[Recent progress in the diagnosis of respiratory disease: respiratory infection].

In Japan, molecular diagnostic techniques and some other diagnostic tools for respiratory infections have been clinically introduced and their use has spread in recent years. In particular, PCR is now commonly used even at the clinical microbiology laboratory level, because PCR based direct detection of infectious disease from various clinical specimens has some advantages over other diagnostic methods. Since PCR is a highly sensitive, specific, rapid method and suitable for slow-growing or culture-difficult pathogens, we must take care in regard to the risk of contamination, the possibility of false-negative results by various PCR inhibitors in the clinical sample, or unstable sensitivity easily influenced by the quality of samples and DNA extraction step.