urinary tract infections - an overview

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Urinary Tract Infections:

Urinary Tract Infections Prepared by B aya n B ela l S uleima n

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Urinary tract infection ( UTI ) is an infection that affects any part of the urinary tract. Mostly Bacterial. UTIs can involve the urethra, prostate, bladder, or kidneys.

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Symptoms may be absent or include urinary frequency and urgency, dysuria, lower abdominal pain, and flank pain. Systemic symptoms and even sepsis may occur with kidney infection.

Epidemiology of UTIs in the United States :

Epidemiology of UTIs in the United States 8 million physician visits/year 10.8% annual prevalence 40%–50% lifetime prevalence in women 1 in 3 women will require antimicrobial therapy before 24 years of age 0.5–0.7 episodes/person-year in sexually active women $1 billion/year for evaluation and treatment.

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Among adults aged 20 to 50 yr , UTIs are about 50-fold more common in women. The incidence increases in patients > 50 yr , but the female:male ratio decreases because of the increasing frequency of prostate disease.

UTI : Etiology:

UTI : Etiology About 95% of UTIs occur when bacteria ascend the urethra to the bladder and, in the case of acute uncomplicated pyelonephritis, ascend the ureter to the kidney. The remainder of UTIs are hematogenous . Systemic infection can result from UTI, particularly in the elderly. About 6.5% of cases of hospital-acquired bacteremia are attributable to UTI.

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The most common causes of UTI infections (about 80%) are Escherichia coli . However , many other bacteria can occasionally cause an infection - for example, Klebsiella , Pseudomonas , Enterobacter , Proteus , Staphylococcus , Mycoplasma , Chlamydia , Serratia and Neisseria spp. far less frequent causes than E. coli . In addition, fungi ( Candida and Cryptococcus spp ), viruses and some parasites ( Trichomonas , Schistosoma ) also may cause UTIs.

Etiology … cont:

Etiology … cont E. coli causes > 75% of community-acquired UTIs in all age groups; Staphylococcus saprophyticus accounts for 5 - 15% of UTIs, mostly in younger women. In hospitalized patients, E. coli accounts for about 50% of cases. The gram-negative species Klebsiella , Proteus, Enterobacter , and Serratia account for about 40%, the gram-positive bacterial cocci Enterococcus faecalis and S. saprophyticus and Staphylococcus aureus account for the remainder.

Pathogenesis ::

Pathogenesis : C olonization, M igration, A ttachment.

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Complicated UTI is considered to be present when there are underlying factors that predispose to ascending bacterial infection. urinary instrumentation, anatomic abnormalities, and obstruction of urine flow. Uncomplicated UTI occurs without underlying abnormality or impairment of urine flow. most common in young women. Risk factors in women include sexual intercourse, diaphragm and spermicide use, antibiotic use, and a history of recurrent UTIs.

Etiology of Uncomplicated UTIs in the US (Women 15–50 years old) :

Etiology of Uncomplicated UTIs in the US (Women 15–50 years old) Gram-Negatives  Escherichia coli (72%)  Klebsiella species (6%)  Proteus species (4%)  Other (5%) Gram-Positives  Enterococcus species (5%)  Other Gram-positive organisms (7%)

Complicated UTI:

Complicated UTI Most common UTI in men aged 16–35 years Most common nosocomial infection. 31 % of hospital-acquired infections.

Clinical classification:

Clinical classification



Clinical Classification:

Clinical Classification Urethritis Cystitis Acute urethral syndrome Prostatitis Asymptomatic bacteriuria Pyelonephritis Perinephric abcess Genitourinary TB


Urethritis Inflammation of the urethra. H ighly associated with sexual activity Non- gonococcal urethritis Gonococcocal urethritis Chlamydia trachomatis Adenovirus Uropathogenic Escherichia coli (UPEC) Herpes simplex Mycoplasma genitalium Reiter's syndrome Trichomonas spp. Ureaplasma urealyticum Neisseria gonorrhoeae

Symptoms & Treatment:

