Microbiology lab

  1. Overview
    • urine is normally sterile
    • it becomes contaminated when urine is voided by the normal flora of the urethra, fecal or vaginal flora; therefore bacteria in the urine does not necessarily mean there is a UTI
  2. UTI infections
    3 ways: hematogenous, ascending route, and catheters, cytoscopes
  3. hematogenous route
    • this is a rare route of UTI infection
    • microorganisms are in the blood stream from another site of infection and are deposited in the kidneys
  4. ascending route
    • this is the most common route
    • microorganisms ascend from the urethra from urogenital area and cause cystitis, or continue ascending up the uereters and causes pyelonephritis
  5. catheters, cytoscopes route
    • this routes happens when microorganisms are deposited into the bladder via catheters or cytoscopes
    • this is a common nosocomial infection
  6. UTI includes...
    • Cystitis
    • Pyelonephritis
  7. Cystits
    • bladder infection is the most commone UTI
    • sx: frequency in urination or dysuria (painful urination)
  8. Pyelonephritis
    • it is kidney infection
    • sx: midback pain and pus in the urine
  9. What are the 2 ways of collecting speciman?
    • Catherized specimen
    • Voided speciman
  10. catheterized speciman
    • this is the best specimen since urine does not pass through the urethra -- very sterile
    • difficult to collect
    • there is a risk of introducing infection due to poor or unsterile technicques
  11. voided speciman
    • patients void midstream urine aka clean catch midstream specimen (CCMS)
    • first stream is to cut down normal flora pathogen
    • patient instruction is important as there is risk of contaminating urine with urethral, vaginal or fecal flora
  12. True UTI diagnostics
    • to determine true UTI and not contamination, a colony count is performed
    • both the number and colonies and the different types of species will tells us if there is a true infection
    • infections normally contain greater than 100,000 organisms/mL of urine
  13. Colony Count
    • > 100,000 organisms/mL is a true UTI
    • between 10,000 - 100,000 organisms/mL is in the gray area - Dr will decide
    • < 10,000 organisms/mL is usually contaminated
  14. Urine sample on a BAP agar
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Card Set
Microbiology lab
UTI pathogens