Urinary tract infection (UTI) Flashcards
What is a UTI?
Urinary tract infections are infections anywhere along the urethra, bladder, ureters and kidneys
What is meant by lower UTI?
Infection confined to the bladder (Cystitis) and urethra
What is meant by upper UTI?
Infection involving the ureters or kidneys (Pyelonephritis)
What is the most common type of organism in UTI?
Gram -ve aerobic bacilli
What are the 2 main groups of gram -ve aerobic bacilli
Lactose fermenters
Lactose non-fermenters
What are some important lactose fermenters in UTI?
- Eschericia coli (E.coli) - Most common
- Klebsiella sp.
- Enterobacter sp.
- Serratia sp.
- Citrobacter sp.
What re the 2 main groups of non-lactose fermenting gram -ve aerobic bacilli?
Oxidase negative
Oxidase positive
What are some important oxidase -ve bacteria in UTI?
- Morganella sp.
- Proteus sp.
- Providencia sp.
What is an important oxidase +ve bacteria in UTI?
Pseudomonas aeruginosa
What is the most common pathogen in UTI?
Escherichia coli (E.coli)
What is a virulence factor of E.coli
Endotoxin - Causes fever
Give the characteristics of proteus UTI
1-10% of UTIs
Foul smelling, like burnt chocolate
Proteus produces urease which breaks down urea to form ammonia, which increases urinary pH
This can lead to the precipitation of salts, leading to struvite stone formation
Give the chacareristics of pseudomonas aeruginosa UTI
Gram negative bacillus
Less common cause of UTI, associated with catheter and instrumentation
It is intrinsically resistant to most oral antibiotics, except ciprofloxacin (4C antibiotic)
Give the characteristics of enterococcus UTI
These are a common form of streptococci found in the GI tract
Examples include:
- Enterococcus faecalis
- Enterococcus faecium
Give the characteristics of staphylococcus saprophyticus UTI
A form of coagulase negative staphylococcus, common in women of childbearing age, commonly causing lower tract community infection
Give the characteristics of staphylococcus aureus UTI
Staph. aureus is uncommon in UTI and is usually in bacteraemia
What are some risk factors for UTI
Women
Catheterised patients
Abnormalities of the urinary tract
Why are women at greater risk of UTI?
Short, wide urethra, proximity of urethra to anus, increased risk with sexual activity and pregnancy
What is acute pyelonephritis?
Infection of the tissue of the kidney
Does urine usually contain bacteria?
No, urine within the kidneys, ureters and bladder is usually sterile
It can be contaminated on the way out by bacteria in the lower end of the urethra
What are some bodily defences for bacteria entering via the urological system?
Urine acidity
Complete voiding
Vesicouteric valve
Mucosal and immunological defences
What are the 2 main routes of infection of the urinary tract?
Ascending route (Bacteria from bowel enters and travels up)
Haematogenous route