Normal Microbiota of the Urinary and Reproductive Systems

Normal Microbiota of the Urinary and Reproductive Systems

Normal Microbiota of the Urinary and Reproductive Systems

  • Normal urine is sterile, However it should become contaminated with microbiota of the skin near the end of its passage through the urethra.
  • Therefore, urine collected directly from the urinary bladder has fewer microorganism contaminants than voided urine.
  • The predominant bacteria in the vagina are the lactobacilli.
  • These bacteria produce lactic acid, which maintains the acidic pH (3.8 to 4.5 ) of the vagina, inhibiting the growth of most other microbes.
  • Most vaginal lactobacilli produce hydrogen peroxide, which also inhibits growth of other bacteria.
  • Estrogens (sex hormones) promote the growth of lactobacilli by enhancing the production o f glycogen by vaginal epithelial cells.
  • The glycogen quickly breaks down into glucose, which the lactobacilli metabolize into lactic acid.
  • Other bacteria, such as streptococci, various anaerobes, and some gram-negatives, are also found in the vagina.
  • The yeast like fungus Candida albicalls is part of the normal microbiota of 10-25% of women, even when they are asymptomatic.
  • Pregnancy and menopause are often associated with higher rates of urinary tract infections.
  • The reason is that estrogen levels are lower, resulting in lower populations of lactobacilli and therefore less vaginal acidity.
  • The male urethra is usually sterile, except for a few contaminating microbes near the external opening.
  • The urinary system normally contains few microbes, but it is subject to opportunistic infections that can be quite trouble.
  • Almost all such infections are bacterial, although occasional infections by pathogens such as schistosome parasites, protozoa, and fungi occur.
  • In addition,  sexually transmitted diseases often affect the urinary system as well as the reproductive system.

Normal Microbiota of the Urinary and Reproductive Systems

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