CH 23: Infectious Diseases Affecting the Genitourinary System

Normal Biota of the Genitourinary Tract

  • The microbial composition varies between men and women:
    • Female urethra:
    • Short, approximately 3.5 cm, allowing for easier microbial access from the anus.
    • Male urethra:
    • Circumcision influences the microbial profile of the penis and urethra.

Normal Biota of the Male Genital Tract

  • Contains many of the same microorganisms found on the external penis, including:
    • Lactobacillus
    • Streptococcus
  • The microbiota of men can change with the onset of sexual activity.
  • Men involved in various sexual practices (vaginal, anal, oral) can carry bacteria that may cause symptoms in female partners, such as bacterial vaginosis (BV) or endometriosis (with an incidence of 1 in 10 women).

Normal Biota of the Female Genital Tract

  • The uterus and higher reproductive organs were previously thought to be sterile. The vaginal canal harbors a diverse microbiota:
    • Lactobacillus species play a critical role in lowering vaginal pH.
    • The microbial community can shift dramatically during:
    • Menstrual cycles
    • Pregnancy
    • The biota in postmenopausal women tends to remain stable.
    • Candida albicans is naturally present at low levels.

Urinary Tract Infections (UTIs)

  • Types:
    • Cystitis: infection of the bladder.
    • Symptoms include:
      • Pain in the pubic region
      • Frequent urination
      • Dysuria (painful urination)
      • Cloudy or blood-stained urine.
    • Pyelonephritis: infection of the kidneys.
    • Additional symptoms:
      • Back pain
      • High fever
    • Can lead to permanent kidney damage.
    • Urethritis: infection of the urethra.

Causative Agents of UTIs

  • Escherichia coli: responsible for 80% of UTIs.
    • Types: Uropathogenic E. coli (UPEC) and Extraintestinal pathogenic E. coli (ExPEC)
    • Use adhesins to bind to the urinary epithelium.
    • Show motility to navigate mucosal surfaces.
    • Transmitted primarily from the gastrointestinal (GI) tract.
  • Preventive advice: Always wipe front to back.
  • Treatment:
    • Nitrofurantoin
    • Phenazopyridine

Urinary Tract Infections - Key Data

  • Common Organisms:
    • Escherichia coli
    • Staphylococcus saprophyticus
    • Enterococcus
  • Transmission Modes:
    • Opportunistic from the GI tract or catheters.
  • Virulence Factors:
    • Adhesins and motility.
  • Diagnosis:
    • Typically culture-based; checking for antimicrobial susceptibilities is standard.
  • Prevention:
    • Hygiene practices; limit catheter use for CA-UTIs.
  • Epidemiology:
    • 90% of community-acquired UTIs caused by E. coli.

Vaginitis

  • Characteristics: Inflammation of the vagina with symptoms such as:
    • Vaginal itching
    • Burning and discharge.
  • Causative agents:
    • Candida albicans (yeast infection)
    • Trichomonas vaginalis

Candida albicans

  • Nature: Dimorphic fungus, normal biota in 50% to 100% of the human population.
    • Found in the mouth, GI tract, and vagina.
    • Detectable through wet prep or Gram staining.
    • Grows as thick, curd-like colonies in the vagina.
  • Treatment: Topical and oral azole medications available.

Trichomonas vaginalis

  • Description: Small, pear-shaped protozoa, often asymptomatic in men.
  • In women, causes:
    • White to green frothy discharge.
    • Raises risks during pregnancy (e.g., premature labor).
  • Treatment: Metronidazole is the preferred medication.

Vaginosis

  • Definition: A common condition in women of childbearing age characterized by discharge and fishy odor without inflammation.
  • Usually caused by a mix of organisms, including Gardnerella vaginalis.
  • More prevalent among sexually active women but not considered sexually transmitted.
  • Can cause complications like pelvic inflammatory disease (PID), infertility, and ectopic pregnancies.

Prostatitis

  • Definition: Inflammation of the prostate gland.
    • Acute Prostatitis: Typically induced by bacteria; often from normal biota of the GI tract.
    • Chronic Prostatitis: Also bacterial but often resistant to antibiotics due to mixed biofilms in the prostate.
  • Symptoms:
    • Pain in the groin/lower back
    • Frequent urination
    • Dysuria
    • Painful ejaculation.
  • Prevention & Treatment: No specific prevention; treated with antibiotics, muscle relaxants, or alpha blockers.

Gonorrhea Signs & Symptoms

  • In males: painful urination, yellowish discharge, many are asymptomatic.
  • In females: mucopurulent/bloody discharge and painful urination; potential development of PID.
  • Transmission can occur perinatally, leading to serious complications.

Neisseria gonorrhoeae

  • Characteristics:
    • Pyogenic, gram-negative diplococcus.
    • Utilizes fimbriae for adherence to mucosal cells; undergoes phase variation to evade immune response.
    • Transmitted through all forms of sexual contact.
  • Increased risk of co-infection with HIV. Antimicrobial resistance is rising for some strains.

Chlamydia

  • Overview: Most prevalent reportable infectious disease in the U.S.
    • Symptoms in males: discharge and painful urination.
    • Symptoms in females: cervicitis, with potential for PID; high asymptomatic rates.
    • Specific form: Lymphogranuloma venereum causes systemic symptoms but often remains dormant.
  • Treatment: Typically cleared with ceftriaxone or azithromycin, with a frequent overlap with gonorrhea infections.

Syphilis

  • History: First identified in the late 15th century; originally believed to have originated from the New World.
    • 1932 Tuskegee Study highlighted unethical research practices regarding untreated syphilis.
  • Signs and Symptoms:
    • Primary: Chancre formation at the pathogen entry site.
    • Secondary: Fever, rash, lymphadenopathy.
  • Tertiary: Serious long-term complications affecting cardiovascular and nervous systems; congenital syphilis can occur.
  • Causative Agent: Treponema pallidum, a gram-negative spirochete.
  • Treatment: Recommended penicillin G.

Genital Herpes

  • Causative Agents: Herpes simplex viruses, particularly HSV-1 and HSV-2.
    • Symptoms include vesicular lesions that are very painful; recurrent outbreaks occur due to latency.
  • Neonatal herpes: Risk during delivery can lead to high mortality if untreated. C-sections recommended if outbreak is present.

Human Papillomavirus (HPV)

  • Description: Causes genital warts and is the primary cause of cervical cancer.
    • Condyloma acuminata presents as branching, cauliflower-like lesions.
  • HPV-16 and HPV-18 are the strains most associated with cervical cancer.
  • Vaccine: 9-valent Gardasil protects against numerous strains.
  • Suggested to continue regular Pap smears for monitoring.

Group B Streptococcus

  • Colony Formation: 10% to 40% of pregnant women carry this pathogen, which poses risks to newborns.
  • Screening recommended at 35-37 weeks of gestation with treatment using penicillin or ampicillin.