Symptoms & Treatment Dysuria , painful micturition In men, purulent discharge usually indicates a urethritis of gonococcal nature, while clear discharge indicates urethritis of non- gonococcal nature . In women up to 80% of infections are with few symptoms or are asymptomatic Treatment : Ceftriaxone - Gonorrhea Fluconazole - Monilial Metronidazole ( Flagyl ) - Trichomonial Co- trimoxazole Tetracyclines


Cystitis Inflammation of the bladder. Most common UTI. Community acquired or nosocomial . Causes may be : Bacterial Viral Fungal Parasitic

Bacterial cystitis :

Bacterial cystitis Most common. The most common organism implicated in UTIs E. coli (80–85)% . Staphylococcus saprophyticus is the cause in (5–10)%. Others contribute the remainder. Enterobacter cloacae Klebsiella pneumoniae Serratia marcescens Proteus mirabilis Pseudomonas aeruginosa

Viral cystitis :

Viral cystitis Adenoviruses Severe bladder irritation , sometimes hemorrhagic . Treatment : Usually self limited (anti-inflammatory medications and hydration).

Fungal cystitis:

Fungal cystitis In immunocompromised and with prolonged hospitalization . Mostly due to: Candida and aspergillus Diagnosis : special culturures Treatment : Amphotericin , ketoconazole.

Urinary Schistosomiasis:

Urinary Schistosomiasis Egg deposition of schistosoma haematobium in the blader wall leads to haematuria and fibrosis of the bladder . The bladder becomes calcified , and there is increased pressure on ureters and kidneys otherwise known as hydronephrosis . Treatment : Praziquanetel .

Acute urethral syndrome:

Acute urethral syndrome ( AUS) , more commonly known as cystitis is an irritation of the bladder NOT caused by a urinary tract infection . Causes include : radiation therapy to the pelvis area, chemotherapy with certain types of medications, and other irritants. The exact cause of noninfectious cystitis is often unknown.

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Symptoms are similar to those caused by a urinary tract infection. The lining of the urethra and bladder becomes inflamed and irritated. Dysuria More frequent urination, or waking up at night to urinate. Urgency feeling that you have to urinate but only a few drops of urine come out. Cloudy, bad smelling .

ACUTE Prostatitis :

ACUTE Prostatitis Acute prostatitis is usually caused by a bacterial infection of the prostate gland. Any bacteria that can cause a urinary tract infection can cause acute bacterial prostatitis, including: Escherichia coli Enterococci Klebsiella pneumonia Proteus mirabilis Pseudomonas aeruginosa Staphylococcus aureus

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Some sexually transmitted diseases (STDs) can cause acute prostatitis , typically in men younger than age 35. These STDs include: Chlamydia Gonorrhea Trichomoniasis Ureaplasma urealyticum

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E . coli prostatitis may occur spontaneously or after Epididymitis Urethritis Urinary tract infections Men ages 20 - 35 who have multiple sexual partners are at an increased risk especially for sexually transmitted bacterial prostatitis.

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This infection is a medical emergency. Treatment : use bactericidal drug , since prostate is inflamed these will penetrate well and eradicate the infection.

Chronic prostatitis:

Chronic prostatitis mainly E.coli . Develops in nearly 5% of acute prostatitis cases. Causes recurrent UTIs. Polonged treatment (4-8 wks ).

in 1999, the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) devised a new classification system:

in 1999, the National Institute of Diabetes and Digestive and Kidney Diseases ( NIDDK ) devised a new classification system

Asymptomatic bacteriuria:

Asymptomatic bacteriuria Asymptomatic bacteriuria is a significant number of bacteria in the urine that occurs without usual symptoms. WBC count in urine may be modestly elevated. Persons who have urinary catheters often will have bacteriuria , but most will not have symptoms. Escherichia coli is the most common organism isolated from patients with asymptomatic bacteriuria .

