BACILLUS
a genus of Gram-positive bacteria
ubiquitous in nature
(soil, water, and airborne dust).

Some species are natural flora in the human intestines.
most species of Bacillus are harmless saprophytes
two species are considered medically significant:
B.anthracis and B. cereus
B. anthracis
causes anthrax in cows, sheep, and sometimes humans.


Anthrax
transmitted to humans via direct contact with animal products
or inhalation of endospores
cells appear to have square ends
• Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis.

• -most commonly occurs in wild and domestic lower vertebrates (cattle, sheep, goats, camels, antelopes, and other herbivores)

• - also occur in humans when they are exposed to infected animals or tissue
• transmitted to humans via direct contact with animal products

• - or inhalation of endospores
CUTANEOUS INFECTION (95% of human cases)
INHALATION ANTHRAX (rare but fatal)
GASTROINTESTINAL ANTHRAX (very rare!)

• Anthrax is most common in agricultural regions where it occurs in animals
it is usually due to an occupational exposure to infected animals or their products
• vaccine is reported to be 93% effective in protecting against anthrax.
Who should be vaccinated
B. cereus
• cause toxin-mediated food poisoning
inhabit many kinds of food including stew, cereal, and milk.
been found in fried rice.
toxins released by the bacterium lead to vomiting and diarrhea, symptoms similar to those of Staphylococcus food poisoning.
proper cold storage of food is recommended immediately after preparation.
LACTOBACILLUS
non-spore-forming bacterium
ferment glucose into lactose, hence the name Lactobacillus.
most common application is industrial-dairy production.
natural flora of the human vagina.
create an acidic environment derive lactic acid from glucose

• Acidic environement inhibits growth of many bacterial species which can lead to
urogenital infections.
generally harmless to humans

• Treatment
- consists of high doses of penicillin in combination with gentamicin.
• promoted as good probiotics for human usage—
Prebiotics ---refers to the soluble fiber component found in certain foods or supplements that stimulate the growth of probiotics in the gastrointestinal tract.
• Lactobacillus Acidophilus
-most commonly used probiotic
Such healthy bacteria inhabit the
intestines and vagina
• -protect against the entrance and
proliferation of "bad" organisms that
• can cause disease.
• the breakdown of food by L. acidophilus leads to production of
• lactic acid
• hydrogen peroxide
•
• and other byproducts that make the environment hostile for undesired organisms
• L. acidophilus also produces lactase, the enzyme that breaks down milk sugar (lactose) into simple sugars
• Probiotics offer a variety of potential therapeutic uses
-Replacing the "friendly" intestinal bacteria destroyed by antibiotics.
Aiding digestion and suppressing disease-causing bacteria.
-Preventing and treating diarrhea
• uses
• Alleviating symptoms of irritable bowel syndrome and, possibly, inflammatory bowel disease
Preventing and/or reducing the recurrence of vaginal yeast infections, urinary tract infections, and cystitis
Enhancing the immune response - yogurt
• Dietary Sources
The primary dietary sources of L. acidophilus include
• - milk enriched with acidophilus
• - yogurt containing live L. acidophilus cultures, miso, and tempeh.
• Available Forms
L. acidophilus preparations consist of dried or liquid cultures of living bacteria.
These cultures are usually grown in milk but can sometimes be grown in milk-free cultures.


• L. acidophilus is available in the following forms:
• Freeze-dried granules
• Freeze-dried powders
• Freeze-dried capsules
• Liquid L. acidophilus preparations (which must be kept refrigerated)

• How to Take It
• Prevention or treatment of diarrhea: 1 to 2 billion viable cells per day
• Vaginal infections: 8 ounces of yogurt

• Clinical experience also suggests that placing yogurt with live acidophilus cultures directly to the vaginal area
Corynebacterium diphtheriae
• Gram positive
strict aerobe
pleomorphic (e.g. club-shaped)
Diphtheria
• infection
– upper respiratory tract (pharynx)
– pseudomembrane
– chocking
– bacteria do not spread systemically
Diptheria toxin
• spreads
• systemic and fatal injury
Treatment
• anti-toxin
• antibiotic
Immunization against diphtheria
(infant)
• disease vanished in US
– without immunization will return
toxoid (+ pertussis and tetanus) DPT
• neutralizing antibodies
colonization not inhibited
– found in normal flora
Clostridium sp
relatively large, Gram-positive, rod-shaped bacteria.

All species form endospores

strictly fermentative mode of metabolism
will not grow under aerobic conditions

vegetative cells are killed by exposure to O2
spores are able to survive long periods of exposure to air


clostridia are ancient organisms
live in virtually all of the anaerobic habitats of nature
where organic compounds are present
soils, aquatic sediments and the intestinal tracts of animals
Clostridium botulinum
Botulism
Botulin is the poison
canning meat, fish, fruits and veggies
In the US an average of 110 cases of botulism are
reported each year
• food poisoning
– rare
– fatal

• germination of spore
• inadequately sterilized canned food
– home
• not an infection
Botulinum toxin
• binds peripheral nerve receptors
– acetylcholine neurotransmitter
• inhibits nerve impulses
• flaccid paralysis
• death
– respiratory
– cardiac failure
Infection with C. botulinum
• Neonatal botulism
– uncommon
– the predominant form of botulism
– colonization occurs
• no normal flora to compete
• unlike adult
Botulinum toxin
• Bioterrorism
– not an infection
– resembles a chemical attack
Treatment
• anti-toxin
• antibiotic therapy (if infection)
Clostridium difficile
"difficile," because they are difficult

pseudomembranous colitis
endoscopy -big white spots
• After antibiotic use
• intestinal normal flora
– greatly decreased
• colonization occurs
• enterotoxin secreted
• pseudomembanous colitis
Therapy
• discontinuation of initial antibiotic (e.g. ampicillin)

• specific antibiotic therapy (e.g. vancomycin)
Clostridium perfringens
invasive pathogen

huge array of invasins and toxins
causes wound and surgical infections
severe uterine infections
• soil, fecal contamination
• war
• gas gangrene
– swelling of tissues
– gas release
* fermentation products
• wound contamination
gas gangrene
foot rot, or boot rot
the foot and leg swell up due to the gas produced
the gas bubbles out
• It smells really fetid like the putrid smell of rotted meat
Pathogenesis
• tissue degrading enzymes
– lecithinase [" toxin]
– proteolytic enzymes
– saccharolytic enzymes

• destruction of blood vessels
• tissue necrosis
• anaerobic environment created
• organism spreads

Without treatment death
occurs within 2 days
Ø effective antibiotic therapy
Ø debridement
Ø anti-toxin
Ø amputation & death is rare

Clostridium tetani
A severe case of tetanus.
muscles, back and legs are rigid
muscle spasms can break bones
can be fatal (e.g respiratory falure
• Non-invasive
Tetanospasmin
• disseminates systemically
• binds to ganglioside receptors
– inhibitory neurones in CNS
• Blocks release of glycine
– Inhibitory neurotransmitter
• stops nerve impulse to muscles
• spastic paralysis
• severe muscle contractions and spasms
• can be fatal
Vaccination
• infant
• DPT (diptheria, pertussis, tetanus)
• tetanus extremely uncommon in US
• tetanus toxoid
– antigenic
– no exotoxic activity