lab 10

• Urine cultures


  Presence of bacteria in voided urine
• Bacteriuria: the presence of bacteria in voided urine
• Ways in which urinary tract infections (UTI) may be acquired

  • Cystitis
  • Pyelonephritis
  • Urethritis

  
• The most frequent causative agent of UTI

  E.Coli
• How is Urine sample obtained

  Usually obtained by catheterization or by voided collection
• Collection of Clean-voided midstream urine sample


  Proper storage
• How is urinalysisperformed

  • Performed on urine sample
  • Rapid dipstick test
• Urine cultures


  • Blood agar, MacConkey agar
  • Presence of pathogenic bacterial species
  • Number of colonies
• Qualitative and quantitative analysis of a simulated urine sample

  1. 10 uL = 10 microliter

  2. 1mL = 1000 uL

  3. 1 uL = 1 microliter
• Significant bacteriuria


  > 100,000 organisms/ml
• Insignificant bacteriuria


  < 10,000 organisms/ml
• Symptoms of cystitis + low counts of the causative agent → acute urethral syndrome
• Neisseria species


  • All Neisseria are Gram-negative diplococci, oxidase-positive
  • Some species are normal flora of the upper respiratory tract, and some are pathogens
• General procedures for laboratory diagnosis of gonorrhea

  1. Smear and cultures

  2. Nucleic acid probe tests and gene amplification assays using urogenital specimen

  
• Diagnosis of N. meningitidis infection

  1. Recovering the organism in cultures of spinal fluid or blood

  2. Following proper identification methods
• All specimens to be cultured for pathogenic Neisseria should be brought promptly and directly to the microbiologist, CO2 and 35oC temperature are necessary

  
• Thayer-Martin agar (aka: VCN agar)


  • Selective for growth of Neisseria species
  • Contains the antimicrobial agents, vancomycin, colistin and nystatin (V-C-N inhibitor) to suppress the normal flora

  
• Gram stain of a urethral exudate


  • Showing typical intracellular Gram-negative diplococci, and pleomorphic extracellular Gram-negative organisms, which is diagnostic for gonococcal urethritis
• What are the physical and chemical properties that can indicate infection

  • Turbidity, pH, WBC, RBC, protein, nitrate, etc.