25a Plague, Tularemia, Brucellosis Flashcards
What is the bacteria that causes bubonic and pneumonic plague?
Yesinia pestis
What are the general properties of Yesinia pestis? Shape and Gram status? O2 status? Lactose status? What family of bacteria? Motile? Catalase? Oxidase?
Large rod-shaped (coccobacillary) Pleomorphic Gram - with bipolar staining Aerobic or faculative aerobic Non-lactose fermenter Family: Enterbactericeae Non-motile Catalase + oxidase negative
What are the three types of stains for Y. pestis?
Wright’s stain
Geimsa stain
Wayson stain
What are the staining Dx features of Geimsa and Wayson staining fo Y. pestis?
“Safety pin” stain = stains on both ends, but not in the middle.
Bi-polar staining
What other bacteria are in family Enterocactericeae?
Y. pestis
Y. pseudotuberculosis
Y. enterocolitica
What is the cycle of transmission of bubonic plague?
Bubonic means very large lymph nodes.
Flea to Mammal (usually rodents or cats) cycle
Details:
flea aquires Y. pestis after a blood meal
Y. pestis obstructs the foregut
Upon next meal, the flee regurgitates Y. pestis into mammal bloodstream
What is the cycle of transmission of pneumonic plague?
Bubonic plague can lead to secondary pnuemonia
Pnuemonia can now spread via respiratory droplets
Respiratory droplets from animal to human or human to human.
What are the circumstances of urban plague?
Animal epidemics ("epizootics") among black rats and their fleas.
As rats die, fleas seek new hosts aka humansWhat are the circumstances of rural plague?
What are the modes of acquisition?
Sporatic cases usually related to travel
10 cases per year in Southwestern U.S. (near the “four corner states)
Acquired by… Flea bite; hand contact with infected mammal; contact with domestic pets
What are natural hosts for bubonic fleas?
Rodents and cats
Is Yersinia pestis INTRA or EXTRA cellular?
Both intra and extracellular pathogenesis.
What are the pathogenic qualities of EXTRAcellular Yersinia pestis?
Are fleas diseased by Yersinia? Why are humans?
CAPSULE required antiphagocytic (F1 antigen)
Capsule has antiphagocytic properties at 37 degrees, but not at 28 degrees. Therefore mammals suffer illness, but fleas do not.
What are the pathogenic qualities of INTRAcellular Yersinia pestis?
V and W antigens are needed for survival within macrophages
There can be persistence within mammilian monocytes
What toxins are present in Yersinia pestis?
Classical LPS endotoxin
Exotoxin
In summary, what are the pathogenic qualities of Yersinia pestis?
CAPSULE
V and W antigens
LPS endotoxin
Exotoxin
What are the clinical features of…
Bubonic plague? (also what is incubation period)
Pneumonic plague?
Septicemic plague?
B: flea bite, 2-6 days incubation, fever, malaise, and painful lymphadenopathy
P: fever, cough, shortness of breath (rapid death, if not treated)
S: flea bite, widespread dissemination via blood, shock,
Disseminated Intravascular Coagulation DIC, skin hemorrhages aka “black death,” plague meningitis, necrosis of digits
Does immunity develop to Y. pestis?
Is there a vaccine?
Antibody develops and is protective
Inactivated vaccine is used by military
What is Dx of Yersinia pestis?
Bubo aspirate
Blood culture
Serology
What are the features confirmed in…
Bubo aspirate
Blood culture
Serology
Aspirate: usually gram stain and culture positive, confirmed by flourescent antibody FA microscopy
Blood: usually positive, may have high number of organisms visible on peripheral smear
Serology: 4x rise in antibody to F1 Capsule antigen
What is the Tx for Yersinia pestis?
10 days of tetracycline, streptomycin, or chloramphenicol
Why are these antibiotics used for Yersinia pestis?
Tetracycline?
Streptomycin?
Chloramphenicol?
Tetracycline: Static, Broad Spectrum, Protein Synthesis Inhibitor (blocks tRNA from 30s)
Streptomycin: Cidal, often used for TB, Protein Synthesis Inhibitor (blocks 30s)
Chloramphenicol: Static, used for some anearobes and B. fragilis, Protein Synthesis Inhibitor (50s inhibitor)
What is the prognosis of Yersinia pestis?
If treated?
If untreated?
Mortality of 60 to 90% if untreated.
5% with early antibiotics
15% overall mortality in the U.S.
What are adverse prognositic features?
Axillary adenopathy
Secondary plague pneumonia
Positive blood cultures
Organisms on peripheral smear
What is Px for Yersinia pestis?
Flea and rodent controls
Inactivated vaccine
What are the general properties of Franciscella tularensis? Size, shape, gram status, capsule status? O2 status? Growth rate? Growth medium required? Temperature status? Infectious dose? Relationship to macrophages?
Small unecapsulated pleomorphic gram negative
Fastidious aerobic slow grower
Requires cysteine and glucose on blood agar (or thioglycollate)
Cold tolerant: can survive in water for 90 days
Infectious does is 5-10 organisms inhaled or intradermal
Phagocytosed by macrophage, but not killed. Can multiply in macrophage and travel throughout the body.
