23.1 Anatomy and Normal Microbiota of the Urogenital Tract

The urinary system is responsible for filtering the blood, excreting wastes, and helping to regulate electrolyte and water balance.
The urinary system includes the kidneys, ureters, urinary bladder, and urethra; the bladder and urethra are the most common sites of infection.
Common sites of infection in the male reproductive system include the urethra, as well as the testes, prostate and epididymis.
The most commons sites of infection in the female reproductive system are the vulva, vagina, cervix, and fallopian tubes.
Infections of the urogenital tract can occur through colonization from the external environment, alterations in microbiota due to hormonal or other physiological and environmental changes, fecal contamination, and sexual transmission (STIs).

23.2 Bacterial Infections of the Urinary System

Bacterial cystitis is commonly caused by fecal bacteria such as E. coli.
Pyelonephritis is a serious kidney infection that is often caused by bacteria that travel from infections elsewhere in the urinary tract and may cause systemic complications.
Leptospirosis is a bacterial infection of the kidney that can be transmitted by exposure to infected animal urine, especially in contaminated water. It is more common in tropical than in temperate climates.
Nongonococcal urethritis (NGU) is commonly caused by C. trachomatis, M. genitalium, Ureaplasma urealyticum, and M. hominis.
Diagnosis and treatment for bacterial urinary tract infections varies. Urinalysis (e.g., for leukocyte esterase levels, nitrite levels, microscopic evaluation, and culture of urine) is an important component in most cases. Broad-spectrum antibiotics are typically used.

Bacterial vaginosis is caused by an imbalance in the vaginal microbiota, with a decrease in lactobacilli and an increase in vaginal pH. G. vaginalis is the most common cause of bacterial vaginosis, which is associated with vaginal discharge, odor, burning, and itching.
Gonorrhea is caused by N. gonorrhoeae, which can cause infection of the reproductive and urinary tracts and is associated with symptoms of urethritis. If left untreated, it can progress to epididymitis, salpingitis, and pelvic inflammatory disease and enter the bloodstream to infect other sites in the body.
Chlamydia is the most commonly reported STI and is caused by C. trachomatis. Most infections are asymptomatic, and infections that are not treated can spread to involve the epididymis of memalesn and cause salpingitis and pelvic inflammatory disease in females.
Syphilis is caused by T. pallidum and has three stages, primary, secondary, and tertiary. Primary syphilis is associated with a painless hard chancre lesion on genitalia. Secondary syphilis is associated with skin and mucous membrane lesions. Tertiary syphilis is the most serious and life-threatening, and can involve serious nervous system damage.
Chancroid is an infection of the reproductive tract caused by H. ducreyi that results in the development of characteristic soft chancres.

Genital herpes is usually caused by HSV-2 (although HSV-1 can also be responsible) and may cause the development of infectious, potentially recurrent vesicles
Neonatal herpes can occur in babies born to infected people and can cause symptoms that range from relatively mild (more common) to severe.
Human papillomaviruses are the most common sexually transmitted viruses and include strains that cause genital warts as well as strains that cause cervical cancer.

Candida spp. are typically present in the normal microbiota in the body, including the skin, respiratory tract, gastrointestinal tract, and female urogenital system.
Disruptions in the normal vaginal microbiota can lead to an overgrowth of Candida, causing vaginal candidiasis.
Vaginal candidiasis can be treated with topical or oral fungicides. Prevention is difficult.

Trichomoniasis is a common STI caused by Trichomonas vaginalis.
T. vaginalis is common at low levels in the normal microbiota.
Trichomoniasis is often asymptomatic. When symptoms develop, trichomoniasis causes urinary discomfort, irritation, itching, burning, discharge from the penis, and vaginal discharge.
Trichomoniasis is treated with the antiflagellate drugs tinidazole and metronidazole.