Micro of Zoonotic Skin Infections - Miller Flashcards
Common symptoms of all zoonotic bacterial infections?
Flu like symptoms (myalgias, fever, malaise)
Morphology/gram stain of Rickettsia, Ehrlichia, and Coxiella? Do they gram stain well?
Short gram negative rods; all obligate intracellular parasites that express LPS. Do not gram stain well
Common pathogenesis of all Rickettsial microbes?
Vasculitis of the endothelial layer, causes a cutaneous rash. LPS mediates the fever/petichae
What organism causes RMSF?
Rickettsia Rickettsii
Vector that commonly transmits RMSF?
Dog ticks
What seasons and where are you most likely to get RMSF?
Spring and summer months; Georgia, North Carolina, and Virginia are the most common
Presentation of RMSF?
Typical flu like symptoms; muscle soreness in the CALVES; rash that STARTS AT THE ANKLES/WRISTS and proceeds proximally (this is pathognomonic); palms and soles are commonly involved (also specific for RMSF)
Severe complications of RMSF if untreated?
CNS change leading to delirium and coma; DIC with circulatory collapse
What test do you use to diagnose RMSF?
Weil-Felix Test
How does the Weil-Felix test work?
Uses antigens derived from Proteus; for some reason Rickettsial specific antibodies cross react with the antigens
What organism causes Epidemic Typhus?
Rickettsia Prowazekii (epidemic and Prowazekii both have “P’s”)
Presentation of epidemic typhus?
flu-like symptoms for 1-3 weeks; rash that spreads from the TRUNK–>distally to extremities (KNOW THIS); palms and soles are not involved with rash (KNOW THIS TOO)
Criteria for diagnosis of epidemic typhus?
When antibodies specific to Rickettsia Prowazekii increase 4x between acute-phase and convalescent serum
What causes Endemic typhus?
Rickettsia typhi
What vector transmits endemic typhus?
Fleas
Presentation of endemic typhus?
Significantly less severe disease that epidemic typhus
What 2 bugs cause Southern tick-borne disease?
Ehrlichia chaffeensis and Anaplasma phagocytophilia
What tick transmits anaplasmosis?
Ixodes ticks
What tick transmits ehrlichiosis?
Lone star deer tick (fucking Texas)
What is the specific name for the disease caused by Ehrlichiosis chaffeensis?
Human monocytic ehrlichiosis
Where specifically in the body does ehrlichiosis infect/replicate?
Monocytes; they’re obligate intracellular parasites
Diagnosis of ehrlichiosis?
Blood smear looking for morulae in circulating monoctyes
Unique symptoms to Ehrilichiosis?
N/V/D, cough, and CONJUNCTIVITIS
What disease does anaplasma phagocytophilia cause?
Human granulocytic anaplasmosis; “Rocky Mountain Spotless Fever”
Why is human ganulocytic anaplasmosis referred to as Rocky Mountain Spotless Fever?
Because rash is uncommon
What does it indicate if there is a rash present in Rocky Mountain Spotless Fever?
Most likely coinfection with Borrelia Burgdorferi
Diagnosis of Anaplasma phagocytophilia
Blood smear looking for mourlae in NEUTROPHILS
Severe complications seen in Anaplasma phagocytophilia?
Renal failure and hemorrhage, respiratory compromise, CNS issues
Morphology of Coxiella Burnetti?
Gram-negative bacillus; obligate intracellular parasite
Primary carriers of Coxiella burnetti?
Sheep, Cattle, Goats
2 common ways Q- fever (coxiella burnetti) is contracted?
Ingestion of contaminated dairy products; contact with contamintated animal viscera (usually birthing of livestock)–> veternarians and farmers at risk
ID50 of Coxiella?
Less than 50; one of the most infectious human pathogens
Typical coure of Q-fever? What about more severe disease?
cutaneous disease with acute febrile illness with atypical PNA lasting 2-4 weeks; most serious disease causes endocarditis and granulomatous hepatitis
Describe spirochetes
Very flexible, highly motile; have a unique cork-screw-like appearance
What 2 species of spirochetes are we concerned with?
Borrelia and Leptospira interrogans
What disase does borrelia burgdoferi cause?
Lyme Disease
Vector for lyme disease (borrelia)
Ixodes tick
Where and when would you get Lyme disease?
Summer months; Northeastern states and Wisconsin
Diagnosis of borrelia?
Stain with Giesma or silver stain
Why is it important that the nymphal stage tick more commonly causes Lyme disease?
They’re tiny so people don’t notice them until they’ve been munching on them for a while
Generalized pathogenesis of Borrelia?
Bugs disseminate from the orignal vector bite through surrounding skin and into bloodstream; ensuing bacteremia allows dissemination to heart, the joints, CNS
Describe the 3 stages of disase in Lyme disease
Stage 1) Erythema chronicum migrans (charactersitic bullseye rash)
Stage 2) Cardiac and neurologic symptoms; Myocarditis with heart block; BILAT FACIAL NERVE PALSY (pathognomonic
Stage 3) development of arthritis in large joints like the knees and shoudlers
Picture of erythema chronicum migrans
Diagnosis of borrelia burgdorferi
Serology using ELISAs to measure IgM/IgG specific for Borrelia; confirm with a Western Blot for any + ELISA
What 2 species cause relapsing fever? What is their vector and where are they found?
Borrelia hermsii and Borrelia recurrentis; small rodents and endemic in the Western US
Clinical presentation of relapsing fever?
Fever that lasts for weeks, resolves, and reccurs with this continuing over 10 times
What do leptospira interrogans look like?
Tightly coiled spirochetes
What is the primary resovoir in the US for leptospira?
Dogs
Other common way to contract leptospira besides canine contact?
Consumption of contaminated water or swimming in contaminated water
Early symptoms of Leptospirosis?
Flu-like symptoms with conjuncitivits
Severe disease symptoms seen in Leptospirosis?
Liver damage (jaundice), Kidney dysfunction (uremia), Lung hemorrhage, Aspetic meningitis
What causes cat scratch disease?
Bartonella Heneslae
Where is bartonella found in the cat?
Normal oral flora
What 2 ways can you get catch scratch disease from a cat?
Scratches or bites; NOT from fecal matter
Clinical presentation of cat scratch disease?
Fever, tender/enlarged lymph nodes on the same side as the bite. Papule may occur at the bite site. Relatively benign disease
Cat scratch disease in AIDS pts?
Bacillary angiomas may form on the skin and visceral organs
Diagnosis of bartonella heneslae?
Warthin-Starry stain
What disease must you r/o in a patient with bacillary angiomomatosis?
Kaposi Sarcoma (most common malignancy in AIDS pt)
