Microbiology Chapter 25: Reproductive and Urinary Tract Infections & Sexually Transmitted Diseases

Chapter 25: Reproductive and Urinary Tract Infections & Sexually Transmitted Diseases

A Glimpse of History

This section provides historical context for syphilis, an ancient and once very common disease, and the discovery of its causative agent.

• Syphilis was historically severe, often fatal, and resistant to early treatments such as mercury and plant products.

• Mutations and natural selection led to more resistant hosts and less virulent microbes over time.

• In 1905, Fritz Schaudinn observed pale, slender, motile organisms (spirochetes) in syphilitic sores, later named Spirochaeta pallida and now known as Treponema pallidum.

Reproductive and Urinary Tract Infections

Infections of the reproductive and urinary tracts are common and can have serious health consequences.

• Urinary Tract Infections (UTIs) are the most frequent healthcare-associated infections and a main origin of fatal bacterial bloodstream infections.

• Puerperal fever is a uterine infection associated with childbirth.

• Sexually Transmitted Infections (STIs) are widespread, with the U.S. having the highest reported incidence among developed countries.

25.1. Anatomy, Physiology, and Ecology

The Urinary System

The urinary system consists of the kidneys, ureters, bladder, and urethra, and is protected by several mechanisms.

• Kidneys filter waste from blood and reabsorb substances.

• Bladder stores acidic urine, which is excreted through the urethra.

• Protective mechanisms include sphincter muscles, downward urine flow, and antimicrobial substances in urine.

• Women are more likely to get UTIs due to shorter urethras.

The Genital System

The genital system differs between females and males and is susceptible to various infections.

• Females: Ovaries, fallopian tubes, uterus, vagina, vulva (labia, clitoris).

• Eggs are released during ovulation and may be fertilized in the fallopian tube, implanting in the uterus.

• The cervix contains antimicrobial mucus except during menstruation and opens to the vagina.

• Infections can occur in the vagina, cervix, and fallopian tubes, potentially leading to infertility.

• Males: Testes (in scrotum), epididymis, vas deferens, prostate gland, penis.

• Sperm and prostate secretions form semen, which has antimicrobial properties.

• Older men may experience enlarged prostate, slowing urine flow and increasing infection risk.

Normal Microbiota

• Urine and urinary tract above urethra are usually free of microorganisms.

• Lower urethra contains resident microbiota: Lactobacillus, Staphylococcus, Corynebacterium, Haemophilus, Streptococcus, Bacteroides.

• Female genital tract microbiota is influenced by hormones; Lactobacillus converts glycogen to lactic acid, resulting in acidic pH that inhibits pathogens.

25.2. Urinary Tract Infections

Bacterial Cystitis (Bladder Infection)

Bacterial cystitis is the most common type of UTI, with varied symptoms and significant epidemiological impact.

• Signs and Symptoms: Burning pain during urination, urgency, frequent small urinations, cloudy or bloody urine, odor, pain above pubic bone, possible fever and back pain if pyelonephritis develops.

• Causative Agents: Usually from normal intestinal microbiota; >80% caused by uropathogenic Escherichia coli (UPEC). Others include Klebsiella, Proteus, Staphylococcus saprophyticus, and in hospitals, Serratia marcescens, Pseudomonas aeruginosa, Enterococcus faecalis.

• Pathogenesis: Pathogens ascend urethra, UPEC uses fimbriae to attach to epithelial cells, forms intracellular bacterial communities (IBCs), evades immune response, and can establish chronic reservoirs.

• Epidemiology: 30% of women develop cystitis; risk factors include short urethra, sexual activity, birth control devices, enlarged prostate, catheterization, paraplegia.

• Treatment and Prevention: Antimicrobials, hydration, urination after intercourse, wiping front to back, low-dose antimicrobials, cranberry juice (effectiveness inconclusive).

Table: Bacterial Cystitis Overview

Aspect	Details
Signs & Symptoms	Painful urination, urgency, cloudy/bloody urine, fever (if pyelonephritis)
Causative Agents	UPEC, Klebsiella, Proteus, Staphylococcus saprophyticus
Pathogenesis	Ascends urethra, attaches via fimbriae, forms IBCs
Epidemiology	Common in women, risk factors: short urethra, sexual activity
Treatment	Antimicrobials, hydration, hygiene

Leptospirosis

Leptospirosis is a zoonotic infection with a wide range of symptoms and global distribution.

• Signs and Symptoms: Often asymptomatic; may include fever, headache, muscle pain, photophobia, redness of eyes, and in severe cases, jaundice, kidney/liver failure, hemorrhage, meningitis.

