Infectious Diseases Affecting the Genitourinary System

Chapter 21: Infectious Diseases Affecting the Genitourinary System

Genitourinary Tract and Its Defenses

  • Definition: The genitourinary tract consists of two distinct organ systems:

    • Urinary Tract: Removes substances from the blood, regulates certain body processes, forms urine, and transports it out of the body.

    • Genital System: Also known as the reproductive system, primarily functions in reproduction.

Urinary Tract

  1. Components of the Urinary Tract:

    • Kidneys: Remove metabolic wastes from the blood, acting as a sophisticated filtering system.

    • Ureters: Tubular organs extending from each kidney to the bladder.

    • Bladder: Collapsible organ that stores urine and empties it into the urethra.

    • Urethra: Conduit for urine to leave the body.

      • In males, it is the terminal organ of the reproductive tract.

      • In females, it is separate from the vagina.

  2. Defenses of the Urinary Tract:

    • Flushing Action of Urine: Helps clear microbes from the urinary tract.

    • Desquamation of Epithelial Cells: Lining of the urinary tract sheds cells and microbes.

    • Normal Biota: Represents the most common microbial threat; normal cells lining the urinary tract have different chemical characteristics than those in the GI tract, preventing GI bacteria from adhering effectively.

  3. Defenses in Urine:

    • Acidic pH: Helps inhibit bacterial growth.

    • Lysozyme: Enzyme that breaks down peptidoglycan in bacterial cell walls.

    • Lactoferrin: Iron-binding protein that inhibits bacterial growth.

    • Secretory IgA: Antibodies specific for previously encountered microorganisms.

Male Reproductive System

  1. Function:

    • Produces, maintains, and transports sperm cells and is a source of male sex hormones.

  2. Anatomical Components:

    • Testes: Produce sperm and hormones.

    • Epididymides: Coiled tubes leading out of the testes.

    • Vas Deferens: Combines with the seminal vesicle, terminating in the ejaculatory duct that empties into the urethra.

    • Prostate Gland: Contributes to semen and located at the base of the urethra.

    • External Organs:

      • Scrotum: Contains the testes.

      • Penis: Houses the urethra.

  3. Innate Defenses:

    • Flushing action of urine helps move microorganisms out of the reproductive system.

Female Reproductive System

  1. Anatomical Components:

    • Uterus

    • Fallopian Tubes

    • Ovaries

    • Vagina

    • Cervix: Connects the uterus to the vagina and is a common site of infection.

  2. Innate Defenses:

    • Vagina lined with mucous membranes and secreted mucus provides protective covering, serving as a major nonspecific defense, especially during childhood and menopause.

    • Secretory IgA: Antibodies specific for previously encountered infections.

  3. Defense Mechanism Changes:

    • The release of estrogen stimulates glycogen secretion, which bacteria ferment into acid, lowering vaginal pH to between 4.2 and 5, providing a hostile environment for pathogens.

    • The pH of the vagina is approximately 7 before puberty. After adolescence, the biota shifts dramatically due to the acidity, aiding in the prevention of harmful microbial establishment.

Concept Check (1)

  • Question: Which of the following is not considered an innate defense of the urinary system?
    A. Flushing action of urine
    B. Acidic pH
    C. IgG antibodies
    D. Lactoferrin
    E. Lysozyme

Normal Biota of the Genitourinary Tract

  • Overview: The urinary system harbors a diverse microbiota differentiated by anatomical location.

  1. Microbial Composition:

    • Lower urethra has a well-established microbiota; upper urinary tract has fewer types and less abundance.

    • Female Urethra: Short (3.5 cm) and near the anus, allowing GI bacteria to cause UTIs.

    • Flora of the Penis: Colonized by aerobic species (Pseudomonas and Staphylococcus) and anaerobic gram-negatives beneath the foreskin.

  2. Normal Biota of the Male Genital Tract:

    • Same biota as urethra, exposed to STIs after sexual activity; circumcision alters this biota, generally leading to a more diverse microbial population.

  3. Normal Biota of the Female Genital Tract:

    • Changes in biota pre- and post-puberty influenced by pH and estrogen.

    • Lactobacillus Species: Thrive in acidic environments, providing safety against harmful microbes; high levels can lead to yeast infections (Candida albicans).

Genitourinary Tract Defenses and Normal Biota Defenses

  1. Urinary Tract (Both Sexes):

    • Defense mechanisms: Flushing action, secretory IgA, lysozyme, lactoferrin in urine, etc.

    • Microbial residents: Nonhemolytic Streptococcus, Staphylococcus, Corynebacterium, and Lactobacillus.

  2. Female Genital Tract (Childhood and Postmenopause):

    • Mucus secretions and secretory IgA provide defense.

    • Microbial residents consistent with urinary tract flora.

  3. Female Genital Tract (Childbearing Years):

    • Acidic pH, mucus secretions, secretory IgA providing protection against pathogens.

    • Microbes: Typically Lactobacillus, but can also include others like Prevotella and Candida albicans.

  4. Male Genital Tract:

    • Similar to urinary tract defenses, with specific microbial populations present on the outer surface of the penis.

Highlight Disease: Urinary Tract Infections

  1. Prevention and Problems:

    • Flushing action minimizes infections; urine can be a growth medium for bacteria.

    • Different forms of UTIs:

    • Cystitis: Bladder infection due to reduced urine flow or bacterial introduction.

    • Pyelonephritis: Kidney infection.

    • Urethritis: Limited to urethra.

  2. Signs and Symptoms:

    • Cystitis: Sudden onset with pain, frequent urge to urinate, burning during urination, cloudy urine, hematuria (blood in urine) leading to orange coloring, low-grade fever, nausea.

    • Pyelonephritis: Back pain, high fever, potential for kidney damage if untreated; acute uncomplicated UTI involves only the bladder.

