Urine infections are caused when bacteria grow in the urine and cause inflammation or irritation in the lining of the bladder, the tube coming out of the bladder (the urethra), and sometimes also in the kidneys. Urine infections are also known as Urinary Tract Infection (UTI).
How do I know if I have a urine infection?
A urine infection usually causes pain and burning when urine is passed, especially as someone is just passing urine. The pain may be worst where the urine come out at the tip of the penis or the vulva. The bladder is inflamed and may be painful, and there may be a desire to pass urine at frequent intervals, even if the bladder is not full of urine. These symptoms are called ‘cystitis’,.
Sometimes urine infections can cause bleeding into the urine, called haematuria.
In some cases a urine infection may occur without these symptoms, and in anyone with a serious infection where the cause is not immediately obvious, a sample of urine should be tested for infection.
How severe is the infection?
Sometimes the injection just affects the lining of the bladder, and causes symptoms of cystits. These infections are usually easy to treat, and sometimes even clear without antibiotic treatment. Sometimes, the infections becomes more severe, causing fever, sweats, and pain in the back, just below the ribs. Doctors call this ‘acute pyelonephritis’. These infections always require antibiotic treatment, and sometimes require hospital admission. Avery severe infection may spread to the blood stream, causing septicaemia (‘blood poisoning’). In this case there is high fever, with sweats and uncontrollable shivering attacks (called ‘rigors’). If left untreated, septicaemia can be life-threatening, so should be treated urgently.
What are the causes of urine infection?
The bugs cause these infections are normally bacteria, and one of the commonest is called E. Coli. This is a bug found inside our bowel, and is also on our skin.
Sometimes fungal infections can cause urine infections, but this is rare unless someone has diabetes or their immune system is suppressed, for example by transplant drugs. Viral infections in the urine are even rarer, and are occasionally seen in people with transplants.
Bugs do not normally grow in the urine, and if infections occur, there is often some often predisposing factor. Some of these are:-
- Urine infections are much commoner in women than in men. This is because the tube leading out of the bladder (the urethra) is much shorter in women than in men, so that it is easier for bugs to travel upwards into the bladder. This can be particular problem after sexual intercourse, especially if the bladder is not emptied soon after intercourse.
- Any abnormality in the structure of the kidneys or bladder may allow urine infections to develop, particularly if it causes incomplete drainage of urine into the bladder or incomplete emptying of the bladder.. Conditions that cause incomplete emptying of the urinary system include:
Urology Services at Bright Kidney Centre
Enlargement of the prostate gland in men
Conditions that can affect the nerve supply to the bladder, such as spina bifida, multiple sclerosis, or spinal injury
Reflux nephropathy. This is a condition where urine is pass backward up to the kidneys when the bladder contracts, instead of all being passed to the outside. It is often associated with kidney damage. It is important to check children very carefully for reflux if they get urine infections
- Diabetes can lead to urine infections, or indeed any other condition which reduces the resistance of the body to infection. If some gets a urine infection unexpectedly, the diagnosis of previously unsuspected diabetes should be considered.
- A catheter draining the bladder makes it almost inevitable that bugs will get into the bladder, and they may cause infections. Therefore, as a general rule, when a catheter tube is necessary, it should be in place for as short a time as possible.
- Dehydration by itself does not usually lead to a urine infection, but when combined with any other predisposing to infection, will make matters much worse. This is because urine flowing through the system ‘flushes’ out bugs.
What tests may be needed?
If a urine infection is suspected, the first check is normally a visual inspection of the urine. Urine infection usually causes some cloudiness of the urine: if the urine is crystal clear, then infection is unlikely. Next a urine test will normally be positive for blood and protein in the urine if infection is present. This test can also detect white blood cells (pus cells ) in the urine; if this is positive, infection is very likely. A negative urine test almost rules out infection
To confirm a urine infection, urine is sent to the laboratory to try and grow the bug, and then to determine its sensitivity to various antibiotics. For otherwise healthy people with ‘one-off’ urine infections, it may not be necessary to send the urine to the laboratory, the infection can be treated without laboratory tests. However, for some with kidney failure, or recurrent infection, urine should be sent to the laboratory.
If someone has recurrent urine infections, or infection affecting the kidneys, other tests may be needed, and in some cases referral to a specialist. An ultrasound scan (test in the X-ray department using sound waves) of the kidney and bladder will be performed, to see what size and shape the kidneys are, whether they have any stones or structural abnormalities, and whether the bladder empties fully.
What is the treatment of urine infection?
The first step is to increase the intake of fluid, to help flush infection out. There is a temptation to drink less fluid if it is painful to pass urine, but it makes things worse to get dehydrated. At least 2 litres of fluid a day (5 large glasses) should be taken; more, the better. Some urine infection can be treated with these measures, and antibiotics may not be necessary.
If antibiotics are needed, the best choice is one to which the bug has been proven to be sensitive in the laboratory. However, it takes 2 days to get this result so in most cases it is best to start treatment right away, using the antibiotic which is most likely to work. If you have an allergy to an antibiotic, or have side effects from antibiotics in the past, tell the doctor prescribing.
Antibiotics are usually given for a course of 3-7 days, depending on the severity of the infection and whether there is underlying kidney disease or diabetes. In severe infections it may be necessary to give antibiotics and fluids through a drip into a vein, but this is not often needed.