2020 Volume 69 Issue 1 Pages 30-35
Mycoplasma pneumoniae antigen tests are widely used in many medical laboratories since their approval by the Japan national health insurance in 2013. Because M. pneumoniae primarily infects the lower respiratory tract, the sampling technique considerably affects the kit performance as throat swabs are usually used as specimens. Therefore, we used bacterial cultures to study the performances of five commercially available kits. M. pneumoniae strains ATCC15531 and ATCC29342 were cultured for 4 and 14 days. The 4-day cultures contain live bacterial cells and the 14-day cultures contain dead bacterial cells. Some kits showed better sensitivity in the 4-day cultures, whereas others showed better sensitivity in the 14-day cultures. This difference is due to the antigen species recognized by the antibodies in the different kits. Cytoplasmic proteins such as the L7/L12 ribosomal protein and DnaK are recognized by the kits with better performances in the 4-day cultures, whereas the plasma membrane attachment proteins such as P1 and P30 are recognized by the kits with better performances in the 14-day cultures. In conclusion, this study showed that different M. pneumoniae kits detect different bacterial proteins, which in turn reflect the bacterial state, i.e., alive or dead.
