Detection of Bacteria in Normal Adult Nasal Cavity Based on Polymerase Chain Reaction–denaturing Gradient Gel Electrophoresis

Abstract

This study investigated the bacterial diversity in a normal adult nasal cavity using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S ribosomal RNA (rRNA) gene fragments and compared the results with those of a culture-based method. We swabbed the inferior turbinate from 19 normal volunteers. The transport media was divided by two, one for bacterial culture and another direct extraction for bacterial DNA. PCR-DGGE was performed from the bacterial DNA and all of the sequences were compared with the reference organism by using the BLAST program (a genome database of GenBank in the National Center for Biotechnology Information, Bethesda, MD). All 224 colonies were obtained from 19 samples by using a culture-based method; however, only 9 kinds of bacteria were detected. Staphylococcus epidermidis was the most frequently detected bacteria, and Staphylococcus aureus was the second most. The detection rates of other bacteria were very low. On the other hand, the PCR-DGGE from direct DNA extraction revealed 34 different bands that corresponded to 23 different kinds of bacteria. There were nine genera, viz., Staphylococcus, Bacillus, Enterobacter, Corynebacterium, Actinobacterium, Hafnia, Moraxella, Dolosigranulum, and Clostridium. Among them, unspecific Staphylococcus species and Enterobacter aerogenes were detected most frequently. Compared with the previous culture-based method, PCR-DGGE can detect much more diversity of bacteria in the nasal cavity.