Urinary tract infections

Urinary tract infection is serious health problem affecting millions of people each year. Infections of urinary tract are the second most common type infections in the human body.

Infections of urinary tract fall into two general anatomic categories; lower urinary tract infection (urethritis and cystitis) and upper tract infections (acute pyelonephrites, prostatitis and intrarenal and perinephric abscesses)

Etiology:

Many microorganisms can infect the urinary tract, but by far the most common agents are the gram negative bacilli which include Escherichia coli, proteus, klebsiella, Enterobacter, pseudomonas and serratia. Gram positive cocci play a lesser role include staphylococcus saprophyticus, staphylococcus-aureus, Enterococci and staphylococcus epidermidis.
E-coli causes > 75% of community acquired UTIs in all age groups and s-saprophyticus accounts for about 10%. In hospitalized patients, E-coli accounts for about 50% of cases.

Pathophysiology:

Most of urinary tract infections are ascending in origin. Disturbances of the normal periurethral flora; which is part of host defense against colonization by pathogenic bacteria; predisposes a person to a urinary tract infection.

Risk factors:

Some people are more prone to getting a UTI than others.

Gender:- females are prone to UTI due to proximity of female urethra to anus, its short length and introduction of bacteria into urinary tract during sexual activity.

Obstruction:- an impediment to the free flow of urine by tumor, stricture stone or prostatic hypertrophy results in hydronephrosis and greatly increased frequency of UTI

Pregnancy:- UTIs are detected in 2-8% of pregnant women and results from decreased ureteral peristalsis, decreased ureteral tone and temporary incompetence of vesicoureteral valves.

Neurogenic bladder dysfunction:- Interference with bladder innervation as in spinal accord injury, tabes dorsalis, multiple sclerosis and diabetes mellitus may be associated with UTI.

Vesicoureteral reflux:- Defined as reflux of urine from the bladder cavity up into the ureters and sometimes into renal pelvis. Vesico ureteral reflux is common among children with anatomic abnormalities of urinary tract. An anatomically impaired vesicoureteral junction facilitates reflux of bacteria and thus upper tract infections.

Diabetes mellitus- Diabetics are more prone to UTI. The risk for UTI complications and fungal related UTIs is also higher in people with diabetes.

Immune system problems - patient's with immune compromised systems such as those with HIV / AIDS or who are undergoing treatment for cancer are at increased risk of all types of infections including UTI and pyelonephrites.

Signs and Symptoms

• Lower urinary tract Infections:- frequent urination along with the feeling of having to urinate even through three be very little urine to pass .
• Nocturia: need to urinate during night.
• Urethritis: discomfort, irritation or pain at urethral meatus or a burning sensation throughout urethra with urination (dysuria)
• Pain in the midline supra pubic region.
• Pyuria: pus in the urine or discharge from urethra
• Hematuria: blood in urine (not always seen to marked eye, but often revealed during urine tests.
• Pyrexia: mild fever
• Cloudy and foul smelling urine
• Urinary incontinence; involuntary leakage of urine
• Confusion especially in elderly
• Urinary tract infections may be asymptomatic

 Kidney Infection

• Vomiting
• Flank pain
• Fever, high grade associated with chills, headache
• Night sweats and fatigue

Diagnosis:

Urine examination:- patients with symptoms of UTI has a spot mild stream urine sample sent for urinolysis, especially for the presence of nitrites, leukocytes or leukocyte esterase.

Urine culture:- to confirm UTI and to look for drug sensitivity other Investigations:-

• Ultrasound: assessment of patient with infection of kidneys (pyelonephrites) to look for calculi, obstruction or other abnormalities.
• CT is more sensitive modality for diagnoses and follow up of complicated UTI

Treatment:

• Following principles underlie treatment of UTI
• Except in acute in complicated cystitis in women. a quantitative urine culture should be performed to confirm infection before antibiotic treatment is begin.
• Factors predisposing to infection such as obstruction and calculi should be identified and corrected if possible
• Relief of clinical symptoms does not always indicate bacteriologic cure
• In general lower urinary tract infections need shorter duration of therapy, while upper tract infections require longer treatment.
• A high (2lt/day) fluid intake should be encouraged during treatment and for some subsequent weeks.

Drugs:

• Low urinary tract infections;
• 3- day regimen with trimethoprim sulfamethoxazole, Nitrofurantion and quinolone (Norfloxacinn, ofloxacin, ciprofloxacin)

Uncomplicated pyelonephritis in women

• Mild to moderate illness
• Oral quinolone for 7-14 days
• Single dose cefriaxone or gentamycin followed by oral trimethoprim - sulfamethaxozole for 14 days
• Severe illness, hospitalization required parenteral quinolone, gentamycin
  ( ± ampicillin) Cefriaxone

Complicated UTI in men and women

• Mild to moderate - oral quinotones for 10-14 days
• Severe illness: Parenteral ampicillin, gentamycin, quinolone cefriaxone etc.

Treatment during pregnancy

• Cystitis: 7 day treatment with amoxicillin, nitrofurantion or a cephalo sporin
• Pyelonephrites – Hospitalization
  
  - Parenteral antibiotics

• Prophylaxis with low dose nitrofurantion in women with recurrent UTI in pregnancy

Recurrent Infection

• Pre treatment and post treatment urine cultures are necessary to confirm diagnosis and identify whether recurrent infection is relapse or re infection
• Relapse:- search should be made for cause (eg. Stones, strictures or other anatomical abnormalities) and should be treated, long term antibiotic treatment is required.
• Re infection:- implies patient has predisposition to periurethral colonization or poor bladder defense mechanisms
• Antibiotic prophylaxis for 6-12 months with trimethoprim 100mg, co-trimoxazole 480mg, Cephalexin 125mg or Nitrofurantion is required.

Prevention

Following measures may reduce the incidence of urinary tract infections

• Do not delay urination when it is necessary
• A daily 2L fluid intake
• Avoidance constipation which may impair bladder emptying
• Topical application of estrogen cream in post menopausal women
• Wipe from front to back to prevent bacteria around anus from entering vagina or urethra
• Take showers instead of tub Baths
• Catheters should be used only when necessary and should be removed as soon as possible
• Clean the genital areas before and after sex.