Gram (+) bacilli Flashcards
Bacillus, Clostridium, Corynebacterium, Listeria
Bacillus anthracis
lab tests
King Anthra’s Axe
Large gram (+) rods in _c_hains
Obligate Aerobe
Spore forming
Capsulated with Poly-D glutamate
Bacillus anthracis
VF
King Anthra’s Axe
EF (edema factor) toxin:
Increases cAMP intercellularily → fluid goes to extracellular space → edema → inhibits host defenses and prevents phagocytosis.
LF (lethal factor) toxin:
Exotoxin that acts as portease and cleaves MAP kinase (a signal transduction protein resposible for cell growth) → Necrosis and Black Eschar (with erythematous ring)
Bacillus anthracis
signs and symptoms
King Anthra’s Axe
Pulmonary anthrax (AKA Wool Sorters Disease)
-Spores get into wool and hide, and people inhale the spores when the animal is handled.
Pulmonary anthrax → can move to mediastinal lymph node → hemorrhagic mediastianitis
Widened mediastinum seen on chest xray
Bacillus anthracis
treatment
King Anthra’s Axe
fluoroquinolone or doxycycline
Bacillus cereus
key facts
King Anthra’s Axe
Aerobic and spore forming
Associated with food poisoning from:
* Reheated fried rice
Clostridium tetani
lab tests
Rhesus Research Revolution
gram (+) bacilli
Obligate Anaerobe
Spore forming
Clostridium tetani
MOA
Rhesus Research Revolution
Spores in dirt enter through puncture wounds and vegetate in wound site, releasing tetanus toxin which travels retrograde through the motor axons to the spinal cord.
* Tetanus toxin cleaves SNARE and inhibits exocytosis of the NT (GABA and glycine) into the synapse or Renshaw cells.
Inhibited GABA and glycine → uncontrolled firing of the motor neurons → spastic paralysis
Renshaw cells sense over activity of nearby motor neurons and attempt to fire to inhibit the motor neurons by releasing GABA and glycine which are inhibited leading to spasm.
Clostridium tetani
signs and symptoms
Rhesus Research Revolution
Spastic paralysis leading to rigidity, rhesus (to grin) sardonicus (evil), and lock jaw.
Arching back similar to Opisthotonos.
Clostridium tetani
Vaccines
Rhesus Research Revolution
DTaP vaccine
Given with diphtheria and pertussis
It is a Toxoid Vaccine (toxin conjugated to protein)
Antibody response is to the toxin (not the organism)
Clostridium botulinum
lab tests
Robotulism
gram (+) bacilli
Obligate Anaerobe
Spore forming
Clostridium botulinum
MOA
Robotulism
Improper canning of food → C. botulinum grows in the anaerobic environment → produces heat stable toxin (a protease)
Cleaves SNARE protein (sim. to tetany toxin) but attacks the motor neurons that release ACh → inhibiting motor neuron release → flaccid paralysis
Toxin is unable to cross the BBB → only the peripheral nervous system
Clostridium botulinum
signs and symptoms
Robotulism
Flaccid paralysis
Descending paralysis (opposite of Guillen barre)
Multiple people
Early symptoms include ptosis (droppy eyes) and diplopia (double vision)
*“Floppy baby syndrome”
Clostridium botulinum
Source of toxin:
Babies vs. Adults
Robotulism
Adults:
Get the toxin by ingestion of pre-formed antigen from improperly canned foods.
Babies:
Get the toxin by ingestion of spores. (*HONEY!!!)
Babies lack robust flora in the gut to out compete C. botulinum → C botulinum will colonize → toxin produced → Floppy baby syndrome
Clostridium difficile
lab tests
Field trip to the chocolate factory
gram (+) bacilli
Obligate Anaerobe
Spore forming
Assay to detect TOXIN in stool
Clostridium difficile
VF
Field trip to the chocolate factory
2 exotoxins:
Exotoxin A: Binds to the brush border of intestine → causes inflammation, cell death, and watery diarrhea.
