Identification of risk factors for infection in an outbreak of Mycoplasma pneumoniae 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, Ran Nir-Paz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)1239-1245
Number of pages7
JournalClinical Infectious Diseases
Volume43
Issue number10
DOIs
StatePublished - 15 Nov 2006
Externally publishedYes

Funding

FundersFunder number
Hadassah University Medical Centers
Hebrew University Medical School
Savyon Diagnostics

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