Urinary tract infections (UTIs) are commonly diagnosed in primary care. They contribute to a large proportion of antibiotic use. UTIs are currently diagnosed using a combination of clinical symptoms, dipstick tests (if appropriate) and laboratory-based culture testing.
Dipstick tests are rapid and can be done in a GP surgery. But they may not accurately diagnose UTIs, are not recommended for all populations (such as people aged over 65 or who have a catheter) and cannot identify the type of bacteria causing the infection. Laboratory-based culture tests can identify bacteria and test for antibiotic susceptibility. But they do not detect all types of bacteria, and the results can take 24 to 72 hours depending on locally available facilities, geographical location, and the day of sample collection. Laboratory test results may sometimes take longer (up to a week) if there are delays in getting samples to the laboratory or a delay in processing.
People are often diagnosed with a UTI based on clinical symptoms alone, and may be prescribed antibiotics empirically (that is, based on the likely cause of the infection in the absence of definite information about what has caused it). When testing is done, people could also be prescribed antibiotics while waiting for test results. NICE's guideline on antimicrobial prescribing for lower UTIs recommends reviewing the choice of antibiotic when microbiological results are available and changing the antibiotic according to the susceptibility results if bacteria are resistant and symptoms are not already improving. It recommends using a narrow-spectrum antibiotic if possible. Clinical experts explained that the first course of antibiotics has often finished by the time laboratory-based culture results are returned.
How UTIs are diagnosed can differ depending on a person's sex, age and if they have a catheter. Public Health England's guidance on diagnosis of urinary tract infections (2020) sets out several flow charts to guide diagnosis for people with suspected acute UTIs. Separate pathways are presented for:
women under 65 years with suspected UTI
men under 65 years with suspected UTI
adults who have a catheter or over 65 years with suspected UTI
infants (from birth) and children under 16 years with suspected UTI.
NICE has assessed 12 point-of-care technologies that can be used for testing in people with suspected UTIs. Based on the features of the tests included in this assessment, the external assessment group (EAG) grouped them into rapid tests (results in less than 40 minutes) and culture-based tests (results in around 16 to 24 hours).
The following rapid tests were assessed:
Astrego PA‑100 analyser with PA AST panel U‑0501 (Sysmex Astrego) detects the presence of bacteria in a urine sample in 10 to 15 minutes. If the urine sample is positive, it assesses the susceptibility of the bacteria to 5 antibiotics (amoxicillin-clavulanic acid, ciprofloxacin, fosfomycin, nitrofurantoin, trimethoprim). Full results take 30 to 45 minutes. The company says that it is CE-in vitro diagnostic (IVD) marked but is not currently available in the UK.
Lodestar DX (Llusern Scientific) detects 6 common UTI-causing bacteria (Escherichia coli [E. coli], Klebsiella spp, Proteus mirabilis, Staphylococcus saprophyticus, Enterococcus spp, Pseudomonas aeruginosa). Results take approximately 40 minutes. The company says that the technology does not yet have regulatory approval.
TriVerity (Inflammatix) is a blood test that identifies if an infection is bacterial or viral, and the severity of the infection. Results take approximately 30 minutes. The company says that the technology does not yet have regulatory approval.
Uriscreen (Savyon Diagnostics) is an enzyme-based test that detects the presence of bacterial catalase in a urine sample. Results take approximately 2 minutes. The company says that the technology is CE-IVD marked.
UTRiPLEX (Global Access Diagnostics) detects the presence of matrix metalloproteinase-8 (MMP8) and human neutrophil elastase (HNE) in a urine sample. Results take approximately 6 minutes. The company says that the technology does not yet have regulatory approval.
The following culture-based tests were assessed:
Diaslide, DipStreak and ChromoStreak (Novamed) are 3 culture-based tests that detect and identify the presence of gram-negative bacteria in a urine sample. ChromoStreak also detects the growth of common UTI-causing bacteria (E. coli, Proteus, and enterococci). Results take about 16 to 24 hours. The regulatory status of the 3 tests is not clear.
Flexicult Human (SSI Diagnostica) is a culture-based test that detects and quantifies the bacteria in a urine sample, and evaluates the susceptibility to 5 antibiotics (mecillinam, nitrofurantoin, ampicillin, sulfamethizol and trimethoprim). It must be incubated overnight and takes 16 to 24 hours for results. The company says that the technology is CE-IVD marked and is available in the UK.
Uricult, Uricult trio and Uricult plus (Aidian) are 3 culture-based tests that detect and identify the presence of gram-negative bacteria in a urine sample. Uricult plus also detects enterococci and Uricult trio also detects gram-negative, beta-glucuronidase-producing bacteria, such as E. coli. Results take approximately 16 to 24 hours. The company says that the technology is CE-IVD marked and available in the UK.
The comparators are:
dipstick testing, then laboratory-based testing (if necessary) or
laboratory-based testing alone.
During consultation, a stakeholder highlighted that diagnosis using clinical symptoms could be included as a comparator in future assessments.