Urinary Tract Infection

Definitions

Microbiology

1. Most UTI are caused gram negative organisms.  These include E Coli (derived from GI tract accounting for 75% of all infections), klebsiella and other Enterobacteriaceae
2. Gram positive organisms causing UTI include enterococcus, staphylococcus and streptococcus group B.  Staphylococcus aureus from an MSU sample may represent haematogenous spread from a deeper source (e.g endocarditis, discitis) and should prompt further history and  investigation.
3. A greater variety of organisms and mixed infections occur in patients with catheters and stents and if immunocompromised eg pseudomonas.
4. Funguria (i.e Candida in urine) is common in hospitalised patients and in those with catheters., and is generally benign (no treatment required).  Invasive infection of the kidney is unusual and difficult to treat (discuss with microbiologist if any indication).

Clinical Presentations of UTI

1. Cystitis – dysuria, frequency, urgency.  Note that strong smelling urine doesn’t necessarily mean UTI
2. Asymptomatic bacteruria – occurs in 25% of women and 10% of men over 65 years and is not associated with increased morbidity – treat only if symptomatic
3. Acute pyelonephritis – suggested by triad of fever with loin pain and loin tenderness
4. Acute prostatitis – pain in abdo above pubic bone, in lower back, in perineum or testes, in addition to symptoms of UTI
5. Frailty syndrome in elderly ie can present with sudden change in mobility or confusion without urinary symptoms or fever.
6. Gram negative septicaemia – UTIs are an important cause
7. Urosepsis – the term is often used loosely but is supposed to mean UTI plus organ dysfunction eg AKI, hypotension, high lactate, altered mental status

Lower UTI in Women Aged Under 65 Years

1. Diagnose a UTI in the presence of two or more urinary symptoms (dysuria, frequency, urgency, visible haematuria or nocturia) and a positive dipstick test result for nitrite.
2. Consider NSAIDs as first-line treatment in women aged <65 years with suspected uncomplicated lower UTI who describe their symptoms as mild.
3. Consider NSAIDs as an alternative to an antibiotic following a discussion of risks and benefit in women aged <65 years with suspected uncomplicated lower UTI when symptoms are moderate to severe.
4. Use short (3-day) courses of antimicrobials for treatment for LUTI, as this is clinically effective and minimises the risk of adverse events.
5. Do not treat asymptomatic bacteriuria in non-pregnant women of any age
6. See flow chart below for diagnostic and management options in non-pregnant women aged <65 years presenting with suspected LUTI

Lower Urinary Tract Infection in Women Aged 65 Years and Over

1. Be aware that women aged 65 years and over, especially those in long-term care facilities, may not display the usual symptoms and signs of UTI that are seen in younger women.
2. Be aware that functional deterioration and/or changes to performance of activities of daily living eg ‘confused and off legs’ may be indicators of urinary infection in frail older people.
3. Remember that UTI is a commoner cause of urinary retention than spinal cord compression or cauda equine syndrome in a frail older women
4. Use of dipsticks for diagnosis of UTI in women aged 65 years and above in long-term care facilities or in frail elderly people requiring assisted living services is not recommended.
5. Send a urine specimen for culture to confirm the pathogen and antibiotic susceptibility in women aged 65 years and above before starting antibiotics for a UTI.
6. See table below for best guess antibiotic choices.
7. Do not treat asymptomatic bacteriuria in non-pregnant women of any age.

Recurrent Lower Urinary Tract Infection in Women

1. Recurrent UTI is defined as recurrences of uncomplicated and/or complicated UTIs, with a frequency of at least three UTIs per year, or two UTIs in the last six months.
2. Diagnosis is made using the same criteria as an acute UTI and consideration of the previous history of UTI.
3. Health Improvement Scotland provide excellent advice on assessment and management of these patients – click here to access

Urinary Tract Infection in Men

1. UTI in men are relatively uncommon and occur mainly in older men, often due to underlying urological issues.
2. Health Improvement Scotland provide excellent advice on assessment and management of these patients – click here to access

Catheter Associated UTI (CA-UTI)

1. CA-UTI in patients with indwelling urethral, indwelling suprapubic, or intermittent catheterisation is defined by the presence of symptoms or signs compatible with UTI with no other identified source of infection along with a positive culture of ≥1 bacterial species in a single catheter urine specimen or in a midstream voided urine specimen from a patient whose urethral, suprapubic, or condom catheter has been removed within the previous 48 hours.
2. Do not dip the urine as this will always be positive in catheterised patients.  Instead, obtain a sample from the catheter sample port and send for culture.
3. In catheterised patients, pyuria (presence of pus in the urine) or presence of foul smelling or cloudy urine alone is not diagnostic of CA-UTI and should not be interpreted as an indication for antimicrobial treatment.
4. Prescribe antibiotics as per local guidelines when CA-UTI appears likely and remember to change the catheter.  Some recommend this is done when the first dose of antibiotic is given, others advise to wait for 24 hours in order to minimise risk that the new catheter will become colonised.  We don’t think it matters hugely which way you do it, providing the catheter is changed.
5. Click here to access Scottish Antimicrobial Prescribing Group (SAPG) decision aid for diagnosis and management of suspected UTI in people with indwelling catheter

Urine Dipsticks

1. In women under 65 years with symptoms suggesting UTI the presence of urine nitrite has 30–40% sensitivity and up to 95-98% specificity for bacterial infection ie 60-70% are false negative but only 2-5% false positive
2. Before carrying out a dipstick test urine should be retained in the bladder for at least four hours to allow conversion of urinary nitrates to nitrite by pathogens. Shorter incubation times may lead to false negative results.
3. On diagnosis of UTI in the presence of two or more urinary symptoms and a positive dipstick test for nitrite, a urine specimen should only be sent for culture if the patient has a history of resistant urinary isolates, has taken any antibiotics in the past six months or fails to respond to empirical antibiotics.
4. Consider sending a urine specimen for culture to inform the diagnosis in patients who present with suspected UTI and two or more urinary symptoms and a negative dipstick test result for nitrite.
5. DO NOT perform urine dipsticks in women over 65 years as they become more unreliable with increasing age.
6. DO NOT use dipstick test in diagnosis of UTI in people with indwelling catheters as bacteriuria is common.

