UTI Flashcards
Define urinary tract infection and give the 2 sub-classifications
Infection of the kidneys, bladder, or urethra.
The presence of a pure growth of > 105 organisms per mL of fresh MSU
Sub-Classification
- Lower UTI - affecting the urethra (urethritis), bladder (cystitis) or prostate (prostatitis)
- Upper UTI - affecting the renal pelvis (pyelonephritis)
Differentiate between uncomplicated and complicated UTI
- Uncomplicated UTI - normal renal tract and function
- Complicated UTI - abnormal renal/genitourinary tract, voiding difficulty/obstruction, reduced renal function, impaired host defences, virulent organism (e.g. S. aureus)
For each part of the urinary tract (kidneys to urethra), state the term used for an infection of said area.
- Pyelonephritis: infection of the kidney- renal pelvis (often occurs via bacterial ascent)
- Cystitis: infection of the bladder. Infectious cystitis is the most common type of UTI
- Urethritis: infection causing inflammation of the urethra.
State the key risk factors for UTI
- sexual activity- strongest risk factor
- spermicide use- eg on condoms decreases vaginal lactobacilli, which facilitates vaginal Escherichia coli colonisation
- post-menopause- reduced oestrogen –> atrophy of GU tract
- benign prostatic hypertrophy and other causes of urine-flow obstruction (men) eg urethral strictures
- positive family history of UTIs- recurrent in mothe - increased 2-4x risk
- history of recurrent UTI
- presence of a foreign body- catheter, stone, suture, surgical material, or exposed polypropylene mesh from pelvic surgery
State the common causitative organisms of UTI
Uncomplicated:
- Escherichia coli = 70-95% of uncomplicated cases
- Staphylococcus saprophyticus = 5-20% of cases
Other: Enterobacteriaceae (e.g. Proteus mirabilis and Klebsiella species), enterococci, group B streptococci, Pseudomo
Complicated:
Broad range of bacteria can cause complicated UTIs, and many are resistant to multiple antimicrobial agents.
- Citrobacter and Enterobacter genera
- P aeruginosa
- enterococci
- Staphylococcus aureus
Summarise the epidemiology of urinary tract infections
- Lifetime incidence of UTIs is 50-60% in adult women
- Increasing incidence with age (doubled rate in women >65)
- 1-3% of GP consultations
- Much more common in females
Recognise the presenting symptoms of urinary tract infections: cystitis
- dysuria
- new nocturia
- cloudy-looking urine
- urgency
- frequency
- risk factors
- visible haematuria
- Suprapubic tenderness
Recognise the presenting symptoms of urinary tract infections: prostatitis
- Flu-like symptoms
- Low backache
- Few urinary symptoms
- Swollen or tender prostate on PR
Recognise the presenting symptoms of urinary tract infections: acute pyelonephiritis
- High fever (in women <65, temperature could just mean cystitis)
- Rigors
- Vomiting
- Loin/flank pain and tenderness
- Oliguria (if AKI)
Recognise the signs of urinary tract infection on physical examination
- Fever
- Abdominal or loin tenderness
- Foul-smelling, cloudy urine
- Visible haematuria
- New or worsening delirium/debility- in women aged over 65 years
- Distended bladder (occasionally)
- Enlarged prostate (if prostatitis)
Identify appropriate investigations for urinary tract infection
1st investigations to order
-
urine dipstick
- positive for nitrite and leukocytes- if negative but still has signs and symptoms then high chance may still have a UTI
- Organisms like E. coli, Klebsiella, Enterobacter, Proteus, Staphylococcus, or Pseudomonas species reduce nitrate to nitrite in the urine
-
urine culture and sensitivity (MSU, clean catch)
- To exclude diagnosis or if the patient failed to respond to empirical antibiotics
- A pure growth of >10^5 organisms/mL is diagnostic
- if there is a risk of antibiotic resistance
- If dipstick –ve but patient symptomatic, or vice versa
- Always send MSU for lab MC&S for male, child, pregnant, immunosuppressed or ill
-
Bloods
- FBC
- U&Es - check renal function
- CRP
- Blood cultures - if systemically unwell and risk of urosepsis
Investigations to consider
-
urine microscopy
- Not a routine diagnostic test.
- May be used to confirm organism and guide antibiotic selection in complicated UTI or pyelonephritis.
- Symptomatic UTI cannot be differentiated from asymptomatic bacteriuria on the basis of urine analysis by microscopy
-
post-void residual
- may demonstrate residual urine after bladder emptying
- cause of UTIs
-
renal ultrasound
- rule out urinary tract obstruction in uncomplicated pyelonephritis and a history of urolithiasis, renal function disturbances, or a high urine pH
-
abdominal/pelvic CT
- kidney or bladder stone, renal abscess
- Avoid in pregnant women
- in unwell patients, for example, if the patient remains febrile after 72 hours of treatment, or immediately in any patient with worsening clinical status
Generate a management plan for urinary tract infection
no catheter in situ: age <65 years and non-pregnant
If they have diagnostic signs/symptoms and/or other urinary symptoms (dipstick positive):
- 1st line –
- immediate empirical antibiotics or prescription for back-up antibiotics- based on symtom severity
- Nitrofurantoin (if eGFR ≥45 mL/minute) or Trimethoprim if low risk of resistance
- As well as symptom severity, base your decision for giving immediate or back-up antibiotics on:
- Risk of complications
- Previous urine culture and susceptibility results
- Previous antibiotic use, which may have led to resistant bacteria
- Patient preference.
- NICE recommends a 3-day course of all the recommended antibiotics (apart from fosfomycin where a single dose is given).
- Men with UTI may need a longer course of antibiotics
-
Supportive care and safety-netting
- Advice to drink enough fluids, and take paracetamol and ibruprofen as pain relief
-
Consider – pathogen-targeted antibiotics
- if bacteria are resistant and symptoms are not improving, selecting a narrow-spectrum antibiotic where possible.
- Prophylactic antibiotics may be used in certain circumstances (e.g. recurrent cystitis associated with sexual intercourse)
Identify possible complications of urinary tract infection
Ascending infection can lead to:
- Pyelonephritis
- Perinephric and intrarenal abscess
- Hydronephrosis or pyonephrosis
- AKI
- Sepsis
Prostatic involvement (e.g. prostatitis) in men with UTIs is common
Summarise the prognosis for urinary tract infection
Prognosis for uncomplicated UTI in women is excellent. With appropriate antimicrobial treatment and resolution of symptoms, there is unlikely to be long-term sequelae.
Prognosis for complicated UTI is very good. Impairment of renal function is rare, but possible
