Microbiology

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Microbiology

• Laboratory Procedures

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• Microbiology the study of microbes (bacteria,
  fungi, and viruses)
• Bacteriology study of bacteria
• Virology study of viruses
• Mycology study of fungi
• Most microbes found on or in the body are
  non-pathogenic, however these organisms can
  produce significant disease if located elsewhere.

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Bacteria are a. Prokaryotic unicellular
organism lacking a true nucleus nuclear
membrane, having genetic material composed of a
single molecule of DNA. b. microscopic organisms
c. reproduce using binary fission d. very
complex despite their small size.
http//learn.genetics.utah.edu/content/begin/cells
/scale/
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Most bacteria come in one of three basic shapes
coccus, rod or bacillus, and spiral
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Arrangements of Cocci

• The coccus
• The cocci are spherical or oval bacteria having
  one of several distinct arrangements based on
  their planes of division.

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diplococcus cocci arranged in pairs
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streptococcus cocci arranged in chains
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a tetrad cocci arranged in squares of 4
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sarcina cocci in arranged cubes of 8
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staphylococcus cocci arranged in irregular,
often grape-like clusters
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II. The rod or bacillus Bacilli are rod-shaped
bacteria. Bacilli all divide in one plane
producing a bacillus, streptobacillus, or
coccobacillus arrangement.
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bacillus single bacilli
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streptobacillus bacilli arranged in chains
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III. The spiral Spirals come in one of three
forms, a vibrio, a spirillum, or a spirochete.
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vibrio a curved or comma-shaped rod
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spirillum a thick, rigid spiral
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spirochete a thin, flexible spiral
Borrelia
Leptospira interrogans
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IV Spores A few bacteria form intracellular
refractile bodies called endospores or
spores. Clostridium are spore formers and are
resistant to heat, desiccation, chemicals, and
radiation.

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Clostridium
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• The primary purpose of microbiology examinations
  is to identify bacterial pathogens.
• How do we do this ???
• -Size
• -Shape
• -Arrangement
• -Cemical Activity

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Bacterial Cultures

• The primary purpose of microbiology is to
  identify bacterial pathogens.
• Culture Media any material, solid, or liquid,
  that can support the growth of microorganisms.

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Types of Culture Media

• Typically prepared agar plates
• Agar dried sea algae
• Agar plates sea algae gelatin

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Types of Culture Media

• Enriched Media
• -Most used in veterinary practice
• -Created to meet the requirements of many
  bacteria
• -Basic nutrient media w/ extra nutrients added
  (egg, blood, serum)
• Ex. blood agar, chocolate agar

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Types of Culture Media

• Selective Media
• -Contain antibacterial substances which inhibit
  certain bacterial growth.
• -Allows the microbiologist to facilitate
  isolation of a particular genus of bacteria.
• Ex. MacConkey agar (contains crystal violet which
  supresses gram-positive bacteria)

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Bacterial Growth
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Specimen Collection

• Aspiration, swabbing (culturette) scraping
• Collection techniques depend on type of lesion,
  location on the body specific test desired

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Specimen Collection

• A complete patient history is vital!!
• Specimen collected aseptically ASAP after the
  onset of symptoms.
• Label specimen container
• Take your time!!

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Grow Your Colonies ?
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Stain For ID

• Gram Stain used to categorize bacteria as either
  gram or gram on the basis of cell wall
  structure.
• Kits contain crystal violet, Grams iodine, a
  decolorizer, and safranin.
• Purple bacteria gram
• Red bacteria gram -

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Mycology

• Fungal study
• Most common fungus studied in veterinary medicine
  dermatophytes / ringworm
• Ringworm invades, skin, nails hair

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• Most common types of ringworm seen in veterinary
  medicine
• -Microsporum canis causes symptoms in dogs,
  cats, humans sometimes other species.
• -Microsporum gypseum causes symptoms in dogs,
  horses, and sometimes other species.

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Dermatophyte Testing

• DTM (standard dermatophyte test medium)
• Turns red in the presence of dermatophytes
• The presence of the red color is not enough for
  diagnosis b/c bacterial contaminants and
  nonpathogenic fungi can cause a positive color
  rxn.

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Woods Lamp Testing

• Microsporum may fluoresce under a black light (
  Woods Lamp)
• Approx 60 of Canis will fluoresce.
• No fluorescence on Woods lamp DOES NOT RULE OUT
  ringworm infection.

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Positive Woods Lamp Exam
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Malassezia (Yeast)

• Commonly found on the skin / ears of dogs and
  cats.