Rickettsiaceae Flashcards
Small (0.5 – 2 um) non-motile, pleomorphic bacilli, have a g(-) cell wall
RICKETTSIACEAE
It is the simplest
bacterial form and
considered transitional
organism between
bacteria and viruses
RICKETTSIACEAE
This group of organisms
infect wild animals, with
humans acting as
accidental hosts
RICKETTSIACEAE
all species require living cells for growth except for
Bartonella quintana
small organism, pleomorphic, gram-negative bacilli and multiplies by binary fission in the
cytoplasm of host cells (the release of mature rickettsiae results in the lysis of the host cell)
Rickettsia
survives only briefly outside of a host and multiply only intracellularly in the cytosol of the host
cell
Rickettsia
Rickettsia :
Lysis of cell wall
Rickettsia prowazekii
Rickettsia:
Filopodium focal lysis
Ricketssia rickettsii
Rickettsia:
Budding
Rickettsia tsutsugamushi
contributes to its intracellular activity.
Phospholipase A2
can be passed from generation to generation of ticks through their eggs (transovarian
passage)
Rickettsia ricketsii
Ricketssia Groups of Bacteria
Spotted fever group
Typhus Group
Scrub typhus group
They grow in the cytoplasm of host cell and released via ―pinching‖ off‖ a host cell membranebound rickettsia
Orientia tsutsugamushi
- It was placed into a separate genus due to the absence of LPS and peptidoglycan, and the
presence of 54 – 58 kDa major surface proteins
It is transovarially maintained in mites (Leptotrombidium
Orientia tsutsugamushi
Humans and rats are accidental, nonessential dead-end hosts
Orientia tsutsugamushi
Small (0.5 um, gram negative coccobacilli and undergo intracellular development cycle following
infection of circulating WBC
Ehrlichia
nfection of circulating WBC
- They undergo 3 developmental stages similar to Chlamydiae: EB, initial bodies and morulae
Ehrlichia