rickettsia and orientia

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Rickettsia Rickettsia and and Orientia Orientia Rickettsia Rickettsia ( ( Rickettsia Rickettsia and and Orientia Orientia ) ) Ehrlichia Ehrlichia ( ( Ehrlichia Ehrlichia and and Anaplasma Anaplasma ) ) small (0.3 × 1 to 2 μm) small (0.3 × 1 to 2 μm) stained poorly with the Gram stain stained poorly with the Gram stain grew only in the cytoplasm of grew only in the cytoplasm of eukaryotic cells eukaryotic cells

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Rickettsia and Orientia. Rickettsia ( Rickettsia and Orientia ) Ehrlichia ( Ehrlichia and Anaplasma ) small (0.3 × 1 to 2 μm) stained poorly with the Gram stain grew only in the cytoplasm of eukaryotic cells. Rickettsia and Orientia. structurally similar to gram-negative rods - PowerPoint PPT Presentation

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Page 1: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• RickettsiaRickettsia ( (RickettsiaRickettsia and and OrientiaOrientia))•EhrlichiaEhrlichia ( (EhrlichiaEhrlichia and and AnaplasmaAnaplasma))•small (0.3 × 1 to 2 μm) small (0.3 × 1 to 2 μm) •stained poorly with the Gram stain stained poorly with the Gram stain •grew only in the cytoplasm ofgrew only in the cytoplasm of

eukaryotic cells eukaryotic cells

Page 2: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• structurally similar to gram-negative rods

• contain DNA, ribonucleic acid (RNA), and enzymes and ribosomes

• multiply by binary fission• inhibited by antibiotics

Page 3: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• maintained in animal and arthropod reservoirs

• transmitted by arthropod vectors (e.g., ticks, mites, lice, fleas)

• humans are accidental hosts• spotted fever group and the typhus

group

Page 4: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• Organism Human Disease Distribution Spotted Fever Group R. Rickettsii Rocky Mountain spo.f. Western hem R. Africae African tick bite f. Eastern-Sou Africa R. Akari RickettsialpoxWorldwid R. Australis Australian tick typhus Australia

R. Conorii Mediterranean spo. f. Mediterranean R.japonica Japanese spotted f. Japan R. Sibirica Siberian tick typhus Siberia, Mongolia, Typhus group R. Prowazekii Epidemic Worldwide R.typhi EndemicWorldwide Scrub typhus group O.tsutsugamishi Scrub typhus Asia, Ocenia

Page 5: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

Page 6: Rickettsia  and  Orientia

Bite of brown dog tick-Bite of brown dog tick-Rhipicephalus sanguineusRhipicephalus sanguineus

Page 7: Rickettsia  and  Orientia
Page 8: Rickettsia  and  Orientia
Page 9: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• peptidoglycan layer is minimal

• LPS has only weak endotoxin activity

• binary fission is slow

Page 10: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia• No toxins• No host immune response• R. rickettsii is most common rickettsial

pathogen in United States • Hard ticks are the primary reservoirs and

vectors (Dermacentor)• Transmission requires prolonged contact

(24 to 48 hours) • Distribution in Western hemisphere• Disease is most common April through

October

Page 11: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• 2-14 days• Painless tick bite• High fever, headache, fever, chills• Rash macular to petechial• First extremities and then trunk• GIS symptoms, respiratory failure• Encephalitis, renal failure

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Page 13: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• Tissue culture and embrynonated eggs

• Microscopy• Serology• PCR

Page 14: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• Tetracycline• Fluroquinolones

Page 15: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• Epidemic typhus• Louse-borne typhus• Humans are the primary reservoir• Replicates in endothelial cells with

resulting vasculitis

Page 16: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia• Humans are the primary reservoir, with person-

to-person transmission by louse vector • It is believed that sporadic disease is spread from

squirrels to humans via squirrel fleas • Recrudescent disease can develop years after

initial infection • People at greatest risk are those living in

crowded, unsanitary conditions • Disease is worldwide, with most infections in

Central and South America and Africa • Sporadic disease is seen in the eastern United

