What is the morphology of Rickettsia?
Rickettsia is a genus of nonmotile, gram-negative, nonspore-forming, highly pleomorphic bacteria that may occur in the forms of cocci (0.1 μm in diameter), bacilli (1–4 μm long), or threads (up to about 10 μm long).
What are the characteristics of Rickettsia?
The rickettsiae are rod-shaped or variably spherical, nonfilterable bacteria, and most species are gram-negative. They are natural parasites of certain arthropods (notably lice, fleas, mites, and ticks) and can cause serious diseases—usually characterized by acute, self-limiting fevers—in humans and other animals.
What is the morphology of Treponema pallidum which causes syphilis?
Treponema pallidum is a spirochaete bacterium with various subspecies that cause the diseases syphilis, bejel, and yaws. It is transmitted only amongst humans. It is a helically coiled microorganism usually 6–15 μm long and 0.1–0.2 μm wide.
What are the characteristics of Treponema pallidum?
Treponema pallidum is a Gram-negative micro-aerophilic bacterium, 6–20 μm long, 0.1–0.2 μm wide and tightly coiled. The treponemes are motile by three flagella (axial filaments) that wrap around the surface of the organism and are covered by the outer membrane which contains lipopolysaccharide.
What is rickettsia in microbiology?
The rickettsiae are a diverse collection of obligately intracellular Gram-negative bacteria found in ticks, lice, fleas, mites, chiggers, and mammals. They include the genera Rickettsiae, Ehrlichia, Orientia, and Coxiella. These zoonotic pathogens cause infections that disseminate in the blood to many organs.
Does rickettsia have cell wall?
The structure of the typical rickettsia is very similar to that of Gram-negative bacteria. The typical envelope consists of three major layers: an innermost cytoplasmic membrane, a thin electron dense rigid cell wall and an outer layer.
What is the morphology of syphilis?
The particular spirochete responsible for syphilis is Treponema pallidum. T pallidum is a fragile spiral bacterium 6-15 micrometers long by 0.25 micrometers in diameter.
Why is pallidum hard to culture?
Unlike most bacteria, the organism that causes syphilis, Treponema pallidum, cannot be cultured in the laboratory. Due to this limitation, research on T. pallidum and syphilis has not benefited from new molecular approaches that have become available in recent years.
What kingdom is Treponema pallidum?
Treponema pallidum
| Kingdom: | Eubacteria |
|---|---|
| Phylum: | Spirochaetes |
| Class: | Spirochaetes |
| Order: | Spirochaetales |
| Family: | Treponemataceae |
What causes rickettsia?
Rickettsiae and rickettsia-like bacteria are usually spread to people through the bites of ticks, mites, fleas, or lice that previously fed on an infected animal. Ticks, mites, fleas, and lice are called vectors because they spread (transmit) organisms that cause disease from one host to another.
What kingdom does rickettsia belong to?
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.
Can Rickettsia be cultured?
It can be cultured outside of eukaryotic cells and is transmitted to humans via lice.
How big is a Treponema pallidum corkscrew shaped organism?
Morphology of Treponema pallidum Treponemes are thin, delicate, helically coiled, corkscrew-shaped organisms. They are microaerophilic and actively motile. They are measures about 10 to 14 micrometers long and 0.1 to 0.2 micrometer wide.
Is the Treponema pallidum a Gram negative bacteria?
Treponema pallidum can be considered a gram-negative bacterium although its cell envelope differs from other gram-negative bacteria. T. pallidum causes syphilis, a sexually transmitted disease that affects the skin and mucous membrane of the external genitalia, and also sometimes the mouth.
What is the virulence factor of Treponema pallidum?
T. pallidum’s virulence factor is still unknown. Untreated syphilis progresses in a series of distinct stages (primary, secondary, latent, and tertiary.) “Infection is initiated when T. pallidum penetrates dermal microabrasions or intact mucous membranes” resulting in primary syphilis.
How many stages of Treponema pallidum are there?
Summary of Treponema pallidum (Syphilis) Treponema pallidum (Syphilis) Syphilis is a sexually-transmitted disease caused by the bacterium Treponema pallidum. There are 3 stages. Primary Syphilis is characterized by localized disease with a painless chancre in the genital region.