UTI-Pathogens

Question 1

UTI-General Clinical info

Answer 1

• UTI = significant bateruria of greater than 10⁵
• Urethritis-Infection & inflammation of urethral mucosa
  
  • _{^{<em><strong>Symptoms:</strong></em> Discharge & pain (dysuria) during urination}}
• Cystitis-Infection/inflammation of bladder _{^{(no discharge)}}
  
  • _{^{<em><strong>Symptoms:</strong></em> urgency increased frequency, dysuria}}
  • _{^{Small vol, smelly<strong> (ammonia)</strong>, Pyuria, Suprapubic tenderness w/low back discomfort}}
• Prostaitis-Infection/Inflammation of prostate _{^{(Cystitis like)}}
  
  • _{^{<em><strong>Symptoms</strong></em>: FEVER, perirectal/low back pain, painful ejaculation}}
• Pyelonephritis- kidney & renal parenchyma _^(pelvis)
  
  • _{^{Follws UTI <strong><u>(ascending-chronic)</u></strong>, Fever, flank pain, WBC casts}}
• Tamm-Horsfall mucoprotein=WBC casts

Question 2

UTI-Risk Factors

Answer 2

• Gender-Common in young women
  
  • _{^{Men have additional defense from <strong>Zinc (prostate</strong>)}}
• Sex-Increases chance & w/use of diaphragm or sperimicide
• Pregers-_{^{dilatation and decreased peristalsis of the ureters=<u>Poor bladder emptying</u>}}
• Age:
• females estrogen reduction _{^{(change in normal flora & thining of membrane)}}
• males 5th decade of life-Prostate hypertrophy
• Blood group P1 Ag-Expressed on urothelium
  
  • _{^{(E.coli frequently binds)}}
• AB blood group-MORE resistant _{^{(Bind to e.coli prevent infection)}}
• Catheters-More frequent put in Higher the risk

Question 3

Etiologic Agents of UTI

Answer 3

• E-coli 90%
• Staphylococcus Sapro 10-20%
  
  • _{^{Common among sexually active women}}
• Klebsiella, Proteus spp, Enterococcus fecalis 5%
• Complicated UTI: Anatomic obstructions or from catheterizations
  
  • _{^{E. Coli, Klebsiella, Proteus spp, Enterococcus sp}}
• Misc: Candida albicans (diabetics)
• Hemorrhagic cysitis-Children _{^{(Adenovirus 11/21-DNA Naked)}}

Question 4

UTI Diagnosis

Answer 4

• Specimen: Mid-stream catch (risk of contamination)
• Direct microscopic exam-_{^{Oil immersion field w/centrifuged urine}}
• Greater than 1 bacterium per oil = **Greater 10⁵ **
• After 3-4 oils find 1 bacterium = Less 10⁴
• Chemical tests (dipsticks):
• Leukocyte esterase released from inflammatory cells
• Nitrate made by bacterial metab _{^{(NO3 to NO2)}}
  
  • _{^{Nitrate conv=E.Coli <u>(best taken in morning-4 hours for conversion)</u>}}
• Cant detect bacteruria below 10⁵
• Culture methods-Quantitative _{^{(calibrated loop)}} & semi
• Plate & dip culture - isolation & ID of causative agent

Question 5

E. Coli (Uropahtogenic)

Answer 5

• Gram (-) lactose fermenter-Oxidase (-)
  
  • _{^{Produces indole from trytophan}}
  • _{^{Decarboxylates Lysine}}
  • _{^{Use of acetate as SOLE carbon source}}
  • _{^{Motile <strong>(virulence factor)</strong>}}
• Transmission: fecal contamination of urethra _^(catheter)
• Virulence factors _{^{<strong>(can stay dorment bladder</strong>)}}:
• Pili/Fimbrae-
• Type 1 (FimH) binds to mannose residue of glycoprotein on Facet urothelial cells (Acute cystitis)
• PAP binds to dimers of galactose (GAL-GAL) on P1 ag of epi cell of UT (Pyelonephritis)-_{^{Mannose resistant}}
• Diagnose: MacConkey agar _{^{(lactose fermenter-Indole from tryptophan)}}

