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
What is an ileal conduit/urostomy?
A system or urinary drainage which a surgeon creates using the small intestine after removing the bladder, creating a channel for urine to reach the skin through this conduit.
Drains the ureters directly to a stoma on the anterior abdominal wall after cystectomy.
Ileal conduits/urostomies can get infected. What are the symptoms?
o Fever
o Ascending infection (upper UTI symptoms)
o Para-stomal skin infections – redness, swelling, pus
What is ‘urosepsis’?
A type of sepsis caused by a UTI. Often caused by UTIs that are not treated quickly or properly.
Symptoms/signs of urosepsis?
Systemic signs of infection related to any underlying urinary source of infection: o Fever o Rigors o Nausea, vomiting, diarrhoea o +/- Haemodynamic compromise o Raised inflammatory markers (CRP, WCC)
Are there always signs of pyelonephritis in urosepsis?
No
What are 3 other diseases that can cause urethral symptoms?
- STIs e.g. Gonorrhoea
- Thrush (vulvovaginal candidiasis)
- Urethral syndrome
Which urethral symptoms can thrush (vulvovaginal candidiasis) cause?
irritation and symptoms such as dysuria
What is ‘urethral syndrome’?
Lower UTI symptoms (urinary frequency, urgency, dysuria, and suprapubic discomfort) but NO RECOGNISED URINARY PATHOGEN
aka; abacterial cystitis, frequency-dysuria syndrome
What are the theorised aetiologies behind urethral syndrome?
Hormonal imbalances, inflammation of Skene glands and the paraurethral glands, a reaction to certain foods, environmental chemicals (eg, douches, bubble bath, soaps, contraceptive gels, condoms), hypersensitivity following UTI, and traumatic sexual intercourse.
Who does urethral syndrome typically affect?
Mostly affects 30-50 year old women
Urinary tract abscesses can also occur.
What is a perinephric abscess? What is it usually due to?
A collection of suppurative material in the renal parenchyma or perinephric space:
- UTIs spreading to kidney
- Surgery
- Bloodstream infection
- Urinary tract obstruction (prolonged bacteraemia)
- Obstruction of infected kidney
- Renal stones
- Diabetes
What type of organisms cause perinephric abscesses?
Gram negative bacilli
What is an intrarenal abscess?
a collection of infective fluid in the kidney
Which organism typically causes intrarenal abscesses? How is it spread here?
Staphyloccus aureus
Haematogenous spread: unilateral, single, renal cortex.
What disease can intrarenal abscesses be associated with?
Pyelonephritis
What is prostatis?
Inflammation of the prostate.
Signs and symptoms of acute bacterial prostatitis?
o Lower urinary tract symptoms.
o Fever
o Tender tense prostate on PR palpation
o Acute retention
What pathogens typically cause acute bacterial prostatitis?
o Typically the normal urinary pathogens, e.g. E. coli
o Can be caused by S. aureus
What are risk factors for prostatitis?
o Procedures involving the prostate e.g. Trans-urethral resection of prostate (TURP) or trans-rectal ultra-sound guided (TRUS biopsy).
o Indwelling urinary catheter
What is over 90% of chronic prostatitis due to?
Chronic pelvic pain syndrome
What is chronic pelvic pain syndrome?
Chronic nonbacterial prostatitis is a common male genitourinary condition characterised by episodes of pain and discomfort that come and go unpredictably. It may also involve inflammation and difficulties with urination.
o Negative urine culture
o Non-bacterial
What is chronic bacterial prostatitis caused by?
o Recurrent UTIs with the same organism
o Asymptomatic in-between
Why is it important to use the narrowest spectrum antibiotic possible?
Reduces risk of things such as C. difficile
Reduces impact on the patient’s microbiome
When should dipsticks not be used?
- Do NOT use for catheter samples
- Unreliable in >65y
- In children:
Do NOT use if <3 months,
3m-3y can use, but if high risk send for culture regardless of result,
>3y they are reliable
What results can dipsticks give?
- Blood (haematuria)
- Protein (proteinuria)
- Nitrite
- White blood cells (leucocyte esterase)
What would a positive dipstick result for nitrites indicate?
Nitrites are generally found in urine due to reduction of nitrates to nitrites by Gram-negative bacteria e.g. E. coli
What is leucocyte esterase? What does it indicate in a dipstick?
o Leucocyte esterase is an enzyme released by neutrophils and macrophages
Positive dipstick indicates pyuria (an increased number of white cells in urine)
In a UTI, which 2 results of a dipstick are important?
The presence of leucocyte esterase and nitrites is important
Why can a dipstick sometimes be negative for nitrite even in the presence of a UTI?
Gram positive uropathogens such as Staphylococcus saprophyticus and Enterococcus do not produce no nitrate reductase and therefore when infection is due to these bacteria, the dipstick will be negative for nitrite.
Why should urine be collected mid stream (MSU)?
o The initial stream will pick up the bacteria colonising the urethra
o The mid-stream better represents any bacteria actually in the bladder (or higher urinary tract)
Why do some urine sample bottles contain boric acid? What is the colour of the top of this bottle?
