urinary system

Understand and discuss the composition of the urinary system and its immune defenses.
Cover the diagnosis, pathogenesis, treatment, transmission, and prevention of diseases related to the urinary system.
Utilize appropriate terminology related to urinary system diseases.

The urinary system is often studied alongside the reproductive system but should be considered separately due to distinct functions and anatomy.
Anatomy of the urinary system includes:
- Kidneys
- Ureters
- Urinary bladder
- Urethra
Function:
- Filter blood to remove waste and form urine for waste elimination.

Except for the kidneys, urinary system structures are lined with mucous membranes.
Mucous production helps protect the urinary tract from infections.
Defenses include:
- Urine flow: Rapid flow aids in carrying away bacteria and dead cells.
- Desquamation: The shedding of old and dead cells, along with bacteria attached to them.

Proximity of urinary and gastrointestinal openings allows normal flora bacteria to potentially cause infections in the urinary tract.
Urinary tract cells have different markers than GI tract cells, inhibiting GI flora attachment.
Urine is generally acidic (average pH = 6), and its composition varies based on metabolic status.
Urine contains antimicrobial proteins:
- Lysozyme
- IgA
- Lactoferrin

UT infections arise when bacteria improperly colonize urinary structures.
Common characteristics of UTIs:
- Highly prevalent, especially among women.
- Estimated that 1 in 3 women will experience a UTI needing antimicrobial treatment before age 24.
- 50% of women will have at least one UTI in their lifetime.
- Annual cost associated with UTIs ranges from $1-2 billion.

Urethritis: Infection of the urethra.
- More likely when urine flow decreases, allowing bacteria to colonize.
Cystitis: Infection of the bladder.
Pyelonephritis: Infection that reaches the kidneys.

Main cause: E. coli (Escherichia coli) accounts for approximately 80% of UTIs, particularly uropathogenic E. coli (UPEC).
Virulence factors of UPEC include:
- Adhesion genes for sticking to urinary tract cells.
- Invasion genes that allow bacteria to enter epithelial cells and grow within them.
- Exfoliative genes that promote the shedding of urinary tract cells.
- Some strains may possess the extended spectrum beta-lactamase (ESBL) gene, conferring resistance to various antibiotics.

UPEC can invade urinary epithelial cells, serving as a hiding mechanism from the immune system and providing resistance to antimicrobial treatment.
Recurrence Rates:
- 25% within 6 months
- 46% within 12 months of the initial infection.

Factors contributing to UTI-causing bacteria include:
- Adhesion molecules specific to urinary tract epithelial cells.
- Flagella: Facilitate movement against urine flow.
- Lipoteichoic acid: Present in S. saprophyticus, enhancing its adherence due to its sticky nature.

UTIs are primarily transmitted from one organ system to another rather than directly between individuals.
Pre-disposing factors include:
- Vaginal colonization
- Obstruction of urinary tract
- Incomplete or infrequent voiding
- Abnormal urinary tract anatomy
- Bacterial pili and fimbriae that help adherence.

Common signs of UTIs:
- Persistent urge to urinate.
- Burning sensation during urination (dysuria).
- Production of small volumes of cloudy urine, potentially with blood (hematuria).
- Pain/pressure in the pubic area, particularly with cystitis.
Pyelonephritis symptoms include high fever and severe effects on the bladder and kidneys.
Untreated UTIs can lead to bloodstream infections (septicemia).

Preventive measures include:
- Frequent bladder emptying.
- Wiping front to back after bowel movements.
- Consumption of cranberry juice can decrease E. coli attachment to urinary cells.
Antibiotics for UTIs:
- Ampicillin
- Amoxicillin
- Trimethoprim-sulfamethoxazole (Bactrim)
- Nitrofurantoin (Macrobid)
- Azithromycin
Pyridium may be given for symptomatic relief from burning and urgency.

Non-bacterial pathogens include Candida (yeast), particularly in catheterized patients.
Candida albicans and Candida auris are noted as significant pathogens.
- Candida auris shows increasing resistance to antifungal treatments, being a rising concern in healthcare as it forms biofilms on medical devices.
Signs and symptoms largely mirror those of bacterial UTIs, often including hematuria.
Diagnosis through fungal culture and microscopy.
Treatment typically involves Fluconazole, while resistant strains may require Amphotericin B.

A rare kidney disease caused by the spirochete Leptospira (eight species capable of human infection).
Transmitted through water contaminated with animal urine, entering the human body via cuts.
Initial symptoms: fever, chills, muscle aches, headaches, vomiting, conjunctivitis.
Potential progression to life-threatening Weil’s syndrome, causing kidney and liver damage, jaundice, anemia, and neurological issues.
Rarely fatal if treated timely.

Immediate treatment with Doxycycline and Penicillin upon diagnosis.
Diagnosis primarily via indirect ELISA or agglutination tests detecting Leptospira-specific IgM.
IgM signifies early exposure to the pathogen.

This lecture concludes the discussion on infectious diseases of the urinary system, encompassing anatomy, defense mechanisms, and the major bacterial and fungal causative agents, their diagnosis, and treatments.