Electron microscopy studies of human intestinal spirochetes

Area of Science:

• Microbiology
• Cell Biology
• Bacteriology

Background:

• Human intestinal spirochetes are a group of bacteria residing in the gastrointestinal tract.
• Understanding their ultrastructure is crucial for differentiating them from other related pathogens and commensals.

Purpose of the Study:

• To analyze the ultrastructure of human intestinal spirochetes using electron microscopy.
• To compare their morphology with other pathogenic and non-pathogenic spirochetes.

Main Methods:

• Electron microscopy was used to examine the ultrastructure of twenty human intestinal spirochete isolates.
• Cells were negatively stained for visualization.
• Treatment with sodium deoxycolate was employed to assess the presence of cytoplasmic microtubules.

Main Results:

• Human intestinal spirochetes displayed loosely waved cell bodies with dimensions of 0.18-0.35 µm in width and 3.9-14.2 µm in length.
• Twin flagellar bundles were observed between the cytoplasmic and outer membranes, with most isolates having five flagella per cell end.
• These spirochetes divide by binary fission and lack cytoplasmic microtubules after sodium deoxycolate treatment, unlike Treponema pallidum and Treponema phagedenis.

Conclusions:

• Human intestinal spirochetes possess distinct ultrastructural characteristics, particularly in their flagellar arrangement and absence of cytoplasmic microtubules.
• Morphologically, they are similar to swine intestinal treponemes but differ significantly from Treponema pallidum and Borrelia burgdorferi.
• These ultrastructural differences aid in the classification and identification of human intestinal spirochetes.