Rickettsia
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Transcript of Rickettsia
RICKETTSIARICKETTSIA
ELIZABETH P. QUILES, M.D.,FPASMPELIZABETH P. QUILES, M.D.,FPASMP
DEPARTMENT OF MICROBIOLOGYDEPARTMENT OF MICROBIOLOGY
OUR LADY OF FATIMA UNIVERSITYOUR LADY OF FATIMA UNIVERSITY
COLLEGE OF MEDICINECOLLEGE OF MEDICINE
RICKETTSIARICKETTSIACHARACTERISTICS:CHARACTERISTICS:
• Structurally similar to gram (-) bacilliStructurally similar to gram (-) bacilli
- DNA & RNA- DNA & RNA
- enzymes for Kreb’s cycle- enzymes for Kreb’s cycle
- ribosomes for protein synthesis- ribosomes for protein synthesis
- inhibited by antibiotics - inhibited by antibiotics Tetracycline & ChloramphenicolTetracycline & Chloramphenicol
• Originally thought to be viruses Originally thought to be viruses because:because:
- small size- small size
- stain poorly with gram stain- stain poorly with gram stain
- grows only in cytoplasm of - grows only in cytoplasm of Eukaryotic cellsEukaryotic cells
- obligate intracellular parasites - obligate intracellular parasites EXCEPT CoxiellaEXCEPT Coxiella
• Reservoirs – animals & arthropodsReservoirs – animals & arthropods• Humans are accidental hostsHumans are accidental hosts• Cell wall:Cell wall:
- peptidoglycan- peptidoglycan - LPS – have weak endotoxic - LPS – have weak endotoxic activity (absent in Ehrlichia) activity (absent in Ehrlichia)
• Genera: Genera: RickettsiaRickettsia RochalimaeaRochalimaeaCoxiellaCoxiella EhrlichiaEhrlichiaOrientiaOrientia
• Stains weakly with gram stain Stains weakly with gram stain Giemsa Giemsa or Gimenez stainor Gimenez stain
• Easily destroyed by heat, drying & Easily destroyed by heat, drying & bactericidal agents EXCEPT Q bactericidal agents EXCEPT Q fever fever due to the formation of due to the formation of endospore-like structure by C. endospore-like structure by C. burnettiburnetti
• Intracellular location:Intracellular location:
typhus group – cytoplasmtyphus group – cytoplasm
spotted fever group – nucleusspotted fever group – nucleus
Rochalimaea – surface of Rochalimaea – surface of Eukaryotic cellsEukaryotic cells
Coxiella & Ehrlichia – Coxiella & Ehrlichia – cytoplasmic cytoplasmic vacuolesvacuoles
PATHOLOGYPATHOLOGYMultiply in endothelial cells of small blood vesselsMultiply in endothelial cells of small blood vessels
VasculitisVasculitis
(skin – rashes;other organs – DIC & vascular (skin – rashes;other organs – DIC & vascular occlusion)occlusion)
Swollen & necroticSwollen & necrotic
Thrombosis of the vesselsThrombosis of the vessels
VECTORS:VECTORS:
RMSF – Dermacentor andersoniRMSF – Dermacentor andersoni
Rickettsialpox – Allodermanyssus Rickettsialpox – Allodermanyssus sanguinussanguinus
Scrub typhus – trombiculid mitesScrub typhus – trombiculid mites
Epidemic typhus – Pediculus Epidemic typhus – Pediculus humanushumanus
Ehrlichiosis – Amblyomma Ehrlichiosis – Amblyomma americanus (lone star tick)americanus (lone star tick)
Trench fever – Pediculus humanusTrench fever – Pediculus humanus
Murine typhus – Xenopsylla cheopis &Murine typhus – Xenopsylla cheopis &
Ctenophalides felisCtenophalides felis
RICKETTSIAL INFECTIONSRICKETTSIAL INFECTIONS
• Fever, headache, malaise, prostration, skin Fever, headache, malaise, prostration, skin rash & hepatosplenomegalyrash & hepatosplenomegaly
• Classified into groups:Classified into groups:1. Typhus Group – Epidemic typhus, 1. Typhus Group – Epidemic typhus, Murine Murine typhus, Scrub typhustyphus, Scrub typhus2. Spotted Fever Group – RMSF, 2. Spotted Fever Group – RMSF, RickettsialpoxRickettsialpox3. Q Fever3. Q Fever4. Trench fever4. Trench fever5. Ehrlichiosis5. Ehrlichiosis
TYPHUS GROUPTYPHUS GROUP
• Maculopapular rashes with the Maculopapular rashes with the sparing of the palms & solessparing of the palms & soles
