Urology
Question 269 of 300
A 23 year old woman presents to the Emergency Department with a 2 day history of dysuria. She reports increased frequency. On examination she has a soft, non-tender abdomen. Urine dipstick is positive for leucocytes and nitrites. Which of the following antibiotics is most appropriate in this patient?
Answer:
Antibiotics for lower UTI in non-catheterised, non-pregnant patients:- Women
- Consider the need for antibiotics depending on severity of symptoms, risk of complications, and previous urine culture results and antibiotic use.
- If prescribing an immediate antibiotic — treat according to sensitivities from recent urine culture (if available), otherwise treat empirically taking account of local antimicrobial resistance patterns.
- For first choice, consider prescribing nitrofurantoin 100mg modified-release twice a day for 3 days (if eGFR ≥45 ml/minute) or trimethoprim 200mg twice a day for 3 days (if low risk of resistance).
Lower Urinary Tract Infection
Urology
Last Updated: 12th February 2021
A lower urinary tract infection (UTI) is an infection of the bladder usually by bacteria, but rarely by other microorganisms such as fungi, viruses, or parasites. Upper UTI includes pyelitis (infection of the proximal part of the ureters) and pyelonephritis (infection of the kidneys and the proximal part of the ureters).
Definitions
- Uncomplicated UTI is infection of the urinary tract by a usual pathogen in a person with a normal urinary tract and normal kidney function.
- Complicated UTI is when one or more risk factors are present that predisposes the person to persistent infection, recurrent infection, or treatment failure. Risk factors for complicated UTI include structural or neurological abnormalities of the urinary tract, urinary catheters, virulent or atypical infecting organisms, pregnancy, and co-morbidities such as poorly controlled diabetes mellitus or immunosuppression.
- Recurrent UTI is repeated UTI, which may be due to relapse or reinfection, and may be defined as 3 or more UTIs in the last 12 months, or 2 or more episodes of confirmed UTI in the last 6 months.
- Asymptomatic bacteriuria is the presence of significant bacteria in the urine, as a result of colonisation of the urinary tract, without symptoms or signs of infection.
Causes
UTI results from pathogenic organisms gaining access to the urinary tract and not being effectively eliminated. Entry of bacteria into the urinary tract may be:
- Retrograde, ascending through the urethra into the bladder
- Via the bloodstream (more likely in immunocompromised people)
- Direct, for example upon insertion of a catheter into the bladder, instrumentation, or surgery
The spectrum of microorganisms which cause UTI is similar in men and women. The most common causative microorganisms are:
- Escherichia coli (80%).
- Staphylococcus saprophyticus (4%).
- Klebsiella pneumoniae (4%).
- Proteus mirabilis (4%).
Less common microorganisms causing UTI include:
- Enterobacter species, Enterococcus species, Serratia marcescens, Pseudomonas species, and Staphylococcus aureus.
- Candida albicans — rare in the community, but may be seen in people with risk factors such as indwelling catheters, or men who are immunocompromised.
UTI is much less common in men than in women — this is is attributed to the shorter urethra in women. Strong risk factors for UTI in men include:
- Age over 50 years.
- Benign prostatic hypertrophy (BPH) and other causes of urine outflow obstruction (for example, urinary tract stones, urethral stricture) — up to 30% of young men with UTI have anatomical or functional abnormalities of the urinary tract, and this is higher in older men.
- Catheterisation — UTI is the most common hospital acquired infection, and the majority of cases result from indwelling catheters.
- Previous urinary tract instrumentation or surgery.
- Previous UTI — the risk of acquiring another UTI increases with each subsequent infection.
Clinical features
- Dysuria — discomfort, pain, burning, tingling or stinging associated with urination.
- Frequency — passing urine more often than usual.
- Urgency — a strong desire to empty the bladder, which may lead to urinary incontinence.
- Nocturia — passing urine more often than usual at night.
- Suprapubic discomfort/tenderness.
- Changes in urine appearance or consistency:
- Urine may appear cloudy to the naked eye, or change colour or odour.
- Haematuria may present as red/brown discolouration of urine or as frank blood.
