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74 Cards in this Set

  • Front
  • Back
what is the etiological agent of anthrax?
Bacillus anthracis
describe the characteristics of Bacillus anthraxis
Gram positive
spore forming
encapsulated rods
when are spores formed from Bacillus anthraxis?
Spores are formed after the organism has been shed from the body
what type of respiration does B. anthracis use?
Aerobic respiration
what is unique about Bacillus anthracis?
it is the only bacterium with a capsule composed of protein
what is the function of the capsule in Bacillus anthracis?
prevent phagocytosis
what are the 3 components of the B. anthracis toxin?
1. Edema factor
2. Lethal factor
3. Protective factor
How do the toxins from B. anthracis act?
B. anthracis toxin act locally on skin and lung. Individually the components have no biological effect by toxicity is produced either of the 1st two factors together with the Ag
How do you acquire a B. anthracis infection?
humans are an accidental host
spores enter abrasion on skin or inhaled
what type of diseases are caused by B. anthracis?
Woolsorter's disease
Cutaneous Anthrax
Intestinal Antrhrax
describe the infection of cutaneous anthrax
spore enters cut > Lesion with black rim + edema > can be treated with antibiotic
If not treated can lead to death due to bacteremia
Woolsorter's disease is caused by what?
Respiratory anthrax
this occurs following inhalation of B. anthracis spores
B. anthracis is inhaled > spores germinate in the lungs phagocytes > bacteria enter blood releasing exotoxin > respiratory distress syndrome > death
which type of B. anthracis infection commonly results in death?
Gastrointestinal antrax
describe the course of B. anthracis in the gut.
Spores ingested in uncooked meat > replicates in gut > releases exotoxin > necrotic lesion in intestine > abdominal pain, bleeding, fluid filled vesicles > death
why does anthrax carry such a high mortality rate?
the release of exotoxin
Is B. anthracis fastidious?
NO grows well on simple media
what is a diagnostic for B. Anthracis?
stained with polychrome methylene blue (McFadyean reaction)
what encourages the formation of a capsule and smooth colonies by B. Anthracis?
growth in CO2
what is the difference between food intoxication and food poisoning
food intoxication: etiological agent pre-formed before ingestion
food poisoning: etiological agent forms toxin once entered body
what disease does Bacillus cereus cause?
food poisoning/intoxication
what are the virulence factors of B. cereus
Heat stable toxin: food associated with spore germination which leads to vomiting within 1-5 hours
Heat liable enterotoxin: after ingestion created and leads to diarrhea within 10-15 hours
where is Bacillus cereus usually found?
on many food especially rice and vegetables
what are the distinguishing features of Bacillus cereus?
large gram positive spore forming rods
motile and non-encapsulated
aerobic respiration
which member of the Bacillus family produces hemolysis on horse and sheep blood agar?
Bacillus cereus
Can Bacillus cereus utilize mannitol?
what temperature should food be cooked at to get rid of Bacillus cereus?
160 degrees
If Bacillus cereus is found in an immunocompromised patient what is most likely going to happen? how do you treat it?
can turn into a bacteremia
treat with gentamycin, vancomycin, ciprofloxacin, or clindamycin
what do you do to treat a patient that is infected with Bacillus cereus and is not immunocompromised?
the illness is usually self limiting
what are the Clostridium bacteria responsible for causing disease in?
Gas Gangrene
Pseudomembranous colitis
which species of Clostridium is responsible for production of botulism toxin?
C. botulinum
true or false
botulism is a food borne intoxication rather than an infection
What type of respiration does Clostridium Botulinum use?
strict anaerobe
True or Fasle
Botulinum toxin is the most potent toxic known
what is the pH range that C. botulinum can be found in?
7-7.3 for growth initiation and toxin production
describe the transmission of C. botulinum
released only upon autolysis of cell
absorbed in small intestine
how does C. botulinum intoxicate the host?
intoxication is associated with disturbances of the PNS function
Toxins specifically acts at the neuromuscular junction to produce complete paralysis of cholinergic nerve fibers at the point of ACh release
-blocks stimulation by excitatory transmission
Death occurs due to paralysis of respiratory organs
Patient may experience diplopia or dysphagia
what is the incubation period for C. botulinum
8-36 hours but may be as late as 8 days after ingestion of toxin
how is the C. botulinum toxin inactivated?
inactivated by heating to 100 degrees C for 10 minutes or 85 degrees C for 30 minutes
what type of antitoxin is available for treat of C. botulinum
Polyvalent antitoxin
what allows for the C. botulinum to be motile
Peritrichous flagella
what is a way to ID C. botulinum in the clinical lab setting?
heat resistant oval spore that is subterminal and larger than the cells
what type of infection has been indicated from giving honey to infants?
