Spore Forming and Non-Spore Forming Gram-positive Bacilli

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Spore Forming and Non-Spore Forming Gram-positive
Bacilli

• SBM 2044
• Medical Microbiology
• Second year UG of BBiomedic Sc

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Spores

• Why do bacteria produce spores?
• Survival
• Classification
• Definition a resting cell, highly resistant to
  dessication, heat, and chemical agents when
  returned to favourable conditions bacteria
  re-activated, the spores germinate to produce
  single vegetative cells.

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SF Bacteria- Bacillus

• Aerobic, G rods in chains, spores are located in
  center of the non-motile bacilli
• Found in soil, water, air and vegetation
• Spores are viable for decades.
• B. cereus produce enterotoxin and cause food
  poisoning.
• B. anthracis infection in human through injured
  skin (cutaneous anthrax), mucous membranes (GI
  anthrax), or inhalation of spores into lung.

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Bacillus anthracis
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SF Bacteria- Bacillus

• Spores germinate in the tissue of entry, and
  growth of vegetative organisms result in
  formation of a gelatinous oedema and congestion.
• Spread via lymphatics to bloodstream and multiply
  freely in blood and tissues.
• Capsulated, poly-D-glutamic acid capsule is
  antiphagocytic

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SF Bacteria- Bacillus

• Anthrax toxin is made up of three proteins
• Protective antigen (PA), edema factor (EF) and
  lethal factor (LF).
• Treatment ciprofloxacin, penicillin G along with
  gentamicin and streptomycin.

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SF Bacteria - Clostridium

• Anaerobic, G, motile rods
• Many decompose proteins of form toxins.
• Found in soil, animal faeces.
• Spores is placed centrally, subterminally or
  terminally most species are motile with
  flagella.

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SF Bacteria - Clostridium

• Many form colonies with a zone of haemolysis on
  blood agar. C perfringens typically produce
  multiple zones of haemolysis around colonies.

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SF Bacteria - Clostridium

• C botulinum causes botulism
• -Distinguished by antigenic type of toxin
• Spores are resistant to 100C for many hours,
  diminished at acid pH or high salt.
• Toxin - 7 antigenic varieties (A ?G). A, B, E
  (F) mainly harmful to human.
• Botulinum toxin is absorbed from gut and binds to
  receptors of presynaptic nervous system and
  cranial nerves.
• Lethal dose to human 1-2 µg.

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SF Bacteria - Clostridium

• Pathogenesis
• Most cases, through ingestion of uncooked food.
• Toxin acts by blocking release of acetylcholine
  at synapses and neuromuscular junctions ? flacid
  paralysis.
• Symptoms such as visual disturbances, inability
  to swallow, speech problem seldom with no
  apparent GI symptoms no fever.

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SF Bacteria - Clostridium

• floppy baby infant botulism. C botulinum
  spores in babies food.
• Treatment antitoxins raised in horses.
• Trivalent (A, B, E) antitoxin must be promptly
  administered intravenously with precautions plus
  adequate ventilations.

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SF Bacteria - Clostridium

• Clostridium tetani cause tetanus.
• Distinguishable by specific flagellar antigens.
• Toxin binds to receptors on the presynaptic
  membranes of motor neurons.

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NSF bacteria

• Generally, members of normal flora of skin and
  mucous membranes of humans.

Aerobic G with High GC content, irregularly shaped Aerobic G with lower GC content, regularly shaped
Corynebacterium Propionibacterium Actinomyces Rhodococcus Listeria Lactobacillus Clostridium Bacillus
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Corynebacterium diphtheriae

• Infects nasopharynx or skin
• Mostly grow aerobically, non-motile
• Irregular swellings/clubbed-shaped granules
  within rod stained with aniline dyes.

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Corynebacterium diphtheriae

• Blood agarpotassium tellurite, tellurite is
  reduced intracellularly

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Corynebacterium diphtheriae

• In respiratory wounds, skin of infected person
  spread by droplets or contact to susceptible
  individuals
• Diphtheria toxin (Dt) is a heat-labile

Inhibits polypeptide chain elongation, by
inactivating EF-2 (with NAD) This abrupt arrest
of protein synthesis results in necrotizing and
neurotoxic effects of Dt.
Transporting A into cell
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Corynebacterium diphtheriae

• Pathogenesis is based upon (1) the ability of a
  given strain of C diphtheriae to colonize in the
  nasopharyngeal cavity and/or on the skin, and (2)
  its ability to produce diphtheria toxin.
• Pathology Dt absorbed into mucous membranes,
  causing destruction of epith and superficial
  inflammatory response. Necrotic epith embedded
  in exuding fibrinRBCWBC grayish
  pseudomembrane
• Disease is principally result of the action of
  toxin formed rather than invasion by the organism

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Corynebacterium diphtheriae

• Vaccination confers protection against disease by
  production of antibodies to the diphtheria toxin.
  The vaccine is produced from purified inactivated
  toxin from a strain of C. diphtheriae.
• Diphtheriae antitoxin (DTP) administered to
  infants, and followed by boosters.
• Treatment rapid suppression of toxin-producing
  bacteria by antimicrobial drugs at the earliest
  diagnosis of diphtheria.

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Listeria monocytogenes

• Small/Short, G,peritrichous flagella, rod. Grow
  on Mueller-Hinton agar (better in sheep
  blood-small zone of haemolysis) facultative
  anaerobe, motile at room temp, catalase
• Listeriosis results from ingestion of
  contaminated food such as cheese and vegie
  primarily affects pregnant women, newborns, those
  with weakened immune system.
• Able to multiply at low temp,
• hence accumulate in contami-
• nated food stored in refrigerator.

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Steps in the invasion of cells and intracellular
spread by L. monocytogenes.

• The bacterium apparently invades via the
  intestinal mucosa. It is thought to attach to
  intestinal cells by means of D-galactose residues
  on the bacterial surface which adhere to
  D-galactose receptors on susceptible intestinal
  cells  The bacterium is taken up by induced
  phagocytosis, which is thought to be mediated by
  a membrane associated protein called internalin.
  Once ingested the bacterium produces
  listeriolysin to escape from the phagosome. The
  bacterium then multiplies rapidly in the
  cytoplasm and moves through the cytoplasm to
  invade adjacent cells by polymerizing actin to
  form long tails.

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Actinomycetes

• Form chains or filaments, facultative anaerobes
  (CO2)
• Actinomycosis is a chronic suppurative and
  granulomatous infection that produces pyogenic
  lesions with interconnecting sinus tracts that
  contain granules. Most cases due to A israelii, A
  naeslundii.
• Commonly affecting cervicofacial, thoracic and
  abdominal actinomycosis.

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References

• http//textbookofbacteriology.net/
• http//www.gsbs.utmb.edu/microbook/
• Brooks Jawetz Medical Microbiology
• Puan Intan Azura Shahdan
• Room F2/A/2/73

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Pseudomonad, Pasteurella

• Pasteurella short G- rods with bipolar
  staining. Animals are their natural hosts in most
  cases.

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Vibrios
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Helicobacter pylori
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Gram-positive Gram-negative
Cocci
Bacilli
Ffastidious, SFspore-forming