Urinary tract infection

Overview

Definition

An infection which involves any part of the urinary tract is called urinary tract infection (UTI). Second most common infection in the body is urinary tract infection. Urinary tract produces urine, urine flows within the body through it, urine is stored within it and expelled out of the body through it.
Urinary tract consists of a) two kidneys b) two ureters c) one urinary bladder and d) one urethra.
Kidneys- One in each side of the vertebral column protected by the lower portion of the rib cage. They are situated at the level between 12th thoracic and 3rd lumbar vertebra. Right sided kidney is at a slightly lower level due to the presence of liver in the right side of the body. They are bean shaped. Size of a kidney is almost the size of fist of a person. They filter the blood and produce urine
Ureters- they are tube-like structures, connect the kidneys with urinary bladder through which urine flows from kidney to urinary bladder.
Urinary bladder- it is a sac like structure that stores urine before urine is expelled out of the body.
Urethra- it is also a tube-like structure, one end of urethra opens in the urinary bladder and the other end opens outside the body. Urine from the urinary bladder expelled out of the body through urethra.
Urinary tract infection in pregnancy needs special mention. Pregnancy causes changes in a woman’s body such as hormonal changes leading to vesicoureteral reflux (reverse flow of urine from urinary bladder to ureters), stasis of urine in urinary tract due to compression by uterus. Urine of pregnant women contain more sugar and protein that increase the chance of bacterial growth. Urinary tract infection in pregnancy may cause preterm labour and low birth weight baby. Therefore each pregnant woman should be tested for urine analysis to detect urinary tract infection whether symptomatic or asymptomatic (i.e., whether there is symptoms of urinary tract infection in a pregnant woman or not)
In babies fever may be the only symptom of urinary tract infection.

Types of urinary tract infection-

Urinary tract infection may involve different parts of the urinary tract and named accordingly.
Upper urinary tract consists of kidneys and Ureters. Infection of kidneys and ureters is known as upper urinary tract infection. Lower urinary tract consists of the urinary bladder and urethra. Infection of urinary bladder and urethra is known as lower urinary tract infection.
Infection of kidney- Pyelonephritis
Infection of ureter- Ureteritis
Infection of urinary bladder- Cystitis
Infection of urethra- Urethritis
Urinary tract infection is also categorised clinically by uncomplicated and complicated. Patients who are immunocompromised, under immunosuppressive therapy, having structural or neurological disease causing stasis of urine, or foreign body in urinary tract are prone to complicated urinary tract infection.

Symptoms of urinary tract infection

There may be urinary tract infection without any symptoms. It is called asymptomatic urinary tract infection
Symptoms of urinary tract infections are-
1 Urinary urgency- There is frequent and strong urge to urinate.
2 Passing small amount of urine in spite of strong urge
3 Urinary incontinence (leakage)
4 Burning sensation during micturition
5 Cloudy or reddish or pinkish urine
6 Foul smelling urine
7 High fever that may be associated with chill and rigor
8 Flank pain or back pain 
9 Lower abdominal pain and/discomfort
10 Pain during sex
Pyelonephritis– in this situation high fever with chill and rigor, nausea, vomiting, weakness, pain in flank, back, bloody urine are prominent. There may be mental changes.
Cystitis– It is the most common type of urinary tract infection. Here urgency of micturition, painful micturition, lower abdominal discomfort and/ pain, cloudy or bloody urine may be prominent
Urethritis– Here the burning sensation during micturition is prominent. There may be discharge from urethra.

Causes of urinary tract infection-

In women most infections are from bacteria in the gut. Bacteria of the gut come out through anus and sometimes due to its close proximity enter the urinary tract through the urethra and multiply in the urinary bladder and infect the urinary tract.
In men most infections are due to stasis of urine in the urinary tract due to some reason.

Causative organisms-

Escherichia coli is the most common causative organism in both complicated and uncomplicated urinary tract infection. It accounts for 90% cases of urinary tract infection. Other organisms are Klebsiella pneumoniae, Staphylococcus saprophyticus, Enterococcus faecalis, Group B streptococcus, Proteus mirabilis, Pseudomonas aeruginosa. Staphylococcus aureus, Candida spp. Enterococcus spp, P mirabilis and P aeruginosa mainly causes complicated urinary tract infection.

