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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 1

Comparison of PCR values for serum and whole blood samples in study using serum specimens for real-time PCR-based diagnosis of human granulocytic anaplasmosis, Canada*

Sample no. IFA titer Serum Ct values
 Whole blood Ct values
 ∆Ct Td‡
Ct-I Ct-R Average† Result Ct-I Ct-R Average† Result
1 <1:64 19.9 NS 19.9 Positive 17.7 16.1 16.9 Positive 3 5
2 <1:64 21.8 NS 21.8 Positive 22 21.1 21.55 Positive 0.25 3
3 <1:64 22.8 21.8 22.3 Positive 22.1 21.5 21.8 Positive 0.5 0
4 <1:64 22.9 NS 22.9 Positive 18.5 17.9 18.2 Positive 4.7 0
5 <1:64 23 22.5 22.75 Positive 20.5 19.7 20.1 Positive 2.65 1
6 <1:64 23.3 22.1 22.7 Positive 19.1 18.1 18.6 Positive 4.1 1
7 <1:64 24.2 24.2 24.2 Positive 21.2 20.9 21.05 Positive 3.15 1
8 1:2048 25 25.8 25.4 Positive 22 21.9 21.95 Positive 3.45 0
9 <1:64 26.6 26 26.3 Positive 24.6 25.4 25 Positive 1.3 0
10 <1:64 26.6 25.6 26.1 Positive 23.2 23.5 23.35 Positive 2.75 0
11 1:512 27 NS 27 Positive 24.8 25.3 25.05 Positive 1.95 2
12 1:64 28 25.3 26.65 Positive 28.6 29.2 28.9 Positive −2.25 0
13 <1:64 28.6 27.5 28.05 Positive 23 22.6 22.8 Positive 5.25 0
14 <1:64 28.8 28.1 28.45 Positive 33 33.3 33.15 Positive −4.7 3
15 <1:64 29.2 28.3 28.75 Positive 27.7 27.1 27.4 Positive 1.35 0
16 1:2048 29.9 27.4 28.65 Positive 26.9 27 26.95 Positive 1.7 0
17 1:64 30 29.2 29.6 Positive 22 21.8 21.9 Positive 7.7 0
18 <1:64 31.7 31.7 31.7 Positive 30.5 30.2 30.35 Positive 1.35 0
19 <1:64 32.4 33.5 32.95 Positive 26.4 26.2 26.3 Positive 6.65 0
20 1:512 32.8 31.7 32.25 Positive 37 36.5 36.75 Positive −4.5 8
21 <1:64 36.4 37.8 37.1 Positive 37.8 37.8 37.8 Positive −0.7 0
22 <1:64 36.5 35.8 36.15 Positive 28.4 28.5 28.45 Positive 7.7 0
23 <1:64 36.7 36 36.35 Positive 32.5 32.7 32.6 Positive 3.75 0
24 <1:64 37.7 36.3 37 Positive 34 34 34 Positive 3 0
25 1:1024 37.8 37.4 37.6 Positive 32 32 32 Positive 5.6 0
26 1:256 38.2 38.3 38.25 Positive 25.1 24.8 24.95 Positive 13.3 −84
27 <1:64 38.3 40 39.15 Negative 37.2 37.6 37.4 Positive 1.75 0
28 <1:64 38.4 35.3 36.85 Positive 24.1 24.2 24.15 Positive 12.7 −4
29 <1:64 38.8 38.2 38.5 Positive 31.3 31.2 31.25 Positive 7.25 0
30 <1:64 40 38.3 39.15 Negative 38.9 39.5 39.2 Positive −0.05 0
31 <1:64 40 40 40 Negative 35.3 36.7 36 Positive 4 0
32 1:64 40 40 40 Negative 33.4 32.9 33.15 Positive 6.85 0
33 <1:64 40 40 40 Negative 30.9 31.0 30.95 Positive 9.05 0

*Only Ct values <40 after repeat extraction were deemed positive. Ct, cycle threshold; Ct-I, Ct values for initial extraction; Ct-R, confirmatory Ct values for repeat extraction; ∆Ct, difference between average serum Ct and average whole blood Ct; IFA, indirect immunofluorescence assay; NS, no sample remaining for repeat extraction; Td, time difference in days between serum sampling (earlier) and whole blood sampling (later). †Average of Ct-I and Ct-R for each isolate. ‡Negative numbers indicate that whole blood was sampled before serum samples.

Main Article

Page created: November 16, 2022
Page updated: December 22, 2022
Page reviewed: December 22, 2022
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