Isolation and identification of Mycoplasma genitalium from high risk populations of sexually transmitted diseases in China

OBJECTIVE: To investigate Mycoplasma genitalium (Mg) infection in high risk populations of sexually transmitted diseases (STDs) in China by means of culture, Mg-DNA detection, observation under an electron microscope (EM) and an atomic force microscope (AFM). METHODS: 227 urogenital specimens taken from both patients in clinics and high risk populations of STDs in Beijing, Nanjing and Shanghai areas were cultured in SP-4 medium for isolation of Mg. Suspicious positive strains were identified first by PCR technique which could amplify the special DNA fragments of Mg adhesion protein (Mg-Pa) and 16S-rRNA sequences. The morphologic features of Mg were observed under EM and AFM. RESULTS: Eight strains were isolated from the 227 specimens, the total positive rate was 3.52%. The isolated strains met the criteria of growth and metabolic conditions required by Mg. Specific fragments of Mg-DNA (374 bp based on Mg-Pa and 402 bp on 16S-rRNA primers, respectively) could be amplified from both the isolates and the genital secretions. Under EM and AFM, Mg showed different shapes, including flask, pear, spindle and globe shape. The typical shape of Mg was flask or pear shape with projecting neck portion and broadened terminal structure under EM and with constrictive ring between the neck and body under AFM. CONCLUSION: Mg infection exists in high risk populations of STDs in China. We highly suggest the use of AFM in dermatological study.