Download URINARY TRACT INFECTIONS

URINARY TRACT INFECTIONS
INTRODUCTION:
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A urinary tract infection (UTI) is a condition where one or more parts of
the urinary system (the kidneys, ureters, bladder, and urethra) become
infected.
UTIs are the most common of all bacterial infections and can occur at
any time in the life of an individual.
Almost 95% of cases of UTIs are caused by bacteria that typically
multiply at the opening of the urethra and travel up to the bladder.
Much less often, bacteria spread to the kidney from the bloodstream.
Urine is normally sterile, that is, free of bacteria, viruses, and fungi
 In healthy women, the vagina is colonized by lactobacilli, a beneficial
microorganism
 It maintains a highly acidic environment (low pH) that is hostile to other
bacteria.
 Lactobacilli also produce hydrogen peroxide, which helps eliminate
bacteria
 Reduces the ability of Escherichia coli (E. coli) to adhere to vaginal
cells.
 E. coli is the major bacterial culprit in urinary tract infections.
CLASSIFICATION
According to anatomic site of involvement:
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Lower tract infection: cystitis, urethritis, prostatitis
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Upper tract infection: pyelonephritis, involving the kidneys
CLASSIFICATION ACCORDING TO
DEGREE
1-Uncomplicated
 Occur in individuals who lack structural or functional abnormalities in
the UT that interfere with the normal flow of urine.
 Mostly in healthy females of childbearing age .
CLASSIFICATION ACCORDING TO DEGREE
2-Complicated
Predisposing lesion of the UT such as congenital abnormality or distortion
of the UT, a stone a catheter, prostatic hypertrophy, obstruction, or
neurological deficit
 All can interfere with the normal flow of urine and urinary tract
defenses.
RECURRENT UTIS
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Multiple symptomatic infections with asymptomatic periods
Reinfection: caused by a different organism than originally isolated and
account for the majority of recurrent UTIs.
Relapse: repeated infections with the same initial organism and
usually indicate a persistent infectious source.
CAUSES
Escherichia (E.) coli is responsible
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for most uncomplicated
cystitis cases in women, especially
in younger women.
E. coli is generally a harmless microorganism originating in the
intestines.
If it spreads to the vaginal opening, it may invade and colonize the
bladder, causing an infection.
The spread of E. coli to the vaginal opening most commonly occurs
when women or girls wipe themselves from back to front after
urinating, or after sexual activity.
CAUSES
Staphylococcus saprophyticus accounts for 5 - 15% of UTIs, mostly in
younger women.
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Klebsiella aerogenes,
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Alcaligenes feacalis,
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Enterococci bacteria,
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Pseudomonas aeruginosa
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Proteus mirabilis
account for most of remaining bacterial organisms that cause UTIs.
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They are generally found in UTIs in older women.
Asymptomatic Bacteriuria
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Common among the elderly
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Bacteiruria > 10 5 bacteria/ml of urine without symptoms
SIGNIFICANT BACTERIURIA
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More than 10 5 bacteria /ml (CFU) of urine in clean catch specimen
1/3 of symptomatic women have CFU counts below this level
A bacterial count of 100 CFU/ml has a high positive predictive value of
cystitis in symptomatic women.
PREDISPOSING FACTORS
Abnormalities in the Urinary Tract that interfere with natural defenses
1-Obstruction can inhibit urine flow, disrupting the natural flushing and
voiding effect in removing bacteria from the bladder and resulting in
incomplete emptying
PREDISPOSING FACTORS
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Condition that result in residual urine
volumes:
– prostatic hypertrophy
– urethral stricture
– calculi
– Tumors
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Drug such as:
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anticholinergic agents
PREDISPOSING FACTORS
 Neurological malfunctions associated with
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stroke
diabetes
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spinal cord injuries.
 Other risk factors include:
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urinary catheter
mechanical instrumentation
 Pregnancy (the use of spermicidies and diaphragms).
CLINICAL PRESENTATIONS
Lower Tract Infection:
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Dysuria
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Urgency
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Frequency
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Nocturia
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Suprapubic heaviness,
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Hematuria in women.
