TY - JOUR

T1 - Antibody response against Mycobacterium avium complex in cystic fibrosis patients measured by a novel IgG ELISA test

AU - Ravnholt, C.

AU - Qvist, T.

AU - Kolpen, M.

AU - Pressler, T.

AU - Skov, M.

AU - Høiby, N.

PY - 2019

Y1 - 2019

N2 - Background: Early signs of Mycobacterium avium complex pulmonary disease can be missed in patients with cystic fibrosis due to subclinical infection or delays in mycobacterial culture. The aim of this study was to determine the diagnostic accuracy of a novel enzyme linked immunosorbent assay for immunoglobulin G against Mycobacterium avium complex, which could help stratify patients according to risk. Methods: A retrospective cross sectional analysis of serum samples from the Copenhagen Cystic Fibrosis Center was performed. Corresponding clinical data were reviewed and patients with cystic fibrosis were assigned to one of four groups based on their mycobacterial culture results. In addition, anti-Mycobacterium avium complex immunoglobulin G levels were measured longitudinally before and after first positive culture in the period 1984–2015. Results: Three-hundred and five patients with cystic fibrosis were included with a median of five nontuberculous mycobacterial cultures. Four individuals had Mycobacterium avium complex pulmonary disease at the time of cross sectional testing and their median antibody level was 22-fold higher than patients with no history of infection (1820 vs. 80 IgG units; p < 0.001). Test sensitivity was 100% (95% CI 40–100) and specificity 77% (95% CI 72–81). Longitudinal kinetics showed rising antibodies prior to first positive culture suggesting diagnostic delay. Conclusions: Antibody screening for Mycobacterium avium complex may be used as a supplement to culture. Although confirmation in a larger cohort is needed, our findings suggest that stratifying a cystic fibrosis population into high- and low-risk groups based on antibody levels may help clinicians identify patients in need of more frequent culture.

AB - Background: Early signs of Mycobacterium avium complex pulmonary disease can be missed in patients with cystic fibrosis due to subclinical infection or delays in mycobacterial culture. The aim of this study was to determine the diagnostic accuracy of a novel enzyme linked immunosorbent assay for immunoglobulin G against Mycobacterium avium complex, which could help stratify patients according to risk. Methods: A retrospective cross sectional analysis of serum samples from the Copenhagen Cystic Fibrosis Center was performed. Corresponding clinical data were reviewed and patients with cystic fibrosis were assigned to one of four groups based on their mycobacterial culture results. In addition, anti-Mycobacterium avium complex immunoglobulin G levels were measured longitudinally before and after first positive culture in the period 1984–2015. Results: Three-hundred and five patients with cystic fibrosis were included with a median of five nontuberculous mycobacterial cultures. Four individuals had Mycobacterium avium complex pulmonary disease at the time of cross sectional testing and their median antibody level was 22-fold higher than patients with no history of infection (1820 vs. 80 IgG units; p < 0.001). Test sensitivity was 100% (95% CI 40–100) and specificity 77% (95% CI 72–81). Longitudinal kinetics showed rising antibodies prior to first positive culture suggesting diagnostic delay. Conclusions: Antibody screening for Mycobacterium avium complex may be used as a supplement to culture. Although confirmation in a larger cohort is needed, our findings suggest that stratifying a cystic fibrosis population into high- and low-risk groups based on antibody levels may help clinicians identify patients in need of more frequent culture.

KW - Accuracy

KW - Diagnostic

KW - Mycobacterium avium

KW - Nontuberculous

KW - Serology

U2 - 10.1016/j.jcf.2018.11.011

DO - 10.1016/j.jcf.2018.11.011

M3 - Journal article

C2 - 30503330

AN - SCOPUS:85057369858

VL - 18

SP - 516

EP - 521

JO - Journal of Cystic Fibrosis

JF - Journal of Cystic Fibrosis

SN - 1569-1993

IS - 4

ER -