UTI Diagnosis & Treatment



1st line Nitrofurantoin SR 100mg bd
  • 3 days for female
  • 5 days for women with renal complications
  • 7 days for men
  • C/I if GFR <45
2nd line Pivmecillinam 400mg tds
  • for 3 days for female
  • 5 days for women with renal complications
  • 7 days for men
3rd line Fosfomycin
  • 3g sachet for female
  • 3g sachet followed by 3g sachet on day 3 for male


  • If sympotms do not improve following treatment, bring in urine sample
  • Drink plenty of water - 1½ to 2 litres per day
  • Advise patient to seek medical attention if they develop fever or loin pain
  • Cranberry juice or tablets prevent bacteria from attacking the lining of the urinary tract. (avoid if history of stones)
  • Avoiding bladder irritants, such as spicy food, alcohol and caffeine

Postmenopausal Females

Offer a vaginal moisturiser


  • Always ask for MSU and send for culture
  • If positive: start empirical antibiotics EVEN if asymptomatic
    • First line: nitrofurantoin (avoid at term) 100mg MR bd 7 days
    • Second line: trimethoprim 200mg BD for 7 days & give folic acid 5mg OD if 1st trimester, avoid if folate low or on folate agonist (eg methotrexate)
    • Third line: cefalexin 500mg BD for 7 days


  • Always ask for MSU and send for culture

Failed treatment 

If no or temporary improvement in symptoms then:

  • check sensitivities on previous MSU or send MSU
  • change antibiotic to next step as above and ensure longer tx course of 5-7 days  

Recurrent Infections

  • ≥ 2 UTIs in 6months or
  • ≥ 3 UTIs in 12 months then:
  • UTI prevention advice - Hydration
  • Ibuprofen for symptom relief
  • Cranberry products work for some women
  • Post-menopausal women - vaginal moisturisers
  • Stand-by or post-coital antibiotics or
  • Hiprex is indicated in the prophylaxis and treatment of urinary tract infections:

    1. As maintenance therapy after successful initial treatment of acute infections with antibiotics.

    2. As long-term therapy in the prevention of recurrent cystitis.

    3. To suppress urinary infection in patients with indwelling catheters and to reduce the incidence of catheter blockage.

    4. To provide prophylaxis against the introduction of infection into the urinary tract during instrumental procedures.

    5. Asymptomatic bacteriuria.

  • Ongoing prophylaxis is not encouraged but can be considered:
    • nitrofurantoin 50-100mg IR at night for 3-6 months the review recurrence rate
    • ciprofloxacin 500mg at night for 3-6 months the review recurrence rate
  • Refer to urology for advice


  • Likely to shorten the duration of symptoms by 1–2 days
  • There is no evidence that treatment leads to poorer outcomes
  • There is also no evidence of effectiveness in women with less severe symptoms
  • Patient leaflet on UTIs


  • < 2 symptoms: ask them to bring sample
    • dipstick
    • positive nitrites = infection
    • Pain relief and consider /delayed antibiotic
  • >2 symptoms: treat 


  • Urinary urgency
  • Dysuria (pain)
  • Increased frequency
  • Suprapubic tenderness
  • Symptoms getting worse

Red Flags

  • Symptoms of pyelonephritis (kidney infection)
    • Fever over 38
    • Pain around back, side, groin, loin, kidneys, WITH shivering and/or nausea and vomiting 
  • Blood in urine - send urine sample to exclude to exclude another cause of haematuria such as urological cancer
  • Discharge - rule out STI

Address Underlying Cause

Diabetics - improve control of blood sugar

Menopause age - local oestrogen cream may help improve vaginal atrophy

Good toilet hygiene is important. For example, washing the area down below with water after passing urine and wiping from front to back help reducing infection. Some advice cleaning the genital area and passing urine before and after intercourse as well. Avoiding tight underwear and wearing cotton underwear can also help.

Urine Culture

  • Urine microscopy and culture are not routinely recommended because the results are not available for immediate decision-making and by the time they are available most women's symptoms will be resolving
  • It is unlikely that routine urine culture is cost-effective
  • Always send urine for culture from the following patients
    • Pregnant women
    • Impaired renal function
    • Immunosuppression 
    • Men
    • recurrent UTIs 
    • in suspected pyelonephritis (temp >=39.4; rigors; nausea; vomiting; diarrhoea; loin pain or tenderness)
    • suspected UTI in children, any sick child and every young child with unexplained fever
    • catheterised patients: Send sample only if features of systemic infection, as bacteriuria is usual
    • abnormalities of genitourinary tract
    • in elderly patients presence of two signs of infection (especially dysuria, fever >38 or new incontinence) is needed before taking a sample

Midstream Specimen of Urine (MSU) and Urine Culture

Initial Assessment of MSU

  • Straw-coloured urine: this is the normal colour of urine in a healthy, hydrated individual.
  • Dark concentrated urine: suggests the individual is dehydrated.
  • Red urine: can be caused by the presence of blood in the urine (macroscopic haematuria), porphyria, drugs such as rifampicin and certain foods (e.g. beetroot).
  • Brown urine: can be caused by the presence of bile pigments (e.g. jaundice) or myoglobin (e.g. rhabdomyolysis) in the urine. Some antimalarial medication, such as chloroquine, also cause brown discolouration of the urine.
  • Clear urine: this is normal for healthy, well-hydrated individuals.
  • Cloudy urine with sediment: may indicate urinary tract infection, renal stones, high protein content (e.g. nephrotic syndrome).
  • Frothy urine: typically associated with significant proteinuria (e.g. nephrotic syndrome).
  • Offensive odour: suggestive of urinary tract infection.
  • Sweet odour: suggestive of glycosuria (e.g. diabetes mellitus

