Open Access Open Badges Research article

Persistent Chlamydia Pneumoniae serology is related to decline in lung function in women but not in men. Effect of persistent Chlamydia pneumoniae infection on lung function

Thorarinn Gislason12, Vilmundur Guðnason13, Bryndis Benediktsdottir1, Isleifur Olafsson4, Thor Aspelund13, Bjarni Thjodleifsson12 and Christer Janson5*

Author Affiliations

1 University of Iceland, Faculty of Medicine, Reykjavik, Iceland

2 Department of Medicine Landspitali University Hospital, Reykjavik, Iceland

3 Icelandic Heart Association, Kopavogur, Iceland

4 Department of Clinical Biochemistry, Landspitali University Hospital, Reykjavik, Iceland

5 Respiratory Medicine and Allergology, Uppsala University, Uppsala, Sweden

For all author emails, please log on.

BMC Pulmonary Medicine 2010, 10:44  doi:10.1186/1471-2466-10-44

Published: 25 August 2010



Chlamydia pneumoniae (C pn) infection causes an acute inflammation in the respiratory system that may become persistent, but little is known about the long-term respiratory effects of C pn infections. Aim: To estimate the long term respiratory effects of C pn with change in forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) as a main outcome variable.


The study comprised of 1109 subjects (500 men and 609 women, mean age 28 ± 6 years) that participated in the Reykjavik Heart Study of the Young. Spirometry and blood samples for measurements of IgG antibodies for C pn were done at inclusion and at the end of the follow-up period (mean follow-up time 27 ± 4 years).


Having IgG against C pn at both examinations was significantly associated to a larger decrease in FEV1 (6 mL/year) and FVC (7 mL/year) in women but not in men. In women the association between C pn and larger FEV1 decline was only found in women that smoked at baseline where having C pn IgG was associated with 10 mL/year decline compared to smokers without C pn IgG. These results were still significant after adjustment for age, smoking and change in body weight.


Our results indicate that persistent C pn serology is related to increased decline in lung function in women but not in men. This effect was, however, primarily found in smoking women. This study is a further indication that the pathophysiological process leading to lung impairment may differ between men and women.