The urinary tract is a single anatomic unit that extends from the urethra to the kidney. In the majority of infections bacteria gain access to the bladder by the urethra, the opening to the bladder. Urinary tract infections (UTI) within the urinary tract can be conveniently divided into that affecting the kidney (Pyelonephritis) or the bladder (cystitis), although they are not mutually exclusive. Urinary tract infections are particularly common, and 50% of women will experience symptoms of a UTI sometime during life. The female urethra is particularly prone to bacteria, owing to its proximity to the anus, and its short lenght of 4 cm. Urinary tract infections are caused by a bacteria, found growing naturally in the bowel and around the anus. The most common bacteria is Escherichia coli (E Coli), it causes approximately 80% of acute infections, although a UTI may also be caused by other bacteria, including for example Proteus, Klebsiella, and occasionally Enterobacter, or acquired during sexual intercourse from a ( STI ) such as Chlamydia trachomatis, Trichomonas vaginalis, Haemophilus vaginalis or Candida albicans.

UTI's are not a sexually transmitted infection although it may be aggravated by sex.

Men are much less prone to UTI as the long urethra within the penis makes infection of the bladder by these bacteria less likely. However it can occur and may cause a discharge from the penis as found in non specific urethritis

Common symptoms, if present, include:

• dysuria
• frequency
• urgency
• fever
• incontinence and retention

Other signs may include blood stained urine (haematuria) and tenderness in the lower abdomen.

Cystitis can cause a frequent desire to urinate. Often only a small amount of urine is passed but there is a burning or scalding pain whilst urinating. It sometimes includes the involuntary passing of a small squirt of urine on coughing or laughing (stress incontinence).

Occasionally, there are other symptoms including fever, shivering, pain in the groin and a general feeling of being unwell. This may mean that the infection has spread to the kidneys (pyelonephritis).

Investigations into a urinary tract infections may involve urine analysis by microscopy and a culture. Urine is examined under a microscope, where the number of bacteria and white blood cells in a urine sample is the basis for diagnosing urinary tract infections. A sample of urine may also be cultured in a substance that promotes the growth of bacteria.

A pelvic exam may also be necessary.

Treatment usually requires a course of antibiotics, ideally tailored according to sensitivity determined from the urine culture, typically this will be amoxycillin or trimethoprim.

Mild cystitis will usually go away by itself within 2-4 days without any treatment, drinking at least 3-4 litres in 24 hours may relieve symptoms. The use of over-the-counter painkillers like paracetamol can help cope with the symptoms (always read the label).

More serious forms of urinary tract infection may need treatment with antimicrobial drugs. However, you may need to have some tests to rule out other possible causes before a treatment is prescribed.

A number of things are believed to help prevent urinary tract infections coming back, although there is little research evidence to support them:

• 
  drinking a lot of fluid to help ‘flush out’ your urinary system (drinking at least two litres of plain water every day is generally good for health)
  
• by deliberately trying to empty your bladder after urinating seems complete (‘double urination’)
  
• by urinating after sexual intercourse
  
• by avoiding nylon underwear and vaginal deodorants.

Frequent symptomatic infections may be given long term low dose antibiotics directed at preventing recurrent infections.

Complications can arise, either through failure to respond to treatment or a relapse, including:

• failure to complete the course of antibiotics prescribed
• re-infection related to bladder problems, for example tumour, or urinary retention eg. neurogenic bladder
• resistant organisms
• postmenopausal urethral atrophy