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 ( immunocompromisedpatients and in neonates). Staphylococcus aureus,Candida species, and Mycobacterium tuberculosis are commonpathogens that travel through the blood to infect theurinary 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 isfound, 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, cancause 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 areeasy to obtain, but potential contamination from thevagina and perirectal area may occur.

Suprapubic aspiration ( rarely usedexcept 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 detectedMicroscopically.

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 quantitativeculture 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 infectioncharacterized 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 withfever, flank pain, and vomiting that fails initial management with parenteral antibiotics.

Bacteria most frequently culturedfrom the urine include E. coli, Klebsiella pneumoniae, and Enterobacter cloacae.

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RADIOGRAPHIC IMAGING

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