Urinary Tract Infection

UTI accounts for ~1% of all GP attendances; common in sexually active women, uncommon in men and children. Ascending infection (bowel organisms colonising the perineum, ascending via the urethra) accounts for 93% of UTIs; haematogenous spread occurs occasionally, especially in the immunocompromised. Most common pathogens: E. coli (especially) and Staphylococcus saprophyticus (>90% combined), plus Klebsiella, Proteus, Enterococcus and other Gram-positive cocci. Multidrug-resistant E. coli strains are an emerging global concern.

• Lower tract: dysuria, frequency, urgency, feeling of incomplete emptying, suprapubic discomfort ± strangury, haematuria, offensive urine
• Upper tract (suggests kidney infection): loin pain ± abdominal pain, fever, chills, sweating, rigors, headache, nausea, vomiting, diarrhoea
• UTI can masquerade as a constitutional/non-specific problem without classic urinary symptoms — especially in infants/young children, the elderly, and occasionally adult women/pregnancy; acute UTI may occasionally present as acute abdominal pain
• Infants/children — non-specific presentation: fever, lethargy/irritability, poor feeding, failure to thrive, vomiting, abdominal pain, diarrhoea; dysuria/frequency only reliably reported after age 2
• Elderly — confusion, behaviour disturbance, fever of undetermined origin
• Risk factors: female sex, sexual intercourse, diabetes mellitus, vesicoureteric reflux, urinary tract obstruction/malformation/stricture, pregnancy, immunosuppression, menopause, diaphragm contraception or spermicide exposure, instrumentation, bladder polyps/carcinoma/diverticula/stones
• Consider the NSAID tiaprofenic acid as a cause of non-infective cystitis; cloudy or malodorous urine alone does not usually need investigation/treatment without other UTI signs

• General: temperature, pulse, respiration, blood pressure
• Loin tenderness/mass (upper tract); suprapubic tenderness (lower tract)
• Consider vaginal examination (women) or rectal examination (men — exquisitely tender, boggy prostate suggests prostatitis)

• Urine dipstick — Leucocytes/nitrite suggestive of UTI — may support empirical treatment if symptomatic; specificity 94-98% but sensitivity only 74-96%, interpret with clinical context
• Microscopy, culture and sensitivity (MCU/MSU) — Definitive diagnosis — significant levels: microscopy WBC >10/mL (pyuria), culture >10^5 CFU/mL. Collect first-morning clean-catch midstream specimen where possible; up to 30% of women with acute cystitis have <10^5 CFU/mL, and it is still reasonable to treat if symptomatic.

• All children
• All males
• All women with: acute pyelonephritis, recurrent infections (>2/year), confirmed sterile pyuria, other features of kidney disease (e.g. haematuria), pregnancy
• Failed antibiotic treatment, or recent international travel

• FBE, ESR/CRP, blood culture — If febrile and unwell (suspected pyelonephritis/septicaemia)
• U&E, eGFR — Kidney function — baseline and in recurrent/complicated infection
• PSA — Men, if prostatic pathology suspected
• Renal ultrasound ± IVU — Severe pyelonephritis (urgent, to exclude obstruction); pregnancy; recurrent/complicated infection; males
• Micturating cystourethrogram (MCUG) — Children <1 year with abnormal ultrasound
• Nuclear scans (DMSA, MAG3) — Occasionally indicated in children with recurrent/complicated UTI
• Prostatic infection studies — Adult males with normal IVU/ultrasound and recurrent infection

• Basic management: urine dipstick; urine microscopy/culture; first-line antibiotic (trimethoprim or cephalexin); alkaliniser for severe dysuria; high fluid intake; check sensitivities and leave or change antibiotics accordingly; consider further investigation per indications above
• Screening/treating asymptomatic bacteriuria is not routinely recommended, except in pregnant women (pyelonephritis/pregnancy complication risk) and patients before elective urological procedures (e.g. TURP)
• Avoid overinvestigation where the likelihood of a structural abnormality is low; ultrasound may still miss calculi, small tumours, clubbed calyces and papillary necrosis

• Rest; drink plenty of fluid — 2-3 cups of water initially, then 1 cup every 30 minutes
• Empty the bladder completely each void
• Analgesia (e.g. paracetamol) for pain
• Alkalinise urine for severe dysuria: sodium citrotartrate 4g orally 6-hourly — not if taking nitrofurantoin
• Wipe front-to-back after opening bowels; drink more water as a general preventive measure; cranberry products are no longer recommended

• No follow-up/repeat culture is required in non-pregnant women who remain asymptomatic after treatment
• Repeat MCU 1-2 weeks after completion in adult males (given the mandate to investigate for an underlying abnormality)
• Repeat MCU not required in children who remain asymptomatic after treatment

1. Confirm likely diagnosis (history ± dipstick); in straightforward acute cystitis in a non-pregnant woman, empirical treatment without culture is reasonable
2. Non-pregnant women, uncomplicated cystitis: trimethoprim 300mg daily for 3 days is first choice; treat for 10 days instead of standard duration if there is a known urinary tract abnormality
3. Adult males, pregnant women, children and pyelonephritis all need a urine specimen sent and a longer course (7-14 days depending on syndrome) — see agent-specific guidance below
4. Modify empirical therapy once culture and susceptibility results are available