Urine Culture

1. Too often patients with suspected UTI have antibiotics prescribed before urine is sent for culture, thereby making it impossible to know whether the urinary tract was responsible for the sepsis/presumed sepsis.
2. If patient is not critically ill then ask nurses to obtain a sample of urine and start antibiotic after they have done so.
3. If patient is critically ill then they will likely need a urinary catheter to monitor their urine output, which should allow you to obtain a specimen of urine before starting antibiotic.
4. In patients who are not critically ill in whom a urine sample is essential but for a variety of reasons is difficult to collect, an in/out catheter sample should be considered.
5. Blood cultures also mandatory in sick patients as commonly septicaemic
6. Older people often have asymptomatic bacteriuria (no symptoms but bacteria in urine) which does not indicate infection.
7. Dark or foul smelling urine alone does not mean infection, and may be a sign of dehydration.
8. Do not send catheter specimens of urine (CSU) unless patient has signs and symptoms of infection as CSU samples will almost always have bacteriuria (bacteria in urine).
9. Review urine culture results to check organism is sensitive to antibiotic prescribed and change to an alternative antibiotic if necessary.
10. Interpretation of the urine culture results – high epithelial cell count or heavy mixed growth may indicate contamination. Ensure correct sampling process is followed and take repeat urine sample if clinically indicated.
11. Be alert to UTI due to resistant organisms such as Extended Spectrum Beta-Lactamase E. coli. Microbiology will provide advice on treatment options. In patients with a previous ESBL UTI discuss with Microbiology the potential treatment options should the patient become symptomatic again.
12. Do not send urine samples for post-antibiotic checks or clearance of infection

Antibiotic Therapy

1. Older people are vulnerable to infection, particularly Clostridioides difficile infection, therefore use of broad spectrum antibiotics such as ciprofloxacin, co-amoxiclav and cephalosporins should be avoided if possible.
2. Second choice antibiotics should always be guided by urine culture and history of antibiotic use.
3. See below for tables showing antibiotic choices based largely on GGC’s latest Infection Management Guideline

Best Guess First Line Antibiotics for UTI

Caution with Quinolones

1. Ciprofloxacin is particularly effective against gram negative bacteria such as E Coli, Klebsiella Pneumoniae, Legionella, Moraxella Catarrhalis and Pseudomonas aeruginosa, but is less effective against gram positive bacteria.
2. Levofloxacin is a quinolone antibiotic with a broad spectrum of activity against gram positive and gram negative organisms and atypical respiratory pathogens.
3. The Medicines and Healthcare products Regulatory Agency (MHRA) have recently issued advice concerning the serious side effects that can occur in a small number of patients taking quinolones – click here to view
4. The most serious of these is achilles tendon rupture
5. Patients are advised to stop taking their quinolone and to contact their doctor immediately if they develop any of the following:
   • Tendon pain or swelling, often beginning in the ankle or calf
   • Pain in joints or swelling in shoulder, arms, or legs
   • Abnormal pain or sensations (such as persistent pins and needles, tingling, tickling, numbness, or burning), weakness in their  body, especially in the legs or arms, or difficulty walking
   • Severe tiredness, depressed mood, anxiety, or problems with memory or severe problems sleeping
   • Changes in vision, taste, smell, or hearing
6. We recommend that you use the MHRA document to discuss risks and benefits of treatment with a quinolone and that you click here to print off our Quinolone Information Leaflet which should be given to the patient.
7. Quinolones should not be co-prescribed with cation containing compounds including iron supplements, calcium and magnesium supplements as this reduces absorption of the antibiotic from the gut.

Other Causes of Lower Tract Symptoms

1. With vaginal discharge – thrush, STIs, malignancy, irritation from IUDs and diaphragms, chemical irritation from latex condoms.
2. Without vaginal discharge – non infective cystitis caused by NSAIDs and urethral syndrome – a complex of symptoms that suggest a UTI but without an underlying infection.

Other Causes of Loin Pain

1. Obstructing renal stone
2. Women of childbearing age – consider ectopic pregnancy and request pregnancy test
3. Patients over 55 years with no other urinary symptoms – consider acute abdominal aortic aneurysm and get urgent surgical opinion.

When to Image the Renal Tract

1. Refer men with second UTI to urology for assess
2. Discuss women with recurrent UTI with ID/micro
3. Sexually active people should be offered chlamydia/gonorrhoea PCR testing

Referrals

1. Refer men with second UTI to urology for assess
2. Discuss women with recurrent UTI with ID/micro
3. Sexually active people should be offered chlamydia/gonorrhoea PCR testing

Links

• NHSD&G Empirical Antibiotic Guidelines for Adults in Secondary Care [pdf]
• SIGN 160 – Management of suspected bacterial UTI in adult women
• SAPG Decision aid for diagnosis and management of suspected urinary tract infection in people with indwelling catheters [pdf]