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44 Cards in this Set
- Front
- Back
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Epidemiology of UTIs:
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*Most common bacterial infection
*Women are more likely to experience UTI than men *Almost half of all women will experience a UTI during their lifetime *Estimated annual cost: $1.6 billion |
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Pathogenesis of UTI:
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What determines which are uropathogenic bacteria?
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*Virulence factors
-Enable attachment to urinary tract by overcoming host defenses -Scavenge limiting nutrients (iron) from the host -Perturb host cells and tissues --> symptomatic UTI -E. coli – most common |
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Virulence factors for bacteria in UTI:
adhesins: |
*Adherence to uroepithelium
*Facilitate colonization and subsequent bacterial-host interactions *Resist flushing by urine flow and bladder emptying *Most adhesins are fimbrial *Type 1 fimbriae (common pili)- Bind to mannose receptors *P fimbriae- Bind to galactose receptors |
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Virulence factors for bacteria in UTI:
siderophores: |
*Iron is a limiting micronutrient for host-invading bacteria
*Consequently, bacteria have developed mechanisms that help them extract iron from the host with the help of siderophore-receptor systems. |
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Virulence factors for bacteria in UTI:
toxins: |
*Cause abnormalities in host cell function and morphology, or cellular lysis
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Virulence factors for bacteria in UTI:
Evading host defenses: |
*Polysaccharide capsules
-Interfere with phagocytosis -Protect against complement-mediated opsonization or lysis *LPS (lipopolysaccharide) -->Inflammatory cascade, Cytokines, Neutrophil influx, Pain and edema, Fever, leukocytosis |
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Summary photo of e. coli UTI pathogenesis:
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don't need to memorize
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Summary photo 2 of e. coli UTI pathogenesis:
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don't need to memorize
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Discuss Proteus miravilis:
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-Common cause of UTI in elderly women. It's a GNR.
-Has urease-->urea-->NH3-->kidney stones |
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top: struvite stones
bottom: carbonate apatite stones *from Proteus mirabilis |
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Urinary tract host defense mechanisms:
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Risk factors for UTIs:
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What's an uncomplicated UTI?
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*UTI in an otherwise healthy, nonpregnant female.
*Always "complicated" in men. |
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Examples of complicated UTIs:
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-Diabetes
-Pregnancy -Previous acute pyelonephritis within previous year -Symptoms > 7 days prior to treatment -Multi-drug resistant uropathogen -Hospital-acquired infection -Renal failure -Urinary tract obstruction -Functional or anatomic urinary tract abnormality -Indwelling urinary catheter, stent, nephrostomy tube -History of UTI in childhood -Renal transplant -Immunosuppression |
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Risk factors for UTI in kids:
diagnosis: treatment: |
*VUR is a risk factor for recurrent pyelonephritis and possible renal scarring. This can result in increased risk of hypertension and chronic kidney disease
*Diagnosis: voiding cystourethrogram. *VUR treatment: antibiotic prophylaxis and/or surgery. |
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Severity grades of vesicoureteral reflux (VUR):
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Special UTI considerations in pregnancy:
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*Physiologic changes
-Increased renal size and glomerular filtration rate -Dilatation of ureters and renal pelvis R > L -Urinary stasis --> Risk of pyelonephritis -Flaccid bladder -Intermittent vesicoureteral reflux |
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Asymptomatic bacteriuria in pregnancy:
screening: diagnosis: |
*2 – 7% of pregnancies
-40% risk of progressing to pyelonephritis -increased risk of preterm birth, low birth weight, and perinatal mortality -Must treat *Screening -at 12-16 weeks gestation *Diagnosis -2 voided specimens with ≥105 cfu/mL of same bacterial strain (in practice treatment is usually started after the first positive specimen, without waiting for second culture) -1 catheterized specimen with 102 cfu/mL |
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Treatment of Asymptomatic bacteriuria in pregnancy:
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*According to antibiotic susceptibility testing
*Antibiotics safe to use: Nitrofurantoin (Macrobid), Amoxicillin, Amoxicillin-clavulanate, Cephalexin Fosfomycin *Obtain follow-up cultures to document clearance *DO NOT USE in pregnancy: *Macrobid with G-6PD deficiency (hemolytic anemia) *Sulfonamides (Bactrim) last trimester (newborn hyperbilirubinemia) *Trimethoprim (Bactrim) first trimester (folic acid antagonist --> birth defects) *Fluoroquinolones (Ciprofloxacin, Levofloxacin) = chondrotoxicity |
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Most common pathogens in acute cystitis:
symptoms: |
*Most common pathogens
-E coli -Other Enterobacteriaceae (Proteus, Klebsiella) -Staphylococcus saprophyticus *Symptoms -Dysuria -Frequency -Urgency -Suprapubic pain -Hematuria |
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Diagnosis of acute cystitis:
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Dipstick urine analysis; look for:
*Leukocyte esterase -Released by leukocytes -Reflects pyuria *Nitrite -Reflects presence of Enterobacteriaceae, which convert urinary nitrate to nitrite -Does not rule out presence of gram-positive bacteria |
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*Pyuria = ≥ 10 WBC/microL
*Examine an unspun (no centrifuge) voided midstream specimen. *Absence of pyuria strongly suggests another diagnosis besides UTI |
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Treatment for acute cystitis:
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*First line therapies for acute cystitis
-Nitrofurantoin (Macrobid) -Trimethoprim-sulfamethoxazole (Bactrim) -Fosfomycin (NOT to be used if pyelonephritis possible (they do not achieve good renal levels)) *Alternatives -Fluoroquinolones |
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Clinical manifestations of acute pyelonephritis:
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Symptoms of acute cystitis PLUS:
*FEVER, chills *Flank pain *Costovertebral angle tenderness *Nausea or vomiting *Sepsis and organ failure (rare) |
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*Acute pyelonephritis
*Numerous PMNs are seen filling renal tubules across the center and right of this picture. These leukocytes may form into a cast within the tubule. Casts appearing in the urine originate in the distal renal tubules and collecting ducts. |
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*WBC cast – diagnostic of upper UTI (pyelonephritis)
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*Acute pyelonephritis. CT scan obtained with intravenous contrast material reveals patchy enhancement of the left kidney. The kidney is minimally enlarged with perinephric stranding, secondary findings that also suggest infection.
