Saturday, March 13, 2010

Urinary Tract Infections:Overview

A urinary tract infection (UTI) is a bacterial infection that affects any part of the urinary tract.
The most common type of UTI is a bladder infection which is also often called cystitis. When the kidney is affected either through ascending or hematogeneous route ( pyelonephritis) UTI can take a serious turn.
Although they cause much annoyance , urinary tract infections can usually be quickly and easily treated with a short course of antibiotics unless it complicated UTI with stone,kidney involvement or generalised factor like decreased immunity-uncontrolled sugars.

Epidemiology

UTIs are most common in sexually active women and increase in diabetics and people anatomical malformations of the urinary tract- obstructing stones,stricture or prostatic enlargement.
• An estimated 150 million UTI occur annually on a worldwide basis resulting in 6 billion USD in direct health care expenditures each year. Prevalence of bacteriuria in females is 3.5%.The life time risk of UTI in females is 50 %.
• UTI account for-
 7 million physician’s office visits
 1 million emergency visits
 1 lac hospital admission
 In total: 1.2% total office visits by females,0.6% total office visits by males





Hygiene Issues:
Since bacteria can enter the urinary tract through the urethra (an ascending infection), poor toilet habits (such as wiping back to front for women) can predispose to infection,



Gender aetiology:
Short urethra in females along with proximity to anus predisposes them to UTI. A common cause of UTI is an increase in sexual activity, such as vigorous sexual intercourse with a new partner, although the reason behind this is unclear. The term "honeymoon cystitis" has been applied to this phenomenon
Anatomical factors:
pregnancy in women, prostate enlargement in men ,stricture urethra etc can predispose to UTIs.



Allergy:

Allergies can be a hidden factor in urinary tract infections. For example, allergies to foods can irritate the bladder wall and increase susceptibility to urinary tract infections. Urinary tract infections after sexual intercourse can also be due to an allergy to latex condoms, spermicides, or oral contraceptives.



Immunity Related:
Diabetics,HIV,people convalescing from prolonged illness are prone for infection.
Foreign Body Related:
Indwelling urinary catheters in women and men who are elderly, prostatic stent can be a major cause of UTIs. Any kind of urological intervention also risks the patient for UTI. Scrupulous aseptic techniques may decrease these associated risks.
Use of vaginal diaphragms, pessaries can aggravate the problem and make woman susceptible for UTIs.



While ascending infections are generally the rule for lower urinary tract infections and cystitis, the same may not necessarily be true for upper urinary tract infections like pyelonephritis which may be hematogenous in origin.
The main cause agent is Escherichia coli. Staphylococcus epidermidis is most common in patients using urinary catheters.





Pathophysiology:


The bladder wall is coated with various mannosylated proteins, such as Tamm-Horsfall proteins (THP), which interfere with the binding of bacteria to the uroepithelium. As binding is an important factor in establishing pathogenicity for these organisms, its disruption results in reduced capacity for invasion of the tissues.



The use of urinary catheters, truama,sexual intercourse,surgical intervention or sexual perversion may physically disturb this protective lining allowing bacteria to invade the exposed epithelium.



Decreased immunity(General-HIV,Diabetes etc) or local(elderly population with genitourinary tract atrophy) leads to defective defensive mucosal activity and hence adherence of the bacteria.




PATHOPHYSIOLOGY IN A NUTSHELL

Asymptomatic Bacteriuria: The presence of bacteria in the urinary tract of older adults, without symptoms or associated consequences, is also a well recognized phenomenon which may not require antibiotics.
Many times asymptomatic bacteuria in elderly poplation is left untreated to avoid side-effects of the drugs.
.

Symptoms:
Burning of urine,abdominal pain,flank pain,frequency of urination,lood in the urine,high or low grade fever,pelvic and low ack discomfort especially in females .Perineal pain/post ejaculatory pain,testicular pain are some of the symptoms as per the location of the infection and its severity.