• For recurrent UTI: single post-coital dose of a suitable agent is adequate in some women; longer courses (3-6 months, occasionally longer) for more severe cases
• Trimethoprim 150mg nocte, or cephalexin 250mg nocte
• Methenamine hippurate 1g (o) bd — bacteriostatic, continuous prophylaxis option, though evidence is inconsistent
• Topical vaginal oestrogen may reduce recurrent UTI risk in postmenopausal women with atrophic vaginitis
• Candiduria: antifungal not recommended unless associated with an indwelling catheter, upper UTI, or systemic candidiasis — then fluconazole 200mg (o) daily for 14 days, and consider removing the catheter/stents

• Requires careful surveillance — asymptomatic bacteriuria should always be excluded early in pregnancy because it tends to progress to a full infection, and is treated the same as acute cystitis given pyelonephritis/pregnancy complication risk
• Acute cystitis (empirical): cephalexin 500mg (o) 12-hourly for 5 days, OR nitrofurantoin 100mg (o) 6-hourly for 5 days, OR amoxicillin/clavulanate 500/125mg (o) 12-hourly for 5 days
• Repeat MCU 1-2 weeks after completing treatment

• By age 10, ~3% of boys and ~10% of girls will have had a UTI; infants/young children often have kidney-pattern infection with generalised symptoms (fever, vomiting, diarrhoea, failure to thrive)
• Specimen collection: bag specimens cannot diagnose UTI; MSU usually feasible from age 3-4; midstream clean catch (MCC) practical and reasonably reliable; suprapubic aspirate (SPA) is the most reliable option, especially in neonates; catheter specimen (CSU) for failed SPA or those unable to void on request
• A urine specimen is essential before starting antibiotics
• Mild infection (≥1 month old): oral therapy for 3-7 days — trimethoprim 4mg/kg (max 150mg) bd, or cephalexin 12.5mg/kg (max 500mg) bd, or trimethoprim/sulfamethoxazole 4/20mg/kg (max 160/800mg) bd; amoxicillin, amoxicillin/clavulanate, norfloxacin or ciprofloxacin may be needed based on susceptibility
• Severe infection (≥12 months septic/vomiting, or any infant <12 months): IV gentamicin + amoxicillin/ampicillin, early switch to oral once improving; total duration usually 10-14 days
• Investigation: <1 year — ultrasound (± MCUG if ultrasound abnormal); >1 year — ultrasound; nuclear scans (DMSA/MAG3) occasionally indicated. A low threshold for investigation is appropriate under 6 months. VUR is found in up to 40% and scarred kidneys (reflux nephropathy) in ~27% of children investigated for UTI — early detection matters because it can prevent scarring, hypertension and chronic kidney failure.

• Typical settings: frailty, immobility, faecal incontinence, inadequate bladder emptying — a particular problem in aged care facility residents
• Presentation may be atypical: fever of undetermined origin, confusion, behaviour disturbance; in men, consider excluding obstructive uropathy from prostatism via ultrasound
• Treat uncomplicated infections the same as other age groups; do not treat asymptomatic bacteriuria; as a rule do not investigate or treat cloudy/malodorous urine alone in aged care residents who are otherwise asymptomatic

• Prostatitis: consider in men with few urinary symptoms but flu-like illness, fever, low backache, perineal pain, and an exquisitely tender prostate on rectal exam. Mild-moderate: trimethoprim 300mg daily or cephalexin 500mg 6-hourly for 2 weeks. Severe: amoxicillin/ampicillin 2g IV 6-hourly plus gentamicin.
• All males with a UTI should be investigated (MCU, U&E, ultrasound) to exclude an underlying abnormality such as prostatitis or obstruction — in males, the prostate is the most common source of recurrent UTI.
• Vulvovaginitis in children (ages 2-8) can mimic UTI with dysuria but is a distinct dermatitis — don't assume UTI in a girl with dysuria without confirming on specimen.
• Genitourinary TB (3-5% of TB cases): dysuria/frequency, possible strangury/loin pain/haematuria, routine culture shows sterile pyuria; diagnosis via specific mycobacterial urine culture, ESR/CRP, biopsy, or characteristic imaging (distorted calyces, medullary calcification).
• UTI is commonly associated with microscopic (occasionally macroscopic) haematuria — but persisting haematuria after treatment should still be investigated (e.g. ultrasound, CT-IVP).

• All patients with urinary tract abnormalities — refer to a nephrologist or urologist for advice on specific management
• Recurrent UTI not controlled by simple measures/prophylaxis outlined above
• Children with recurrent UTI
• Males with urinary infections not clearly localised to the prostate
• Patients with impaired kidney function

• Advise on non-antibiotic prevention strategies for recurrent infection: adequate hydration, front-to-back wiping, post-coital voiding; discuss post-coital prophylaxis if intercourse-related
• Explain that repeat testing/follow-up is not needed if symptoms resolve (non-pregnant women, children) — but to return if symptoms persist or recur
• Safety-net pregnant women and parents of young children clearly, given the higher stakes (pyelonephritis in pregnancy; renal scarring in children) if untreated or inadequately treated
• Advise men with a first UTI that investigation is required — it is not 'just cystitis' in males the way it often is in women

• Most symptomatic UTIs are acute cystitis in sexually active women with anatomically normal urinary tracts
• A clinical diagnosis based on experience, plus a positive nitrite dipstick and pyuria on office microscopy, generally enables immediate empirical treatment
• A 3-day course of trimethoprim 300mg daily is a suitable first choice for acute uncomplicated cystitis in women
• Avoid quinolones (norfloxacin/ciprofloxacin) as first-line agents — reserve for proven resistance; cotrimoxazole is not first-line (no advantage over trimethoprim, more side effects)
• Treatment failure is usually due to a resistant organism or an underlying urinary tract abnormality
• Organisms other than E. coli (e.g. Pseudomonas) on culture should prompt consideration of an underlying tract abnormality