• Causative Agent: Leptospira interrogans, a slender, aerobic Gram-negative spirochete with hooked ends; >250 antigenic types.

• Pathogenesis: Entry via mucous membranes or skin breaks, disseminates via bloodstream, immune system clears except in kidneys, immune phase can cause vascular injury and kidney failure.

• Epidemiology: Worldwide, especially tropics; transmitted via contaminated animal urine, survives in mud/water, infects humans through water, soil, food.

• Treatment and Prevention: Antibiotics (early), avoid animal urine, vaccines for animals, tetracycline prophylaxis for high-risk individuals.

Table: Leptospirosis Overview

Aspect	Details
Signs & Symptoms	Fever, headache, muscle pain, jaundice, kidney failure
Causative Agent	Leptospira interrogans
Pathogenesis	Entry via mucosa/skin, disseminates, immune phase injury
Epidemiology	Worldwide, animal urine transmission
Treatment	Antibiotics, prophylaxis, animal vaccination

25.3. Genital System Diseases

Bacterial Vaginosis (BV)

Bacterial vaginosis is a common vaginal infection with unclear etiology and significant reproductive health implications.

• Signs and Symptoms: Thin, grayish-white, bubbly discharge with fishy odor; may lead to pelvic inflammatory disease (PID) and sterility; ~50% asymptomatic.

• Causative Agent: Unknown; associated with decreased Lactobacillus and increased Gardnerella vaginalis, anaerobic streptococci, Mobiluncus, Prevotella, Mycoplasma.

• Pathogenesis: Loss of vaginal acidity, disruption of microbiota, increase in clue cells (epithelial cells covered with bacteria), fishy odor from anaerobic metabolism.

• Epidemiology: Most common in sexually active women, increased risk with certain behaviors (thongs, douching, multiple partners), not proven to be sexually transmitted.

• Treatment and Prevention: Antibiotics, prevention by abstinence, limiting partners, avoiding douching/thongs; treatment of male partners does not prevent recurrence.

Table: Bacterial Vaginosis Overview

Aspect	Details
Signs & Symptoms	Grayish-white discharge, fishy odor, PID risk
Causative Agent	Unknown; decreased Lactobacillus, increased anaerobes
Pathogenesis	Loss of acidity, clue cells, anaerobic metabolism
Epidemiology	Sexually active women, behavioral risk factors
Treatment	Antibiotics, behavioral prevention

Vulvovaginal Candidiasis (VVC)

VVC is a fungal infection of the vagina, commonly caused by Candida albicans.

• Signs and Symptoms: Intense itching and burning, thick clumpy discharge, red/swollen mucosa with cottage cheese-like clumps.

• Causative Agent: Candida albicans, a yeast part of normal microbiota in ~1/3 of women.

• Pathogenesis: Normally asymptomatic; overgrowth occurs with disruption of immune system or microbiota (menstruation, pregnancy, antibiotics), leading to inflammation.

• Epidemiology: Predisposed by pregnancy, diabetes, oral contraceptives, antibiotics; not spread person-to-person.

• Treatment and Prevention: Antifungals (nystatin, clotrimazole, fluconazole); minimize antibacterial use, treat underlying conditions.

Table: Vulvovaginal Candidiasis Overview

Aspect	Details
Signs & Symptoms	Itching, burning, clumpy discharge, red mucosa
Causative Agent	Candida albicans
Pathogenesis	Overgrowth after microbiota/immune disruption
Epidemiology	Pregnancy, diabetes, antibiotics; not contagious
Treatment	Antifungals, treat underlying conditions

Key Terms and Concepts

• Spirochete: A type of bacteria with a spiral shape and motility, e.g., Treponema pallidum.

• Fimbriae: Hair-like appendages on bacteria that aid in attachment to host cells.

• Clue cells: Vaginal epithelial cells covered with bacteria, diagnostic for BV.

• Pelvic Inflammatory Disease (PID): Infection of female reproductive organs, can lead to infertility.

• Antimicrobial substances: Chemicals in urine and genital secretions that inhibit microbial growth.

Example: Pathogenesis of UPEC in Cystitis

• UPEC attaches to bladder epithelial cells via fimbriae.

• Induces cell death and sloughing, allowing entry into underlying tissue.

• Forms intracellular bacterial communities, evades immune response, and establishes chronic infection.

Additional info:

• Tables have been reconstructed from slide content and standard microbiology knowledge.

• Some details expanded for clarity and completeness.