What are the characteristics of Rickettsia?

CHARACTERISTICS: Rickettsia rickettsii is an obligate intracellular alpha proteobacteria that belongs to the Rickettsiacae family(1,2,3). It is a small (0.2-0.5 m by 0.2-0.3 m) pleomorphic, gram-negative coccobacillus which multiplies by binary fission and has both DNA and RNA(1,2,3).

Is Rickettsia a Cocci?

Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 m in diameter), bacilli (14 m long), or threads (up to about 10 m long).

Is Rickettsia a gram-negative rod?

Rickettsia species are small, Gram-negative bacilli that are obligate intracellular parasites of eukaryotic cells.

How are Rickettsia classified?

Rickettsial Classification Rickettsia and Orientia are obligate-intracellular, Gram-negative bacteria primarily associated with arthropods. Historically, Rickettsia were classified into three major groups based on serological characteristics, namely the ‘typhus group’, ‘spotted fever group’ and ‘scrub typhus group’.

Is rickettsia aerobic or anaerobic?

In general, rickettsiae are small, aerobic, coccobacillary a-proteobacteria with a number of unusual features, exemplified by their strict intracellular lifestyle within host cell cytoplasm, fastidious growth requirements, association with arthropods with the ability to be maintained in nature via transovarial and …

How does Rickettsia Rickettsii get energy?

As obligate intracellular parasites, Rickettsial species can only replicate in host cells because they cannot produce their own ATP and must derive this energy source from the host cells which they infect.

Where is Rickettsia Rickettsii found?

Although it was first identified in the Rocky Mountains, Rocky Mountain spotted fever is most commonly found in the southeastern part of the United States. It also occurs in parts of Canada, Mexico, Central America and South America.

What kingdom is Rickettsia Rickettsii in?

The genus Rickettsia encompasses a large group of obligate intracellular, Gram-negative bacteria that fall under the family Rickettsiaceae, order Rickettsiales, class Alphaproteobacteria, phylum Proteobacteria.

Does Rickettsia Rickettsii have a capsule?

This group includes Rickettsia prowazekii, which causes a disease called epidemic typhus, and Rickettsia typhi, which causes murine typhus, also called endemic typhus. Now, Rickettsiae are small bacteria, measuring only 0.7 to 2 micrometers in diameter. They have a plasma membrane that’s surrounded by a microcapsule.

Is rickettsia a protozoa?

The rickettsia are bacteria which are obligate intracellular parasites. They are considered a separate group of bacteria because they have the common feature of being spread by arthropod vectors (lice, fleas, mites and ticks).

Is rickettsia a bacteria or parasite?

Rickettsiae are bacterial obligate intracellular parasites ranging from harmless endosymbionts to the etiologic agents of some of the most devastating diseases known to mankind.

What is the difference between rickettsia and Chlamydia?

Chlamydia is considered to be completely dependent on its host for supply of ATP and other energy-rich molecules, whereas Rickettsia utilizes cytosolic ATP only during an early phase of the infectious cycle [28].

How many species of Rickettsia are there?

Rickettsia species are gram negative, strictly intracellular bacilli, which multiply within the cytosol of endothelial cells. Spotted fever group rickettsiosis now includes 26 validated species, of which 17 are recognized human pathogens Table 1) (43). R.

What is endemic typhus?

Endemic typhus fever is a disease caused by bacteria called Rickettsia typhi or Rickettsia felis. The disease is also known as murine typhus. Who gets endemic typhus fever? Endemic typhus fever occurs worldwide, most commonly in areas where rats and people live in close contact.

Is Rickettsia Rickettsii aerobic?

Rickettsia rickettsii is a small coccobacillus bacterium. They are aerobe and stain Gram negative. Their genomes number about 1 to 1.5 million bases. They are obligate intracellular parasites of eukaryotic cells, living in their hosts’ cytoplasm or nucleus.

What is the shape of Rickettsia typhi?

(bacterium) Curved, straight or bean-shaped: bacilli come in many variants and are widely spread. Rickettsia typhi is a Gram-negative, aerobic, rod-shaped bacterium.

Does Rickettsia Rickettsii require oxygen?

Rickettsia: A member of a group of microorganisms that (like viruses) require other living cells for growth but (like bacteria) use oxygen, have metabolic enzymes and cell walls, and are susceptible to antibiotics.

How does a Rickettsia Rickettsii move?

rickettsii organisms move through the cell cytoplasm at an average rate of 4.8 0.6 m/min (mean standard deviation). This speed was 2.5 times slower than that of L. monocytogenes, which moved at an average rate of 12.0 3.1 m/min.

Which is the vector of Rickettsia Rickettsii?

Although many genera and species of ixodid ticks are naturally infected with rickettsiae, Dermacentor andersoni and D.variabilis are the major vectors of R. rickettsii.

How is Rickettsia Rickettsii transmitted?

Most rickettsial organisms are transmitted by the bites or infectious fluids (such as feces) inoculated into the skins from ectoparasites such as fleas, lice, mites, and ticks. Inhaling bacteria or inoculating conjunctiva with infectious material may also result in infection.

What disease does lone star tick carry?

ehrlichiosis The lone star tick is a very aggressive tick capable of spreading disease to humans. The nymph and adult females most frequently bite humans and transmit disease. These ticks are able to transmit Ehrlichia chaffeensis and Ehrlichia ewingii (both cause human ehrlichiosis), tularemia, and STARI.

Where are Rocky Mountain ticks?

Rocky Mountain wood ticks are found in Rocky Mountain states and Southwestern Canada from elevations of 4,000 to 10,500 feet. These ticks are able to transmit Rocky Mountain spotted fever, Colorado tick fever, and tularemia.

Is commonly called tick fever?

Rocky Mountain spotted fever (RMSF) is a bacterial disease spread by ticks. It typically begins with a fever and headache, which is followed a few days later with the development of a rash. …

Rocky Mountain spotted fever
Causes Rickettsia rickettsii spread ticks
Diagnostic method Based on symptoms

Does Rickettsia Rickettsii form spores?

rickettsii is an obligate intracellular parasite that survive by an endosymbiotic relationship with other cells. R. rickettsii is a non-motile, non-spore forming aerobic organism. Cells are typically 0.30.5 0.82.0 m in size.

Is Rickettsia Rickettsia pathogenic or nonpathogenic?

Interestingly, Rickettsia species with small genomes, such as Rickettsia prowazekii, are more pathogenic to humans than those with larger genomes. This review also examines the growth kinetics of pathogenic and non-pathogenic species of SFG rickettsiae (SFGR) in mammalian cells.

How do you get ehrlichiosis?

These bacteria are spread to people primarily through the bite of infected ticks including the lone star tick (Amblyomma americanum) and the blacklegged tick (Ixodes scapularis). People with ehrlichiosis will often have fever, chills, headache, muscle aches, and sometimes upset stomach.

How are Rickettsia similar to viruses?

Rickettsiae are microorganisms that share features of both bacteria and viruses. They can be destroyed by antibiotics like bacteria, but can only live and multiply inside living host cells like viruses.

What does Ehrlichia chaffeensis cause?

If HME is left untreated, life-threatening symptoms, such as kidney failure and respiratory insufficiency, may develop in some cases. Human Monocytic Ehrlichiosis is caused by the bacteria Ehrlichia chaffeensis (or E. chaffeensis).