and paired convalescent serum samples in study using serum specimens for real-time PCR-based diagnosis of human granulocytic anaplasmosis, Canada*

Sample no. Acute serum samples
 Convalescent serum samples
 Time, d† Conversion‡
IFA titer Ct-I Ct-R PCR status IFA Ct-I Ct-R PCR status
1 <1:64 23.7 24.7 Positive 1:128 40.0 NA Negative 24 Yes
2 <1:64 24.3 NS Positive 1:512 35.5 NS Positive 33 Yes
3 <1:64 25.1 NS Positive <1:64 27.6 NS Positive 42 No
4 <1:64 25.8 NS Positive 1:1024 39.9 37.1 Positive 13 Yes
5 <1:64 26.8 NS Positive 1:512 40.0 NA Negative 56 Yes
6 1:64 28.0 25.3 Positive 1:256 40.0 NA Negative 49 Yes
7 1:2048 28.2 30.4 Positive 1:2048 40.0 NA Negative 12 No
8 <1:64 28.8 28.1 Positive 1:128 40.0 NA Negative 21 Yes
9 <1:64 29.7 NS Positive <1:64 40.0 NA Negative 39 No
10 1:1024 31.0 29.9 Positive 1:1024 40.0 NA Negative 28 No
11 <1:64 31.2 31.4 Positive <1:64 40.0 NA Negative 0 No
12 <1:64 31.7 31.7 Positive 1:256 40.0 NA Negative 51 Yes
13 1:1024 32.4 32.8 Positive 1:256 39.8 40.0 Negative 8 No
14 <1:64 32.4 33.4 Positive 1:256 40.0 NA Negative 38 Yes
15 1:512 32.8 31.7 Positive 1:512 40.0 NA Negative 27 No
16 <1:64 34.7 36.3 Positive <1:64 40.0 NA Negative 38 No
17 1:1024 35.6 36.3 Positive 1:512 40.0 NA Negative 57 No
18 <1:64 36.1 37.8 Positive 1:64 40.0 NA Negative 10 No
19 <1:64 37.5 36.8 Positive 1:256 40.0 NA Negative 46 Yes

*Only Ct values <40 were deemed positive. Ct, cycle threshold; Ct-I, initial Ct values (in duplicate); Ct-R, confirmatory Ct values for repeat extraction; IFA, indirect immunofluorescence assay; NA, not applicable; NS, no sample remaining for repeat extraction. †Time difference between acute and convalescent serum sampling. ‡Seroconversion was defined as >4-fold increase in IFA titer between acute and convalescent samples.

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Page created: November 16, 2022
Page updated: December 22, 2022
Page reviewed: December 22, 2022
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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