Ricketssia, Coxiella, Ehrlichia, Batronella Flashcards
3 genera in the Rickettsiae family
Rickettsia, Coxiella, and Ehrlichia
Rochalimaea
a family related to Rickettsia that are not strictly intracellular and now part of the Bartonella family
Cell structure of Rickettsia
small gram negative bacilli or coccobacilli that are strictly intracellular pathogens
What host enzymes to Rickettsia use and what happens when cells are outside the host
ATP, Coenzyme A, and NAD. When they are outside the host their metabolism stops and their membranes leak
How do Rickettsia get inside host cells
They initiate a phagocytosis-like process and escape the endocytic vacuole to replicate
Clinical manifestations of Rickettsia
Fever, headache, external rash and focal lesions
How do Rickettsia cause rashes
Pathogen infects vascular endothelium, which causes RBCs to leak and results in rash and petechial lesions
Why are Rickettsia rarely cultured
Growth is difficult (needs tissue or fertile eggs) and can cause infection by aerosol
Tests for Confirmatory and Presumptive diagnosis of Rickettsia
Confirmatory diagnosis is good immunoassay with a rise in antibody titer from acute to convalescent sera and presumptive diagnosis with high convalescent titer and typical symptoms
Rocky Mountain Spotted Fever
Caused by Rickettsia conorii from prolonged wood, dog, or lone star tick bite mostly in children and presents with fever headache, confusion, myalgia, and rash on ankles and wrists that spread to trunk (esp palms and soles)
Therapy and Prevention of Rocky Mountain Spotted Fever
Chloramphenicol in the first week for serious illness and children under 8 and trtracycline as second choice, removing ticks within 4-6 hours should prevent transmission; killed vaccine for military and researchers
Rickettsiapox
Urban disease caused by Rickettsia akari from house mite bite; self limiting illness that begins with a papulovescicle at the bite site and progresses to fever and rash; treat with tetracycline
Epidemic Typhus
Caused by Rickettsia prowazekii from infected body louse; 1-2 weeks after bite fever headache, myalgia, malaise, and rash on the trunk that spreads to extremitis; CNS and heart complications; treat with tetracycline or chloramphenicols
Recrudescent Typhus or Brills Disease
Reactivation of old Rickettsia prowazekii that have laid dormant in reticuloendothelial cells 10-40 years later because aging has caused immune system fading
Murine Typhus
Caused by Rickettsia Typhi from infected rodent flea bite; headache, fever, myalgia and rash; treat with tetracycline and chloramphenicol
Scrub Typhus
Spread by rodent mites infected with Rickettsia Tsutagamushi in Asia and South Pacific; lesion at bite site and symptoms similar to other typhus
Q Fever
Caused by Coxiella burnetti in respiratory system that is spread by aerosols from cattle, sheep and goats to ranchers, vets, researchers, and slaughterhouse workers; affects liver and can cause endocarditis, encephalitis, and periarditis; vaccine for at-risk professions and treat with tetracycline
Human Monocytic Ehrlichiosis
Macrophages infected with Ehrlichia chaffeensis from dog/lone star/Ixodes tick bite, which causes fever, hypotension, confusion, renal failure, pancytopenia, GI hemorrhage, and hepatocellular injury; diagnose with PCR and treat with tetracycline
Human Granulomacytic Anaplasmosis
Granulocytes infected with Anaplasma phagocytophilum from Ixodes deer tick bite, which causes fever, chills, head/muscle ache, nausia, vomiting, abnormal LFT, decreased platelet/WBC, and possibly kidney failure and meningitis; treated with tetracycline
Trench Fever
Caused by Bartonella Quintana from louse and presents with fever, rash, bone pain, and spenomegaly; treat mild immunocompetent people with 14 days oral erythromycin or tetracycline and severe disease with longer 3rd generation cephalosporin
Cat Scratch Fever
Bartonella henselae spread by cat scratch; causes blister and lymph node swelling in children, more severe systemic disease in adults, and very severe bacillary angiomatosis in AIDS patients; diagnosis with antibody titer or exclusion of other diseases and antibiotic use is controvertial
Parinaud Oculoglandular Syndrome
Severe form of cat scratch fever with conjuctival sore and swollen lymph nodes around the ear that can result when primary infection is in the eye