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No systemic symptoms
Upper Tract Infection:
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Flank pain
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Costovertebral tenderness,
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Abdominal pain
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Fever
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Nausea
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Vomiting
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Malaise
CLINICAL PRESENTATIONS
Elderly Patients:
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Frequently do experience specific urinary symptoms
Altered mental status, change sin eating habits, or GI symptoms
Patients with catheters
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Will have no lower tract symptoms
Just flank pain and fever.
LABORATORY FINDINGS
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Symptoms alone are unreliable for diagnosis
Examination of the urine is the cornerstone of diagnosis.
Collection of Urine:
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Mid stream clean catch method is preferred method.
LABORATORY FINDINGS
Collection of Urine:
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Catheterization for patient who are uncooperative or unable to void, but
introduction of bacteria in the bladder occurs at 1-2%
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Suprapubic aspiration bypasses the contaminating organism in the
urethra, safe and painless.
DIAGNOSIS:
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Based on isolation of significant numbers of bacteria from a urine
specimen
Microscopic examination
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is performed by preparing a gram stain that indicates the
morphology of the organism and help direct the selection of an
appropriate AB.
DIAGNOSIS:
M icroscopic examination
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The presence of one organism per oil-immersion field in an un
centrifuged sample correlates with 100,000 bacteria/ml.
DIAGNOSIS
Pyuria: WBC > 10 WBC/mm3
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it only signifies the presence of inflammation
Sterile Pyuria is associated with urinary tuberculosis, chlamydial, and
fungal infections
Hematuria, non-specific, may indicate other disorders such as calculi or
tumor
Proteinuria is found in the presence of infection
DIAGNOSIS:
Biochemical tests
1-dipstick test for nitrite: bacteria in the urine reduce nitrate→ nitrite
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false –negatives are common and caused by
gm+ve or pseudomonas that do not reduce
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low urinary PH
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frequent voiding and dilute urine.
Chemical Analysis
Chemical Analysis
DIAGNOSIS:
Quantitative urine culture
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Based on properly collected urine
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Urine is normally sterile
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Determines the number of bacteria present in a urine sample
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1/3 of symptomatic women have bacteria < 10 5.
DIAGNOSIS:
Quantitative urine culture
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one organism per oil immersion field correlates with 100,000 CFU/ml
by culture
Susceptibility
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determine bacterial susceptibility to different antimicrobials.
TREATMENT
Desired outcome
o Prevent or treat systemic consequences of infection
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Eradicate the invading organism
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Prevent reoccurrence of infection.
TREATMENT
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Antibiotics are the main treatment for all UTIs.
A variety of antibiotics are available, and choices depend on many
factors, including whether the infection is:
 complicated or uncomplicated
 primary or recurrent
Treatment decisions are also based on the type of patient:
 man or woman,
 a pregnant or non-pregnant woman,
 child,
 hospitalized or non-hospitalized patient,
 person with diabetes.
SYMPTOMATIC ABACTERIURIA
Acute urethral syndrome
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Females, present with dysuria & pyuria
Urine culture reveals < 105 bacteria /ml
Accounts for half the complaints of dysuria in women
Most likely infected with a small number of bacteria.
SYMPTOMATIC ABACTERIURIA
Chlamydial Treatment
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1g of azithromycin or doxycycline 100 mg bid for 7 days
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Concomitant treatment of sexual partner is required to cure this
infection and prevent recurrence.
ASYMPTOMATIC BACTERIURIA
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Patients with no urinary symptoms
Have two consecutive urine cultures with > 10 5
The majority are elderly and female
Aggressive treatment does not affect infection, complications or
mortality
Also present in pregnant women
Relapse and reinfection are common and chronicity occurs which is
difficult to eradicate.
ASYMPTOMATIC BACTERIURIA
Management
Groups who benefit from treatment:
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pregnant women
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patient with renal transplant
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Patient who will undergo urinary procedure
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Depend on age and whether they are pregnant
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In children: conventional treatment because of greater risk for renal
damage
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In non-pregnant female: controversial
ASYMPTOMATIC BACTERIURIA
Management
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In elderly: two groups
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Persistent bacteriuria:
Intermittent bacteriuria
Mostly seen as a benign disease and does not warrant treatment
Two cultures should be obtained to confirm the presence of bacteria
ASYMPTOMATIC BACTERIURIA
Management
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Ambulatory treatment is effective in removing bacteria for 6 months
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Only 50% remained free of bacteria for 1 year
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Hospitalized patients: therapy in non-efficacious