Rickettsia conori - MegaMicro

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Rickettsia conori

Microbiology > Bacteriology > Intracellular bacteria > Rickettsia
1.       Structure:
a.       R. Conorii have a gram-negative cell wall and are coccobacilli.
2.       Pathobiology:
b.      Rickettsia Conorii (R. Conorii) is an intracellular small gram-negative proteobacteria that produces Boutonneuse fever (aka Mediterranean Spotted Fever).  They are obligate intracellular pathogens that depend on the entry, growth, and replication within the cytoplasm of a host cell. One inside a non-phagocytic host cell the bacteria adhere to its vacuole and can begin to divide and polymerize the host actin filaments to be linked intra and intercellularly. R. Conorii internalization involves surface proteins with unidentified host cell receptors. The R. Conorii invade and proliferate in the endothelial cells of small vessels and can cause endothelial injury and tissue necrosis.
3.       Epidemiology:
a.       R. Conorii is found in Mediterranean countries (Africa and Europe), India, and the Middle East. It is tick-transmitted by the brown dog tick, Rhipicephalus sanguineus.
4.       Laboratory Diagnosis:
a.       Diagnosis can be made via serologic methods, the Weil-Felix test, ELISA, or immunofluorescence assays in the biopsy material of the primary lesion.
5.       Disease Manifestations:
a.       R. Conorii can spread via the lymphatic vessels to the lymph nodes and by bloodstream to other tissues like the lungs, spleen, and liver. The tick bite causes a characteristic rash and distinct black spot at the site of the bite (tache noire). The major clinical features of Boutonneuse fever is fever, rash, and the tache noire. The incubation period is around seven days before symptoms of the disease manifest, chills, high fevers, muscular and articular pains, severe headache, and photophobia.
6.       Treatment:
a.       Doxycycline
b.      Also chloramphenicol, macrolides, fluoroquinolones                
Related concepts
Boutonneuse fever
Meditteranean Fever
brown dog tick
tache noir
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