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The product of the rpoN gene is an alternative sigma factor of RNA polymerase which is required for transcription of a number of genes in members of the family Enterobacteriaceae, including those that specify enzymes of nitrogen assimilation, amino acid uptake, and degradation of a variety of organic molecules. We have previously shown that transcription of the pilin gene of Pseudomonas aeruginosa also requires RpoN (K. S. Ishimoto and S. Lory, Proc. Natl. Acad. Sci. USA 86:1954-1957, 1989) and have undertaken a more extensive survey of genes under RpoN control. Strains of P. aeruginosa that carry an insertionally inactivated rpoN gene were constructed and shown to be nonmotile because of the inability of these mutants to synthesize flagellin. The mutation in rpoN had no effect on expression of extracellular polypeptides, outer membrane proteins, and the alginate capsule. However, the rpoN mutants were glutamine auxotrophs and were defective in glutamine synthetase, indicating defects in nitrogen assimilation. In addition, the P. aeruginosa rpoN mutants were defective in urease activity. These findings indicate that the sigma factor encoded by the rpoN gene is used by P. aeruginosa for transcription of a diverse set of genes that specify biosynthetic enzymes, degradative enzymes, and surface components. These rpoN-controlled genes include pili and flagella which are required for full virulence of the organism.

Many cases of mucopurulent cervicitis (MPC) are idiopathic and cannot be attributed to the known cervical pathogens Neisseria gonorrhoeae, Chlamydia trachomatis, or herpes simplex virus. Because Mycoplasma genitalium is associated with nongonoccocal urethritis in men, its role in MPC, the corresponding syndrome in women, was investigated. Archived cervical specimens from women recruited in the Harborview Sexually Transmitted Disease Clinic in Seattle from 1984 to 1986 were tested, using polymerase chain reaction, in a study that identified other causes of and risk factors for MPC. M. genitalium was detected in 50 (7.0%) of 719 women. Young age, multiple recent partners, prior miscarriage, smoking, menstrual cycle, and douching were positively associated with M. genitalium, whereas bacterial vaginosis and cunnilingus were negatively associated. After adjustment for age, phase of menstrual cycle, and presence of known cervical pathogens, women with M. genitalium had a 3.3-fold greater risk (95% confidence interval, 1.7-6.4) of MPC, which suggests that this organism may be a cause of MPC.

M genitalium was more prevalent than Neisseria gonorrhoeae but less prevalent than Chlamydia trachomatis, and it was strongly associated with sexual activity.

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