The effect of culture media dilution on recovery of rapidly growing mycobacteria.

Nontuberculous mycobacteria (NTM) are important environmental opportunistic pathogens of human and animals. Rapidly growing mycobacteria (RGM) are important emerging pathogens causing NTM infections. Unfortunately, the majority of microorganisms in the environment resist cultivation in the laboratory. The aim of the study was to investigate whether the nutrients in the medium have impact on the growth of RGM in vitro. We first assessed the growth rate of rapidly growing mycobacteria strains in broth medium with different dilutions, including M. abscessus, M. chelonae, and M. fortuitum. Our data demonstrate that the majority of M. abscessus, M. chelonae and M. fortuitum strains prefer to grow in nutrient-rich MH medium, whereas a small proportion of RGM strains grew faster in diluted culture medium. Our study identified that dilution culture has a different impact on recovery of various RGM strains.