Mycoplasma genitalium in non-gonococcal urethritis--a study in Swedish male STD patients. 
Urethral swab specimens obtained from 101 men attending an STD clinic were examined for the presence of Mycoplasma genitalium by polymerase chain reaction (PCR) amplification.  Fifty patients had non-gonococcal urethritis (NGU), and 51 patients were included as controls without urethritis.  M. genitalium DNA was detected in 13 (26%) of the urethritis patients and in 5 (10%) of the control patients (P=0.06).  No patient positive for M. genitalium had a simultaneous chlamydial infection.  Thus, in the 36 patients with non-chlamydial NGU, the prevalence of M. genitalium infection was 36% (P=0.007 compared with controls).  All patients with M. genitalium positive urethritis had a high grade urethritis defined as >10 polymorphonuclear cells per high power microscopical field.  Compared with the control group, those with M. genitalium positive urethritis had more often had a history of urethritis than had those with chlamydial NGU or those with M. genitalium negative, non-chlamydial NGU.