Risk factors of urinary tract infection-


1 Female- Females are more prone to urinary tract infection as the urethra of a woman is short and infection can reach the bladder easily to cause urinary tract infection. Chance of urinary tract infection in a woman’s lifetime is 50%. Some women suffer from repeated urinary tract infection. Chance of urinary tract infection in a male person’s lifetime is 10%.
2 Sexual activity-  More often sexual activity and many sexual partners increase the risk of urinary tract infection
3 Women who use spermicidal agents and diaphragms for birth control are at higher risk of urinary tract infection.
4 Menopause- Changes in urinary tract after menopause make a woman more vulnerable to urinary tract infection.
5 Abnormality in urinary tract- Any abnormality in urinary tract that prevents passing of urine from the body or causes reverse flow of urine in urinary tract increases the risk of developing urinary tract infection.
6 Any blockage in the urinary tract- Such as enlarged prostate, stones, strictures increases the risk of urinary tract infection.
7 Any disease that causes stasis of urine – Such as spinal cord injury increases the risk of urinary tract infection.
8 Low immunity- Diabetes, immunosuppressive diseases or use of immunosuppressants increases the risk of urinary tract infection.
9 Surgical procedure in urinary tract, urinary bladder catheterization, prolonged in situ catheter in urinary bladder  increases the risk of urinary tract infection.
10 Bowel incontinence also increases the risk of urinary tract infection.
11 Genetic susceptibility may increase the chance of urinary tract infection. 

Diagnosis of urinary tract infection-

 When urinary tract infection is suspected the following tests may be done to diagnose it.
1 urinalysis- A clean catch of midstream urine is examined in the laboratory to see whether there is excessive number of white blood cells (WBC) in urine, whether there is blood, or bacteria in urine.
2 Urine Culture and Sensitivity- urine is kept in culture media in the laboratory for multiplication of organisms present in it. Thus it can detect the organism responsible for causing the infection. It also determines which antimicrobials can be used to treat the infection (sensitive) and which antimicrobials are resistant.
3 CBC (Complete blood count) and blood culture can help to determine whether infection has spread to the bloodstream or not.
In case of recurrent urinary tract infection the following tests may also be done
a) Different imaging techniques such as Ultrasonography, CT Scan, MRI- These can detect any abnormality in the urinary tract such as stone, tumor, blockage, congenital abnormality, any complication of urinary tract infection etc. 
IVP(intravenous pyelogram) – in this imaging technique intravenous dye is injected and x-ray is taken as the dye passes through the urinary tract to see the urinary tract. Retention of urine, urinary reflux and any obstruction can be seen by IVP.
Plain x ray can detect stones that may cause urinary tract infection
b) Cystoscopy- Here a long thin tube with a lens and light source (Cystoscope) is introduced through the urethra to see inside of urethra and bladder directly for any pathology. 

Complications of urinary tract infection- 

Urinary tract infection is treatable. But when it involves kidneys or when bacteria from urinary tract enters the bloodstream it may cause serious problems such as sepsis, renal damage or fatal outcomes if not urgently and adequately treated
Pregnant women may give birth to premature and low birth weight babies.
There may be stricture of urethra which increases the chance of recurrent infections.

Prevention of urinary tract infection- 

1 Drink plenty of water ( 6-8) glasses/day to dilute urine, and urinate frequently so that bacteria don’t get enough time to multiply and flushed out from the body.
2 Drain the bladder fully and don’t hold urine.
3 Avoid alcohol, citrus juice, drinks containing caffeine and spicy foods which may irritate the bladder.
4 Wipe front to back so that bacteria in and around anus cannot spread to the urethra and vagina.
5 Wash genitals before sexual intercourse and urinate before and after it.
6 Use shower instead of bath
7 Avoid using diaphragm and spermicidal agents and adopt other birth control measures. Use water based lubricants during sex if needed.
8 Avoid douches, deodorant sprays, scented powders which can irritate urethra
9 Change pad frequently during menstruation and try to use sanitary pad and avoid using tampons.
10 Keep genital area clean and dry. Use loose cotton underwear. Avoid tight clothes that may cause moisture formation. Moisture can help bacteria to grow.
11 After menopause vagina becomes dry and there is an increased chance of urinary tract infection, estrogen vaginal cream may be used in this situation.
12 Cranberry juice may be helpful to prevent urinary tract infection though not proven scientifically.

Treatment of urinary tract infection-

Different antibiotics may be used to treat urinary tract infection. It is important to treat the infection adequately and without delay, otherwise recurrence and resistance to the antibiotic may occur. Antibiotics may be used cotrimoxazole-trimethoprim combination, quinolones, Amoxicillin-clavulanic acid combination, nitrofurantoin etc.
Treatment of chronic urinary tract infection-
1 Low dose antibiotic for a prolonged period 6 months or more may prevent repeated infection. 
2 Taking a single dose of antibiotic after sex each time.
3 Taking measures to prevent urinary tract infection.