According to most textbooks on urology, infections of the urethra are considered somewhat as follows:
The nongonorrheal infection is caused by:
Bacteria other than the gonococcus.
Nongonorrheal urethritis is caused by bacteria conveyed to the urethra from without in or from within out. Simple nongonorrheal urethritis caused by chemical or mechanical irritants is transitory and disappears as soon as the cause is removed.
In view of the large number of exposures to nongonorrheal organisms to which the average urethra is subjected, infections from without in should be more common than from within out but they are not, because the urethra is more vulnerable to this class of infection and, in addition, the passage of the urine along the urethra has a tendency to wash the infection away.
Examination of the literature for the past ten years reveals little of importance with regard to the
CORBUS BC. PYELONEPHRITIS AND ITS RELATION TO NONGONORRHEAL URETHRITIS. JAMA. 1927;89(26):2162-2165. doi:10.1001/jama.1927.02690260010003