Urinary Tract Infection (UTI)

What is a urinary tract infection (UTI)? 

Urinary tract infections (UTIs) occur when bacteria is present within the urinary tract in significant numbers. UTIs are common in women, with 1 in 5 adult women aged 20-65 years experiencing a UTI at least once a year. Approximately 50% of women will experience UTIs at least once in their life.

Cystitis (bladder infection) makes up the majority of these infections. Involvement of the upper urinary tract (pyelonephritis) is less common compared to that of cystitis but can be associated with more serious complications.

What are the different types of urinary tract infection (UTI)?

Urinary tract infections may be classified by where the infection occurs in the urinary tract or its severity (uncomplicated versus complicated). 

• Cystitis (bladder infection): This is the most common type of UTI which occurs when bacteria infects the bladder.

• Urethritis (urethra infection): This type of UTI affects the urethra, the tube that carries urine out of the body.
  

• Pyelonephritis (kidney infection): A more severe UTI that affects the kidneys.

Patients will receive different investigations and treatments depending on the severity and location of the infection

What happens if a UTI is left untreated?

If UTI is left untreated, the infection can spread upwards to the kidneys, causing infection in the kidneys and even renal failure. It can also spread via the blood stream (septicaemia) to affect the body in general, which may be fatal in the worst cases.

What are the symptoms of urinary tract infections (UTI)? 

The onset of UTIs can be associated with one or more of the following symptoms:

• Pain on passing urine (dysuria), often described as a burning sensation
• Urinary urgency
• Passing urine more frequently than usual
• Passing foul-smelling urine or cloudy urine
• Sensation of bladder fullness or lower abdominal discomfort
• Fever
• Blood in the urine (haematuria)
  
• Flank pain and tenderness over the lower back area next to the spine (may suggest involvement of the upper urinary tract)
  

As UTI is a common occurrence in women, one should be aware of its symptoms. If you have any of the above symptoms, it is advisable to see a doctor early. Early recognition and appropriate treatment often result in full recovery.

When should you see a doctor?

It is important to seek medical attention if you experience symptoms of a urinary tract infection, especially if they persist or worsen. 

Additionally, you should see a doctor if:

• Symptoms do not improve after a few days of home treatment or prescribed antibiotics
• You experience recurrent UTIs (two or more UTIs within 6 months)
• You have fever or chills, which may indicate that the infection has spread to the kidneys
• You are pregnant and suspect a UTI, as untreated infections can lead to complications for both mother and baby
• You have underlying health conditions, such as diabetes or kidney problems, that could increase the risk of complications
  

Prompt medical attention can help prevent the infection from worsening and avoid further health issues.

How are urinary tract infections (UTI) prevented?

Whilst UTIs can be easily treated with antibiotics, the prevention of UTIs or the avoidance of recurrent infection is equally important.

About 25% of women with acute cystitis develop recurrent UTIs. Most recurrent infections are from bacteria present in the faecal or periurethral reservoirs. Some strategies can be undertaken to reduce the risk of recurrent infections.

Lifestyle changes

• Premenopausal women are advised to increase fluid (water) intake to at least 1.5 litres per day. This is not applicable to people who have to be on fluid restriction regimes for other medical conditions such as congestive heart failure.
• Sexually active women can try to pass urine immediately after intercourse to reduce the risk of introduction of bacteria into the bladder from sex.
• Wipe yourself from front to back after using the toilet to avoid bacteria from the stool contaminating the bladder. Avoid using diaphragms and spermicides and consider other forms of contraception
• Avoid use of vaginal deodorants and douches
• Wash the genital area with water and normal soap during showers

Vaginal oestrogen replacement

Use of vaginal oestrogen cream or inserts in post-menopausal patients where applicable.

Non-antibiotic treatments

• Probiotics (oral or local)
• Cranberry products
• D-Mannose
• Methenamine
  

Prophylactic antibiotics

A once-daily dose of an appropriate antibiotic (usually taken for a minimum duration of three months) may be indicated in patients with a history of multiple episodes of UTI to minimise the risk of recurrence of infection. Postcoital antibiotics may also be considered for patients who suffer from UTIs after sexual intercourse.

Treatment of any existing structural abnormalities

If recurrent UTI occurs against a background of structural abnormalities in the urinary tract (e.g., stones, kidney cysts), consideration should be given to the treatment of these conditions to eradicate the source.

Treatment of any vaginal / lower genital tract infection

These infections may spread to the urinary tract. As such, they should be treated promptly if present. 

What causes urinary tract infections (UTI)?

In 80-90% of cases of uncomplicated cystitis, Escherichia coli (E. coli) is involved. This bacteria is present in 70-95% of both upper and lower UTIs. Other common pathogens are Enterococcus faecalis, Klebsiella species, Proteus species.

What are the risk factors for urinary tract infections (UTI)?

The largest group of patients with UTIs is adult women. Women are more prone to UTIs than men because in females, the urethra is much shorter and closer to the anus.

The occurrence of UTI also varies with age. The incidence of UTI is ten times higher in adolescent girls as compared with boys and this continues throughout adult life.

