rickettsia
TRANSCRIPT
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 ?? ?? ??