The SP-4 culture medium, developed originally for newly isolated plant and insect mycoplasmas (spiroplasmas), has markedly improved the recovery of Mycoplasma pneumoniae from human clinical materials. This medium, in combination with a direct fluorescent antibody test, can enhance the recovery and identification of the organism by 30-40 percent over conventional culture procedures. Although these modifications are a clear improvement in diagnostic techniques for M. pneumoniae, the time required for growth and identification of the agent is still a major disadvantage for rapid clinical diagnosis. Thus, there remains a critical need for techniques that can specifically identify the major antigens (or other components) of the organism within the first week of the infection.