Other predisposing factors include:

• Menopause. Rates of UTI are higher in postmenopausal women for a few reasons. For one, the presence of bladder or uterine prolapse can cause incomplete bladder emptying and stasis (reduced flow or stoppage of flow) of urine which in turn promotes the growth of pathogens. Also, the loss of oestrogen after menopause leads to changes in the vaginal flora, especially the loss of lactobacilli, and increases your susceptibility to infection.
• Sexual activity. UTIs are very common in women aged 18-30 years as UTIs are associated with coitus (the so-called ‘honeymoon cystitis’). In this age group, sexual intercourse is the cause of 75-90% of bladder infections, with the risk of infection being related to the frequency of sex. The use of spermicides and diaphragms for contraceptive purposes further increases the risk of UTIs as it causes a change in the vaginal flora and eradication of the vaginal lactobacilli.
• Recent instrumentation of the urinary tract (e.g., catheterisation, cystoscopy, urodynamic studies). The insertion of foreign instruments into the urinary tract promotes the translocation of bacteria colonised around the periurethral area into the bladder and other parts of the urinary tract. This increases the risk of developing bacteriuria (the presence of bacteria in the urine) in significant numbers eventually leading to a UTI.
  
• Foreign bodies (e.g., catheters, urinary stones). Urinary catheters are the most important risk factor for bacteriuria. Catheters introduce organisms into the bladder and promote colonisation by providing a foreign surface for bacteria to adhere to and by causing irritation of the bladder mucosa. 80% of UTIs that occur while in hospitals or healthcare institutions are related to urethral catheterisation, and 5-10% are related to manipulation of the genitourinary tract. Urinary stones similarly irritate the bladder as well as provide a nidus for bacteria to adhere to, thereby increasing the risk of developing a UTI.
• Neurological disorders, drugs or pelvic organ prolapse. These conditions may cause incomplete emptying of the bladder, thereby promoting stasis of urine which increases the risk of UTI development.
• Medical conditions (e.g., diabetes). Diabetes leading to glycosuria (sugar in the urine) makes for a fertile breeding ground for bacteria. A study showed that 9.4% of patients with type 2 diabetes had a UTI compared to only 5.7% of people without diabetes.
• Co-existing diseases involving the pelvis (e.g., tumours, inflammatory bowel disease).

How are urinary tract infections (UTI) diagnosed?

The diagnosis of a UTI can be suspected from a well-taken history and physical examination.

Specific tests to confirm a UTI include a urine dipstick, urine analysis and urine culture. Detection of pyuria (white blood cells or pus cells in the urine) on dipstick and urine analysis or presence of nitrite is suggestive of a UTI.

Associated findings can include microscopic haematuria (blood in the urine which cannot be detected by the naked eye). The urine culture will help in the identification of the organism causing the infection and the antibiotics it is sensitive to.

No imaging studies (scans) are required in the routine evaluation of an uncomplicated cystitis.

How are urinary tract infections (UTI) treated?

Empirical antibiotics are usually prescribed for UTIs. The patient may be prescribed alternative antibiotics after the urine culture results are available if the initial antibiotic is found to be ineffective against the infection.

The duration of treatment of the UTI depends on the antibiotic in use. Some common first-choice agents for the treatment of uncomplicated cystitis in women include nitrofurantoin, Bactrim or beta-lactams such as Cephalexin.

You may also be given medication to make the urine more alkaline and asked to drink more water.

Most patients can be treated on an outpatient basis. However, hospital admission for management of complicated UTIs may be indicated in some patients. Complicating factors include the presence of structural abnormalities (e.g., stones, indwelling catheters), metabolic disease (e.g., diabetes, pre-existing kidney disease) or patients who are immunosuppressed and therefore more prone to serious infections (e.g., HIV, patients on chemotherapy).

Recurrent urinary tract infection

Recurrent UTI is defined as having UTI three or more times in a year. This can be due to the same or different bacteria. In these cases, further investigations may need to be done (e.g., renal ultrasound, intravenous pyelogram, cystoscopy, urine for tuberculosis and cytology) to look for any underlying causes and complications of recurrent UTIs.

Patients with recurrent UTIs may be given prophylactic antibiotics for a period of at least three months. They will also be advised on the various preventive measures and the importance of keeping good personal hygiene.

References

1. European Association of Urology Guidelines on Urological Infections: Summary of the 2024 Guidelines https://doi.org/10.1016/j.eururo.2024.03.035

2. Urinary tract infections — appropriate diagnosis and antibiotic use for uncomplicated cystitis and Pyelonephritis (no date) UTI – Appropriate Diagnosis And Antibiotic Use For Uncomplicated Cystitis And Pyelonephritis (Dec 2023). Available at: https://www.ace-hta.gov.sg/docs/default-source/acgs/uti-appropriate-diagnosis-and-antibiotic-use-for-uncomplicated-cystitis-and-pyelonephritis-(dec-2023).pdf?sfvrsn=1bb4f1a0_8