States

Page 17: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• 2- to 30-day incubation period • nonspecific symptoms • less than 40% of the patients had a

petechial or macular rash • myocarditis and central nervous

system dysfunction • Brill-Zinsser disease-milder

Page 18: Rickettsia  and  Orientia

RickettsiaRickettsia and and OrientiaOrientia

• MIF test is the diagnostic method of choice

• Tetracyclines and chloramphenicol • Formaldehyde-inactivated typhus

vaccine

Page 19: Rickettsia  and  Orientia

Rickettsia typhiRickettsia typhi• Endemic or murine typhus • worldwide • Rodents are the primary reservoir, • Rat flea (Xenopsylla cheopis) is the

principal vector • 7 to 14 days • A rash develops • Typically restricted to the chest and

abdomen • Indirect fluorescent assay

Page 20: Rickettsia  and  Orientia

Orientia tsutsugamushiOrientia tsutsugamushi • Scrub typhus• Mites• Asia, Oceania• 6-18 days• Sudden onset• Maculo-papular rash• LAP, SM• Tetracycline, chloramphenicol

Page 21: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella

• Anaplasmataceae: Anaplasma, Ehrlichia, Neorickettsia, and Wolbachia

• survival within a cytoplasmic vacuole in the infected arthropod or mammalian cell

• infection of hematopoietic cells

Page 22: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella

Multiple morulae of Ehrlichia canis in DH82 tissue culture cells

Page 23: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella

• Small, intracellular bacteria • Stain poorly with Gram stainReplicates in

phagosome of infected cells • Intracellular growth protects bacteria from

immune clearance • Able to prevent fusion of phagosome with

lysosome of monocytes or granulocytes • Initiates inflammatory response that

contributes to pathology

Page 24: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella• Depending on the species of Ehrlichia, important

reservoirs are white-tailed deer, white-footed mouse, etc

• Ticks are important vectors, but transovarian transmission in inefficient

• Disease in United States is most common in the Atlantic states; northern, central, and southern Midwest states; and northern California

• People at greatest risk are those exposed to ticks in the endemic areas

• Disease is most common from April to October

Page 25: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella• Human monocytic ehrlichiosis is caused by E.

chaffeensis • 1 to 3 weeks after a tick bite, patients develop a

flulike illness with fever, headache, and myalgias • Gastrointestinal symptoms develop in fewer than

half the infected patients • late-onset rash develops in 30% to 40% of

patients • Leukopenia, thrombocytopenia, and elevated

serum transaminases

Page 26: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella

• Canine Granulocytic Ehrlichiosis E. ewingii • Human anaplasmosis, A. phagocytophilum • More than half the infected patients require

hospitalization, and severe complications are common

• Mortality is rare

Page 27: Rickettsia  and  Orientia

Ehrlichia, AnaplasmaEhrlichia, Anaplasma, and , and CoxiellaCoxiella• Giemsa-stained preparations of peripheral blood

should be performed, morulae diagnostic • PCR• Tetracycline, rifampin pregnant women• Vaccines are not available

Page 28: Rickettsia  and  Orientia

Coxiella burnetiiCoxiella burnetii• more closely related to Legionella and

Francisella • Q fever, which may be asymptomatic in

humans and develops either acutely or as a chronic infection

• small, pleomorphic coccobacillus (0.2 to 0.7 μm)

• The small replicating cells will mature to large-cell variants, which then evolve to stable spores

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Coxiella burnetiiCoxiella burnetii

• inhalation of airborne particles • more by the environment• Coxiella proliferate in the respiratory

tract and then disseminate to other organs

• pneumonia and granulomatous hepatitis

• most chronic infections manifest as endocarditis

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Coxiella burnetiiCoxiella burnetii• antigenic variation • C. burnetii is extremely stable in harsh

environmental conditions • Many reservoirs, including mammals, birds, and

ticks • Most human infections associated with contact

with infected cattle, sheep, goats, dogs, and cats • Most disease acquired through inhalation;

possible disease from consumption of contaminated milk; ticks are not an important vector for human disease

• Worldwide distribution• No seasonal incidence

Page 31: Rickettsia  and  Orientia

Coxiella burnetiiCoxiella burnetii

• Acute diseases include influenza-like syndrome, atypical pneumonia, hepatitis, pericarditis, myocarditis, meningoencephalitis

• Chronic diseases include endocarditis, hepatitis, pulmonary disease, and infection of pregnant women

Page 32: Rickettsia  and  Orientia

Coxiella burnetiiCoxiella burnetii• most common presentation of chronic Q fever

is subacute endocarditis • culture (not commonly performed),

polymerase chain reaction (PCR), or by specific serologic tests

• serology is the most commonly used diagnostic test

• Tetracycline• combination of drugs, such as rifampin

and either doxycycline or trimethoprim-sulfamethoxazole