Dynamics of pneumococcal acquisition and carriage in young adults during training in confined settings in Israel.
BACKGROUND
Outbreaks and sporadic cases of pneumococcal illness occur among young adults in confined settings. Our aim was to characterize pneumococcal acquisition and carriage among healthy young adults in Israel during military training in confined settings.


METHODS
During the years 2007-2008, an observational longitudinal study was conducted in three cohorts of healthy soldiers, during a 7-month basic training period. Epidemiological data, oropharyngeal and nasopharyngeal cultures were sampled on 5 occasions: before and 3, 6, 12 and 24 weeks after start of training. Samples were processed within 2-18 hours. Relatedness of isolates was investigated by capsular typing of all isolates and pulsed-field gel electrophoresis to determine acquisition and transmission. Carriage and acquisition patterns were analyzed and multivariable logistic regression analysis was performed to assess the impact of time on acquisition after mixing, controlling for other covariates.


RESULTS
Pneumococci were recovered on 202 of 1872 visits among 742 individuals, including 40 different serotypes. Mean carriage prevalence increased in all visits following training initiation. Acquisition during training was high, as 36.9% of individuals acquired pneumococci at least once during training, and for almost one fourth of the whole population this occurred during the first 6 weeks. Significant clustering was noted. Sharing drinking glass/bottle was found to be a significant and common risk factor for pneumococcal acquisition.


CONCLUSIONS
Pneumococcal acquisition is highly frequent when young adults live in close contact in confined settings, especially early after mixing.
Medical Corps, Israel Defence Force, Tel HaShomer, Israel. hlevine@hadassah.org.il
Hagai
H
Levine
Ran D
RD
Balicer
Salman
S
Zarka
Tamar
T
Sela
Vladislav
V
Rozhavski
Daniel
D
Cohen
Raid
R
Kayouf
Ruhama
R
Ambar
Nurith
N
Porat
Ron
R
Dagan
D000328:Adult; D002353:Carrier State; D006801:Humans; D007557:Israel; D008137:Longitudinal Studies; D008297:Male; D008889:Military Personnel; D012044:Regression Analysis; D013296:Streptococcus pneumoniae / Q000302:isolation & purification*; D055815:Young Adult