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Spore Forming and Non-Spore Forming Gram-positive Bacilli


Spore Forming and Non-Spore Forming Gram-positive Bacilli SBM 2044 Medical Microbiology Second year UG of BBiomedic Sc Spores Why do bacteria produce spores? – PowerPoint PPT presentation

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Title: Spore Forming and Non-Spore Forming Gram-positive Bacilli

Spore Forming and Non-Spore Forming Gram-positive
  • SBM 2044
  • Medical Microbiology
  • Second year UG of BBiomedic Sc

  • 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.

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
  • B. anthracis infection in human through injured
    skin (cutaneous anthrax), mucous membranes (GI
    anthrax), or inhalation of spores into lung.

Bacillus anthracis
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

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.

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

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

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.

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

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.

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

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

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

Corynebacterium diphtheriae
  • Blood agarpotassium tellurite, tellurite is
    reduced intracellularly

Corynebacterium diphtheriae
  • In respiratory wounds, skin of infected person
    spread by droplets or contact to susceptible
  • 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
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
  • Disease is principally result of the action of
    toxin formed rather than invasion by the organism

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.

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.

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.

  • Form chains or filaments, facultative anaerobes
  • 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
  • Commonly affecting cervicofacial, thoracic and
    abdominal actinomycosis.

(No Transcript)
  • http//textbookofbacteriology.net/
  • http//www.gsbs.utmb.edu/microbook/
  • Brooks Jawetz Medical Microbiology
  • Puan Intan Azura Shahdan
  • Room F2/A/2/73

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

Helicobacter pylori
Ffastidious, SFspore-forming
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