The constant downward flow of urine through the ureter and bladder tends to militate against ascending infections. Micturition itself irrigates the urethra. This is an effective response in the long male urethra, but less so in the female. The most common offending organism being coliform bacillus from the perineal area. Faulty aseptic technique during catheterisation can therefore result in urinary tract infections, which is one of the most common hospital acquired infections.
Some vaginal deodorants disturb the pH balance of the vaginal area and can result in infection.
Here again the opportunistic Candida albicans can cause thrush. In post menopausal females the production of acid in the vagina decreases and this can result in a condition known as senile vaginitis. The surface of the eyeball is constantly irrigated with tears produced by the lachrymal glands. Tears contain high levels of lysozyme, in fact the highest of any of the body secretions, and as a result this forms an effective barrier against infection. If the diet is lacking in Vitamin A the production of lysozyme in the tears decreases and can result in a predisposition to eye infection.