Detection of mixed Mycoplasma species

Immunofluorescence can be used to demonstrate mixed species within a mycoplasma culture; however, it may fail to do so if one species is present in very low numbers. To enhance the detection of minor components in such mixtures, a technique was developed, based on the growth inhibition test, whereby the growth of the major component in a mixed culture was inhibited, thus permitting the minor component to emerge. The method was applied to 67 field isolates from chickens and turkeys, which had been examined by immunofluorescence and were thought to contain only one mycoplasma species. Of these, 26 cultures were found to be mixtures, and in some instances the pathogenic species Mycoplasma gallisepticum and M. meleagridis were revealed.