Red top
Boric acid makes sure the urine is preserved and suitable for testing for cells and bacteria that indicate a UTI, if the sample cannot be analysed within 4 hours of collection.
What can a large amount of epithelial cells in urine indicate?
A large amount may indicate an infection, kidney disease, contamination etc
What is sterile pyuria?
Sterile pyuria is the persistent finding of WCCs in the urine in the absence of bacteria
Pus cells (raised WCC) in the urine
No organisms grown (with standard lab methods)
What are 4 causes of sterile pyuria?
- Inhibition of bacterial growth (e.g. antibiotics or specimen contaminated with antiseptic)
- “Fastidious” (hard to grow) organisms
- Urinary tract inflammation
- Urethritis (Sexually transmitted pathogens)
Which Sexually transmitted pathogens can lead to sterile pyuria?
o Neisseria gonorrhoeae
o Chlamydia trachomatis.
Which Fastidious” (hard to grow) organisms can lead to sterile pyuria?
Mycobacterium tuberculosis, Haemophilus spp., Anaerobes
How is early morning urine (EMU) collected?
An early morning urine sample is the first pass urine of the day and should be collected into three separate containers over three consecutive days. This sample MUST be the first urine of the day.
What UTI indications suggest the need for further investigations?
Recurrent UTI
Any UTI in male patient
Any UTI in childhood
Pyelonephritis
What is non-antimicrobial management for UTIs?
Increase fluid intake; flush it out the system, also works as preventative method
Anti-inflammatories – e.g. NSAID Ibuprofen (pain)
Device removal if no longer indicated. If still needed: change (under prophylaxis).
Drainage if obstruction / abscess.
What defines a ‘recurrent’ UTI?
> 3 episodes within 12 months.
How long is the antibiotic course for females with cystitis?
3 days
How long is the antibiotic course for males with cystitis?
Longer course; 7 days
If men present with recurrent UTIs, what should you be thinking?
Prostate
What is empiric therapy for pylonephritis?
- Broad action against likely urinary pathogens required
- Need to be systemically active: Cefuroxime, Aztreonam, Ciprofloxacin, Gentamicin
Treatment for prostatitis?
Need to penetrate the prostate, most antibiotics have poor penetration into prostatic tissue. Penetration is better in the inflammation present in acute prostatitis
Empirical options:
o Piperacillin-tazobactam (IV only)
o Ciprofloxacin (IV/PO)
What are the situations where asymptomatic bacteriuria should be treated?
- Pregnancy
- Infant
- Prior to urological procedures
Why should pregnant women with asymptomatic bacteriuria be treated?
Association with upper UTI, pre-term delivery, and low birth weight babies
Why should infants with asymptomatic bacteriuria be treated?
Prevention of pyelonephritis and renal damage
Why should patients with asymptomatic bacteriuria be treated prior to urological procedures?
Prevention of pyelonephritis and renal damage
What lifestyle modifications can be suggested for UTIs?
o Increased fluid intake
o Review of contraception (away from spermicide & cervical diaphragm)
o Voiding before and after coitus
o Oestrogen replacement in post-menopausal women: local or oral
o Cranberry products… maybe
Clinical case 1
- 92 year old
- Female
- No clinical details
- Catheter urine sample
- WCC +++
- Scanty epithelial cells
- Culture: coliform +++
What does this suggest?
This may represent catheter colonisation only.
Clinical Case 2
- 5 year old
- Male
- Frequency & dysuria
- MSU
- WCC +++
- Scanty epithelial cells
- Culture: Coliform (likely E. coli) moderate growth
What does this suggest?
Needs antibiotic treatment:
• Cephalexin S
• Amoxicillin S
• Trimethoprim S
Are there any renal tract abnormalities? Suggest further investigation
Clinical Case 3
- 75 years old
- Female
- Clinical details: “routine”
- MSU
- WCC <40 (none)
- Scanty epithelial cells
- Enterococcus +++
What does this suggest?
May represent asymptomatic bacteriuria, which is common in the >65s.
Clinical Case 4
- 45 year old
- Female
- No clinical details
- MSU
- WCC <40 (none)
- Epithelial cells +++
- Mixed enteric flora/coliforms
What does this suggest?
Note epithelial cells and mixed growth – this suggests contamination. Suggest careful repeat if current clinical symptoms.
Clinical Case 5
- 50 years old
- Male
- Recurrent UTI symptoms
- WCC ++
- No epithelial cells
- Coliform (likely E. coli) +++
What does this suggest?
Recurrent UTIs are suggestive of prostatitis (check previous results). Treatment:
• Ciprofloxacin R
• Cotrimoxazole S
Clinical Case 6
- 23 years old
- Female
- “Cystitis”
- WCC+++
- No epithelial cells
- Coliform (likely E.coli)
What does this suggest?
Treatment:
• Trimethoprim R
• Nitrofurantoin S
• Pivmecillinam S
No interpretative comment needed as clear details & evidence of UTI.
Upper vs lower UTI symptoms?
“Lower” UTI: dysuria, frequency,
“Upper” UTI: Fever, flank / loin pain, +/- LUT symptoms.