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Infecting organisms are diverse and include: Pseudomonas aeruginosa, Enterococcus species, and group B streptococcus . Organisms isolated in patients with asymptomatic bacteriuria will be influenced by patient variables: healthy persons will likely have E . coli, whereas a nursing home resident with a catheter is more likely to have multi-drug–resistant polymicrobic flora (e.g. P . aeruginosa).

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Certain people are at a higher risk for kidney infections if they develop asymptomatic bacteriuria . The following increases your risk: Diabetes Infected kidney stones Kidney transplant Older age Pregnancy -- up to 40% of pregnant women with untreated asymptomatic bacteriuria will develop a kidney infection Vesicoureteral reflux in young children Most of these patients are best left untreated , because the usual result of treatment is the establishment of highly resistant organisms.


pyelonephritis Pyelonephritis is bacterial infection of the kidney parenchyma . About 20% of community-acquired bacteremias in women are from pyelonephritis . uncommon in men with a normal urinary tract . About 250,000 patients per year in the US.


PATHOGENESIS Two potential routes : (1) the hematogenous route , Because the kidneys receive 20% to 25% of the cardiac output, any microorganism that reaches the bloodstream can be delivered to the kidneys. The major causes of hematogenous infection are : S. aureus , Salmonella species, P. aeruginosa, and Candida species


(2) the ascending route , from the urethra to the bladder, then from the bladder to the kidneys via the ureters . Implicated pathogens mostly include: – E. coli – P. mirabilis – K. pneumoniae . Others : E. cloacae , Serratia , P.aeruginosa .


Treatment Pyelonephritis is a dangerous infection and must be treated promptly. Rest Drinking large amount of water Antibiotics: 10-14 days until symptom free Treat related diseases: diabetes, renal stones, vaginal infection, etc

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Antimicrobial therapy Three goals - control or prevention of the development of urosepsis - eradication of the invading organism - prevention if recurrences Medications - trimethoprim- sulfamethoxazole - fluoroquinolones - ampicillin, amoxicillin, first-generation cephalosporins

Perinephric abcess:

Perinephric abcess Perirenal abscess is a pocket of pus caused by an infection around one or both kidneys. Most perirenal abscesses are caused by urinary tract infections that start in the bladder, spread to the kidney, and then spread to the area around the kidney. Other causes of perirenal abscess include surgery in the urinary tract or reproductive system and bloodstream infection. The biggest risk factor for perirenal abscess is kidney . Stones are found in 20 - 60% of patients with perirenal abscess. Other risk factors for perirenal abscess include: Diabetes Having an abnormal urinary tract Trauma

Perinephric abcess:

Perinephric abcess Perirenal abscess is a pocket of pus caused by an infection around one or both kidneys . Most perirenal abscesses are caused by urinary tract infections that start in the bladder , spread to the kidney , and then spread to the area around the kidney . Other causes of perirenal abscess include surgery in the urinary tract or reproductive system and bloodstream infection .

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Stones are found in 20 - 60% of patients with perirenal abscess. Other risk factors for perirenal abscess include: Diabetes Having an abnormal urinary tract Trauma

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Tests include : CT scan Ultrasound of the abdomen Urinalysis Urine culture Treatment : To treat perirenal abscess, the pus can be drained through a catheter that is placed through the skin or with surgery . Antibiotics should also be given, at first through a vein (IV).

Genitourinary Tuberculosis:

Genitourinary Tuberculosis 1.2-2.6 % in first world. 15-20% of T.B cases in developing countries. Clinical findings : Sterile pyuria , 20% without pyuria .

Renal TB:

Renal TB Organisms settle in medulla. Formation of granulomas > caseation and tissue destruction. Calcification and scarring. May end with renal failure. (4.5%)

Tuberculous ureteritis:

Tuberculous ureteritis Results from renal tuberculosis. Scarring > obliteration of the ureter.

Tuberculous cystitis:

Tuberculous cystitis Fibrosis and fistulas Gulf-hole orifice. Other types : TB epididymitis ,TB urethritis.

What should we do ?:

What should we do ? Prevention .