04a: Zoonotic Bacteria Flashcards
Zoonotic diseases are transmitted from (X) to humans (directly/indirectly) via (Y).
X = animals
Directly or indirectly (Y = vectors like insects/mites)
Two most common zoonotic diseases in U.S.
- Lyme disease
2. RMSF
T/F: Diagnosis of zoonotic diseases is typically presumptive, based on clinical presentation and patient history.
True - lab tests take too long
Rickettsia organisms cause which diseases? What’s the cell shape and gram reaction?
RMSF, Epidemic and Endemic Typhus
Rods; gram-negative
Major virulence factors of Rickettsia.
- Intracellular growth (obligate intracellular parasite!)
2. Endotoxin
Transmission of Rickettsia rickettsii to humans is via (X) vector and mammalian reservoirs are (Y).
X = dog tick (arthropod) bites Y = dogs/rodents
List the common clinical findings of Rickettsia.
Flu-like symptoms:
- HIGH fever/chills
- Myalgia, prostration (weakness)
- Severe headache
List the specific clinical findings of Rickettsia rickettsii infection, aka (X) disease.
X = RMSF
Rash that starts on hands/feet (including palms/soles) and extends centrally; macular then progresses to petechiae.
T/F: RMSF can be fatal if not treated within a month of symptom onset.
False - within 8 days of symptom onset!
(X) is the causative agent for RMSF (Rocky Mountain Spotted Fever).
X = Rickettsia rickettsii
(X) is the causative agent for Epidemic Typhus.
X = Rickettsia prowazekii
Transmission of Rickettsia prowazekii to humans is via (X) vector and mammalian reservoirs are (Y).
X = lice Y = humans
T/F: Epidemic Typhus is not a real problem in the U.S.
True - in areas of poverty or refugee camps
List the specific clinical findings of Rickettsia prowazekii infection, aka (X) disease.
X = Epidemic Typhus
Maculopapular rash (starts at trunk about 1 week after flu-like symptom onset); spreads peripherally (spares face, palms/soles) and becomes petechial
(X) is the causative agent for Endemic Typhus.
X = Rickettsia typhi
Transmission of Rickettsia typhi to humans is via (X) vector and mammalian reservoirs are (Y).
X = flea Y = rodents
T/F: Endemic Typhus is not a real problem in the U.S.
True - typically in travelers from Africa, Asia, South Europe
T/F: Endemic and Epidemic Typhus have nearly identical clinical presentation.
False
List the specific clinical findings of Rickettsia typhi infection, aka (X) disease.
X = Endemic Typhus
- Potential rash development
- GI/respiratory involvement; CNS involvement (45% of pts)
T/F: Endemic Typhus can be fatal if not treated within a month of symptom onset.
False - uncomplicated course with full recovery; especially mild in children
List first and second choice treatment for Rickettsial disease.
- Tetracyclines (doxycyline)
2. Chloramphenicol
Coxiella burnetii is a gram-(pos/neg) bacteria with which shape? Infection is associated with which disease?
Gram-neg
Coccobacillus;
Q Fever
T/F: Coxiella burnetii is obligate intracellular parasite.
True
Transmission of Coxiella burnetii to humans is via (X) vector and mammalian reservoirs are (Y).
X = no vector; via inhaling aerosolized material contaminated with urine, feces, placental tissue (or via drinking unpast. milk) Y = cattle, sheep, goats
T/F: 80% of Coxiella burnetii infections are asymptomatic.
False - about 50%
Acute Q fever presents with (X) symptoms and, if untreated, usually progresses to:
X = flu-like (NO RASH)
Recovery (even without antibiotics); can take few months
About 30-50% of patients with Q fever develop (X) and some even develop (Y).
X = pneumonia Y = hepatitis
Small portion (5%) of patients develop chronic Q fever and present with (X), which has (Y)% mortality if untreated.
X = endocarditis Y = 40
T/F: Q fever isn’t an important disease in the U.S.
False
T/F: There are no vaccines available for Rickettsia or Coxiella burnetii.
False - ANIMAL vaccines for Coxiella burnetii exist
Ehrlichia chaffeensis is the causative agent for (X) disease. It is gram-(pos/neg) and has which shape?
X = Human monocytic ehrlichiosis (HME)
Gram-neg, short rods ** NO pepditoglycan or LPS!
T/F: Ehrlichia chaffeensis and Anaplasma phagocytophilum are obligate intracellular parasites.
True
Transmission of Ehrlichia chaffeensis to humans is via (X) vector and mammalian reservoirs are (Y).
X = Lone Star Tick Y = humans
A significant portion (50-90%) of patients with (X) zoonotic disease(s) present with leukopenia, thrombocytopenia, and elevated (Y).
X = HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) Y = aminotransferases
T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) are rash-free.
False - 30% of patients with HME may present with rash
T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) are both treated with doxycycline.
True
T/F: HME (Human Monocytic Ehrlichiosis) and HGA (Human Granulocytic Anaplasmosis) can be prevented via vaccination.
False - no vaccines; remain tick-free
Anaplasma phagocytophilum is the causative agent for (X) disease. It is gram-(pos/neg) and has which shape?
X = Human granulocytic anaplasmosis (HGA)
Gram-neg, short rods ** NO pepditoglycan or LPS!
T/F: Ehrlichia chaffeensis and Anaplasma phagocytophilum are not problematic in the U.S.
False
(X) zoonotic bacteria form morulae during (intra/extra)-cellular replication.
X = Erhlichia (in monocytes) and Anaplasma (in granulocytes);
Intracellular (within phagosomes)
Zoonotic bac: About (X)% of patients with HME require hospitalization. And (Y)% of patients with HGA.
X = Y = 50
T/F: Mortality rates from Erhlichia and Anaplasma infections (HME/HGA) are virtually negligible.
False..
HME: 2-3%
HGA: about 1%
T/F: Erhlichia and Anaplasma infections are more prevalent in young children, under 1 y.o.
False - among elderly
Transmission of Anaplasma phagocytophilum to humans is via (X) vector and mammalian reservoirs are (Y).
X = Ixodes scapularis tick Y = humans, horses, dogs
Causative agent for Lyme is (X). It’s gram-(pos/neg) and what shape?
X = Borrelia burgdorferi
Spirochete! No gram stain (seen in silver or Giemsa stains or darkfield microscopy)
Irregular, loosely coiled
Borrelia burgdorferi is transmitted to humans via (X) vector and the mammalian reservoir is (Y).
X = ticks (esp. Ixodes scapularis) Y = white-footed mouse (and to lesser extent white-tailed deer)
Early, localized Lyme infection may have which clinical presentation?
- Erythema migrans (80% of time), which is painless, circular/bullseye rash
- Potential flu-like symptoms
Early, disseminated Lyme infection may have which clinical presentation?
- CV (carditis with AV block)
2. CNS (meningoencephalitis, cranial neuropathies - Bell’s Palsy, radiculitis, peripheral neuropathy)
Late, disseminated Lyme infection may have which clinical presentation?
Arthritis (esp knee) and maybe subtle lyme encephalopathy or polyneuropathy
T/F: All stages of Lyme are diagnosed via clinical presentation/patient history and serological tests.
False - serological tests not for classic erythema migrans (early, localized Lyme)
First step of Lyme serological test is (X), to detect (Y).
X = ELISA Y = anti-B. burgdorferi Ab
Second step of Lyme serological test is (X), to detect (Y).
X = Western blot Y = IgM and IgG against specific B. burgdorferi Ag
Stage 1/mild Lyme treated with:
Oral doxycycline or ampicillin (short course)
Late stage (severe), invasive Lyme treated with:
Ceftriaxone