- Typical features may be absent, in particular with frail, elderly patients, and/or cognitive impairment and/or catheterised and/or in institutionalised care, atypical symptoms include:
- Generalised non-specific clinical features such as delirium, lethargy, fever, incontinence, reduced ability to carry out activities of daily living and anorexia.
- Pyelonephritis should be suspected in people with fever, loin pain or rigors.
Differential diagnosis
- Women
- Pyelonephritis
- Other urological or genitourinary conditions such as atrophic vaginitis, lichen sclerosus, lichen planus, urolithiasis, or interstitial cystitis
- Dermatological conditions such as psoriasis, irritant or contact dermatitis
- Alternative or serious diagnoses such as ectopic pregnancy
- Malignancy (gynaecological, or urological)
- Other infections such as sexually transmitted infections (for example chlamydia, gonorrhoea, genital herpes simplex), candida, threadworm, tuberculosis and schistosomiasis
- Trauma due to genitourinary procedures, sexual intercourse, sexual abuse or physical activity (such as cycling)
- Adverse drug effects — some drugs such as cyclophosphamide, opioids, and nifedipine can cause urinary tract symptoms
- Men
- Acute prostatitis
- Bladder, or renal malignancy
- Epididymitis
- Pyelonephritis
- Sexually transmitted infections
- Urethritis
- Other urological disorders, such as benign prostatic hyperplasia (BPH)
Investigations
In women:
- Urine dipstick:
- If the woman is under 65 years of age, and does not have risk factors for complicated UTI, urine dipstick can be used as an aid to diagnosis — dipstick is unreliable in women aged older than 65 years and those who are catheterised.
- If dipstick is positive for nitrite or leukocyte and red blood cells (RBC) UTI is likely. A urine sample (morning sample most reliable) for culture and sensitivities should be sent if previous antibiotic treatment has failed or there is a possibility of antibiotic resistance.
- If dipstick is negative for nitrite and positive for leukocyte, UTI is equally likely to other diagnosis. Send urine for culture to confirm diagnosis.
- If urine dipstick is negative for all nitrite, leukocyte and RBC, UTI is less likely. No need to send sample for urine culture — consider other diagnoses.
- Urine culture:
- A sample should be sent for urine culture in all women with suspected lower UTI who:
- Are pregnant.
- Are older than 65 years.
- Have symptoms that are persistent or do not resolve with antibiotic treatment.
- Have recurrent UTI (2 episodes in 6 months or 3 in 12 months).
- Have a urinary catheter in situ or have recently been catheterised.
- Have risk factors for resistance or complicated UTI such as abnormalities of genitourinary tract, renal impairment, residence in a long term care facility, hospitalisation for more than 7 days in the last 6 months, recent travel to a country with increased resistance or previous resistant UTI.
- Have atypical symptoms.
- Have visible or non-visible (on urine dipstick) haematuria.
- A sample should be sent for urine culture in all women with suspected lower UTI who:
In men:
- In men with symptoms suggestive of a UTI, confirm the diagnosis by urine culture and sensitivity. Obtain a urine sample for culture before starting empirical drug treatment. Only send a urine sample for culture in a man with an indwelling catheter if there are features of systemic infection.
- Do not rely on urine dipstick tests or microscopy to diagnose UTI in men. Dipsticks are poor at ruling out infection, although they may be helpful in some clinical situations to decide if a working diagnosis of UTI should be made. If the dipstick test is negative for nitrites and leukocyte esterase, UTI is less likely, especially if symptoms are mild. However, the presence of these markers does not rule in UTI, although positive nitrite makes UTI more likely (positive predictive value 96%). Do not use urine dipstick in patients with an indwelling catheter or in those aged over 65 years.
Management
- Admit patients to hospital if they develop systemic symptoms such as fever, rigors, chills, vomiting or confusion, or if the patient is dehydrated or unable to tolerate oral fluids and drugs.
- Advise patient on self-care measures:
- Simple analgesia such as paracetamol (or if preferred and suitable, ibuprofen) can be used for pain relief.
