Urinary and Reproductive System Infections: Microbiology Study Notes

Urinary System Infections

Overview of Urinary Tract Infections (UTIs)

Urinary tract infections (UTIs) are among the most common bacterial infections, affecting both the upper and lower urinary tract. They can lead to significant morbidity, especially if not promptly diagnosed and treated.

• Upper UTI: Involves the kidneys and ureters.

• Lower UTI: Involves the bladder and urethra.

Upper UTI

• Kidney damage/Renal failure: Kidneys lose ability to filter waste and balance fluids; may require dialysis or transplant. Bacteremia (bacteria in blood) can occur and may be fatal.

• Pyelonephritis: Inflammation of the kidney(s).

• Ureteritis: Inflammation of the ureter(s).

Lower UTI

• Cystitis: Inflammation of the bladder (commonly referred to as "UTI").

• Urethritis: Inflammation of the urethra.

Etiology and Types of UTIs

• Bacteria are the most common cause.

• GI tract is the major reservoir:

  • Gram-negative enteric bacteria: Majority of cases; Uropathogenic Escherichia coli (UPEC) is the main causative agent.

  • Gram-positive enteric bacteria: Staphylococcus saprophyticus is a notable cause.

• Types of UTIs:

  • Uncomplicated: Occur in healthy individuals; usually resolve with drug therapy.

  • Complicated: Associated with catheters, urinary tract malformations, or underlying health conditions; may not resolve with standard treatment.

• Catheter-Associated UTIs (CAUTIs): Common healthcare-associated infection (HAI); most frequent cause of secondary bacteremia.

Signs, Symptoms, Diagnosis, and Prevention

• Lower UTI symptoms: Dysuria (painful urination), pyuria (pus/WBCs in urine), hematuria (blood in urine), cloudy/smelly urine, lower abdominal pain.

• Upper UTI symptoms: Fever, nausea, vomiting, severe abdominal and back (flank) pain, risk of permanent kidney damage.

• Diagnosis: Urinalysis for WBCs and culture; identification of causative agent.

• Treatment: Antibiotic therapy.

• Prevention:

  • Avoid holding urine for long periods.

  • Drink 6-8 glasses of water daily.

  • Urinate before and after sexual activity.

  • Avoid unnecessary catheter use.

Genital Tract Infections: Sexually Transmitted Infections (STIs)

Overview of STIs

Sexually transmitted infections (STIs) are infections primarily transmitted through sexual contact, affecting the urogenital tract. Many STIs are asymptomatic, which contributes to their spread.

• Common symptoms: Dysuria, lumps/sores, unusual discharge, rash, bleeding, pain during intercourse, or no symptoms at all.

• Most STIs are asymptomatic.

Bacterial STIs

Bacterial STIs are generally treatable and curable with antibiotics.

Chlamydia trachomatis

• Characteristics: Gram-negative, lacks peptidoglycan cell wall, obligate intracellular pathogen.

• Main diseases: Chlamydia (most common bacterial STI), Lymphogranuloma venereum (LGV).

• Transmission: Sexual contact; infects epithelial cells of mucous membranes. Known as the "Silent Epidemic" due to frequent asymptomatic cases.

• Life Cycle:

  • Elementary bodies (EB): Infectious form, released when infected cells rupture; responsible for entry and exit from host cells.

  • Reticulate bodies (RB): Non-infectious, replicative form inside host cell phagosomes (inclusions).

• Signs and Symptoms:

  • Men: Dysuria, urethritis, cloudy discharge, testicular pain/swelling; complications include chronic inflammation, reactive arthritis, infertility.

  • Women: Dysuria, vaginal itching/burning, odorous discharge, bleeding, painful sex, pelvic pain; complications include pelvic inflammatory disease (PID), adverse pregnancy outcomes, infertility.

• Diagnosis: Nucleic Acid Amplification Tests (NAATs) on vaginal swabs, urine, or ocular swabs.

• Treatment: Antibiotics; partners from past 60 days must also be treated. Untreated infections can cause permanent damage and infertility.

Lymphogranuloma venereum (LGV)

• Invasive, ulcerative, chronic STI of lymph nodes/lymphatics caused by certain biovars of C. trachomatis.

• Stages:

  1. Painless genital ulcer at infection site; rectal pain (proctitis).

  2. Invasive infection of lymphatics; swollen, painful lymph nodes (buboes).

  3. Persistent inflammation can obstruct lymphatic vessels if untreated.

Neisseria gonorrhoeae (Gonorrhea)

• Characteristics: Gram-negative diplococcus; can cause systemic disease.

• Transmission: Sexual contact; infects mucous membranes. Untreated cases can lead to disseminated disease, permanent damage, and infertility.

• Signs and Symptoms:

  • Men: Dysuria, purulent discharge, urethritis, epididymitis, prostatitis.

  • Women: Dysuria, vaginal discharge, bleeding, pain during sex, abdominal pain/pressure.

