Ricketssia, Coxiella, Ehrlichia, Batronella

Question 1

3 genera in the Rickettsiae family

Answer 1

Rickettsia, Coxiella, and Ehrlichia

Question 2

Rochalimaea

Answer 2

a family related to Rickettsia that are not strictly intracellular and now part of the Bartonella family

Question 3

Cell structure of Rickettsia

Answer 3

small gram negative bacilli or coccobacilli that are strictly intracellular pathogens

Question 4

What host enzymes to Rickettsia use and what happens when cells are outside the host

Answer 4

ATP, Coenzyme A, and NAD. When they are outside the host their metabolism stops and their membranes leak

Question 5

How do Rickettsia get inside host cells

Answer 5

They initiate a phagocytosis-like process and escape the endocytic vacuole to replicate

Question 6

Clinical manifestations of Rickettsia

Answer 6

Fever, headache, external rash and focal lesions

Question 7

How do Rickettsia cause rashes

Answer 7

Pathogen infects vascular endothelium, which causes RBCs to leak and results in rash and petechial lesions

Question 8

Why are Rickettsia rarely cultured

Answer 8

Growth is difficult (needs tissue or fertile eggs) and can cause infection by aerosol

Question 9

Tests for Confirmatory and Presumptive diagnosis of Rickettsia

Answer 9

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

Question 10

Rocky Mountain Spotted Fever

Answer 10

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)

Question 11

Therapy and Prevention of Rocky Mountain Spotted Fever

Answer 11

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

Question 12

Rickettsiapox

Answer 12

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

Question 13

Epidemic Typhus

Answer 13

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

Question 14

Recrudescent Typhus or Brills Disease

Answer 14

Reactivation of old Rickettsia prowazekii that have laid dormant in reticuloendothelial cells 10-40 years later because aging has caused immune system fading

Question 15

Murine Typhus

Answer 15

Caused by Rickettsia Typhi from infected rodent flea bite; headache, fever, myalgia and rash; treat with tetracycline and chloramphenicol

Question 16

Scrub Typhus

Answer 16

Spread by rodent mites infected with Rickettsia Tsutagamushi in Asia and South Pacific; lesion at bite site and symptoms similar to other typhus

Question 17

Q Fever

Answer 17

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

Question 18

Human Monocytic Ehrlichiosis

Answer 18

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

Question 19

Human Granulomacytic Anaplasmosis

Answer 19

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

Question 20

Trench Fever

Answer 20

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

Question 21

Cat Scratch Fever

Answer 21

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

Question 22

Parinaud Oculoglandular Syndrome

Answer 22

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