Urinary Tract Infections

Urinary Tract Infections
Lobna A AlJuffali,MSc
Fall 2010
Urinary Tract Infection (UTI)
 Most common bacterial infections in humans:
 7million office visits per year
 1 million hospitalizations
 15-20% of women will have a UTI during their lifetime.
 From ages 1 to 50,UTIs predominantly occur in women
 After 50 men are affected because of prostate problems.
 defined as the presence of microorganism in the urine that
cannot be accounted for by contamination.
 The organisms have the potential to invade the tissues of the
urinary tract and adjacent structures.
 The presence of bacteria is termed bacteriuria
 fungi in the urine is termed or funguria
Anatomy of UTS
Classification based on anatomic site
 Lower tract infections include
 cystitis (bladder)
 urethritis (urethra)
 prostatitis (prostate gland)
 epididymitis.
 Upper tract infections (such as pyelonephritis) involve the
kidney and are referred to as pyelonephritis.
Uncomplicated UTIs
Are not associated with structural or neurologic
abnormalities that may interfere with the normal flow of
urine or the voiding mechanism. Include
 acute cystitis and pyelonephritis in healthy individuals
 They have the lowest risk of complications or treatment
Complicated UTIs
Can be acute or chronic
are the result of a predisposing lesion of the urinary tract such as:
 Metabolic factors:
 Renal Failure
 Diabetes Mellitus
 Kidney transplantation
 Functional abnormalities:
 neurologic al bladder.
 Structural abnormality
 a congenital abnormality
 distortion of the urinary tract,
 a stone
 indwelling catheter
 prostatic hypertrophy
 Obstruction
Recurrent UTIs
 Recurrent UTIs are characterized by multiple symptomatic
episodes with asymptomatic periods occurring between these
 These infections are either due to reinfection or to relapse.
 Reinfections are caused by a different organism and account for
the majority of recurrent UTIs.
 Relapse represents the development of repeated infections
caused by the same initial organism. Occur within 2-4 weeks after
treatment has ended.
 Persistent infections
Asymptomatic bacteriuria
 is a common finding, particularly among those 65 years of age and
 when there is significant bacteriuria >105 bacteria/mL of urine in
the absence of symptoms.
 Patients with infection usually have more than 105 bacteria/mL of
urine, although as many as one-third of women with symptomatic
infection have less than 105 bacteria/mL.
Symptomatic abacteriuria
 or acute urethral syndrome consists of symptoms of
frequency and dysuria in the absence of significant
 This syndrome is commonly associated with Chlamydia
Significant bacteriuria
is a term used to distinguish the presence of microorganisms
that represent true infection versus contamination of the
urine as it passes through the distal urethra prior to
Criteria for defining significant
 ≥ 102 CFU coliforms/ml or ≥ 105 CFU noncoliforms/ml in a
symptomatic female
 ≥ 103 CFU bacteria/ml in a symptomatic male
 ≥ 105 CFU bacteria/ml in asymptomatic individuals on two
consecutive specimens
 Any growth of bacteria on suprapubic catheterization in
symptomatic patient
 ≥ 102 CFU bacteria/ml in catheterized patient
 The bacteria causing UTIs usually originate from bowel flora
of the host.
 Bacteria are then believed to enter the bladder from the
 Once in the bladder, the organisms multiply quickly and can
ascend the ureters to the kidney.
UTIs can be acquired via three
possible routes:
The ascending,
Lymphatic pathways.
 In females, the short length of the urethra and proximity to the
perirectal area make colonization of the urethra likely.
 Patients who are unable to void urine completely are at greater
risk of developing UTIs and frequently have recurrent infections.
Three factors determine the
development of UTI:
the size of the inoculum
2. virulence of the microorganism
3. competency of the natural host defense mechanisms.
Virulence Factor Of Bacteria
 Their ability to adhere to urinary epithelial cells by fimbriae,
resulting in colonization of the urinary tract, bladder
infections, and pyelonephritis.
 Hemolysin, a cytotoxic protein produced by bacteria that
lyses a wide range of cells including erythrocytes,
polymorphonuclear leukocytes, and monocytes
 Aerobactin, which facilitates the binding and uptake of iron
by Escherichia coli
Community-acquired Infections (%)
nosocomial infections (%)
E. Coli
E. coli,
Staphylococcus saprophyticus
Pseudomonas aeruginosa
Other gram negtive bacilli
Klebsiella pneumoniae
Klebsiella pneumoniae
Candidaspp. (critically ill and chronically
catheterized patient).
