What are the two main groups of obligate intracellular parasitic bacteria mentioned in the chapter, and why can they not live independently?
The two main groups of obligate intracellular parasitic bacteria mentioned are rickettsias and chlamydias. They cannot live independently because they require host cells for growth and metabolism, as they cannot survive or multiply outside a host cell and cannot carry out metabolism completely on their own.
Rickettsias are very tiny, gram-negative bacteria that are pathogens alternating between a mammalian host and blood-sucking arthropods. They cannot survive or multiply outside a host cell and are closely attached to their hosts because they cannot carry out metabolism completely on their own. Chlamydias, on the other hand, are similar in their obligate intracellular parasitic nature, requiring host cells for growth and metabolism. However, they are not transmitted by arthropods and were once considered a type of virus due to their tiny size and parasitic lifestyle.
Key points
- Rickettsias and chlamydias are obligate intracellular parasitic bacteria.
- Rickettsias are gram-negative and require a host cell for survival and metabolism.
- Chlamydias also require host cells but are not transmitted by arthropods.
- Both groups cannot live independently outside host cells.
Talaro's Foundations in Microbiology
Kathleen Park Talaro
EIGHTH EDITION · McGraw-Hill, a business unit of The McGraw-Hill Companies, Inc.