Trichomonas Hominis: Morphology and Characteristics

Trichomonas hominis

• Cosmopolitan distribution, non-pathogenic, and associated with diarrheic stools
• Most commonly found flagellate next to Giardia lamblia and Dientamoeba fragilis
• Flagellates move rapidly in a jerky, non-directional manner
• Axostyle and undulating membrane are diagnostic
• No cyst stage, only trophozoites

Morphology of Trichomonas hominis

• Size: 7-20 um long, 5-18 um wide
• Shape: Pear-shaped
• Motility: Nervous, jerky
• Nucleus: One, with a small central karyosome, no peripheral chromatin
• Flagella: 3-5 anterior, 1 posterior extending from the posterior end of the undulating membrane
• Axostyle extends beyond the posterior end of the body
• Full body length undulating membrane
• Conical cytostome cleft in anterior region ventrally located opposite the undulating membrane

Enteromonas hominis

• Distributed worldwide in warm and temperate climates
• Ingestion of cysts appears to be the primary cause
• Considered as non-pathogenic
• E.hominis cysts overlap with Endolimax nana cysts, binucleated cysts indicate probable E.hominis
• Infection occurs after ingestion of cysts in fecally contaminated food or water, or on fomites

Morphology of Enteromonas hominis

• Cyst characteristics:
  • Size: 3-10 um long, 4-7 um wide
  • Shape: Oval, elongated
  • Nucleus: 1-4, binucleated and quadrinucleated nuclei located at opposite ends, central karyosome, no peripheral chromatin
• Trophozoite characteristics:
  • Size: 3-10 um long, 3-7 um wide
  • Shape: Oval, sometimes half-circle
  • Motility: Jerky
  • Nucleus: One, with central karyosome, no peripheral chromatin
  • Flagella: 4; 3 directed anteriorly, 1 directed posteriorly
  • Axostyle that extends beyond the posterior end of the body

Trichomonas tenax

• Anaerobic flagellated protozoan found in the oral cavities of humans and animals
• Associated with periodontal disease
• Most prevalent inflammatory disease affecting oral cavities
• Evidence suggests that it can cause damage to mammalian cells and secrete virulent proteins, such as cysteine
• Trophozoites survive in the body as mouth scavengers that feed primarily on local microorganisms

Morphology of Trichomonas tenax

• Size: 3-10 um long, 4-7 um wide
• Shape: Oval, elongated
• Nucleus: 1-4, binucleated and quadrinucleated nuclei located at opposite ends, central karyosome, no peripheral chromatin
• No other structures

Retortamonas intestinalis

• Rarely reported in clinical stool samples
• Distributed worldwide in warm and temperate climates
• Ingestion of cysts appears to be the primary cause
• Common in crowded places with poor sanitation practices
• Considered as non-pathogenic

Morphology of Retortamonas intestinalis

• Cyst characteristics:
  • Size: 3-9 um long, up to 5 um wide
  • Shape: Lemon-shaped, pear-shaped
  • Nucleus: 1, located in anterior-central region with central karyosome, may be surrounded by a delicate ring of chromatin granules
  • 2 fused fibrils resembling a bird’s beak in the anterior nuclear region, only visible in stained preparations
• Trophozoite characteristics:
  • Size: 3-7 um long, 5-6 um wide
  • Shape: Ovoid
  • Motility: Jerky
  • Nucleus: One, with small central karyosome, ring of chromatin granules on nuclear membrane
  • Flagella: 2, anterior
  • Cytostome extending halfway down body length with well-defined fibril border opposite the nucleus in the anterior end

Pentatrichomonas hominis

• Common in some animals, like rats and cats
• Considered as non-pathogenic
• Transmissible through contaminated water, also sometimes a potential cause of childhood dysentery

Morphology of Pentatrichomonas hominis

• Size: 8-20 μm long, 3-14 μm wide
• Flagella: 5 anterior flagella plus 1 posterior flagellum
• No cyst stage, only trophozoites