Key facts:
Top Tip: Complicated UTI (or an ill patient) requires investigation and rapid treatment
Key Differential Diagnoses
Renal colic
Pelvic inflammatory disease
Acute appendicitis
Key Investigations
- Uncomplicated: Urinalysis, MSU
- Complicated: add FBC, ESR, CRP
U+E, LFT, Bone, Glucose
CXR
BC
Key Treatment
- Uncomplicated: PO TRIMETHOPRIM 200 mg bd
- Complicated: IV GENTAMICIN 5 mg/kg od + IV CO-AMOXICLAV 1.2 g tds
Key Management
Decision
Complicated: Renal US
Background
UTI is rarely a serious disease in itself; but it is a common cause of acute confusion in the elderly, which can be life-threatening
Introduction
- One third of women will have been treated for at least one UTI by the age of 26 years, a figure that increases to approximately 60% during a woman's lifetime
- Escherichia coli causes 80% of outpatient UTIs in otherwise healthy people. These are usually 'uncomplicated UTIs'
- But UTI infection can also be 'complicated' eg acute pyelonephritis; or more importantly, the first presentation of a (treatable) structural disease of the urinary tract, or diabetes mellitus
- Assume all men (children, and pregnant women) have a complicated UTI; and exclude a structural cause
- A 'positive' dipstick does not diagnose UTI, or 'negative' test exclude infection - for certain. An MSU (or CSU) is required
- Also 'mixed growth' or 'no growth' does not mean urinary infection have been excluded
- A 'mixed growth' is infection (several bugs), so do not disregard it
- Not all UTI's require treatment. Eg, alot of elderly people have a dipstick +ve asymptomatic UTI, that does not necessarily require treatment
- Do not assume that confusion is caused by a positive dipstick (or proven UTI) if the two problems occur together. Look for other causes too
- Asymptomatic bacteriuria does not need Rx. In pregnancy uti (even bacteriuria) needs treatment
- UTI can cause life-threatening disease in the frail elderly, and is a potent cause of confusion in that group
Definition
Infection of urinary tract: from urethra (urethritis), bladder (cystitis) to pelvis (pyelonephritis); can also affect prostate (prostatitis)
Epidemiology
(Pyelonephritis)
Female: outpatient = 12-13 cases/10,000 pa; inpatient = 3-4 cases/10,000 pa
Male: 2-3 cases/10,000 pa; 1-2 cases/10,000 pa
Incidence highest among young women, followed by infants and the elderly population [Ref]
Organisms
Escherichia coli is the commonest organism (80% community-acquired but <40% hospital-acquired)
Note: other organisms (below) more associated with structural abnormalities)
Proteus
Staphylococcus
Streptococcus faecalis
Klebsiella
Pseudomonas
Note: TB classically causes a sterile pyuria
Types
- Uncomplicated
- Complicated =
Most cases pyelonephritis
Ill, male, child, pregnant woman
Abnormal urinary tract (structural problem of urinary tract)
Rising creatinine
Immunosuppressed
Virulent organism
Note: assume all men (and children) have a complicated UTI; and exclude a structural cause
Risk factors
DM
Female sex, pregnancy, intercourse
Stones, bladder catheter, structural renal tract abnormality
Chronic liver disease
UTI Symptoms
Lower urinary tract
Dysuria/frequency/urgency
Haematuria
Foul-smelling urine
Suprapubic pain
Fever
Upper urinary tract
Loin pain
Fever/rigors
Other manifestation of severe sepsis
Note: symptoms of UTI can occur without evidence of infection (eg abacterial cystitis/urethral syndrome and loin-pain haematuria syndrome)
Key questions
"When did the symptoms start?"
"Any UTIs or unexplained fevers in early life?" (reflux nephropathy)
"Any family history of dialysis/transplantation?" (reflux nephropathy)
Signs
Nil, or
Loin tenderness
Signs of severe sepsis
Investigation
Uncomplicated UTI, and some cases of mild pyelonephritis, do not need investigation other than MSU; with no US
Blood
FBC, ESR, CRP
U+E, LFT, Bone, Glucose (may be first presentation of DM)
BC (20% pyelonephritis will be +ve)
Other
Urinalysis: leucocytes?, nitrites?
