Gram positive

•  No Gram positive aerobes

Gram negative

•  No Gram negative aerobes

Anaerobic
Most including:

•  Bacteroides fragilis

•  Clostridia including C. difficile
  Excluding:

•  Propionibacterium acnes

Other

•  H. pylori

•  Anaerobic protazoa - Entamoeba

•  Giardia

•  Trichomonas