micro ex 4

What are the three general groups of the Gram‑positive bacilli of medical importance?

endospore formers, non endospore formers, irregular shaped & staining properties

What bacilli are the endospore‑formers?

bacillus, clostridium

What bacilli are the NON‑endospore‑formers?

listeria, erysipelothrix

Which genera of bacilli have irregular shaped and staining properties?

corynebacterium, propionibacterium, mycobacterium, actinomyces, nocardia

What are the two spore‑forming Bacilli genera?

Genus bacillus, genus clostridium

What are the general characteristics of the genus Bacillus?

gram positive

endospore forming

motile rods

What is Bacillus a source of?

antibiotics

What is the primary habitat of Bacillus?

soil !

What are the 2 species of medical importance in the genus Bacillus?

Bacillus anthracis

Bacillus cereus

What are the virulence factors of Bacillus anthracis?

polypeptide capsule + EXOtoxins

List the 3 types of anthrax.

cutaneous

pulmonary

gastrointestinal

For cutaneous anthrax: how do spores enter, what forms, and what is its danger level?

spores enter thru skin,

black sore “eschar” forms

least dangerous (anthrax)

For pulmonary anthrax: how do spores enter the body?

inhalation of spores

For gastrointestinal anthrax: how do spores enter the body?

ingestion of spores

How is anthrax treated?

with antibiotics

What are the two types of vaccines mentioned?

live spores + toxoid to protect livestock

purified toxoid for high risk jobs & military personnel

What diseases does the genus Clostridium give rise to?

botulinum, gas gangrene, tetanus, and rlly bad diarrhea

How does your notes describe the Clostridium as a group overall?

large diverse group of anaerobes

What is the Gram reaction and shape of Clostridium?

gram positive rods

What does your notes say these Clostridium organisms generally “cause”?

dangerous diseases or rlly bad diarrhea

Despite being pathogenic, where is Clostridium actually part of your normal flora?

LOWER gi tract and rarely your mouth

List the 4 major species of Clostridium from your notes.

C. botulinum

C. difficile

C. perfringens

C. tetani

According to your notes, what does being an anaerobe mean?

oxygen can harm some of Clostridium microbes

Why does it make sense that Clostridium like to live in the lower GI?

bc there is little oxygen there

What “bummer” does fermentation by these Clostridium microbes create?

fermentation creates gas

What is true of ALL Clostridium species regarding spores?

all clostridium species are spore formers

What do Clostridium cells look like most of the time, and what do they look like when forming spores?

Usually look like rods, look like tennis rackets when forming spores

What does your notes say about Clostridium spores in terms of resistance among living cells?

Bacterial spores are among the most resistant of all living cells.

What did the 1995 Cal Tech scientist discover about Clostridium spores?

Spores from digestive tract of bees entombed in amber for 40 mil years were still viable

What extreme condition can some Clostridium spores resist involving a rocket exhaust?

3000 deg celsius heat

What extreme condition have other Clostridium spores survived involving liquid helium?

-269 deg celsius bathed

What happens once Clostridium spores are made?

they wait and sit around for more favorable conditions to grow in

Where are Clostridium spores found?

in soil

Why have Clostridium species (and Bacillus anthracis) been routinely studied as potential biological weapons?

because of their high resistance in extreme conditions

How do Clostridium spores infect humans, and what condition do they need to start causing disease?

as soon as they infect humans and find a moist warm anaerobic spot —> can start causing disease

What temperature and time are usually required to kill Clostridium spores?

100 deg celsius for 3-5 hrs

If Gram (+) rods AND spores are seen under the microscope, what organisms are suspected?

Clostridium and Bacillus

What disease is Clostridium perfringens the cause of?

Gas gangrene

What rank does Clostridium perfringens hold among causes of food poisoning, and what food is it usually associated with?

3rd most common cause of food poisoning, due to contaminated meat

Why does Clostridium perfringens cause different diseases?

bc it depends on where it invades

For C. perfringens food poisoning: what must happen for someone to get sick?

they must ingest a LOT, 1mil to 10mil organisms per gram of food to even get sick

Is C. perfringens food poisoning an intoxication or an infection? (And what actually makes you sick?)

it's an infection, but the enterotoxin A produced by ingested bacteria is what makes you sick

Under what conditions does C. perfringens food poisoning usually occur?

When undercooked food (toxins aren’t inactivated) sits around in conditions that allow bacteria germination AND growth

What is the onset time for symptoms of C. perfringens food poisoning, and what symptoms occur?

8-18 hrs, nausea, abdominal cramping, diarrhea

How long does C. perfringens food poisoning last?

24 hours

Why do many people not realize they had food poisoning from C. perfringens?

they don’t exp vomiting, so they think they just had the “24 hr flu”

What serious condition related to C. perfringens has been reported, and what is its mortality rate?

necrotizing bowel disease with a high mortality rate of 50% (sporadically reported)

What is another way C. perfringens can enter the body besides ingestion?

wound infection

Why are wound infections often complicated (according to your notes)?

multiple bacteria are working together

Can C. perfringens be present in a wound without causing the infection?