Interpretation of MSU

  • water-soluble sugar molecule
  • known as glycosuria
  • causes of glycosuria include diabetes mellitus, renal tubular disease and some diabetic medications (e.g. SGLT2 inhibitors)
  • absence of glucose in the urine is normal
  • indicates the amount of red blood cells, haemoglobin and myoglobin in the urine
  • red blood cells, haemoglobin and myoglobin in the urine may indicate urinary tract infection, renal stones, injury to the urinary tract, myoglobinuria (rhabdomyolysis), nephritic syndrome and malignancy of the urinary tract
  • absence of red blood cells, haemoglobin and myoglobin in the urine is normal
  • a breakdown product of gram-negative organisms such as E.Coli
  • nitrites in the urine is suggestive of urinary tract infection
  • the absence of nitrites in the urine is normal, however, does not rule out a UTI
  • known as proteinuria
  • causes of proteinuria include nephrotic syndrome and chronic kidney disease
  • the absence of protein in the urine is normal 



  • water-soluble yellow pigment
  • bilirubin in the urine suggests increased serum levels of conjugated bilirubin, which can occur in conditions such as biliary obstruction (e.g. pancreatic cancer)
  • the absence of bilirubin in the urine is normal
  • breakdown product of fatty acid metabolism
  • suggests increased fatty acid metabolism, which occurs during starvation and in conditions such as diabetic ketoacidosis
  • the absence of ketones in the urine is normal
  • represents the acidity of the urine
  • normal range: 4.5 – 8
  • Causes of low urinary pH include starvation, diabetic ketoacidosis and other conditions that cause metabolic acidosis (e.g. sepsis)
  • Causes of raised urinary pH include urinary tract infection, conditions that cause metabolic alkalosis (e.g. vomiting) and medications (e.g. diuretics) 
Leukocyte esterase
  • an enzyme produced by neutrophils and therefore, when positive, it indicates the presence of white cells in the urine
  • causes of a positive leukocyte esterase include urinary tract infection and any condition that could result in haematuria
  • negative leukocyte esterase test is normal
  • byproduct of bilirubin breakdown in the intestine and it is normally excreted in the urine
  • normal range: 0.2 – 1.0 mg/dL
  • low levels of urobilinogen can be caused by biliary obstruction
  • increased levels of urobilinogen in the urine can be caused by haemolysis (e.g. haemolytic anaemia, malaria) 
Specific gravity
  • indicates the amount of solute dissolved in the urine
  • normal range: 1.002 – 1.035 mOsm/kg
  • low specific gravity caused by conditions that result in the production of dilute urine such as diabetes insipidus and acute tubular necrosis
  • raised specific gravity caused by dehydration, glycosuria (e.g. diabetes mellitus) and proteinuria (e.g. nephrotic syndrome) 

 Interpretation of Urine Culture Results

MSU/culture Result & Interpretation
White cellls
  • >10^4/mL: inflammation
  • in adults no white cells present indicates no inflammation & reduces culture significance
  • pregnancy is associated with physiological pyuria
  • in *sterile pyuria consider Chlamydia trachomatis (especially if 16-24 years), other vaginal infections, other non-culturable organisms, including TB or renal pathology
  • *Sterile pyuria is the presence of elevated numbers of white cells (>10/cubic mm) in a urine which appears sterile using standard culture techniques. The causes of sterile pyuria include:

    • a treated urinary tract infection (UTI) within 2 weeks of treatment/inadequately treated (UTI)
    • UTI with fastidious culture requirement
    • renal stones
    • prostatitis
    • chlamydia urethritis
    • renal papillary necrosis (e.g. from analgesic excess)
    • tubulo-interstitial nephritis
    • genitourinary tuberculosis (always consider - do 3 early morning urines)
    • interstitial cystitis
    • urinary tract neoplasm
    • polycystic kidney
culture of single organisms 
  •  >=10^4 colony forming units (CFUs)/mL + urinary symptom
  • >=10^3 CFU/mL of Escherichia coli or Staphylococcus saprophyticus
  • lower counts can also indicate UTI if patient is symptomatic 
epithelial cells 
  •  the presence of epithelial cells is not neccessarily an indicator of perineal contamination
  • culture result should be interpretated with symptoms and repeated if significance is uncertain
mixed growth 
  • may indictae perineal contamination
  • however a small proprtion of UTIs may be due to genuine mixed infection
  • consider a retest if syptomatic 
red cells 
  • may be present in UTIs
  • chemical tests may be more sensitive than microscopy as a result of the detection of haemoglobin released by haemolysis
  • refer people with persistant haematuria post UTI to urology 

1) Health Protection Agency (Accessed April 21/4/14). Diiagnosis of UTI Quiick Reference Guide for Primary Care.1) Health Protection Agency (Accessed April 21/4/14). Diiagnosis of UTI Quiick Reference Guide for Primary Care.

Trimethoprim Cefalexin Nitrofurantoin Pivmecillinam Fosfomycin

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