No diagnostic utility of antibody patterns against Klebsiella pneumoniae capsular serotypes in patients with axial spondyloarthritis vs. patients with non-specific low back pain: a cross-sectional study.
OBJECTIVE
To investigate whether antibody response patterns against Klebsiella pneumoniae capsular serotypes can discriminate patients with axial spondyloarthritis (axSpA) from patients with non-specific low back pain (LBP).


METHODS
Immunoglobulin (Ig)G and IgA antibodies against K. pneumoniae capsular serotypes K2, K26, K36, and K50 were measured, and antibody seropositivity compared between groups and analysed for patient correlation in five different groups: (a) 96 patients fulfilling the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for axSpA; (b) 38 patients with either a positive magnetic resonance imaging (MRI) scan as defined by ASAS or a positive human leucocyte antigen (HLA)-B27 status plus one clinical SpA feature, characterized as 'non-axSpA'; (c) 82 non-specific LBP patients; (d) 40 healthy blood donors and (e) 43 patients with diagnosed ankylosing spondylitis (AS) served as the negative and positive control groups.


RESULTS
There was no difference in IgG and IgA seropositivity against all serotypes between the axSpA, non-axSpA, and LBP groups. No significant correlations were found between anti-Klebsiella antibodies and age, gender, HLA-B27, or high-sensitivity C-reactive protein (hsCRP). IgG seropositivity against K50 was more frequent in AS (25.6%) than in axSpA (13.5%, p < 0.05). axSpA patients with radiographic sacroiliitis and AS controls concordantly had the highest frequency of seropositivity for ≥ 2 serotypes (21%).


CONCLUSIONS
The antibody patterns against K. pneumoniae serotypes K2, K26, K36, and K50 did not discriminate between early axSpA and non-specific LBP.
a King Christian 10th Hospital for Rheumatic Diseases , Gråsten , Denmark.|b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.
L T
http://orcid.org/0000-0001-8116-0812
LT
Hermansen
c Department of Medicine , Hospital Lillebælt , Vejle , Denmark.|d Department of Rheumatology , Aarhus University Hospital , Aarhus , Denmark.
A G
AG
Loft
a King Christian 10th Hospital for Rheumatic Diseases , Gråsten , Denmark.|b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.
A A
http://orcid.org/0000-0002-3051-5019
AA
Christiansen
e Department of Rheumatology , Odense University Hospital , Odense , Denmark.|f Institute of Clinical Research , University of Southern Denmark , Odense , Denmark.
H L
HL
Munk
g Department of Biology and Environmental Science and NanoScience Centre , University of Jyväskylä , Jyväskylä , Finland.
L
http://orcid.org/0000-0002-7470-5770
L
Gilbert
h Department of Radiology , Aarhus University Hospital , Aarhus , Denmark.|i Research Department , Spine Centre of Southern Denmark, Hospital Lillebælt , Middelfart , Denmark.
A G
AG
Jurik
b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.|i Research Department , Spine Centre of Southern Denmark, Hospital Lillebælt , Middelfart , Denmark.
B
B
Arnbak
b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.|i Research Department , Spine Centre of Southern Denmark, Hospital Lillebælt , Middelfart , Denmark.
C
C
Manniche
a King Christian 10th Hospital for Rheumatic Diseases , Gråsten , Denmark.|b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.
U
U
Weber
j Copenhagen Centre for Arthritis Research , Centre for Rheumatology and Spine Diseases, Rigshospitalet , Glostrup , Copenhagen , Denmark.
M
M
Østergaard
j Copenhagen Centre for Arthritis Research , Centre for Rheumatology and Spine Diseases, Rigshospitalet , Glostrup , Copenhagen , Denmark.
S J
http://orcid.org/0000-0002-6500-9263
SJ
Pedersen
k Department of Clinical Immunology , Odense University Hospital , Odense , Denmark.
T
http://orcid.org/0000-0001-6968-148X
T
Barington
e Department of Rheumatology , Odense University Hospital , Odense , Denmark.|f Institute of Clinical Research , University of Southern Denmark , Odense , Denmark.
P
P
Junker
a King Christian 10th Hospital for Rheumatic Diseases , Gråsten , Denmark.|b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.
K
http://orcid.org/0000-0002-5475-7610
K
Hørslev-Petersen
a King Christian 10th Hospital for Rheumatic Diseases , Gråsten , Denmark.|b Institute of Regional Health Research , University of Southern Denmark , Odense , Denmark.
O
O
Hendricks
D000293:Adolescent; D000328:Adult; D000907:Antibodies, Bacterial / Q000276:immunology*; D016667:Bacterial Capsules / Q000276:immunology; D002097:C-Reactive Protein / Q000276:immunology; D016022:Case-Control Studies; D003718:Denmark; D005260:Female; D015796:HLA-B27 Antigen / Q000235:genetics; D006801:Humans; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007711:Klebsiella pneumoniae / Q000276:immunology*; D017116:Low Back Pain / Q000276:immunology*; D008279:Magnetic Resonance Imaging; D008297:Male; D058566:Sacroiliitis / Q000000981:diagnostic imaging / Q000235:genetics / Q000276:immunology*; D065288:Serogroup; D025242:Spondylarthropathies / Q000000981:diagnostic imaging / Q000235:genetics / Q000276:immunology*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging / Q000235:genetics / Q000276:immunology; D055815:Young Adult
D000907:Antibodies, Bacterial; D015796:HLA-B27 Antigen; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D002097:C-Reactive Protein