Question 6

Staphylococcus Saprophyticus

Answer 6

• Gram (+) cocci-Catalase (+)
• Coag (-) non-hemolytic/non-mannitol fermenter
• Novobiocin resistant _{^(cathomycin)}
  
  • _{^{S. aureus & S. epidermis novobiocin sensitive}}
• Transmission-Inoculation from skin _{^{(sexually acitive women)}}
• Disease: Acute urethral syndrome, Cystitis & RARE cases of pyelonephritis
• _ Diagnose:_ Catalase test (+) w/Novobiocin culture

Question 7

Enterococcus faecalis/faecium

Answer 7

• Group D Ag-Gram (+)-chains/pairs & PYR +
• Catalase (-) & bacitracin/optochin resistant
• Grow in 6.5% NaCl & 40% bile _{^{(hydrolyzes it)}}
• Found in urethra, female GT _{^{(endogenous/exogenous)}}
• High risk: Hospital (catheter), broad spectrum antibios (vancomycin)
• Disease: Cystitis & pyelonephritis
• _{^{<strong>Misc</strong>-Soft tissue infections <em><strong>after colon surgery/trauma </strong></em>(bacteremia & endocarditis)}}
• Diagnose: Bile Esculin agar (black=hydrolize)
  
  • _{^{PYR + =Detection ofenzyme <strong>pyrolidonyl arylamidase</strong>}}
• Treat: Dual w/aminoglycosides & cell wall antibios
  
  • _{^{Resistance to vancomycin growing}}

Question 8

Kelbsiella pneumoniae (enterobacteria)

Answer 8

• Gram (-) Rods, Lactose fermenter, NON-motile
• High mucoid colonies due to **LARGE capsule **
• Inoculation from feces or URT normal flora
• High risk: Hosital pts (catheter)
• Disease: Cystitis & pyelonephritis
• Diagnose: Clinical presentation (history)
• Treat: Multidrug resistant & vancomycin resistant
• Grows on MacConkey agar

Question 9

Proteus Species (UTI)

Answer 9

• HIGHLY motile swarming colonies - ^{enterobacteriacae}
• P. Mirabilis _{^{<strong><u>(sensitive to penicillin)</u></strong>}}
• P. Vulgaris _{^{<u><strong>(HIGHLY resistant to antibios)</strong></u>}}
• Gram (-) rod, non-lactose fermenter, Urease (+)
• Normal flora of colon found in Nosocomial (hospital)
• Disease: Cystits & pyelonephritis
• Nephrolithiases-Large Stag horn ^{_{(kidney stones)}}
  
  • _{^{Prevention w/prompt treatment of cystitis or recurrent infections}}
• Virulence factors:
• Urease-Urea to NH3 + CO2 increase pH precipitation of Mg phos = Struvite stones - Obstruct urine flow
  
  • _{^{Bacteria hide inside stones<strong> (escape antibiotics)</strong>}}
  • _{^{Makes urine alkaline=favorable for other bacteria to grow}}
  • _{^{High pH or smell indicative of proteus}}
• LPS-Inflammation & tissue damage
• Culture: _{^{Swarming colonies, Urease (+)-coffin crystals, Lactose fermenter}}

Question 10

BK Virus (BKV)

Answer 10

• Papovaviridae-Polyomavirus _{^{(related to JC virus)}}
• Naked ds DNA - latent infection in kidney & lymph
• Disease found in immunocompromised-_{^{<strong><u>Spread though resp</u></strong>}}
• High risk: Renal & BM transplant, pregers, old age
• Pathogenesis: replicated in URT->spread in blood
• Seeds in renal tissue & lymph-_{^{remains latent in lymph}}
• Disease: BK-assoc nephro (BKAN)
• Hemorrhagic cysitis
  
  • Ureteral stenosis ^{<strong>_{(pain on urination)}</strong>}
• Tubulo nephritis-Inflammation of spaces between tubules-Lead to renal failure

Question 11

BK Virus (BKV)-Clinical

Answer 11

• Diagnose: Detection appear 3+ months after transplant
• Urine sample-infected epi cells exfoliate _{^{(decoy cells)}} appear w/intranuclear inclusion bodies
• Renal biopsy-cytopathic changes not specific
  
  • _{^{Confirmation w/stains or PCR}}
• Treatment: Decrease immunosupression therapy
  
  • Cidofovir (nucleotide analog)