Bacteriology Intro

• In the context of bacterial identification, what genus is specifically associated by being gm(+), catalase (+) and coagulase (+)?

  Staphylococcus aureus
• What is the characteristic property of the cell wall of bacteria belonging under "Mollicutes"?


  They are cell-wall deficient.
• What are the genus of bacteria belonging under "Mollicutes"?


  Ureaplasma and Mycoplasma
• What is the largest bacteria?

  Bacillus anthracis
• What is the smallest bacteria?

  Mycoplasma
• What is usually the common cause of UTI in sexually active young women?

  Staphylococcus saprophyticus
• What is the characteristic of Staphylococcus epidermidis that makes it biochemically different from Staphylococcus saprophyticus?

  S.epidermidis is sensitive to Novobiocin while S. saprophyticus is resistant
• What is the representative bacteria belonging to Group A Streptococcus?


  Streptococcus pyogenes
• What is the part of gram positive bacteria that is stained in gram stain? 


  Murein layer or Peptidoglycan layer
• Exotoxin = released by living gm(+) bacteria; effect is LOCALIZED

  Endotoxin = released upon cell death of gm(-) bacteria; effect is SYSTEMIC
• What are the specific bacteria that has specific virulence factors indicates below respectively?

  Protein A, M Protein, Muramic Acid

  Staphylococcus aureus, Streptococcus pyognes, Mycobacterium tuberculosis
• Lowenstein-Jenssen Medium (LJ) is used for specific isolation of what bacteria?

  Mycobacterium tuberculosis
• It is the process in which naked DNA of a bacteria is absorbed by another bacteria of the same species

  Bacterial Transformation
• It is the process in which two similar species of bacteria uses a sex pili to transfer genetic material from one to the other.

  Bacterial Conjugation
• It is a gm(-) coccobacilli that has a safety pin appearance when using Wayson Stain. Neisseria gonorrhea
• It is the bacteria that has a very thick Mycolic acid layer, resisting gram staining. Mycobacterium tuberculosis
• What is the average size range of a prokaryote?


  0.4 to 2 micra
• What is the longest bacterium?


  Genus Borrelia
• Mollicutes have a special property in which thier cell membrane has but all the other bacteria dont. This substance is called what?


  Sterol
• EXOTOXIN

  • produced by gram (+)/(-) organisms
  • It is protein in nature
  • It is excreted by living bacteria
  • Heat-labile
  • High toxicity
  • Effect of the toxin is localized
• ENDOTOXIN

  • produced by gram (-) bacteria
  • Lipopolyssacharide in nature
  • released only following cell death
  • heat stable
  • low toxicity
  • Effect is systemic

  It is detected in body fluids using "Limulus Lysate Test".

  • Reagent: extract of horse shoe crabs
  • Positive: Clumping
• What is the usual site of antibiotic action in a bacteria?

  Cell wall
• What is the usual target bacterial structure for gram staining?

  Cell wall
• Cell Wall comparison:?

  Gram (+) bacteria = Thicker peptidoglycan with techoic acid

  Gram (-) bacteria = Thinner peptidoglycan without techoic acid
• It is the ability to cause a disease.

  Pathogenicity
• It is "the degree of infection" or a "measure of pathogenicity"

  Virulence
• It refers to the properties of a bacteria that aid to increase virulence, thus increasing its pathogenicity.

  Virulence factors
• Bacterial Capsule

  • also called K/Vi Antigen
  • a very important virulence factor for a lot of bacteria
  • confers resistance to phagocytosis
  • responsible for the "mucoid" appearance of colonies

  "Neufeld Quelling Test" is a test detects the presence of a capsule

  • (+): Presence of swelling of bacteria under the microscope
  • (-): Absence of swelling of bacteria under the microscope
• Bacteria with capsule and their main component:

  Polysaccharide capsule

  • Streptococcus pneumoniae
  • Klebsiella pneumoniae
  • Neisseria meningitidis

  Polypeptide D-glutamic acid capsule

  • Bacillus anthracis

  Hyaluronic Acid capsule

  • Pasturella multocida

  Polyribosyl Ribitol Phosphayte Capsule

  • Haemophilus influenzae

  Alginate Capsule

  • Pseudomonas aeuroginosa
• What are the common stains used to stain bacterial capsules?

  India Ink, Nigrosin, Mucicarmine

  India ink is a "negative stain". It stains the "background" which makes the bacterial capsule more evidently seen under the microscope.
• Encapsulated bacteria when stained under the gram stain, their capsules give of a "halo-like" appearance.
• Bacterial "pili" is also called "fimbriae".

  • They are commonly found on gram (-) organisms

  There are two types of Pili:

  • Common or "Somatic" Pili is generally used for bacterial adherence and attachment to surfaces. Attachment is also termed as the first step in infection.
  • "Sex" pili is used for bacterial gene conjugation. The bacteria will exchange genetic material which aids in the formation of "antibiotic" resistance of some strains of bacteria.
• Bacterial endospores are "protective" structures of the bacteria that enables the organism to be "resistant" to harsh environments. The endospore is made of up "Dipiconolic Acid" aka "Calcium Dipicolinate".
• Bacterial endospres are often regarded as the "target of steriliztion" through autoclaving at 121 degrees C, 15 PSI, for 15 minutes.
• Bacterial Endospores can have 3 types depending on where they are formed at in a single bacterial cell.

  Terminal Spores = spores that are formed at one end of the bacteria

  Central Spores = spores that are formed in the center of the bacteria

  Sub-terminal spores = spores that are formed between the central and end of the bacteria.

  Clostridium tetani has Terminal Spores

  Bacillus anthracis has Central Spores

  Clostridium botulinum has Subterminal Spores
• Schaeffer and Fulton is "special" stain that is used to stain bacterial "endospores".

  
  

  Primary Dye: Malachite green

  Counterstain: Safranin

  Result: Spores will stain "green" while other structures stain "red"
• Dorner's Stain will also stain bacterial spores which uses Carbol Fuchsin and Nigrosine.
• Flagella is the organ that provides locomotion to bacteria. However, in spiral organisms, flagella are often called "Axial Filaments" or "Periplasmic Flagella". These structres can be obersved in what organisms?


  Borrelia spp., Treponema spp., and Leptospira spp.

  Their motility is also best observed at what temperature? Room Temperature.
• There are many ways to test for bacterial motility:

  1. Hanging Drop Method is commonly used as presumptive test for the motility and identity of what organism? Listeria monocytogenes.
  2. Flagellar stains such as Grey's and Leifson's uses what substance in their stains to detect the presence of flagella? Tannic Acid.
  3. Semi-solid Media such as "Sulfide Indole Motility" (SIM) and "Motility Indole Ornithine" (MIO) are used to detect motility as well.
  4. Growth at the site of inoculation = non-motile
  5. Growth outside the site of inoculation = motile
• Match the motility and the batceria who has that motility:?

  Corkscrew = Spirochetes spp. (Borrelia, Treponema, Leptospira)

  Shooting star = Vibrio cholerae

  Darting = Campylobacter spp.

  Gliding = Capnocytophaga gingivalis (does not have flagella; non-motile)

  Twitching = Kingella kingae (pili-induced motility; classified as non-motile) and Bartonella spp.

  Tumbling = Listeria monocytogenes