EPIDEMIC TYPHUS EPIDEMIC TYPHUS (LOUSEBORNE TYPHUS)(LOUSEBORNE TYPHUS)
• Etiology: R. prowazekiiEtiology: R. prowazekii
• severe systemic infection & severe systemic infection & prostration prostration
• more fatalmore fatal
• Brill-Zinsser Disease Brill-Zinsser Disease recrudescent diseaserecrudescent disease
ENDEMIC TYPHUS ENDEMIC TYPHUS (MURINE TYPHUS)(MURINE TYPHUS)
• Etiology: R. typhiEtiology: R. typhi
• similar features with Epidemic similar features with Epidemic typhus but milder & rarely fatal typhus but milder & rarely fatal except in the elderlyexcept in the elderly
SCRUB TYPHUSSCRUB TYPHUS
Etiology: Orientia tsutsugamushiEtiology: Orientia tsutsugamushi
• resembles Epidemic typhus except resembles Epidemic typhus except for the ESCHAR for the ESCHAR
• generalized lymphadenopathy & generalized lymphadenopathy & lymphocytosislymphocytosis
• cardiac & cerebral involvement may cardiac & cerebral involvement may be severebe severe
SPOTTED FEVER GROUPSPOTTED FEVER GROUP
• Rash appear 1Rash appear 1stst on the extremities on the extremities with involvement of the palms & with involvement of the palms & solessoles
RICKETTSIALPOXRICKETTSIALPOX
• Etiology: R. akariEtiology: R. akari
• mild disease resembling Varicellamild disease resembling Varicella
• firm red macule at the bite site firm red macule at the bite site deep-seated vesicle deep-seated vesicle eschar eschar
Q FEVER (QUERY FEVER)Q FEVER (QUERY FEVER)
• Etiology: Coxiella burnettiEtiology: Coxiella burnetti
• MOT: inhalation of dust containing MOT: inhalation of dust containing the organism or aerosolsthe organism or aerosols
• Excreted in the urine, feces & milkExcreted in the urine, feces & milk
• Individuals at risk: food handlers, Individuals at risk: food handlers, ranchers & veterinariansranchers & veterinarians
• Resembles Influenza & nonbacterial Resembles Influenza & nonbacterial pneumonia, hepatitis or pneumonia, hepatitis or encephalopathyencephalopathy
• No rash or local lesionNo rash or local lesion
• Weil Felix test (-)Weil Felix test (-)
TRENCH FEVERTRENCH FEVER
• Etiology: R. quintanaEtiology: R. quintana
• Manifestations: headache, Manifestations: headache, exhaustion, pain, sweating, cold exhaustion, pain, sweating, cold extremities & fever with roseolar extremities & fever with roseolar rashrash
• Relapses occurRelapses occur
EHRLICHIOSISEHRLICHIOSIS
• ETIOLOGY:ETIOLOGY:E. sennetsu – Sennetsu feverE. sennetsu – Sennetsu feverE. chaffeensis – Human E. chaffeensis – Human
ehrlichiosusehrlichiosus• Leukocytic rickettsia – parasitize Leukocytic rickettsia – parasitize
lymphocytes, neutrophils & lymphocytes, neutrophils & monocytesmonocytes
SENNETSU FEVER:SENNETSU FEVER:
• Fever, cervical lymphadenopathy, Fever, cervical lymphadenopathy, inc. peripheral mononuclear cells & inc. peripheral mononuclear cells & atypical lymphocytesatypical lymphocytes
HUMAN EHRLICHIOSIS:HUMAN EHRLICHIOSIS:
• Similar to RMSFSimilar to RMSF
• Leukopenia & thrombocytopeniaLeukopenia & thrombocytopenia
• Only 20% of cases present with rashOnly 20% of cases present with rash
DIAGNOSISDIAGNOSIS
• Weil-Felix test – not specificWeil-Felix test – not specific
• Serological tests – most sensitive & Serological tests – most sensitive & specificspecific
- microimmunofluorescence- microimmunofluorescence
- microagglutination- microagglutination
- complement fixation- complement fixation
DISEASEDISEASE WEIL-FELIXWEIL-FELIX
OX19OX19 OX2OX2 OXKOXK
Epidemic typhusEpidemic typhus ++++ +/-+/- --
Endemic typhusEndemic typhus ++++ -- --
Scrub typhusScrub typhus -- -- ++++
RMSFRMSF ++ ++ --
RickettsialpoxRickettsialpox -- -- --
Q feverQ fever -- -- --
Trench feverTrench fever ?? ?? ??