Genitourinary Tract Infections

What parts of the genitourinary system are normally free of microorganisms?

Urine and the urinary tract above the bladder entrance

What part of the genitourinary system contains normal flora?

Lower urethra

What organisms make up the normal flora of the lower urethra?

Lactobacillus, Staphylococcus, Corynebacterium, Streptococcus

What are the most common infections of the genitourinary system?

Urinary tract infections (UTIs)

How common are UTIs in the United States?

~7 million doctor visits annually

What is bacterial cystitis?

Infection of the urinary bladder, part of UTIs

Why do UTIs affect women more than men?

Shorter urethra and closer proximity to anus allow easier bacterial ascent

What is the usual source of bacteria causing UTIs?

Normal intestinal flora

How do organisms usually cause UTIs?

 Ascend the urethra into the bladder

What is the incubation period for bacterial cystitis?

Short (often 1–3 days)

Describe the pathogenesis of UTIs.

Ascending infection from urethra → bladder → possibly kidneys

What is the typical treatment for UTIs?

Antibiotics

Why are UTIs common in hospitalized patients?

Use of urinary catheters

What symptoms commonly suggest an STD?

Discharge, painful urination, genital sores or ulcers, itching, burning

Why is the incidence known for some STDs but not others?

Some are reportable diseases; many are asymptomatic and underreported

What is the causative agent of gonorrhea?

Neisseria gonorrhoeae

What type of bacteria is Neisseria gonorrhoeae?

Gram-negative diplococcus

Where is Neisseria gonorrhoeae often found during infection?

Inside leukocytes in urethral pus

How is gonorrhea transmitted?

Intimate sexual contact

How well does N. gonorrhoeae survive outside the host?

Poorly

What is the incubation period for gonorrhea?

2–7 days

Describe the pathogenesis of gonorrhea.

Bacteria attach to mucosal epithelial cells, cause inflammation and pus formation

What is the treatment for gonorrhea?

Antibiotics (resistance is increasing)

What is notable about gonorrhea epidemiology in the U.S.?

Second most reported STD after chlamydia

What factors influence gonorrhea infection?

• Use of birth control pills

• Sex without condoms

• Lack of immunity

• Presence of carriers

What is the causative agent of chlamydia?

Chlamydia trachomatis

What type of bacterium is Chlamydia trachomatis?

Obligate intracellular, spherical bacterium

What diagnostic structure does Chlamydia trachomatis form?

Inclusion bodies

How many chlamydial types cause STDs?

Approximately eight

What is the incubation period for chlamydia?

1–3 weeks

Describe the pathogenesis of chlamydia.

Infects host cells and multiplies intracellularly forming inclusion bodies

What is the treatment for chlamydia?

Antibiotics

How many chlamydia cases are reported annually in the U.S.?

~4 million

What percentage of young women may be asymptomatic carriers?

~14%

What non-sexual transmission source is associated with chlamydia?

Non-chlorinated swimming pools

How can newborns be affected by chlamydia?

Conjunctivitis during birth

What is the causative agent of syphilis?

Treponema pallidum

What type of bacterium is Treponema pallidum?

Motile spirochete

Why can’t Treponema pallidum be cultured in a lab?

It cannot be cultivated on artificial media

What method is used to identify Treponema pallidum?

Darkfield microscopy

What is the incubation period for syphilis?

About 3 weeks

Why is syphilis often misdiagnosed?

Symptoms vary and mimic other diseases

What are the three stages of syphilis?

Primary, secondary, tertiary

Describe primary syphilis.

Painless red ulcer (hard chancre) on genitalia

Describe secondary syphilis.

Symptoms heal spontaneously followed by latency

Describe tertiary syphilis.

Damage to organs such as heart and nervous system

Why is syphilis epidemiologically dangerous in pregnancy?

Can cross the placenta (congenital syphilis)

What is the usual causative agent of genital herpes?

Herpes simplex virus type 2 (HSV-2)

What is the incubation period for genital herpes?

2–20 days

What are the initial symptoms of genital herpes?

Itching and burning

What lesions develop in genital herpes?

Blisters that rupture into painful ulcers

Why does genital herpes recur?

Virus remains latent in host cells

What cells are infected to form herpes blisters?

Epithelial cells

What follows ulceration in herpes infection?

Latency

What causes recurrence of herpes symptoms?

Replication of virions from latent DNA

How can newborns contract herpes?

Passage through infected birth canal

What is the causative agent of HPV infections?

Human papillomavirus (HPV)

What type of virus is HPV?

Non-enveloped, double-stranded DNA virus

How many types of HPV exist?

Nearly 100

How many HPV types are sexually transmitted?

~30

How many HPV types are strongly associated with cancer?

~15

What is the incubation period for HPV?

About 3 months

What symptoms are associated with HPV?

Asymptomatic, genital warts, cervical lesions

How does HPV enter the body?

Through abrasions in tissue

When do warts usually appear after HPV infection?

~3 months

Does removing warts eliminate HPV?

NO

Can HPV be transmitted during childbirth?

Yes, to the fetus

What is the most important risk factor for HPV?

Multiple sexual partners

What role do Pap smears play?

Detect abnormal cervical cells and HPV changes

What is the incubation period for HIV?

6 days to 6 weeks

What are the causative agents of HIV disease?

HIV-1 and HIV-2

Which HIV type is most common in the U.S.?

HIV-1

Where is HIV-2 most common?

West Africa and India

How does HIV-2 differ from HIV-1?

Less transmissible, slower disease progression

What cells does HIV primarily infect?

Mononuclear phagocytes and Helper T-cells

What are early HIV symptoms?

Fever, headache, sore throat, rash, muscle aches

What follows the acute HIV illness?

Long asymptomatic period

When is HIV considered AIDS?

When severe immunodeficiency and AIDS-defining conditions occur

Name examples of AIDS-defining conditions.

Opportunistic infections, cancers, severe weight loss, chronic diarrhea

Describe HIV pathogenesis.

Viral RNA → DNA via reverse transcriptase → integrates into host genome

What are the most critical cells destroyed by HIV?

Helper T-cells (CD4⁺)

Why does immunodeficiency develop in HIV?

Progressive destruction of Helper T-cells

List mechanisms of Helper T-cell destruction.

• Viral lysis

• CD8⁺ cytotoxic T-cells

• Natural killer cells

What occurs during the asymptomatic interval of HIV?

Virus persists but immune system still partially functions

How can HIV be inactivated on surfaces?

Commercial disinfectants

Why are condoms not 100% effective against HIV?

Virus can be transmitted via areas not covered

Why is combination drug therapy (“cocktail”) used?

Reduces resistance and targets multiple viral stages

What types of drugs are used in HIV treatment?

Reverse transcriptase inhibitors and protease inhibitors

Why is creating an HIV vaccine difficult?

• High mutation rate

• Antigenic variability

• Virus hides in host cells

• Requires humoral and cellular immunity