URINARY TRACT
INFECTION
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There are 4 possible modes of bacterial entry into the
genitourinary tract:
1- Periurethral bacteria ascending
2- Hematogenous spread ( immunocompromised
patients and in neonates). Staphylococcus aureus,
Candida species, and Mycobacterium tuberculosis are common
pathogens that travel through the blood to infect the
urinary tract.
3- Lymphatogenous spread ( little scientific support )
4- Direct extension of bacteria from adjacent organs
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CAUSATIVE PATHOGENS:
At least 80% of the uncomplicated cystitis and pyelonephritis are due
to E. coli, with most of pathogenic strains belonging to the O serogroups.
In hospitalacquired UTIs, a wider variety of causative organisms is
found, including Pseudomonas and Staphylococcus spp.
UTIs caused by S.aureus often result from hematogenous dissemination.
Group B beta-hemolytic streptococci can cause UTIs in pregnant
women.
S. saprophyticus, once often thought of as urinary contaminants, can
cause uncomplicated UTIs in young women.
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DIAGNOSIS:
urinalysis and urine culture
voided specimen (Most often).
In children who are not toilettrained, a urine collection device (such as a bag)
These 2 methods of urine collection are
easy to obtain, but potential contamination from the
vagina and perirectal area may occur.
Suprapubic aspiration ( rarely used
except in children and selected patients).
Urinary catheter (urine specimen should be obtained from the collection port on
the catheter).
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Urinalysis:
More than 3 WBCs per high-power field suggests a possible
infection.
When bacteria counts are >100,000 CFU/mL, bacteria can be
detected
Microscopically.
Leukocyte esterase: breakdown of white blood cells (WBCs)
Urinary nitrite: reduction of dietary nitrates by many gram
negative bacteria
Esterase and nitrite can be detected by a urine dipstick and are
more reliable when the bacterial count is >100,000 colony-
forming units (CFU) per milliliter.
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Urine Culture:
The gold standard for identification of UTI is the quantitative
culture of urine for specific bacteria.
Traditionally, >100,000 CFU/mL is used to exclude
contamination.
However, studies have clearly demonstrated that clinically
significant UTI can occur with <100,000 CFU/mL bacteria in the
urine.
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KIDNEY INFECTION
Acute Pyelonephritis
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PRESENTATION AND FINDINGS:
chills, fever, and costovertebral angle tenderness.
lower-tract symptoms such as dysuria, frequency, and
urgency.
Sepsis may occur, with 20–30% of all systemic sepsis
resulting from a urine infection.
Leukocytosis,
increased erythrocyte sedimentation,
and elevated levels of C-reactive protein
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MANAGEMENT:
Parenteral therapy should be maintained until the
patient defervesces.
If bacteremia is present, parenteral therapy should be
continued for an additional 7–10 days and then the
patient should be switched to oral treatment for 10–14
days.
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Emphysematous Pyelonephritis:
Emphysematous pyelonephritis is a necrotizing infection
characterized by the presence of gas within the renal
parenchyma or perinephric tissue.
About 80–90% of patients with emphysematous
pyelonephritis have diabetes; the rest of the cases are
associated with urinary tract obstruction from calculi or
papillary necrosis.
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PRESENTATION AND FINDINGS:
Patients with emphysematous pyelonephritis present with
fever, flank pain, and vomiting
that fails initial management with parenteral antibiotics.
Bacteria most frequently cultured
from the urine include E. coli, Klebsiella
pneumoniae, and Enterobacter cloacae.
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RADIOGRAPHIC IMAGING
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