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*Renal abscess: Fluid-filled collection in the left kidney, with septations and thick walls seen on a contrast-enhanced CT scan
*complication of pyelonephritis *can't be treated with meds alone |
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*Perinephric abscess on a CT scan - appears as a soft-tissue mass with a thick wall that may enhance after introduction of intravenous contrast material.
*complication of pyelonephritis *can't be treated with meds alone |
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*Emphysematous pyelonephritis
*Presence of gas in the urinary tract tissue *Associated with diabetes and urinary tract obstruction *Severe cases may require percutaneous drainage or surgical debridement |
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*Urine sediment showing multiple "coffin lid" magnesium ammonium phosphate crystals that form only in an alkaline urine (pH usually above 7.0) caused by an upper urinary tract infection with a urease producing bacteria. Struvite STONES.
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*"Staghorn calculus". Seen here is a horn-like stone extending into a dilated calyx, with nearly unrecognizable overlying renal cortex from severe hydronephrosis and pyelonephritis.
*Nephrectomy may be performed because the kidney is non-functional and serves only as a source for infection. *Extreme struvite stones due to UTI. |
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Treatment of uncomplicated and complicated pyelonephritis:
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*Uncomplicated pyelonephritis
-Outpatient -Fluoroquinolones *Complicated or severe pyelonephritis -Hospitalize -IV Ceftriaxone or aminoglycosides -If risk of antibiotic-resistant infection, may need broad-spectrum beta-lactam antibiotics -Tailor antibiotic therapy to susceptibility results of urine and/or blood cultures -Urology consultation to address underlying urinary obstruction or neurogenic bladder |
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Describe nosocomial UTIs:
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*Number one cause of hospital acquired infections.
*Due almost exclusively to indwelling urethral (Foley) catheters *Inevitably infected if use prolonged *Now considered “non-reimbursable” by Medicare. |
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Prevention and treatment of nosocomial UTIs:
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How to obtain a correct specimen for urine analysis:
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*Put a new catheter in
*Old cath will have bacteria in it for sure. *Don't take specimen from the bag. |
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Discuss biofilms on catheters:
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*Can't kill bugs on a device
*Have to replace the device! |
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Catheter awareness?
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*Providers were unaware of the catheter 28% of the time
*Unawareness rates: 21% students, 22% interns, 27% residents, *38% attendings *Providers were more likely to be unaware of the catheter when there was no appropriate indication for use. |
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-Define recurrent UTI:
-Risk factors in young women -Risk factors in post-menopausal -Management? |
≥ 2 infections in 6 months, or ≥ 3 infections per year
*In young women -Risk factors: sexual intercourse, spermicide use, and greater propensity to colonization with uropathogens (genetic) *In post-menopausal women -Risk factors: decreased bladder emptying (urinary incontinence, presence of cystocele, increased post-voidal residual urine) *Antimicrobial prophylaxis highly effective -Continuous, post-coital, or intermittent self-treatment -Bactrim or fluoroquinolone |
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Chronic bacterial prostatitis:
-when do you suspect it? |
*Repeated UTIs with isolation of the same organism from the urine
*Some men may be asymptomatic with only persistent bacteriuria *Diagnosis ideally should reflect the same organism recovered from urine and prostatic secretions (“the four glass test”; historic only) *Treatment: fluoroquinolones for at least 6 weeks if the organism is susceptible; TMP-SMX as alternative |
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What is Sterile Pyuria?
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*When sexually active patients present with dysuria and pyuria, but no growth on urine cultures.
Suspect/Exclude: *Vaginitis *Chlamydia infections *Herpes simplex infections |
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How do you diagnose a UTI?
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-Have to have SYMPTOMS first.
-Then, urine analysis to confirm infection. |
