8. Laboratory Findings

Laboratory Findings :

Conjunctival Swab

• Coag(-) staph ® skin contaminant
• Routine culture sent for mycobacterial work-up
• AFB smear done
  • POSITIVE

Routine Mycobacterial Cultures

• Acid fast stain of smear
• Inoculate Middlebrook 7H11 media
  • Split plate with antibiotics (PACT) on one side
• Inoculate Lowenstein-Jensen slant
  • Egg based media
  • Malachite green added for bacterial inhibition
• Inoculate Bactec bottle

Bactec System

• Radiometric, automated system to detect growth of mycobacteria
  • C14 labeled palmitic acid
  • PANTA added
  • Growth index recorded based on radioactive CO2 production
• Growth index (>300)
  • Can use DNA probes for rRNA
  • Mycobacterium tuberculosis
  • Mycobacterium gordonae
  • Mycobacterium avium complex
  • Mycobacterium kansasii

Breakpoint #4

• What are some of the parameters used to classify the different mycobacteria?