Lecture 12: UTIs Flashcards
UPEC and Proteus mirabilis
The are eight risk factors I should be aware of and quote.
What are the common risk factors for developing a UTI?
- Loss of sphincter function.
- Foreign bodies (e.g., catheters)
- Mucosal damage
- Abnormal urine constituents (e.g., glucose).
- Incomplete bladder emptying.
- Dehydration
- Poor hygiene
- Frequent sexual intercourse.
Glucose in the urine may support bacteria proliferation. Incomplete bladder emptying is quite common in elderly males who experience prostatitis (inflammation of the prostrate gland). Bacteria may survive in stagnant pools of urine.
Why are women at a higher risk of UTIs than men?
Women have a shorter urethra, making it easier for bacteria to ascend into the urinary tract.
List 6 symptoms.
What are the common symptoms of a UTI?
- Increased frequency and urgency of urination.
- Dysuria (painful urination).
- Suprapubic pain.
- Haematuria (blood in urine).
- Cloudy urine (pyuria and bacteriuria).
- Foul-smelling urine.
What methods are used to detect UTIs?
Dipstick tests, leukocyte esterase detection, and nitrate reduction tests.
What are the two major routes of UTI infections?
- Ascending UTIs – start in the urethra and can progress to the bladder and kidneys.
- Haematogenous UTIs – bacteria from the bloodstream establish infection in the kidney.
What are the three main types of UTI infections?
- Pyelonephritis (kidney infection).
- Cystitis (bladder infection).
- Urethritis (urethra infection).
Which bacterial species is the most common cause of UTIs?
Uropathogenic Escherichia coli (UPEC).
What is the second most common pathogen to cause of UTIs, particularly in young, sexually active women?
Staphylococcus saprophyticus (coagulase-negative).
What virulence factors allow UPEC to adhere to urinary epithelial cells?
Type 1 and Type P pili, which bind surface carbohydrates on urinary epithelial cells.
What is the function of FimH adhesin in UPEC infections?
Binds to mannose sugars on uroplakin glycoproteins of urinary epithelial cells, allowing bacterial adhesion.
What is the function of PapGII adhesin in UPEC infections?
Binds to globobiose sugar on kidney epithelial cells, aiding bacterial colonization.
What is the role of LPS in UPEC infections?
Stimulates an inflammatory response.
What is the function of alpha-haemolysin in UPEC infections?
A pore-forming exotoxin that binds calcium ions, damaging host cells.
How does UPEC evade the immune system?
By forming intracellular bacterial communities and persisting in quiescent intracellular reservoirs.
Why is UPEC infection recurrence poorly understood?
Possible factors include genetic predisposition, the colon acting as a bacterial reservoir, or latent infections in quiescent intracellular reservoirs.
What is the first-line treatment for uncomplicated UTIs?
Nitrofurantoin.
Why is Nitrofurantoin an effective treatment for UTIs?
It is effective against E. coli and is not commonly used for other infections, reducing the risk of antibiotic resistance.
What are 3 alternative treatments for UTIs?
- Pivmecillinam
- Trimethoprim
- Fosfomycin
What bacterial species is associated with both UTIs and kidney stone formation?
Proteus mirabilis.
What is the primary distinguishing characteristic of Proteus mirabilis?
Hypermotility due to swarming, where bacteria migrate once a population threshold is reached.
How does Proteus mirabilis contribute to kidney stone formation?
Produces urease, which breaks down urea into ammonia and carbon dioxide, increasing urine pH and causing calcium and magnesium carbonate precipitation.
What virulence factors does Proteus mirabilis use to establish infection?
Urease, pili for adhesion, and IgA protease (helps evade immune response).
Where is Proteus mirabilis commonly found in the environment?
In soil, water, and sewage, and it can colonize the intestine.
Besides UTIs, what other infections can Proteus mirabilis cause?
Wound infections, pneumonia, and septicaemia in immunocompromised patients.
