Urinary Tract Infection Flashcards
Define a UTI
An infection of any part of your urinary system.
Define an infection
The invasion of body tissues by a pathogenic organism which causes an immune response, giving rise to symptoms.
Why are UTIs 10x more common in females?
Due to length of urethra
What are 6 predisposing factors for UTIs?
- Female
- Urinary stasis
- Urological instrumentation (including catheters)
- Sexual intercourse
- Fistulae
- Congenital abnormalities
How can pregnancy predispose you to UTIs?
Due to hormonal ureteral dilation, hormonal ureteral hypoperistalsis, and pressure of expanding uterus against ureters.
These factors lead to URINARY STASIS
Why do more men get UTIs as they get old?
Prostatic hypertrophy –> obstruction leads to URINARY STASIS
What other factors can cause urinary stasis?
o Urinary stones, strictures, neoplasia
o Residual urine (poor bladder emptying)
What 2 fistulae can predispose you to UTIs?
A urinary fistula is an abnormal connection between a urinary tract organ and another nearby organ.
- Recto-vesical: between colon and bladder
- Vesico-vaginal: between bladder and vagina
How can fistulae predispose you to UTIs?
Direct movement of bacteria from the genital/GI tract to the urinary tract
Which congenital abnormality can predispose you to UTIs?
Vesico-ureteric reflux (VUR)
What is vesico-ureteric reflux (VUR)?
A condition in which urine flows backward from the bladder to one or both ureters and sometimes to the kidneys.
State whether the following organs are sterile or colonised:
a) kidneys
b) ureter
c) urethra
d) bladder
a) sterile
b) sterile
c) colonised
d) usually considered sterile, but this may not always be the case
What does ‘sterile’ mean?
Free of all biological contaminants (e.g. fungi, bacteria, viruses), not just those that can cause disease.
Which bacteria is the majority of UTIs caused by?
More than 90% of UTIs are due to enteric Gram-negative organisms, more than 80% of which are E. coli.
Are most UTIs caused by gram-negative or positive bacteria?
Gram-negative
What makes up the perineal flora?
Skin flora:
o Mainly coagulase negative staphylococci
Lower GI tract flora:
o ‘Internal’ colonising bacteria are often found on the skin around the relevant oriface
o {Anaerobic bacteria}
o Aerobic bacteria
Enterobacterales (aka “coliforms”), enteric Gram negative bacilli
Gram positive cocci
o Enterococcus spp.
Why do most bacteria that cause UTIs come from?
Gut (enteric)
UTIs can also be caused by haematogenous spread, although this is rare.
Which organism is mainly involved in this?
Staphylococcus aureus
What are the 6 most common organisms that cause UTIs (in descending order)?
- E. coli
- Staphylococcus saprophyticus (CNS)
- Proteus mirabilis
- Enterococcus spp.
- Klebsiella spp.
- Pseudomonas aeruginosa
Why is it important that a urinary sample is taken properly?
If the urine is not collected in a sterile manner the urine sample may be ‘contaminated’ by bacteria that originate from the skin or genital area, and not from the urinary tract.
What is ‘asymptomatic bacteriuria’? Who is it most common in?
No symptoms of a UTI but cultured urine sample grows a single organisms in significant numbers.
particularly in the >65s
What is cystitis?
Cystitis is inflammation of the bladder –> lower UTI
What are the symptoms of cystitis?
Dysuria Frequency Urgency Supra-pubic pain or tenderness Polyuria, nocturia, haematuria
Which antibiotic is the first choice treatment for cystitis?
Nitrofurantoin
What spectrum is Nitrofurantoin?
Broad spectrum; effective against gram-negative and positive
Why is Nitrofurantoin used to treat LOWER UTIs only?
Only effective in bladder; concentrates in urine:
Lower UTIs only (not for prostatitis)
Inadequate for systemic infections
What alternative antibiotics can be used to treat UTIs?
Pivmecillinam
Trimethoprim
Fosfomycin
What is pyelonephritis?
Kidney infection (pyelonephritis) is a type of urinary tract infection (UTI) that generally begins in your urethra or bladder and travels to one or both of your kidneys.
Symptoms of pyelonephritis?
Infection of the kidney and/or renal pelvis
Symptoms of lower UTI
Loin/abdominal pain or tenderness
Fever
Other signs of systemic infection: rigors, nausea, vomiting, diarrhoea, elevated CRP, WBC
What is a ‘complicated’ UTI?
UTI occurring in a host with:
Underlying abnormality (structural / functional)
o Urinary stasis – obstruction / retention
Presence of “foreign body”
o Catheter / other device / renal calculi
o Biofilm
Children <10-12, Men <65: suspect unless confirmed otherwise
What is an ‘uncomplicated’ UTI?
One occurring in a normal host who has no structural or functional abnormalities, is not pregnant, or who has not been instrumented (for example, with a catheter).
What is a catheter-associated UTI (CA-UTI)?
A urinary tract infection associated with urinary catheter use
How can an indwelling catheter result in bacteriuria?
Biofilm formation leads to colonisation as enables bacteria to stick to catheter.
Manipulation or catheter removal may also result in bacteraemia.
When would antibiotic prophylaxis be indicated for CA-UTI?
o Previous symptomatic CA-UTI with catheter change/removal
o Traumatic catheterisation (including 2 or more attempts)
o Purulent urethral/suprapubic catheter exit site discharge
o Catheter or meatal/suprapubic catheter exit site colonisation with Staphylococcus aureus (including MRSA).
Why is dipstick testing not an effective method for detecting urinary tract infections in catheterised adults?
There is no relationship between the level of pyuria and infection in people with indwelling catheters (the presence of the catheter invariably induces pyuria without the presence of infection).
Symptoms of CA-UTI?
o Irritation o Pus around catheter o Systemic symptoms o No dysuria or urgency, rarely urinary frequency due to catheter o Supra-pubic pain or tenderness
What is a ‘nephrostomy’?
Percutaneous straight into the kidney in order to drain urine, normally due to acute obstruction
Nephrostomies can get infected. What are the symptoms?
o Fever
o Pain, tenderness at the site
o Haematuria or purulent discharge
o Unlikely to get bladder symptoms
