Journal Article

Identification of Risk Factors for Infection in an Outbreak of <i>Mycoplasma pneumoniae</i> Respiratory Tract Disease

Eyal Klement, Deborah F. Talkington, Oshri Wasserzug, Raid Kayouf, Nadav Davidovitch, Roger Dumke, Yael Bar-Zeev, Merav Ron, Jonathan Boxman, W. Lanier Thacker, Dana Wolf, Tsilia Lazarovich, Yonat Shemer-Avni, Daniel Glikman, Enno Jacobs, Itamar Grotto, Colin Block and Ran Nir-Paz

in Clinical Infectious Diseases

Published on behalf of Infectious Diseases Society of America

Volume 43, issue 10, pages 1239-1245
Published in print November 2006 | ISSN: 1058-4838
Published online November 2006 | e-ISSN: 1537-6591 | DOI:
Identification of Risk Factors for Infection in an Outbreak of Mycoplasma pneumoniae Respiratory Tract Disease

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Background. Mycoplasma pneumoniae is one of the most common pathogens that causes community-acquired respiratory tract infection. Outbreaks are well known, and all age groups are susceptible. An outbreak in an army training unit afforded an opportunity to identify possible risk factors for morbidity.

Methods. An outbreak of respiratory illness that occurred in a unit comprising 91 trainees was investigated and analyzed as a cohort study. M. pneumoniae infection was suspected on clinical grounds and was confirmed by polymerase chain reaction, culture, and serologic testing. Data regarding medical history, symptoms, signs, and laboratory tests were collected.

Results. During a period of 12 days, 41 soldiers (45.1%) had respiratory illnesses, of which 10 (11.0%) were pneumonia. Comparison of symptomatic and asymptomatic individuals revealed that smoking was associated with higher rates of disease (risk ratio, 2.1; 95% confidence interval [CI], 1.3–3.2; P < .005) and seroconversion (risk ratio, 2; 95% CI, 1.2–3.4; P = .03). In multivariate analysis, both lower acute immunoglobulin G values (adjusted odds ratio, 7.8; 95% CI, 1.4–42.5; P = .018) and smoking (adjusted odds ratio, 5.6; 95% CI, 1.5–20.4; P = .01) were associated with symptomatic infection; stratification according to smoking status revealed that immunoglobulin G levels among nonsmokers were protective. Patients who had pneumonia had lower lymphocyte counts (1400 ± 258 vs. 2000 ± 465 cells/µL; P = .001).

Conclusions. Smoking and lower preexisting immunoglobulin G levels were strongly associated with M. pneumoniae respiratory infection. These findings emphasize the importance of immunity and cessation of smoking for the prevention of disease. The high attack rate emphasizes the extent of infection transmission among healthy persons living in close contact.

Journal Article.  3971 words.  Illustrated.

Subjects: Infectious Diseases ; Immunology ; Public Health and Epidemiology ; Microbiology

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