Bacterial Morphology

• morphology refers to the shape and size of a bacteria
• 0.25 - 1 micrometer in width and 1-3 micrometer in length
• neisseria spp. and streptococcus pneumoniae

  diplococci
• streptococcus spp.

  cocci in chain
• micrococcus tetragena

  tetrads
• micrococcus luteus


  sarcina
• staphylococcus spp.

  cocci in cluster
• found in ocean residue (African coast)

  thiomagarita namibienses
• small and short bacillus ex. Haemophilus

  fingerprint pattern
• large, square cut ends, spore forming bacillus

  ex. Bacillus anthracis


  arranged in chain
• large, rounded ends, non spore forming bacillus

  ex. fusobacterium spp.


  arranged in chain
• arrange in serpentine cord or crawling snake ex. mycobacterium tuberculosis

  slim, slender like bacillus
• branching or filamentous bacilli ex. Nocardia spp.
• Irregular baccili

  • club shaped
  • remembers X,Y,Z or Chinese characters
  • ex. corynebacterium diphtheriae
• Curved or comma bacillI

  • Vibrio spp.
• S or C shaped bacilli

  • resembles seagul wing
  • Helicobacter spp.
  • Arcobacter spp.
• Spiral with two or more curves

  • quite rigid
  • ex: Spirilum minor
  • rat bite infection
• Loosely twisted spiral

  • resembling stretch spiral
  • Borrelia spp.
  • Lyme disease
• Tightly twisted spiral

  • corkscrew
  • ex: Treponema palladium
  • syphilis
• Tightly twisted spiral with one or both ends bent into hook

  • interrogative symbol
  • Leptospira interrogans
  • Leptospirosis
• Direct/Simple Stain

  • Crystal violet
  • Methylene blue
  • Malchite Green
• Differential stain

  • contains two or more chromogens
• Gram staining differentiates gram positive: violet from gram negative: red/pink
• Acid fast staining differentiates AF organism: Red from Non AF organism: Blue/Green
• Fluorochrome stain uses fluoresrescent dyes such as auramine or rhodamine or both
• Pappenheim

  • Mycobacterium tuberculosis - Red
  • Mycobacterium lacticola - Blue
• Baumgarten Stain

  • Mycobacterium tuberculosis - Blue
  • Mycobacterium leprae - Red
• Stain for cell wall

  • Victoria blue dye - stains blue
• Stains for Capule

  • HISS - Pale brown
  • TYLER -light violet
  • MUIR - light blue
  • GIN - unstained capsule
  • WADSWORTH - Capsule-Pink Bacteria - Blue
  • WELCH - pale violet
• Stain for Granules

  • Loeffler Alkaline Methylene Blue - Red
  • ALBERT - Blue black
  • NEISSER - Dark blue
  • LINDERGAN - reddish brown
  • BURKES TECHNIQUE - modified gram staining technique
  • LJUBINSKY - dark violet
• Stains for Bacterial Spores

  • FULTON SCHAFFER - Green
  • DORNER -Red
  • WIRTZ CONKLIN - Green
• Stains for Flagella

  • Gray
  • Silver
  • Fisher conn
  • Leifson
• Stains for Rikettsia

  • CASTAÑEDA - blue
  • MACHIAVELO - red
  • GIEMSA - blue
• Stains for Chlamydia

  • GIMENEZ - red
  • MACHIAVELO - red
  • GIEMSA - purple
• Stains for Mycoplasma

  • DIENES - blue
• Stains for Bipolar Bodies (Yersinia pestis)

  • WAYSON - red
• SIZE

  • PINPOINT - colonies less than 1mm
  • SMALL - slightly the same size of pinhead
  • MEDIUM - slightly larger than pinhead
  • LARGE - 6-8mm
• Smooth - circular without interruption
• Undulate - wavy edge
• Rhizoid- crenated edge