Note: false+ves and -ves: frail elderly can have urinary dipstick abnormalities (leucocytes/nitrites), but no UTI; and cause of sepsis or confusion is elsewhere; conversely, a negative test does not exclude UTI
[Ref]
MSU
Pure growth of >10x5 is diagnostic; pyuria = > 20 WC, on microscopy
Note: if patient has urinary catheter, do a CSU; CSUs from long-term indwelling catheters are often +ve, with an organism grown. Note also, some frail elderly patients have a +ve MSU (and organism) without a catheter. Do not treat either group, unless you think it is is the primary problem; or they are unwell, with no obvious diagnosis
CXR
± KUB, if looking for stones; ± KUB/CT, for the very rare emphysematous pyelonephritis; suspect in patients with diabetes, severe sepsis, with no obvious cause. Classic finding is gas in body of kidney
± pregnancy test
Acute pyelonephritis (renal biopsy; not normally necessary)
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Emphysematous pyelonephritis
This is rare but life-threatening, mainly seen in patients with poorly controlled diabetes (90% have DM). It is a necrotising infection of the renal parenchyma and its surrounding areas that results in the presence of gas in the renal parenchyma, collecting system, or perinephric tissue. It has a 50% mortality. E Coli is the organism in 70% of cases. The classic finding is gas within the body of the kidney. Bilateral nephrectomy may be necessary (really!): [Ref]
Key investigations
MSU
± Renal US (complicated)
Specialist investigations
Renal US or CT (perinephric abscess? scarring of reflux nephropathy?); CT not normally necessary
Differential diagnoses
Renal colic
Pelvic inflammatory disease (ask re vaginal discharge, dyspareunia etc)
Acute appendicitis (RIF)
Acute cholecystitis (RUQ)
Acute diverticulitis (either R or LLQ)
Sexually-transmitted disease
Note: ask if could be pregnant
Treatment
Uncomplicated UTI, and cases of some mild pyelonephritis, do not have to be admitted
UTI Treatment
Drugs:
- Uncomplicated: PO TRIMETHOPRIM 200 mg bd
- Complicated: IV GENTAMICIN 5 mg/kg od + IV CO-AMOXICLAV 1.2g tds
Procedures:
IV (+ fluids, if dry)
Prescribing issues
If use GENTAMICIN, check levels at 48h, 4d, 6d etc
Admit?
Uncomplicated: not normally necessary
Complicated: usually, especially if toxic
Bed plan
Medical admission ward
± Renal/urology
± ITU
Referrals
Renal, if not getting better at 48h, or if very unwell
Urology, if think abscess possibility
The Rest
Complications
Pyonephrosis; renal or perinephric abscess
Severe sepsis/shock
Follow-up
GP
Renal 2 weeks; if have been very unwell, or any structural lesion seen on Renal US
Prognosis
Usually good, almost always make complete recovery. However there is a subset of frail elderly patients, with acute pyelonephritis, with a very high mortality (>90%): [Ref]
Risk stratification
(who can be managed as outpatient)
Uncomplicated UTI, and some cases of pyelonephritis, can be managed as an outpatient
2° Prevention
+ Health promotion
If further infections, ask to be referred back to renal physician, or urologist
If recurrent, low dose prophylactic antibiotic at night (take after intercourse if that is precipitant in a woman); or rotating antibiotics
Don't forget
- False positive and negative dipsticks and MSUs are well recognised
- A 'mixed growth' is infection (several bugs), so do not disregard it
- May be first presentation of DM
- May be first presentation of serious, but treatable, structural urinary disease
- DO renal US in all complicated cases
- Emphysematous pyelonephritis
Red flags
- Severe sepsis/shock
- Complicated UTI
