10.5061/DRYAD.95X69P8JZ
Lashnits, Erin
0000-0003-0949-5698
North Carolina State University
North Carolina Institute of Medicine
Maggi, Ricardo
North Carolina State University
North Carolina Institute of Medicine
Jarskog, Fredrik
University of North Carolina
Bradley, Julie
North Carolina State University
North Carolina Institute of Medicine
Breitschwerdt, Edward
North Carolina State University
Frohlich, Flavio
University of North Carolina at Chapel Hill
University of North Carolina at Chapel Hill
Schizophrenia and Bartonella spp. infection: A pilot case–control study
Dryad
dataset
2021
National Center for Advancing Translational Sciences
https://ror.org/04pw6fb54
UL1TR002489
Office of the Director
https://ror.org/00fj8a872
T32OD011130
North Carolina State University
https://ror.org/04tj63d06
College of Veterinary Medicine Bartonella/Vector Borne Disease Research
Foundation Fund
2021-06-23T00:00:00Z
2021-06-23T00:00:00Z
en
https://doi.org/10.1089/vbz.2020.2729
49145 bytes
8
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Recently, infections with emerging zoonotic bacteria of the genus
Bartonella have been reported in association with a range of CNS symptoms.
Currently, it remains unknown if Bartonella spp. infection is
associated with symptoms of schizophrenia/schizoaffective disorder
(SCZ/SAD). The objective of this study was to determine if there is an
association between Bartonella species infection and SCZ/SAD. A secondary
objective was to determine if SCZ/SAD symptoms were more severe among
participants with documented Bartonella spp. infection. Using a
case–control study design, 17 cases and 13 controls were evaluated with a
series of clinical and cognitive assessments. Blood samples were collected
and tested for Bartonella spp. infection using serological,
microbiological, and molecular techniques. People with SCZ/SAD were more
likely than healthy volunteers to have Bartonella spp. DNA in their
bloodstream, with 11 of 17 cases (65%) positive by Bartonella spp. droplet
digital PCR (ddPCR). In comparison, only one healthy volunteer was
Bartonella spp. ddPCR positive (8%, p = 0.0024). Based on serology,
Bartonella spp. exposure was common among people with SCZ/SAD (12 of 17)
as well as among healthy volunteers (12 of 13), with no significant
difference between the groups ( p = 0.196). Within the case group of
people with SCZ/SAD, there was no significant difference in SCZ/SAD
severity scores between people with and without ddPCR evidence of
Bartonella spp. infection. This pilot study provides preliminary evidence
in support of future investigations that should examine a
potential contribution of Bartonella spp. infection to SCZ/SAD.
Study Design and Setting This was a prospective case-control study
conducted at University of North Carolina-Chapel Hill and approved by the
UNC-Chapel Hill Biomedical Institutional Review Board (#19-0114).
Participants were enrolled between March 1 and October 31, 2019. Cases
were recruited from the local community using fliers and newspaper
advertisements. Controls were healthy volunteers recruited from the
surrounding local community via targeted online and email advertising. To
minimize selection bias, recruitment material did not specify the purpose
of the study. Participants provided written informed consent prior to
enrollment and were compensated $80 for their time. This manuscript was
prepared in accordance with STROBE guidelines for case-control studies;
the checklist is included as supplementary material.(Vandenbroucke et al.,
2007) Participants Inclusion criteria for cases was a diagnosis of
schizophrenia or schizoaffective disorder (confirmed by the Structured
Clinical Interview for DSM-V); clinical stability as demonstrated by no
psychiatric hospitalizations for the past 3 months; stable dosing of
antipsychotic medications (no changes in medication or dose for 1 month
prior to enrollment); ability to provide written informed consent; and at
least one set of blood samples collected for microbiological and molecular
testing. Controls were considered healthy based on self-reported health
status, and were excluded if reporting a previous diagnosis of
schizophrenia or schizoaffective disorder. Controls were included from a
local volunteer population, expected to have similar Bartonella spp.
exposures. Variables, Data Sources, and Measurement Whole blood and serum
were collected from each participant. To increase the likelihood for
detection of intermittent bacteremia, blood was collected twice within a
one-week period.(Pultorak et al., 2013) As described previously,(Edward B.
Breitschwerdt et al., 2019; Lantos et al., 2014; Maggi et al., 2011) each
participant was tested using six indirect fluorescent antibody (IFA)
assays, each representing a unique Bartonella species or subspecies.
Bartonella vinsonii subsp. berkhoffii (genotypes I, II, and III), B.
henselae, B. koehlerae, and B. quintana IgG antibodies were determined
using cell culture-grown bacteria as antigens and following standard IFA
techniques. A sample was considered Bartonella spp. seroreactive at an IFA
titer of ≥1:64 for any one or more antigen. Bartonella alpha
proteobacteria growth medium (BAPGM) enrichment blood culture and qPCR was
performed as previously described.(Edward B. Breitschwerdt et al., 2019)
Briefly, qPCR targeting the Bartonella intergenic 16S-23S rRNA (ITS)
region was performed on DNA extracted from the following: each whole blood
sample, and whole blood culture-enriched in BAPGM at 7, 14, and 21 days of
culture. A sample was considered BAPGM/qPCR positive if any one or more of
these four qPCR tests was positive on any one or more sample. In addition
to BAPGM/qPCR, all blood and BAPGM enrichment blood culture DNA
extractions were tested for Bartonella spp. DNA by droplet digital PCR
(ddPCR) using the QX200 Droplet Digital PCR (Bio-Rad, Hercules, CA)
system. Digital PCR amplification of the Bartonella 16S-23S ITS region,
and the human hydroxymethylbilane synthase (HMBS) as house-keeping human
reference gene, was conducted as previously validated and described.(Maggi
et al., 2020) Bio-Rad QuantaSoft Analysis Pro software was utilized to
analyze the fluorescent drop distribution and to define the positive DNA
detection thresholds for each channel (FAM channel 1 for Bartonella, and
HEX channel 2 for house-keeping gene amplification). A sample was
considered BAPGM/ddPCR positive if any one or more of these four ddPCR
tests was positive on any one or more whole blood sample. For the primary
aim, study participants were considered to have Bartonella spp. exposure
if they were Bartonella spp. seroreactive at an IFA titer of ≥1:64 for any
one or more antigen. Participants were considered to have Bartonella spp.
infection if they were positive on any one or more BAPGM/qPCR or
BAPGM/ddPCR assay. All Bartonella testing was performed by researchers
blinded to participant identity and group assignment. SCZ/SAD symptom
severity was measured with a series of clinical and cognitive assessments
including the Positive and Negative Syndrome Scale (PANSS),(Kay et al.,
1988) Brief Assessment of Cognition in Schizophrenia (BACS),(Keefe et al.,
2004) and Quality of Life Enjoyment and Satisfaction Questionnaire
(Q-LES).(Ritsner et al., 2005) PANSS results were analyzed using the
positive, negative, and general symptom subscores, and a total PANSS
score. BACS results for each primary measure were first converted to Z
scores, then the Z scores from each primary measure were averaged to
create a BACS composite score. For the Q-LES, the results were normalized
to the possible total score and reported as a percentage. Data on possible
confounders or effect modifiers was collected with a questionnaire (health
history questionnaire, Supplementary material 2) assessing employment,
geographic location, health history, and animal and insect vector contact.
See metadata tab and supplementary file #2 (Bartonella health history
questionnaire).