Microbiology of Urinary Tract Infections Flashcards
What is a UTI?
An infection that affects part of the urinary tract
What are UTIs like?
Asymptomatic (subclinical infections)
Symptomatic (disease)
What are different examples of UTIs? What are they?
Asymptomatic bacteriuria (ASB)
Cystitis (inflammation of the bladder)
Prostatitis (inflammation of the prostate)
Pyelonephritis (symptomatic infections of the kidneys)
What typically causes cystitis?
A bacterial infection: bacteria enter the urethra and the bladder, and they begin to multiply
What are the different types of prostatitis?
Acute bacterial prostatitis: caused by sudden bacterial infection
Chronic bacterial prostatitis: characterized by recurrent bacterial infections of the prostate gland
How does prostatitis arise?
Bacteria enter the urethra, prostate and bladder
What is acute pyelonephritis a result of ?
Bacterial invasion of the renal parenchyma
What is acute pyelonephritis?
It is a potential organ and/or life-threatening infection that often leads to renal scarring
What usually causes pyelonephritis?
In most cases; ascending cystitis infection combined with anatomical defects
What kind of anatomical defects can lead to pyelonephritis? (3) Who do they mostly present in?
- Defective vesicoureteral junction (50% of children with UTIs have reflux)
- Bladder outlet obstruction (older males due to prostatic hypertrophy)
- Hematogenous infection <2% of UTIs (usually occurs in clinical settings of substantial bacteremia, like sepsis)
What are the symptoms of cystitis? (5)
- Dysuria: Pain or burning sensation during urination
- Hematuria: blood in the urine
- Urgency & Frequency
- Pain in the lower abdomen: lower back and suprapubic pain
- Pyuria: urine looks turbid/cloudy because of presence of pus
What are the symptoms of pyelonephritis? (3)
- Pain on either side of the lower back
- Fever and chills
- Nausea and vomiting
What population are UTIs most common in?
Women because of the anatomy of the urethra compared to men
What is the most common example of UTI?
Cystitis
When do men start being affected by UTIs and why?
After the age of 50, men start to get affected as well, more commonly because of the obstruction from prostatic hypertrophy
What is the prevalence of ABS among women?
5% among women between ages 20 and 40 and 40 to 50% among elderly women
During the neonatal period which gender is more commonly affected by UTIs and why?
Slightly higher among males because more likely to have congenial urinary tract anomalies
What determines whether or not the bacteria can establish an infection?
Bacteria can enter the bladder, but whether or not they can establish an infection depends on the interplay between the host, pathogen, and environment
Why is urine a good environment for bacteria to grow and multiply?
It has a lot of waste products that bacteria can feed on
What are the factors relating to the organism that determine infection, colonization, or elimination?
Type of organism
Presence of virulence factors
Expression of virulence factors
What are the factors relating to the host that determine infection, colonization, or elimination?
Genetic background
Behavioral factors
Underlying disease
Tissue-specific receptors
What are the factors relating to the environment that determine infection, colonization, or elimination?
Vaginal ecology
Anatomy/urinary retention
Medical devices
What is the pathogenesis of UTIs? (11)
They ascend from the urethra to the kidneys:
Contamination of the periurethral area
Colonization: occurs in the urethra
Uroepithelium penetration: occurs in the bladder
Neutrophil infiltration
Bacterial multiplication and immune system subversion
Biofilm formation
Epithelial damage due to toxins and proteases
Ascension: occurs in the ureters
Pyelonephritis: occurs in the kidneys
It can even lead to acute kidney injury
Bacteremia
What is the colonization of UTIs like?
Pathogen colonizes the periurethral area and ascends through the urethra towards the bladder