General Approaches to Identification of Mycoplasma, Ureaplasma, and Obligate Intracellular Bacteria

Mycoplasma, Ureaplasma, and obligate intracellular bacteria (Anaplasma, Chlamydia, Coxiella, Ehrlichia, Orientia, Rickettsia, and Tropheryma) differ from others by several characteristics. This includes the lack of efficiency for characterization using Gram stains and, except for Mycoplasma and Ureaplasma species and to a limited extent Coxiella burnetii and Tropheryma whipplei, the obligatory requirement for intracellular growth within a eukaryotic host cell. Thus, the most frequently used tests in clinical microbiology laboratories, Gram staining and axenic culture, are inefficient for detection and diagnosis. As a result, this has often been accomplished by an alternative staining method, such as Giemsa and Wright stains of clinical samples, by histopathologic or direct fluorescent-antibody analysis of biopsy samples; or most often by detection of antibody responses using a variety of serologic tests. The application of nucleic acid tests is now the standard practice for some of these bacteria. Additionally, improvements in axenic and cell culture methods have significantly enhanced their detection and the ability to render laboratory-based diagnoses for the diseases that they cause.