C. botulinum
the toxin and vegetative organism have been isolated in the stool
what is the difference in treatment between an adult with botulism and a baby with botulism poisoning
adults get botulism from ingesting food with the neurotoxin present > flaccid paralysis > need for intubation> and ventilatory support
Infant can acquire the poisoning through the ingestion of honey with the bacteria present > toxin produced in infant GI tract > muscle weakness and difficulty swallowing > floppy baby > hospitalization & supportive care
how is Clostridium tetani transmitted?
classically follows a puncture wound by a rusty nail but can also follow skin trauma because the C. tetani is found in the soil
what is the molecular weight of C. tetani?
68000 daltons
True or False
Clostridium tetani is extremely toxic
how is C. Tetani identified clinically
incubation is 4-10 days
muscle stiffness followed by spasms of the masseter muscles. Tetanospasmins cause clenching of the jaw producing grimace, arched back, and flexed arms, extension of lower limbs
where is the site of action located for the C. Tetani toxin?
what is the end result of intoxication with C. tetani toxin?
excitation of the central nervous system and blocking of synaptic inhibition in the spinal cord at the inhibitory terminals that use glycine and GABA as NT
is there a vaccine for Clostridium tetani?
DPT: diptheria, pertusis, and tetani
how is immunity to Clostridium Tetani maintained?
a single booster every ten years
what type of complications are common with a C. tetani infection?
respiratory complication
aspiration pneumonia, atelectasis
where does the tetani toxic bind?
C. tetani toxin binds to ganglioside in synaptic membrane
dependent upon number and position of sialic acid residue in ganglioside
how is the disease caused by C. tetani?
blocking of inhibitory release of NT leading to constant stimulation of muscles
how is a person with C. Tetani treated?
with antisera
clean wound
supportive care
Hyperbaric chamber promotes healing and killing of the strict anaerobes
True or False
both C. Tetani and C. botulinum can cause respiratory failure but through two different mechanism.
what species of Clostridium causes gas gangrene?
Clostridium perfringens
what is the most commonly involved type of clostridium with wound infection?
Clostridium perfringens
what are the three levels of infection caused by C. perfringens?
1. simple contamination
2. Anaerobic cellulitis
3. Clostridial Myonecrosis
Describe the simple contamination caused by C. perfringens
due to ubiquity of clostridia, most wounds are contaminated with these organisms. Germination and growth are not common in these cases
What occurs in anaerobic cellulitis caused by C. perfringens
Clostridial pores germinate and vegetative cells grow in DEAD tissue. This form is usually not life threatening unless not treated
what is the life threatening infection called by Clostridium perfringens? describe
clostridal myyonecrosis
spreads quickly from dead tissue and kills adjacent living tissue, the incubation period is short and victim may go into irreversible shock
where is Clostridium perfringens found?
in soil and GI tract of humans and animals
what are the distinguishing characteristics of C. perfringens?
rods with subterminal spores, double zone of hemolysis on BAP, antigenic typing
what other types of infections may Clostridium perfringens be involved in?
uterine infection following abortion
septicemia usually associated with malignancy
what are the treatments for a Clostridium perfringens infection?
Extensive debridement
Hyperbaric chamber, increased oxygen concentration
what is the pathogen associated with antibiotic associated pseufomembranous colitis?
Clostridium difficile
what does Clostridium difficile cause? how?
Pseudomembranous colitis
when a patient has been given other antibiotics they kill off the normal flora anaerobes and this allows C. difficile to grow at high numbers because it is usually suppressed with all the other bacteria growing. When it grows in high numbers it produces exotoxins
How do you treat a patient with C. difficile?
Vancomycin because most of the time C. diff is resistant to other antibiotics
what type of toxin does C. difficile produce?
heat labile enterotoxins A and B which damage epithelial lining the bowel
how is C. difficile transmitted?
it is an opportunistic pathogen that is the normal floral of the gut
How would you clinically diagnose a C. difficile infection?
Toxin in feces by immunoassay or tissue culture cytotoxicity culture
true or false
Pseudomembranous colitis can be rapidly fatal especially in a compromised host
what confirms the diagnosis of Clostridium difficile?
toxin in the stool