3.2.2 Bacillus, Listeria and Corynebacterium Flashcards
What allows bacillus organisms to survive in the environment?
Spore-forming
What’s wrong with Bob?
Bob has Bacillus anthrasis
What are the symptoms associated with inhalational anthrax? What is the associated mortality rate?
What is one of the key features of inhalational anthrax seen on imaging?
Mediastinal widening
What are the two forms of GI anthrax?
Oropharyngeal: local ulceration leading to regional lymphadenopathy (tonsilitis), edema and fever
Intestinal: ulcer w/ initial symptoms of fever, nausea, vomiting, malaise, followed by bloody diarrhea or sepsis
What is the key feature of cutaneous anthrax?
Painless pauple develops into a black necrotic ulcer (eschar) with edema
What is the pathogenesis of bacillus?
What is the unique feature of the antiphagocytic capsule of bacillus?
Poly-D-glutamic acid
What are the two active subunits of the A3-B7 anthrax exotoxin?
Edema (EF): activates adenylate cyclase -> increased cAMP
Lethal factor (LF): inactivates MAP-kinase-kihase -> results in necrosis
Draw a diagram of the bacillus A-B toxin pathogeneis.
After a presumptive diagnosis of Bacillus is made, what confirmatory labs are conducted by the CDC?
What is the DOC for Bacillus anthrasis?
Ciprofloxacin
What preventive measure can be enacted if a patient is at risk for inhalation anthrax?
60 days of antibiotic prophylaxis
What human mAb targets PA of Bacillus anthrasis?
Raxibacumab
What are some of the defining characterstics of Bacillus cereus?
Gram pos, spore-forming, facultative anaerobe, motile, beta-hemolytic on SBA, ubiquitous in soil
What causes the emetic form of GI dz caused by Bacillus cereus?
Heat-stable enterotoxin
What causes the diarrheal form of GI dz caused by Bacillus cereus?
Heat-labile toxin
What type of eye pathogy is associated with Bacillus cereus?
What is the DOC for Bacillus cereus?
Vancomycin or Clindamycin
Proper refrigeration of food
What diagnostic tests can help lock down a diagnosis of Bacillus cereus?
Contaminated food or infected patient specimen (eye, IV, site, etc)
Generally no fecal samples
What are the general characteristics of Listeria?
What type of hemolysis is Listeria?
Weak beta-hemolytic: zone of lysis is narrow
What unique about Listeria and its growth?
Grows at 4 degrees Celcius, refrigeration of food is not sufficient
What subgroup of the population is at most risk for a Listeria infection?
Pregnant Women (risk increased 20-fold)
What are some characteristics of Early-onset Listeria dz?
Transplacentally acquired
Granulomatosis infanticeptica: disseminated abscesses and granuloma in multiple organs
80% mortality rate
What are some characteristics of Late-onset Listeria dz?
Acquired at birth or soon thereafter
Meningoencephalitis, septicemia
70% mortality rate
What are some of the dz’s caused by Listeria in immunocompromised pts?
Meningitis, bacteremia, 50% fatality rate in severely immunocompromised pts and infants
Where do Listeria infections typically initiate?
Enterocytes or M cells in Peyer’s patches
What type of immunity is essential for clearing a Listeria infection?
Cell-mediated immunity
What are the 4 main virulence factors of Listeria?
Internalins (Inl): forced phagocytosis
Listeriolysin O (LLO): pore-forming hemolysin
2 Phospholipases (PI-PLC, PC-PLC)
Actin-binding protein (ActA): Mediates actin polymerization
Draw a diagram of Listeria pathogenesis
What are two unique features of Listeria when it comes to culturing?
Cold-enrichment and umbrella-like growth
What allows for Listeria to acquire resistance so easily?
Conjugative plasmids from enterococci
What are the DOC for Listeria?
Ampicillin (meningitis: IV) or TMP-SMX
What are the characteristics of Corynebacterium diptheriae?
What is the activity of the A-portion of the diptheria A-B exotoxin?
ADP-ribosylates elongation factor -> shutting down protein synthesis
What are the different toxoid vaccines?
DTaP, Td and Tdap
What are the characteristics of respiratory diptheria?
What are the unique cultures that can identify diptheria?
Tellurite-containing differential chocolate agar
Elek test
What is the rx of diptheria infection in pt who was not immunized?
Immediate administration of antitoxin
DOC: erythromycin or penicillin
What is not produced following diptheria infection?
Protective antibodies - immunization of convalescent patient
What is the typical vaccination schedule for diptheria?