• The majority of UTIs are caused by a single organism;
however, in patients with stones, indwelling urinary
catheters, or chronic renal abscesses, multiple organisms may
be isolated.
Predisposing Factors
 Age
 Female gender
 Diabetes mellitus
 Pregnancy
 Immunosuppression
 Urinary tract instruments
 Urinary tract obstruction
 Renal disease; renal transplantation
 Neurological dysfunction
Clinical presentation
 Symptoms alone are unreliable for the diagnosis of bacterial
 The key to the diagnosis of a UTI is the ability to
demonstrate significant numbers of microorganisms present
in an appropriate urine specimen to distinguish
contamination from infection.
 Elderly patients frequently do not experience specific
urinary symptoms, but they will present with altered mental
status, change in eating habits, or GI symptoms.
Signs and symptoms
 Lower UTI: Dysuria, urgency, frequency, nocturia,
suprapubic heaviness Gross hematuria
 Upper UTI: Flank pain, fever, nausea, vomiting, malaise
Physical examination
 Upper UTI: Costovertebral tenderness
Laboratory tests
 Bacteriuria
 Pyuria (white blood cell count >10/mm)
 Nitrite-positive urine (with nitrite reducers (E. coli).)
 Leukocyte esterase-positive urine (pyuria).
 Antibody-coated bacteria (upper UTI)
Laboratory tests
 A standard urinalysis should be obtained in the initial assessment
of a patient.
 Microscopic examination of the urine should be performed by
preparation of a Gram stain of unspun or centrifuged urine.
 The most reliable method of diagnosing UTIs is by quantitative
urine culture.
 The goals of treatment for UTIs are to prevent or treat
systemic consequences of infection, eradicate the invading
organism, and prevent recurrence of infection.
 The management of a patient with a UTI includes
 initial evaluation
 selection of an antibacterial agent and
 duration of therapy,
 and follow-up evaluation.
 The initial selection of an antimicrobial agent for the treatment of
UTI is primarily based:
 on the severity of the presenting signs and symptoms,
 the site of infection, and
 whether the infection is determined to be complicated or
 The ability to eradicate bacteria from the urinary tract is
directly related to the sensitivity of the organism and the
achievable concentration of the antimicrobial agent in the
 The therapeutic management of UTIs is best accomplished by
first categorizing the type of infection: acute uncomplicated
cystitis, symptomatic abacteriuria, asymptomatic bacteriuria,
complicated UTIs, recurrent infections, or prostatitis.
Acute Uncomplicated Cystitis
 These infections are predominantly caused by E. coli, and
antimicrobial therapy should be directed against this
organism initially.
 Other causes include S. saprophyticus and occasionally K.
pneumoniae and Proteus mirabilis.
Acute Uncomplicated Cystitis
 Short-course therapy (3-day therapy) with trimethoprim–
sulfamethoxazole or a fluoroquinolone (e.g., ciprofloxacin,
levofloxacin, or norfloxacin) is superior to single-dose
therapy for uncomplicated infection and should be the
treatment of choice.
 Amoxicillin or sulfonamides are not recommended because
of the high incidence of resistant E. coli.
 Follow-up urine cultures are not necessary in patients who
 If sulfa allergy nitrofuranton 100 mg PO bid x 5 days
Symptomatic Abacteriuria
 Single-dose or short-course therapy with trimethoprim–
sulfamethoxazole has been used effectively, and prolonged courses
of therapy are not necessary for the majority of patients.
 If single-dose or short-course therapy is ineffective, a culture
should be obtained.
 If the patient reports recent sexual activity, therapy for Chlamydia
trachomatis should be considered
 azithromycin 1 g as a single dose
 doxycycline 100 mg twice daily for 7 days.
Asymptomatic Bacteriuria
 The management of asymptomatic bacteriuria depends on the age
of the patient and, if female, whether she is pregnant.
 In children, treatment should consist of conventional courses of
therapy, as described for symptomatic infections.
 In the nonpregnant female, therapy is controversial; however, it
appears that treatment has little effect on the natural course of
 Most clinicians feel that asymptomatic bacteriuria in the elderly is
a benign disease and may not warrant treatment.
 The presence of bacteriuria can be confirmed by culture if
treatment is considered.
Uncomplicated Pyelonephritis
 FQ for 2 weeks managed in outpatient setting
 Trimethoprim-sulfamethoxazole
Complicated Urinary Tract Infections
Acute Pyelonephritis
 The presentation of high-grade fever (greater than 38.3°C
[100.9°F]) and severe flank pain should be treated as acute
pyelonephritis, and aggressive management is warranted.