- Encourage intake of enough fluids to avoid dehydration.
- Antibiotics for lower UTI in non-catheterised, non-pregnant patients:
- Women
- Consider the need for antibiotics depending on severity of symptoms, risk of complications, and previous urine culture results and antibiotic use.
- If prescribing an immediate antibiotic — treat according to sensitivities from recent urine culture (if available), otherwise treat empirically taking account of local antimicrobial resistance patterns.
- For first choice, consider prescribing nitrofurantoin 100mg modified-release twice a day for 3 days (if eGFR ≥45 ml/minute) or trimethoprim 200mg twice a day for 3 days (if low risk of resistance).
- A delayed script can be considered instead of immediate antibiotics if symptoms are mild and there are no risk factors for complicated infection. Advise the woman to start antibiotics if symptoms do not improve within 48 hours or worsen at any time.
- Men
- If hospital admission is not needed offer an antibiotic taking into account previous urine culture and susceptibility results, and previous antibiotic use, which may have led to resistant bacteria.
- Start empirical antibiotic drug treatment with trimethoprim 200 mg twice daily for 7 days or nitrofurantoin (if eGFR ≥ 45 ml/minute) 100 mg (modified-release) twice daily for 7 days, taking into account local antimicrobial resistance data.
- Women
- Advise all patients to seek urgent medical review if symptoms worsen rapidly or significantly at any time or fail to improve within 48 hours of starting antibiotics — consider the possibility of alternative or serious diagnoses such as pyelonephritis or sepsis.
- Specific scenarios:
- UTI in catheterised patients:
- If the catheter has been in place for more than 7 days, check for blockage and consider removing the catheter or, if this cannot be done, changing it as soon as possible — do not delay antibiotic treatment in the interim. Before antibiotics are taken send a sample from mid-stream urine if the catheter has been removed or from the new catheter if changed — ensure the laboratory are aware of previous antibiotic use and that this is a suspected catheter associated UTI.
- Offer an immediate antibiotic, first-choice oral antibiotic (for lower UTI symptoms only) is nitrofurantoin (if eGFR ≥45 ml/minute) 100mg modified-release twice a day for 7 days or trimethoprim (if low risk of resistance) 200mg twice a day for 7 days or amoxicillin (only if culture results available and susceptible) 500mg three times a day for 7 days.
- UTI associated with haematuria:
- If patients have suspected UTI associated with visible or non-visible haematuria, advise retesting of urine after completing treatment with an appropriate antibiotic — if haematuria is persistent, consider possible underlying causes and referral for further investigation.
- UTI in pregnant women:
- For uncomplicated first lower UTI in a pregnant woman, send a midstream urine sample for culture and sensitivities before antibiotics are taken, and offer an immediate antibiotic prescription. As first choice antibiotic consider prescribing nitrofurantoin (avoid at term) 100mg modified-release twice a day for 7 days if eGFR ≥45 ml/minute.
- Offer an immediate antibiotic prescription to pregnant women with asymptomatic bacteriuria (confirmed with a repeat sample). Take into account urine culture and susceptibility results and previous antibiotic use and choose from: Nitrofurantoin (avoid at term) 100 mg modified-release twice a day for 7 days if eGFR >45 ml/minute, amoxicillin (only if culture results available and susceptible) 500 mg three times a day for 7 days or cefalexin 500 mg twice a day for 7 days.
- Recurrent UTI:
- Manage acute UTI, ensuring that a urine sample has been sent for culture and sensitivities before antibiotics are started.
- Advise patients about behavioural and personal hygiene measures and self-care treatments that may help to reduce the risk of UTI.
- Seek specialist advice on further investigation and management, or refer to urology. Refer urgently using a suspected cancer pathway referral for an appointment within 2 weeks if a urological cancer is suspected.
- UTI in catheterised patients:
Complications
Complications of urinary tract infection (UTI) include:
- Pyelonephritis
- Renal impairment or failure
- Renal and perirenal abscess
- Sepsis
- Urinary stones
- Prostatitis in men
- UTI in pregnancy is associated with preterm delivery and low-birth weight
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
