Background: The aim of this study was to determine the prevalence of asymptomatic nasopharyngeal carriages in immunocompromized children by using a multiplex reverse transcriptase-polymerase chain reaction (mRT-PCR) assay kit.
Methods: We obtained clinical samples by nasopharyngeal swabs from 42 patients with underlying immune deficiency from May 20, 2008 to May 22, 2008. The children were free from signs of respiratory tract infections at the time of sampling. Isolated cDNA was extracted and after this the DNA was examined using a multiplex primer set for pneumonial bacteria detection (Seeplex^Ⱂ PneumoBacter ACE Detection, Seegene, Seoul, Korea). The amplified PCR products were separated on 2% agarose gels and stained with ethidium bromide and a screentape system (Lab901, Scottland, UK) and then they were compared. The nasopharyngeal swab culture was done simultaneously and this was compared with the results of mRT-PCR.
Results: A total of 42 patients (males: 24, females: 18) aged between 1.2 and 16.3 years (median: 9.2 years) were included in this study. The mRT-PCR detected bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Chlamydia pneumoniae, and Bordetella pertussis) in 28 patients (66.6%). Of these 28 patients, 4 patients (14.3%) showed more than 2 bacteria: 2 patients were positive for two bacteria (S. pneumoniae and H. influenzae, H.influenzae and B. pertussis) and 2 patients were positive for three bacteria (S. pneumoniae, B. pertussis and C. pneumoniae, C. Pneumoniae, H. influenzae and B. pertussis). S. pneumoniae was cultured in one patient (2.4%).
Conclusions: The mRT-PCR is a sensitive tool for the detection of the asymptomatic nasopharyngeal carriages. The clinical significance of the bacteria detected in immunocompromized patients by mRT-PCR will need further evaluation. (Korean J Hematol 2009;44:220-226)

Keywords: Nasopharynx, Immunocompromized patients, Reverse transcriptase polymerase chain reaction