Elderly people may not present with urinary symptoms instead they present with generalised weakness,low grade fever or even hypothermia. Uncontrolled UTI in elderly people can have mortality of 40 %

Diagnosis:
Generally has a spot mid-stream urine sample sent for urinalysis, specifically the presence of nitrites, leukocytes or leukocyte esterase.
If there is a high bacterial load without the presence of leukocytes, it is most likely due to contamination.
The diagnosis of UTI is confirmed by a urine culture.
If the urine culture is negative:
• symptoms of urethritis may point at Chlamydia trachomatis or Neisseria gonorrheae infection.
• symptoms of cystitis may point at interstitial cystitis.
• in men, prostatitis may present with dysuria(Abacterial prostatitis/painful bladder syndrome).
A negative urine test can also suggest the presence of unusual bacteria or viruses causing symptoms of UTI.
In severe infection, characterized by fever, rigors or flank pain, renal function tests are performed. A CT scan may be needed to rule out abscess formation.
Work-up:

However, UTI in young infants and adults must receive some imaging study, typically a Ultrasonography/Micturating cystourethrogram, to ascertain the presence/absence of congenital urinary tract anomalies. Males too must be investigated further.
Specific methods of investigation include x-ray, Nuclear Medicine, MRI and CAT scan technology.
Treatment
Uncomplicated UTIs
Most uncomplicated UTIs can be treated with oral antibiotics such as trimethoprim, cephalosporins, nitrofurantoin, or a fluoroquinolone (e.g., ciprofloxacin or levofloxacin).
The Infectious Disease Society of America recommends SMX/TMP (trimethoprim and sulfamethoxazole) as a first line agent in uncomplicated UTIs rather than fluoroquinolones such as ciprofloxacin. Trimethoprim is one widely used antibiotic for UTIs and is usually taken for seven days. It is often recommended that trimethoprim be taken at night to ensure maximal urinary concentrations to increase its effectiveness.
A three-day treatment of trimethoprim/sulfamethoxazole or ciprofloxacin is usually all that is needed.
Pyelonephritis
If the patient has symptoms consistent with pyelonephritis, intravenous antibiotics may be indicated.
Regimens vary, and include quinolones (e.g. levofloxacin),Cephalosporins,Penicillins etc.The aminoglycosides-netilmycin,amikacin are usually combined with these. These are continued for 48 hours after fever subsides. The patient may then be discharged home on oral antibiotics for a further 5 days.
If the patient makes a poor response to IV antibiotics (marked by persistent fever, worsening renal function),then imaging is indicated to rule out formation of an abscess either within or around the kidney, or the presence of an obstructing lesion such as a stone.
This further needs drainage of the abscess, stenting for obstructed kidney or draining the kidney with percutaneous nephrostomy.
Children
For simple UTIs children often respond well to a three-day course of antibiotics.



Antibiotics used in UTIs





Recurrent UTIs
Patients with recurrent UTIs may need further investigation.
This may include ultrasound scans of the kidneys and bladder or intravenous urography (X-rays of the urological system following intravenous injection of iodinated contrast material).
If there is no response to treatment, other causes like Interstitial cystitis,malakoplakia,carcinoma in situ or Tuberculosis may be the reason.
During cystitis, uropathogenic Escherichia coli challenge innate defenses by invading superficial umbrella cells and rapidly increasing in numbers to form intracellular bacterial communities (IBCs). By working together, bacteria in biofilms build themselves into structures that are more firmly anchored in infected cells and are more resistant to immune system assaults and antibiotic treatments. This is often the cause of recalcitrant chronic Urinary Tract Infections.
Prevention
The following are measures that studies suggest may reduce the incidence of urinary tract infections. These may be appropriate for people, especially women, with recurrent infections:
• Do not delay urination when it is necessary(Infrequent voidin is common in young women-further it becomes habbit).
• Drinking lots of water may also help.
• Cleaning the urethral meatus (the opening of the urethra) after intercourse and passing urine immediately after intercourse has been shown to help.
• It has been advocated that cranberry juice can decrease the incidence of UTI. A specific type of tannin, called A Type Proanthocyanidin, found only in cranberries and blueberries prevents the adherence of certain pathogens (eg. E. coli) to the epithelium of the urinary bladder.


• The tannins that are found in green tea drunk in a daily dose of around 600mls can provide an excellent and cost effective alternative to cranberry juice in the prevention and prevelance of chronic infection.

• For post-menopausal women, a randomized controlled trial has shown that intravaginal application of topical estrogen cream can prevent recurrent cystitis- which can make vagina and lower genitourinary tract supple, moist and resistant to infections. .


• Often long courses of low-dose antibiotics(suppressive antibiotic course) for 6 -12 months are taken at night to help prevent otherwise unexplained cases of recurring cystitis.This is combined with monthly urine routine examination or culture examination
• Ladies getting infection after sexual intercourse can start post-coital prophylaxis with ciprofloxacin.This method is quite effective.

• Recurrent UTIs can also be treated with self start therapy with 3 day course of antibiotics like fluoroquinolones and getting at the same time dip-slide culture to confirm the culture sensitivity.
• Breastfeeding can reduce the risk of UTIs in infants.



final plan to treat UTI

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