Yes! or it only takes a secondary role

If C. perfringens IS causing disease in a wound, what are the two possible pathways?

Anaerobic cellulitis

gas gangrene

In anaerobic cellulitis, where does the bacteria spread, and does it invade the muscle?

(What tissue space?)

Fascial space aka fasciitis , NO it doesn’t invade muscle

What type of tissue does anaerobic cellulitis usually destroy?

unhealthy tissue

What kinds of diseases predispose someone to anaerobic tissue conditions?

Diseases that decrease blood circulation to tissue, e.g. atherosclerosis, diabetes

What does “myo” mean?

muscle

Why does gas gangrene produce gas?

the bacteria c. perfringens is a fermenter, fermentation always = gas

What does the gas cause on physical exam, and what is this called?

crackling on palpitation aka “crepitation” or “crepitus”

Does gas gangrene kill healthy or unhealthy tissue?

healthy tissue :(

What systemic problems can gas gangrene lead to?

fever, sepsis, etc

How fast does gas gangrene move, and what drastic measure is often required?

very fast, often requires limb amputation

Besides surgery, what other treatment is mentioned for gas gangrene?

hyperbaric oxygen

For gas gangrene and C. perfringens, what infection must be ruled out because it can look similar?

Group A strep infections caused by Strep pyogenes

What is the main symptom associated with Clostridium difficile?

diarrhea !

What two conditions is C. diff a cause of?

antibiotic-associated diarrhea

pseudomembranous colitis

What has happened to the frequency of C. diff infections over time?

become more frequent!!

Do healthy people ever carry C. diff?

yes, a small # of healthy ppl carry it

How does the percentage of C. diff carriers in hospitals compare to healthy people?

LARGE % of ppl in hospitals carry c. diff

How is C. diff spread?

passed in feces, spreads from unwashed hands

Is c. diff easy to spread?

YES !! highly contagious + easy to spread

Is C. diff opportunistic, and what makes it become opportunistic?

yes its opportunistic, and it becomes opportunistic bc antibiotics kill off normal flora (giving it the chance to take over)

What symptom does C. diff cause that is uncomfortable but not life‑threatening?

loose stools

What serious, life‑threatening condition can C. diff cause?

pseudomembranous colitis

What is the first step in treating a C. diff infection?

getting off antibiotics to take other antibiotics

What additional supportive treatment can be added for C. diff?

can also take probiotics

What unusual but effective treatment can be used for patients with recurring C. diff infections?

stool transplant (donor stool), for patients with recurring infections which recolonizes with normal flora

What disease does Clostridium botulinum cause?

botulism

What is botulism caused by — the organism itself or something it produces?

the neurotoxin c. botulinum produces

How potent is the botulinum neurotoxin according to your notes?

one of the most potent poisons

What does the botulinum neurotoxin block?

NMJ, aka neuromuscular junction

What two major symptoms result from this neurotoxin’s action? (C. botulinum)

blurred vision

flaccid paralysis

Do you need to be infected with the organism itself to get botulism?

no, contact isn’t needed. solely ingesting toxin-contaminated food can give you botulism

Where are C. botulinum spores found in relation to food?

during the gathering and processing

What happens if proper temperature and pressure are NOT achieved during food processing (C. botulinum)?

anaerobic conditions where air is evacuated, but spores remain

What conditions favor spore germination and vegetative growth?

anaerobic conditions — favor spore germination and vegetative growth

What potent toxin is released once the spores germinate for C. botulinum?

“botulin” = toxin

What does the toxin “botulin” do once it reaches neuromuscular junctions?

it blocks the release of acetylcholine, which is necessary for muscle contractions to occur

How can botulinum toxin be prevented from causing disease?

toxin can be inactivated at boiling temps

What is the treatment for botulism?

antitoxin + supportive measures

What is the reservoir for Clostridium tetani?

soil + gi tract of animals

What disease does Clostridium tetani cause?

tetanus, aka “lockjaw”

Which 3 groups are most commonly affected by tetanus?

geriatric (older) patients,

IV drug abusers,

neonates (newborns) in developing countries

Through what kinds of injuries do C. tetani spores usually enter the body?

accidental puncture wounds, burns, umbilical stumps, frostbite, crushed body parts

What is the name of the neurotoxin produced by C. tetani?

tetanospasmin

What does tetanospasmin bind to, and what does it block?

it binds to the neuromuscular junctions and blocks the release of neurotransmitter for muscular contraction inhibition —> caused muscles to tighten uncontrollably

What is the most common cause of death in tetanus?

paralysis of respiratory muscles (they cant breathe)

What is the overall goal of tetanus treatment?

deter degree of toxemia / infection + maintain homeostasis

What therapy is used to inactivate circulating toxin for C. tetani?

antitoxin therapy

Why can’t antitoxin therapy reverse all symptoms for tetanus?

it inactivates circulating toxin, but can’t counteract already bound toxins

What antibiotics can be used to control C. tetani infection?

penicillin and tetracycline

What other supportive medication may be used to help with tetanus symptoms, and how often is the booster needed?

a muscle relaxants vaccine, Tdap! Needs booster every 10 years