Bacte basics

• Staphy vs Micrococcus

  • Both gram positive cocci
  • Catalase (+)
• Streptococcus spp. categorisation based on hemolytic pattern

  • Beta
  • Alpha
  • Non-hemolytic
• Beta hemolytic streptococci

  Group A (gas) = Streptococcus pyogenes<|>Group B (heat stable) = S. agalactiae<|>Group C = S. equi and S. dysgalactiae
• Alpha hemolytic streptococci


  With lancefield antigen<|>Based on: C-carbohydrate (polysaccharide)<|>Location = cell wall<|>Group present: Group D<|>Viridans streptococcus (green)<|>Anginosus grp<|>Mutans grp<|>Mitis grp<|>Salivarius grp<|>Without lancefield antigen<|>Based on: C-substance<|>Bacteria present: S. pneumoniae (no c-carbohydrate)
• Non-hemolytic streptococci


  Not member of viridans but has d antigen<|>Bacteria present: Enterococcus, Streptococcus
• Group B streptococci are acid stable, the rest are acid labile
• Protein A

  Resist phagocytosis (antiphagocytic)<|>Staphylococcus aureus
• Protein F

  Fibronectin binding protein<|>Function: adherance (attach bacteria to cell wall?)<|>Staphylococcus pyogenes
• Protein M

  Resist phagocytosis (antiphagocytic)<|>Group A beta streptococci
• Capsule of Streptococcus pyogenes

  Hyaluronic acid
• Biochemical test for Group A streptococci

  Routine test: Bacitracin<|>Additional/Confirmatory if susceptible: PYR
• Capsule of Streptococcus agalactiae

  Sialic acid
• Biochemical test for Group B streptococci

  Hippurate hydrolysis and Camp test
• Biochemical test for Viridans streptococci

  Confirmatory: Leucine aminopeptidase test (LAP)
• Capsule of Streptococcus pneumoniae

  Polysaccharide
• Biochemical test for Streptococcus pneumoniae

  Routine test: optochin test (Taxo p)<|>Additional test: bile solubility, and quellung reaction
• Biochemical tests for Enterococcus

  PYR<|>Bile esculin<|>6.5% NaCl tolerance test
• Neisseria gonorrhoeae syndrome in males is called Arginine-Hypoxanthine-Uracil (AHU) strain
• Neisseria gonorrhoeae syndrome in females is called Fitz-Hugh Curtis syndrome
• Neisseria meningitidis syndrome is called Waterhouse Friderichsen syndrome
• Colony morphology characteristics

  • Pinhead = Staphylococcus
  • Pinpoint = Streptococcus
  • Coin with a raised rim = Streptococcus pneumoniae
  • Moraxella catarrhalis = a
  • Bulls eyes colony = Yersinia
  • Wrinkled leathery colony = Pseudomonas stutzeri
  • Star shape with four to six points = Aggregatibacter actinomycetemcomitans
  • Rosette or sticklike structure = Cardiobacterium hominis
  • Safety pin = Yersinia and Pasteurella
  • Ground glass or cut glass = Legionella
• TSI reactions

  Enterobacter = either K/K or ____<|>Proteus = A/A<|>Ferment sucrose
• Pigments produced by bacteria

  • Prodigiosin - Serratia marcescens, Serratia rubdaea, Serratia plyymuthica
  • Pyoverdin - green Pseudomonas aeruginosa
  • Pyocyanin - blue Pseudomonas aeruginosa
  • Pyorubin - red Pseudomonas aeruginosa
  • Pyomelanin - brown Pseudomonas aeruginosa
• Odors produced by bacteria

  • Old sock = Staphylococcus aureus
  • Rotten potato = Serratia odorifera
  • Burnt chocolate = Proteus
  • Fruity grape-like/taco-like odor = Pseudomonas aeruginosa
  • Earthy odor = Burkholderia pseudomallei
  • Fruity apple-like = Alcaligenes faecalis
  • Mousy odor or bleach-like odor = Haemophilus influenzae
  • Chlorine bleach like odor = Eikenella corrodens
• Selective media


  • Neisseria gonorrhoeae: Thayer martin, Modified thayer martin, Martin-lewis, New york city, GC-LECT
  • Yersinia enterocolitica and Aeromonas: Cefuldin-iirgasan-novobiocin (CIN)
  • Vibrio: TCBS
  • Campylobacter: Skirrow, Butzler
  • Legionella: BCYE with L cysteine, Feeley gorman
  • Bordetella: Bordet gengou (potato blood glycerol), Regan Lowe transport medium
• Motility characteristics

  • Shooting star = Vibrio
  • Darting = Campylobacter
  • Twitching = Kingella
  • Gliding = Capnocytophaga spp
• Koch-Weeks bacillus = Haemophilus aegyptius
• Bacillus anthracis is the largest pathogenic bacteria
• Haemophilus ducreyi is the smallest pathogenic bacteria
• Gram stain appearance of bacteria is like a school of fish
• Bacillus cereus has a frosted glass appearance
• Hemolytic pattern is used to differentiate Bacillus anthracis