bacte additional emerut

• Basic Principles of Specimen Collection

  • Maintain viability of organisms with minimal contamination
  • Collect specimen in acute phase of infection before antibiotics
  • Select correct anatomic site
  • Collect specimen using proper technique and supplies with minimal contamination
  • Collect appropriate quantity of specimen
  • Package specimen in container or transport medium to maintain viability and avoid hazards
  • Label specimen accurately with anatomic site, patient info, date and time
  • Transport specimen to lab promptly or store in environment that won't degrade organism(s)
  • Notify lab if unusual pathogens or bioterrorism agents suspected
• Transport media


  Substances that do not promote multiplication of microorganisms but ensure their preservation, available in swab collection systems
• Transport media


  • Stuart or Amie transport medium
  • Transport systems with charcoal to absorb fatty acids
  • JEMBEC system for N. gonorrhoeae
  • Direct inoculation of nasopharyngeal swabs for B. pertussis
• Specimen Priority Levels


  • Critical/Invasive (e.g. amniotic fluid, blood, CSF)
  • Unpreserved (e.g. body fluids, drainage, feces, sputum, tissue)
  • Quantitation Required (e.g. catheter tip, urine, tissue)
  • Preserved (e.g. feces, urine, swabs)
• Types of Culture Media

  • Nonselective (support growth of most nonfastidious microbes)
  • Selective (support growth of one type/group, suppress others)
  • Differential (allow grouping based on characteristics)
  • Enriched (contain growth enhancers for fastidious organisms)
  • Enrichment broth (liquid medium to encourage growth of particular organism)
• Isolation Techniques


  1. General purpose isolation streak

  2. Flaming loop between plates to prevent carryover

  3. Quantitative inoculation for urine specimens
• Incubation conditions


  • Temperature (35-37°C), environmental atmosphere (aerobic, anaerobic, capnophilic, microaerophilic)
  • Most bacteria 48-72 hours, anaerobes/broths 5-7 days, unusual organisms may require special conditions
• Isolation of Unusual or Fastidious Bacteria