Systematics – members of the family Spirochaetaceae: Which genera listed below are classified within the family Spirochaetaceae and share the characteristic flexible, helical, motile morphology?

Introduction / Context:
Spirochaetes are slender, helically coiled bacteria exhibiting unique motility by periplasmic endoflagella (axial filaments). Recognizing genera within Spirochaetaceae supports clinical reasoning for diseases such as syphilis and Lyme borreliosis.

Given Data / Assumptions:

• Family Spirochaetaceae includes several medically and environmentally relevant genera.
• Treponema (e.g., T. pallidum), Borrelia (e.g., B. burgdorferi), and Spirochaeta are prototypical members.
• Question tests taxonomic awareness at the genus level.

Concept / Approach:
All three listed genera display the spirochaete body plan and axial filament-driven motility, placing them within Spirochaetaceae. Their clinical relevance spans sexually transmitted infections (Treponema), vector-borne diseases (Borrelia), and environmental niches (Spirochaeta).

Step-by-Step Solution:
Identify each genus as a known spirochaete. Confirm they belong to Spirochaetaceae in classical microbiology classification. Select the inclusive answer “All of these.” Recall hallmark motility: periplasmic flagella.

Verification / Alternative check:
Microscopy of spirochaetes shows characteristic corkscrew motion; clinical testing often uses dark-field or serology due to culture difficulty.

Why Other Options Are Wrong:
Single selections omit other true members; “none” contradicts well-established taxonomy.

Common Pitfalls:
Confusing Spirochaetaceae with morphologically similar but taxonomically separate curved or helical bacteria (e.g., Campylobacter, Helicobacter).

Final Answer:
All of these.