Module 17: Diseases of the Genitourinary tract

Bacterial Vaginosis

• Vaginitis: inflammation of vagina due to infection

• Ecological mystery - cause thought to be due to decrease in Lactobacillus vaginal bacteria that allows other organisms to proliferate and change pH

• Not specific to sexually active women and considered a nuisance rather than a serious threat

  • Factor in premature birth and low birth-weight infants

Causative agents:

• Candida albicans (fungus)

• Trichomonas vaginalis (protozoan)

• Gardnerella vaginalis (bacteria)

Diagnosis:

• pH > 4.5

• Copious frothy discharge,

• Fishy odor

• Clue cells present in discharge

Transmission:

• Can be passed on via sex but not typical

Neisseria gonorrhoeae (Virulence)

• Attaches via fimbriae and invades spaces separating columnar epithelial cells

• LOS and endotoxin

• Phase variation: can turn certain genes on and off

• Antigenic variation

• IgA protease — can lead to chronic infection

• Blebbing - release of outer membrane vesicles that can facilitate immune evasion.

Gonorrhea

Causative agent: Neisseria gonorrhoeae

• One of the most reported STIs; ~ 1.6 million new infections in 2018 (50% in people 15-24)

Transmission:

• Can spread to other parts of the body

  • skin

  • conjunctiva

  • meninges

Signs and symptoms:

• Men — painful urination, yellow, green, or white discharge of pus-containing material from urethra - apparent with few days; sometimes testicles become swollen and tender. Can migrate to rectal infection

• Women — only cervix infected; originally asymptomatic, eventually some pelvic pain, discharge, intermenstrual bleeding (not part of menstrual cycle) and painful urination; can cause PID which can lead to infertility. Can travel to endometrium, fallopian tubes infection

• Pharyngeal and anal gonorrhea also common

• Can cause urethritis

Treatment:

• No effective immunity: Ag variation and Opa proteins

Chlamydia trachomatis (Virulence)

• Obligate intracellular parasite

• Can grow intracellularly

• Elementary body: Metabolically inactive yet very infectious form that has ridged enveloped body that allows it to survive outside of the hosts cells

• Reticula body: large non infectious rapidly dividing body that grows in vacuole of host cells. Energy parasites that come with ribosomes which become elementary bodies at the end of its life cycle

• Unique cell wall

  • LPS membrane but has no peptidoglycan

• Certain strains can lead to infection of lymphatic system

Chlamydia

Causative agent: Chlamydia trachomatis

• Most common reportable infectious disease in US

• 75% of cases are asymptomatic

Signs and symptoms:

• Painful urination and watery discharge

• Mild in men; asymptomatic in women

• Can lead to epididymis in men and inflammation of uterine tubes

• Can lead to pelvic inflammatory disease in women

• Genital infections associated with increased risk of cervical cancer

Diagnosis:

• Culturing via special culture conditions; urine sample

Treponema pallidium (Virulence)

• G- spirochete; stains poorly; generation time of 30 hours; low oxygen requirements

• Relies on host for many macromolecules needed for life; ineffective outside mammalian host

• No LPS but does have G-

• Nor virulence factors but does produce lipoproteins that trigger immune response in the host that leads to tissue damage and lets it evade phagocytes

• Rapidly enters bloodstream and invades deeper tissue

Syphilis

Causative agent: Treponema pallidum

Signs and symptoms:

• Primary stage (10-21 dpi): small, painless, hard-based chancre at site of infection; fluid highly infectious and will see lymph node swelling

• Secondary stage (several wpi): skin rashes on mucus membrane, loss of hair, malaise, mild fever, rarely some neurological symptoms - lesion infectious. Appear as wart like white regions called condylomata. Very contagious

• Latent period: no symptoms; can last 2-4 years, not infectious

• Tertiary Stage: A gumma arises in 25% of untreated people years (10-20) later

• Congenital syphilis — early sign - snuffles

HSV-2 (virulence)

• inhibits maturation of dendritic cells

• has surface glycoproteins on envelope that promote coding the virus with Ab and compliment factors to make them look like self cells

Genital Herpes

Causative agent: HSV-2 (Herpes simplex virus 2)

• 1 in 4 people over 30 has HSV-2 and is unaware of the infection

Signs and symptoms:

• Lesions and burning sensation

• Appearance of vesicles (fluid infectious)

• Painful urination

• irritation

• Men: watery discharge

• discomfort

Transmission:

• Semen may contain virus and condoms may not provide protection due to vesicles on external genitals of women

• Reoccurrence due to lifelong latent infection

• Neonatal herpes

Treatment:

• No cure for herpes

• Antivirals recommended for alleviating symptoms and faster healing

Genital Warts

Causative agent: Papillomavirus

• Predilection for growth on mucous membranes that lines organs

• 1 million new cases per year; most common worldwide

• Cannot be cultured for in men

• women: can be swabbed for cells and see presence of koilocytes

• warts = condylomata

• Warts can be treated but not cured

  • 90% of cases clear spontaneously within 2 years

Signs and symptoms:

• Women: large, resemble cauliflower with multiple fingerlike projections or can be smooth

• Men: penile lesions often flat and inapparent

Treatment:

• Two vaccines available

Lentivirus

• Formation of provirus makes it impossible to eliminate HIV from a persons body

HIV

• HIV is a retrovirus of the genus Lentivirus

  • 2 identical strands of RNA, reverse transcriptase, and integrase

• Based on T cell count

Transmission:

• via direct contact with contaminated fluids

• Sharing needles

• Sexual contact

3 stages of the disease:

• Stage 1: Acute HIV infection

  • Flue like illness

  • Very contagious

• Stage 2: Clinical latency (can take years)

  • replicating at low levels

  • no signs or symptoms detected

  • Anti retroviral therapies can extend this period for decades and is less likely to transmit the virus to others

• Stage 3: Acquired immunodeficiency syndrome (AIDS)

  • weakness

  • weight loss

  • fever

  • swollen lymph glands

  • sweats

  • chills