What is a Category A priority agent (NIH)?
From NIH website.
Category A pathogens are those organisms/biological agents that pose the highest risk to national security and public health because they
Can be easily disseminated or transmitted from person to person
Result in high mortality rates and have the potential for major public health impact
Might cause public panic and social disruption
Require special action for public health preparedness
Epidemiology of Franciscella tularensis (tularemia)…
What is the cycle of infection?
What are common routes of human infection (3)?
Zoonotic disease transmitted from animals or arthropods to humans.
Widespread in the northern hemisphere.
1) Rabbit: contact or partially cooked meat
2) Arthropod-borne: Ticks, Deer flies
3) Other: handling infected tissues, animal bite, LABORATORY AEROSOLS, shaking dog AEROSOL»_space; TULAREMIA PNUEMONIA
What time of year is infection from Franciscella tularensis (tularemia)…
Rabbit meat?
Arthropods?
R: Winter
A: Summer
Pathogenesis of Franciscella tularensis (tularemia)…
What are the progressive symptoms of initial infection to organ disease?
Skin lesion»_space; lymphatics»_space; lyphadenopathy»_space; bacteremia»_space; granuloma formation in the reticuloendothelial system ie spleen and liver
Franciscella tularensis (tularemia)
Is the infection INTRA or EXTRA cellular?
Are the toxins ENDO or EXO?
INTRAcellular survival in monocytes. Doesn’t exclude EXTRAcellular.
ENDOtoxin plays role in initial systemic symptoms
What are the clinical features of Franciscella tularensis (tularemia)…
What are the immediate symptons?
What are specific syndromes (3)?
Abrupt onset fever, chills, malaise
Ulceroglandular: skin ulcer and adenopathy
Typhoidal bacteremia»_space; Granuloma (different than Y. pestis)
Pneumonia (10-15%)
What is Dx for Franciscella tularensis (tularemia)?
What are concerns during Dx?
Difficult and dangerous to culture (culture can become aerosol and infect lab workers)
Florescent antibody staining of node biopsy
Serology 4x titer or titer > 160
What does Franciscella tularensis (tuleremia) cross-react with in terms of serology?
Similar serology to Brucella
What is Tx for Franciscella tularensis (tularemia)?
Streptomycin 10 days
Tetracycline 14 days
Chloraphenicol
Ciprofloxacin may be used
Why are Streptomycin and/or Tetracycline used?
Why is Chloramphenicol used?
Why is Ciprofloxacin used?
Streptomycin: Cydal, Protein Synth Inhibitor 30s
Tetracycline: Static, Broad Spectrum, Protein Synth Inhibitor 30s
Chloramphenicol: Static, some anaerobes, 50s protein inhibitor
Ciprofloxacin: Cidal, G- enterics and some G+ (also P. aeruginosa), inhibits DNA gyras
What is mortality rate for Franciscella tularensis if treated?
<1%
What is Px for Franciscella tularensis (tularemia)?
Tick prevention
Rabbits and Muskrats: wear protective gloves
Vaccine
What is the vaccine for Franciscella tularensis?
Who should get the vaccine?
Live attenuated
Lab workers
Trappers
Brucella species and (Brucellosis) General characteristics... What is shape and gram status? What is growth rate? What is required for optimal growth? How hardy is brucella?
Pleomorphic fastidious G -
Grows slowly
Requires 10% CO2
Hardy: survives in dust and soil
Brucella is also called (2 common names)?
Malta fever
Metaterranean remittent fever
What is the general transmission cause for Brucella?
Soonotic disease from transmission of unpasteurized dairy products and direct tissue contact
What are the common species of Brucella?
B abortus
B suis
B melitensis
B canis
What animals and transmission are associated with…
B abortus:
B suis:
B melitensis:
B canis:
These are important because transmission differs for each.
B abortus: cattle, contaminated milk or direct tissue contact, especially placenta
B suis: swine, tissue contact, airborne, slaughterhouse workers
B melitensis: goats and sheep: unpasteurized dairy
B canis: dog urine at kennels
What is the pathogenesis of Brucella in farm animals?
Infectious abortions
What is the pathogenesis of Brucella in humans?
Reticuloendothelial (spleen and liver: enlarged)
Organisms are ingested by PMN»_space; multiply in monocytes»_space; form GRANULOMAS in liver, kidney, spleen, and bone marrow
Granulomas always mean slow growth.
What are the clinical features of Brucella?
Systemic and non-focal
Fever of undetermined origin (FOU)
Chills, myalgias, arthalgias, headache
Whatt are complications of Brucella?
Intracellular persistenc causes prolonged symptoms and relapse
Osteomyelitis (vertebral)
Endocarditis (culture negative)
What is Dx of Brucella?
Occupational history
Blood culture takes 21 days
Serology 4x titer
Bone marrow biopsy if difficult to Dx
What is Tx for Brucella?
Doxycycline plus rifampin for 6 weeks
What is relapse and mortality rates for treated Brucella?
25% relapse
2% mortality
What is Px for Brucella?
Pasteurization of dairy
Control animal reserviors
Vaccination of young female cows and farmers
Herd and individual testing via antibody test of milk samples
Workers: gloves and eye protection
