The aim of this study was to determine the prevalence of asymptomatic nasopharyngeal carriages in children using a multiplex reverse transcriptase-polymerase chain reaction (mRT-PCR) assay kit.

We obtained nasopharyngeal swabs from 33 children without any underlying disease from July 25 to July 28, 2008. The children were free from the signs of respiratory tract infections at the time of sampling. DNA was extracted from the swabs and subjected to multiplex RT-PCR using a primer set for the detection of pneumococci (Seeplex® PneumoBacter ACE Detection Seegene, Seoul, Korea). The amplified PCR products were separated on 2% agarose gels and stained with either ethidium bromide or screen tape system (Lab901 Scotland, UK).

A total of 33 children (male, 15 female, 18) aged between 3.2 and 16.3 (median, 8.2) years were included in this study. The mRT-PCR detected colonized bacteria ( Streptococcus pneumoniae , Hemophilus influenzae , Chlamydia pneumoniae , and Bordetella pertussis ) in 30 children (90.9%). Of these, 13 children (39.4%) showed more than 2 bacteria: 12 children were positive for 2 bacteria ( S. pneumoniae and H. influenzae ) and 1 child was positive for 3 bacteria ( S. pneumoniae , H. influenzae , and C. pneumoniae ).

mRT-PCR was found to be a sensitive tool for the detection of asymptomatic nasopharyngeal carriages. Clinical significances of the bacteria detected by mRT-PCR will have to be evaluated in the future.