  • Can infect eyes, throat, gingiva, rectum; newborns may develop eye or respiratory infections (can be fatal).

• Complications: PID (females), infertility, disseminated gonococcal infection (DGI) with hemorrhagic pustules, rash, fever, arthritis, blindness.

• Diagnosis: Clinical signs, Gram stain (Gram-negative diplococci in discharge), culture, NAATs.

• Treatment: Antibiotic therapy (resistance is increasing); eye ointment for newborns.

Treponema pallidum (Syphilis)

• Characteristics: Gram-negative spirochete; chronic, systemic STI.

• Transmission: Sexual contact via syphilitic chancre (ulcer), contaminated blood, congenital transmission.

• Stages:

  1. Primary: Painless chancre at infection site; heals in 3-6 weeks; bacteria may disseminate.

  2. Secondary: (Most common stage for diagnosis) Skin-wide rash (including palms/soles), mucous patches, fever, malaise, lymphadenopathy, patchy hair loss, sore throat.

  3. Tertiary: Late stage; affects brain, nervous system, heart, skin; gummas (tumorous lesions), chronic inflammation, permanent disability, life-threatening.

• Diagnosis: Blood, CNS, or lesion fluid/tissue tests; "Great Imitator" due to varied symptoms.

• Treatment: Antibiotics effective in primary and secondary stages.

Eukaryotic and Viral STIs

Protozoan STI: Trichomonas vaginalis (Trichomoniasis)

• Characteristics: Flagellated protozoan parasite; most common, curable STI.

• Transmission: Sexual and skin-to-skin contact; infects vagina, cervix, urethra (women), urethra (men), mouth, throat, anus.

• Signs and Symptoms:

  • Often asymptomatic, especially in men.

  • Men: Itching/burning inside penis, burning with urination/ejaculation, foul-smelling discharge.

  • Women: Fishy, green-yellow, frothy discharge; genital redness, burning, itching (vaginitis); burning with urination; pain with sex.

• Complications: Premature birth, low birth weight, increased susceptibility to other STIs (including HIV).

• Diagnosis: Wet mount microscopy and/or NAAT of discharge or urine.

• Treatment: Antimicrobial therapy; treat sexual partners.

Viral STIs

Viral STIs are treatable but not curable; management focuses on symptom control and prevention of transmission.

Herpes Simplex Virus (HSV-1 and HSV-2)

• HSV-2: Second most prevalent STI; lifelong infection; majority asymptomatic.

• Transmission: Direct contact (not fomites); neonatal herpes can be fatal.

• Symptoms (6 stages):

  1. Prodrome: Non-specific symptoms (itching, pain).

  2. Inflammation: Red, tender, inflamed skin.

  3. Blisters: Fluid-filled blisters (classic symptom).

  4. Ulcers: Blisters burst, forming ulcerative sores.

  5. Crusts: Ulcers dry and scab.

  6. Healing: Scabs fall off.

• Latency: Virus remains dormant in peripheral nerves; periodic reactivation; lifelong infection.

• Diagnosis: Fluid sample from blisters (NAAT), culture, blood test; outbreaks can be diagnostic.

• Treatment: No cure; antivirals reduce symptoms and recurrences.

Human Papillomavirus (HPV)

• Most common STI worldwide.

• Often asymptomatic; usually cleared by immune system within 2 years, but can persist as lifelong infection.

• Clinical manifestations:

  • Low-risk strains (6, 11): Genital and respiratory warts; rarely cause cancer.

  • High-risk strains (16, 18): Genital and oral cancers; typically do not cause warts.

• Transmission: Skin-to-skin contact; often asymptomatic.

• Screening and Vaccination:

  • Women: Pap smear for abnormal cervical cells.

  • Men: No routine screening.

  • Vaccination available for prevention.

Human Immunodeficiency Virus (HIV)

• Pathogenesis: Attacks CD4+ T cells, leading to immunodeficiency (AIDS).

• Transmission: Via bodily fluids (blood, semen, vaginal secretions, breast milk).

Table: Comparison of Major Bacterial STIs

Pathogen	Gram Stain/Type	Main Disease(s)	Symptoms	Diagnosis	Treatment
Chlamydia trachomatis	Gram-negative, lacks peptidoglycan, obligate intracellular	Chlamydia, LGV	Often asymptomatic; dysuria, discharge, pelvic/testicular pain	NAATs (swab/urine)	Antibiotics
Neisseria gonorrhoeae	Gram-negative diplococcus	Gonorrhea	Often asymptomatic; dysuria, purulent discharge, PID, DGI	Gram stain, culture, NAATs	Antibiotics (resistance increasing)
Treponema pallidum	Gram-negative spirochete	Syphilis	Chancre, rash, systemic symptoms, gummas (late)	Serology, lesion fluid/tissue tests	Antibiotics (early stages)