Micro & Infections Flashcards
What are the 4 G- rods with animal reservoirs?
brucella
francisella
pasteurella
bartonella
Features of Brucella
facultative intracellular
granuloma forming
How is Brucella transmitted?
transmitted through drinking contaminated milk or skin during butchering
How does Brucella present?
joint/back pain flu-like symptoms depression travel/unpasteurized milk history blood cx negative because it has a long incubation period
How is Brucella treated?
6 wk combo:
doxycycline
streptomycin or rifampin
How is tularemia transmitted?
transmitted by ticks/flies from rabbits or cutaneous exposure to an infected animal
What is the disease caused by Francisella?
Tularemia
Features of Francisella
G- rod
found in central US
How does tularemia present?
ulcerations
fevers/muscle aches
painful axillary lymph nodes
exposure to rabbits or ticks
How is tularemia diagnosed?
serology
How is tularemia treated?
2 wks of 1:
streptomycin
gentamycin
doxycycline
What does Pasteurella look like under methylene blue?
bipolar staining
How is Pasteurella transmitted?
dog or cat bites
What infections does pasteurella cause?
osteomyelitis
endocarditis
meningitis
What is cat scratch disease?
Bartonella
How does Bartonella present?
fever
lymph nodes
bacillary angiomatosis in immunocompromised pts
What disease does Bacillus anthracis cause?
anthrax
How does anthrax present?
cutaneous: pigmented eschar edema Inhalation (wool-sorter's disease): hemorrhagic mediastinitis sepsis
What dz does Borrelia burgdorferi cause?
Lyme
Where does Lyme occur?
New England
How long does it take a tick to transmit Borrelia?
36-72 hrs
What rash is ass’d with Lyme?
erythema migrans
What are early signs of Lyme? (within 1 month)
fever/chills headache muscle/joint pain lymph nodes erythema migrans
What are the late signs of Lyme? (over 1 month)
severe headache/neck stiffness
facial palsy
more erythema migrans rashes
arthritis w/ severe pain/swelling
How is Dengue virus transmitted?
Aedes mosquitoes
How does Dengue fever present?
severe fever
rash
leukopenia
severe muscle/joint pain
How does Dengue hemorrhagic fever present?
dengue fever
progresses to hemorrhagic shock
How many serotypes exist of Dengue?
4
What is antibody-enhanced disease?
antibodies recognize but don’t destroy new serotype
antibody-coated virus is taken up more quickly by cells
complement fixation leads to more vascular permeability
What most commonly infects joint replacements?
staph epi
What most commonly infects native joints?
staph aureus most common overall
Neisseria gonorrhoeae common in sexually active individuals
How is septic arthritis diagnosed?
cloudy fluid with >20,000 PMN/ul and low glc compared to BG
What is Pott’s disease?
spinal TB from hematologic spread
Who gets bone/joint infections with nontyphoid Salmonella?
sickle cell pts
expanded bone marrow with low blood flow
Where does osteomyelitis infect in kids and adults?
kids: metaphysis of long bones (doesn’t spread to joint)
adults: vertebral bodies, metaphysis spreading to joint
Why are metaphyses more likely to be infected?
vessels make hairpin turns and have slow blood flow
What osteomyelitis changes are seen on x-ray?
lytic lesions at the abscess
Which joints have a physis within the joint capsule? Why is this important?
allows direct spread on infection to joint distal fibula radial head/neck proximal humerus proximal femur
How does osteomyelitis present?
local pain
fever
tenderness
elevated ESR, CRP
How long does it take for osteomyelitis to show up on x-ray?
1-2 wks
How is osteomyelitis treated?
antibiotics (oral/IV/local)
I&D or debriedment
What are osteomyelitis complications?
infectious arthritis
chronic infection
recurrent infections
How does chronic osteomyelitis appear on x-ray?
"bone within a bone" new bone (involucrum) growing around the dead bone (sequestrum)
What is a Marjolin ulcer?
squamous cell carcinoma in a sinus tract or burn
How is chronic osteomyelitis treated?
antibiotics
remove sequestra or implants
establish blood supply
What is a commonly infected joints in IV drug users?
SC joint
What are the most commonly infected joints?
hips
knees
What are complications of septic arthritis?
synovial cell death
chondrolysis
condrocyte death
All begin within 24 hrs
How does septic arthritis present? Diagnosed?
inflammation and effusion
ID effusion with ultrasound/MRI
Diagnosed with joint aspiration
What is a potential cause of an infected shoulder replacement?
P acnes
