Difference Between Chlamydia and Rickettsia

The key difference between Chlamydia and Rickettsia is their mode of transmission. Chlamydia transmits from person to person while Rickettsia transmits by arthropod vectors. Another main difference between Chlamydia and Rickettsia is that Chlamydia cannot produce ATP while Rickettsia can produce some ATP since they have a cytochrome system.

Chlamydia and Rickettsia are two bacterial genera of Kingdom Monera. These bacteria are gram-negative and are obligate intracellular parasites. They are only able to survive inside the host cell or organism. They are medically important since they cause different diseases to animals and humans.

CONTENTS

1. Overview and Key Difference
2. What is Chlamydia 
3. What is Rickettsia
4. Similarities Between Myasthenia Chlamydia and Rickettsia
5. Side by Side Comparison – Chlamydia and Rickettsia in Tabular Form
6. Summary

What is Chlamydia?

Chlamydia is a group of gram-negative bacteria which are obligate intracellular parasites of higher animals (mammals and birds). They are unable to produce ATP. Hence, they totally depend on host ATP. They have both DNA and RNA, unlike viruses. They are also able to produce proteins. However, since they are bacteria, they are susceptible to antibiotics.

Figure 01: Chlamydia spp.

Chlamydia trachomatis, C. pneumonia, and Chlamydophila psittaci are three species which cause serious illnesses. Conjunctivitis, cervicitis, and pneumonia are three of its common infections. The transmission of this bacteria occurs human to human.

What is Rickettsia?

Rickettsia is a genus of grams negative bacteria, which are also obligate intracellular parasites. This causes spotted fevers (Rocky mountain spotted fever) and epidemic typhus in humans. These bacteria transmit to humans via arthropod vectors.

Figure 02: Rickettsia

Rocky mountain spotted fever is a severe illness caused by Rickettsia, where ticks transmit the bacteria to humans and rodents. This genus has cytochrome systems. Hence they are capable of producing some ATP. But those ATPs are not enough for their survival; hence, they steal ATP from the host via ATP/ADP translocators. Furthermore, this genus multiplies by binary fission.

What are the Similarities Between Chlamydia and Rickettsia?

• Chlamydia and Rickettsia are grams negative bacteria.
• Both these bacteria are pathogenic microorganisms.
• Both are obligatory intracellular parasites/pathogens.
• These two bacteria have small, pleomorphic coccobacillary forms.
• Both are susceptible to various antibiotics.
• The cell wall of both bacteria resembles gram-negative cell wall.
• Chlamydia and Rickettsia posses DNA and RNA.
• Both groups are not able to grow in culture media that are not alive.
• They can be grown in tissue/cell culture and embryonic egg york.
• Both groups have the body size of large viruses.

What is the Difference Between Chlamydia and Rickettsia?

Summary – Chlamydia vs Rickettsia

Chlamydia and Rickettsia are two groups of gram-negative bacteria. Both bacterial types are obligate intracellular parasites. They are very small bacteria having the size of large viruses. Since both types cause diseases to humans, they serve as medically important bacteria. Transmission of Chlamydia occurs from person to person. Rickettsia transmits via arthropod vectors. This is the difference between Chlamydia and Rickettsia. In addition, both parasites steal energy in the form of ATP from the host via ATP/ADP translocators.

Reference:

1. “Introduction to Chlamydia and Rickettsia.” Introduction to Chlamydia and Rickettsia – Microbiology – Medbullets Step 1, Available here.
2. “Ch 12 Chlamydia, Rickettsia Etc.” Ch 12 Chlamydia, Rickettsia Etc Flashcards – Cram.com, 1 July 2009, Available here.

Image Courtesy:

1. “Chlamydia trachomatis Bacteria and the PmpD Protein (6829956633) By NIAID – Chlamydia trachomatis Bacteria and the PmpD Protein (CC BY 2.0) via Commons Wikimedia
2. “Rickettsia rickettsii” By CDC – Rocky Mountain Spotted Fever info page from the CDC (Public Domain) via Commons Wikimedia

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