Exotoxin B: disrupts cytoskeleton integrity by depolymerizing actin → enterocyte death and necrosis → Yellow grey exudate forms pseudomembrane that covers the colonic mucose (a pseudomembranous colitis)
Clostridium difficile
source
Field trip to the chocolate factory
Caused by poorly washed hands (Nosocomial diarrhea) transfering spores
or
Antibiotics (Clindamycin) wiping out normal flora allowing C. difficile to colonize then create the toxins.
Clostridium difficile
treatment
Field trip to the chocolate factory
Oral Vancomycin
Metronidazole
Fidaxomicin *
* (mentioned in lecture and on a UWorld question, but is not in FA 2018 or sketchy)
Clostridium perfringes
lab tests
Private Ringen’s Motorcycle Accident
gram (+) bacilli
Obligate Anaerobe
Spore forming
Double zone of hemolysis
Clostridium perfringes
signs and symptoms
Private Ringen’s Motorcycle Accident
Large amounts of flesh exposed to dirt and dust
(* Motorcycle accidents or deep penetrating military combat wounds)
C. perfringes causes Gas Gangrene. Clostridial myonecrosis, gas produced under the tissue and has a cracking sound on palpation.
Slow onset watery brown diarrhea due to spores first needing to reproduce in the gut before producing the toxin
Clostridium perfringes
VF
Private Ringen’s Motorcycle Accident
α toxin effects lipid bilayer and lyses RBC’s
lecithiinase, a phospholipase, involved in myonecrosis and can cause red cell hemolysis
Clostridium perfringes
treatment
Private Ringen’s Motorcycle Accident
IV Penicillin G
Corynebacterium diphtheria
lab tests
Corazon de la Corrida (Heart of the bullfight)
gram (+) bacilli
C. diphtheria is club shaped and y or v shaped
Non-spore forming
Metachromatic granules that stain (Red) with aniline dyes (rest of cell stains blue)
Plate on Tellurite and Loeflers media
Eleks test: in-vitro assay w/ antitoxin onit to determine if toxic or non-toxic strain
Corynebacterium diphtheria
MOA
Corazon de la Corrida (Heart of the bullfight)
Found in throat and tonsil, transmitted by respiratory droplets.
2 subunits A and B (A is active and B is binding)
Toxin causes ribosylation of EF2 (elongation factor) → inhibits ribosome function → inhibits protein synthesis → cell death
Leads to pseudomembranous exudate in oral pharynx
Will damage myelin of nerve fibers → neuropathy
Corynebacterium diphtheria
signs and symptoms
Corazon de la Corrida (Heart of the bullfight)
* Immigrants most likely to get C. diphtheria
Can cause airway obstruction and lymphopathy → * bulls neck (thickening of the neck)
Myocarditis like arrhythmias and heart block (lethal effect).
Neuropathy from damaged myelin.
Corynebacterium diphtheria
Vaccines
Corazon de la Corrida (Heart of the bullfight)
DTaP vaccine
Given with tetanus and pertussis
It is a Toxoid vaccine
Listeria monocytogenes
lab tests
Santa’s List
gram (+) bacilli
ß hemolytic
Catalase (+)
Listeria monocytogenes
MOA
Santa’s List
Facultative Intracellular: (“Actin Rocket”)
Rapidly polymerizes actin along the cell wall allowing it to move quickly inside the cell.
Extracellular:
Tumbling motility using flagella
Listeria monocytogenes
Source
Santa’s List
Listeria survives AND multiplies in near freezing temperatures and can contaminate food even if refrigerated.
* Milk and cheese
Listeria monocytogenes
Pregnancy
Santa’s List
Pregnant women are more likely to get listeria then anyone else. (adults over 60 also high risk)
May lead to termination or disease in the newborn.
Newborns can get meningitis from the mom.
Listeria monocytogenes
treatment
Santa’s List
Ampicillin