  3. Causative Agents:

    • Distinction between health care-associated and community-acquired UTIs.

    • Catheter-associated UTIs (CA-UTIs): Prevention recommended against excessive catheter use.

    • 95% of UTIs stem from normal GI flora, primarily Escherichia coli (80%).

    • Other common pathogens: Staphylococcus saprophyticus, Klebsiella pneumoniae, Proteus mirabilis.

  4. Transmission and Epidemiology:

    • Community-acquired infections stem from GI tract to urinary system; more common in women due to anatomy.

    • Recurrent UTIs in women can be due to E. coli invaders that evade antibiotics.

  5. Treatment:

    • Nitrofurantoin (Macrobid): Commonly used for various UTI etiologies.

    • Phenazopyridine (Pyridium): Relieves symptoms but should not be used beyond two days due to dyeing urine.

    • Many strains of E. coli show resistance to penicillin derivatives.

Reproductive Diseases Caused by Microorganisms

  • Many reproductive diseases can be sexually transmitted.

    • Common STIs: Chlamydia, gonorrhea, and syphilis show rising incidence rates in the U.S., partly due to budget cuts in STD clinics.

Discharge Diseases with Major Manifestations in the Genitourinary Tract

  1. Definition: Diseases that increase fluid discharge in the male and female reproductive tracts.

  2. Agents Include:

    • Trichomoniasis

    • Gonorrhea

    • Chlamydia

Highlight Disease: Gonorrhea

  1. Signs and Symptoms in Males:

    • Urethritis with painful urination, yellowish discharge.

    • Many cases are asymptomatic; potential to spread to prostate and epididymis leading to infertility.

  2. Signs and Symptoms in Females:

    • Infection may involve both urinary and genital tracts.

    • Mucopurulent or bloody discharge; painful urination possible.

    • Serious complications arise when it ascends to the uterus and fallopian tubes leading to Salpingitis and Pelvic Inflammatory Disease (PID).

  3. Consequences:

    • Bloodstream invasion can lead to joint problems and skin rashes; prenatal screening recommended due to serious eye infections in neonates from infected mothers.

  4. Causative Agent:

    • Neisseria gonorrhoeae: Gram-negative diplococcus bacteria.

  5. Transmission and Epidemiology:

    • Spread through sexual contact; asymptomatic carriers increase transmission.

  6. Culture and Diagnosis:

    • Grows best in CO2 rich environments; tests include oxidase and catalase tests.

  7. Prevention and Treatment:

    • No vaccine available; using condoms and dual treatment for potential chlamydia co-infection is standard.

Chlamydia

  1. Prevalence:

    • Most common reportable STD in the U.S.; actual infection rates likely 5-7 times higher due to asymptomatic cases.

  2. Causative Agent:

    • Chlamydia trachomatis: Small gram-negative obligate intracellular bacterium.

  3. Signs and Symptoms:

    • Males: Urethritis, symptoms similar to gonorrhea, possible epididymitis.

    • Females: Cervicitis, salpingitis, and common PID risk especially due to high asymptomatic rates.

  4. Life Cycle:

    • Involves two stages: Elementary Bodies (EB) and Reticulate Bodies (RB), with replication occurring in host cells.

  5. Pathogenesis:

    • Survives and proliferates within host cells, triggering inflammation that can lead to tissue damage in reproductive tracts.

  6. Transmission and Epidemiology:

    • Predominantly a human pathogen; higher infection rate in adolescent women.

    • Congenital transmission results in conjunctivitis and pneumonia in newborns.

  7. Culture and Diagnosis:

    • PCR and ELISA tests for rapid detection; urine tests available for screenings.

  8. Prevention:

    • Avoiding contact with infected secretions; regular screenings recommended for young women.

Vaginitis and Vaginosis

  1. Definitions:

    • Vaginitis: Inflammation with symptoms such as itching and discharge.

    • Vaginosis: Similar to vaginitis but lacks significant inflammation.

  2. Main Agent:

    • Candida albicans: Common yeast infection; can be detected through specific tests during pelvic examination.

Prostatitis

  1. Definition:

    • Inflammation of the prostate gland caused primarily by bacteria from the intestinal tract, leading to acute or chronic forms that can be unresponsive to antibiotics.

  2. Symptoms:

    • Groin pain, frequent urge to urinate, difficulty urinating, and painful ejaculation.

  3. Treatment:

    • Common antibiotics include ciprofloxacin and levofloxacin.

Genital Ulcer Diseases

  1. Overview:

    • Common infectious conditions leading to lesions: Syphilis, Chancroid, and Genital Herpes.

    • Associated with increased risk of HIV infection due to open lesions.

  2. Syphilis:

    • Stages: Primary (chancre formation), Secondary (intense symptoms), Tertiary (long latency and complications).

    • Pathogenesis: Treponema pallidum involved, with serious implications for tissues and organs over time.

  3. Diagnosing Syphilis:

    • Detection via dark-field microscopy and antibody testing; treatment requires immediate public health follow-up.

Human Papillomavirus Infection

  1. Causative Agent:

    • HPV: Nonenveloped DNA viruses, over 100 types. Some types linked with cancer, particularly cervical cancer.

  2. Transmission:

    • Direct contact; nearly all sexually active adults will contact HPV in their lifetime.

  3. Culture and Diagnosis:

    • Pap smears and PCR-based screening tests, especially important for women over 30.

  4. Treatment:

    • No cure for HPV; prevention via vaccination recommended for girls and boys starting at age 9.

Group B Streptococcus “Colonization”

  1. Epidemiology:

    • 10-40% of women asymptomatically colonized; nonpregnant women face no ill effects.

    • Pregnant women may experience complications, with half of infants colonized during birth or via ruptured membranes.