 Severely ill patients with pyelonephritis should be hospitalized and
IV drugs administered initially.
 The duration for treatment is 14 days
 At the time of presentation, a Gram stain of the urine should be
performed, along with urinalysis, culture, and sensitivities.
Complicated Urinary Tract Infections
Acute Pyelonephritis
Gram stain reveals grampositive cocci,
Streptococcus faecalis
• ampicillin.
• Amoxicillin or Amoxicillincalvulanic acid 14 days
• IV FQ, an aminoglycoside with or
without ampicillin,
In the seriously ill patient • or an extended-spectrum cephalosporin
with or without an aminoglycoside.
• 14 days
If the patient has been
hospitalized in the last 6
months, has a urinary
catheter, or is in a
nursing home,
• P. aeruginosa and enterococci infection, as
well as multiply-resistant organisms, should
be considered.
• ceftazidime, ticarcillin-clavulanic acid,
piperacillin, aztreonam, meropenem, or
imipenem, in combination with an
aminoglycoside, is recommended.
Complicated Urinary Tract Infections
Acute Pyelonephritis
If the patient responds to initial combination therapy, the
aminoglycoside may be discontinued after 3 days.
Follow-up urine cultures should be obtained 2 weeks after the
completion of therapy to ensure a satisfactory response and
to detect possible relapse.
Urinary Tract Infections in Males
 The conventional view is that therapy in males requires prolonged
 A urine culture should be obtained before treatment, because the
cause of infection in men is not as predictable as in women.
 If gram-negative bacteria are presumed,
 trimethoprim–sulfamethoxazole
 or a fluoroquinolone is a preferred agent.
 Initial therapy is for 10 to 14days.
 For recurrent infections in males, cure rates are much higher with
a 6-week regimen of trimethoprim–sulfamethoxazole.
Recurrent Infections
Recurrent episodes of UTI (reinfections and relapses) account
for a significant portion of all UTIs.
 Assess for pharmacologic reason for treatment failure.
 Treat longer 2-6 weeks
 If relapse occurs after 6 weeks of treatment, urologic
examination should be performed, and therapy for 6 months
or even longer may be considered.
2 or less UTI in a
3 or more UTI in a year
Related to sexual
3 or more UTI in a year
Not related to sexual
3 day treatment
prophylaxis with
cephalexin 250 mg
Nitrofurantoin 50100mg
Daily or 3 times a wk
Nitrofurantoin 50100mg
Norfloxacin 200 mg
cephalexin 250 mg
6 months
Urinary Tract Infection in Pregnancy
 In patients with significant bacteriuria, symptomatic or
asymptomatic, treatment is recommended in order to avoid
possible complications during the pregnancy.
 Therapy should consist of an agent with a relatively low
adverse-effect potential (a sulfonamide, cephalexin,
amoxicillin, amoxicillin/clavulanate, nitrofurantoin)
administered for 7 days.
Antibiotics to avoid in Pregnancy
 Tetracyclines should be avoided because of teratogenic effects
 sulfonamides should not be administered during the third
trimester because of the possible development of kernicterus
and hyperbilirubinemia.
 fluoroquinolones should not be given because of their
potential to inhibit cartilage and bone development in the
Catheterized Patients
 When bacteriuria occurs in the asymptomatic, short-term catheterized
patient (less than 30 days), the use of systemic antibiotic therapy should
be withheld and the catheter removed as soon as possible.
 If the patient becomes symptomatic, the catheter should again be
removed, and treatment as described for complicated infections should
be started.
 The use of prophylactic systemic antibiotics in patients with short-term
catheterization reduces the incidence of infection over the first 4 to 7
 In long-term catheterized patients, however, antibiotics only postpone
the development of bacteriuria and lead to emergence of resistant
 P. aeruginosa, Proteus spp.,K. pneumoniae, E. coli.
Trimethoprim–sulfamethoxazole × 4–6 weeks
Quinolone× 4–6 weeks
 Acute prostatitis may require IV therapy initially
 The conversion to an oral antibiotic can be considere dafter the patient is
afebrile for 48 hours or after 3 to 5 days of intravenous therapy.
 The total course of antibiotic therapy should be 4-6weeks
 Chronic prostatitis may require longer treatment periods (6 to 12 weeks) or
Management of UTIs in females.
Management of UTIs in males.

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