Procedures and Biochemical Identification of Bacteria

  1. Define Bacteremia
    Bacteria in the blood
  2. Define Septicemia
    Bacteria increasing in numbers in the blood causing harm to the patient
  3. When are bacteria in the highest numbers in the blood?
    Just before the fever spikes
  4. What is important to remember when collecting blood cultures?
    The volume of blood collected probably has the greatest effect on isolation of bacteria
  5. What do blood cuture bottles often contain?
    Sodium polyanethol sulfonate (SPS) - an anticoagulant that also inhibits complement and inactivates neutrophils, and inhibits growth of some bacteria
  6. What Clinical specimens are normally sterile sites?
    • Blood
    • CSF
    • Lower respiratory specimens
    • Urine
    • Cervix
  7. What is the purpose of CSF?
    • Surrounds the brain and spinal cord
    • Carries nutrients and waste
  8. Define meningitis
    Inflammation of the meninges
  9. Define encephalitis
    Inflammation of the brain
  10. What are the most common isolates found in the CSF?
    • Neisseria meningitidis
    • Strep pneumoniae
    • Strep agalactiae (Group B)
    • E. coli
    • Staph aureus
    • Listeria monocytogenes
  11. What are the most important pathogens isolated in throat cultures?
    • Strep pyogenes (Group A)
    • Group B Strep
    • Group C Strep
    • Group G Strep
    • Arcanobacterium species
  12. What are sputum specimens used for?
    Used to diagnose lower respiratory tract infections (pneumonia)
  13. Name common significant isolates of sputum samples
    • Strep pneumoniae
    • Klebsiella pneumoniae
    • Staph aureus
    • Pseudomonas aeruginosa
    • Haemophilus influenzae
    • Legionella pneumophila
    • Mycoplasma pneumoniae
  14. What organism is found in sputums and causes community acquired pneumonia and is the most common cause of pneumonia in geriatric patients?
    Strep pneumoniae
  15. What organism is found in sputums and is associated with nosocomial pneumonia and pneumonia in alcoholics?
    Klebsiella pneumoniae
  16. What organism is found in sputums and causes nosocomial and sever pneumonia in patients with CF (cystic fibrosis)?
    Pseudomonas aeruginosa
  17. What organism is found in sputums and causes infection in infants, children, and the immunosuppressed?
    Haemophilus influenzae
  18. What organism is found in sputums and primarily infects middle-aged males?
    Legionella penumophilia
  19. What organism is found in sputums and causes primary atypical pneumonia, which is mostly seen in young adults?
    Mycoplasma pneumoniae
  20. Define bacteriuria
    Bacteria in the urine (but may not indicate a UTI)
  21. Name some common sigificant isolates found in the urine
    • E. coli
    • Klebsiella species
    • Enterobacter species
    • Proteus species
    • Staph aureus
    • Staph saprophyticus
    • Enterococcus species
    • Pseudomonas aeruginosa
    • Yeast
  22. What bacteria in the stool causes gastroenteritis?
    • Shigella species
    • Salmonella
    • Campylobacter jejuni
    • E. coli (O157:H7)
    • Yersinia enterocolitica
    • Clostridium difficile
    • Vibrio species
  23. What significant isolates are generally looked for when dealing with the genital tract?
    • Neisseria gonorrhaeae
    • Chlamydia trachomatis
    • Gardnerella vaginalis
  24. What organisms cause cervicitis and urethritis?
    • Neisseria gonorrhoeae
    • Chlamydia trachomatis
  25. What causes BV (or nonspecific bacterial vaginitis)?
    • Due to overgrowth of some species of normal vaginal flora - most likely Mobiluncus
    • Gardnerella vaginalis is an indicator of BV
  26. What causes PID (pelvic inflammatory disease)?
    Complication of infection caused by Neisseria gonorrhoeae or Chlamydia trachomatis, involving the endometrium or fallopian tubes
  27. What causes Prostatitis?
  28. What organisms are commonly the cause of superficial skin infections?
    • Staph aureus
    • Strep pyogenes (Group A)
  29. What organisms are commonly the cause of folliculitis (hair follicle infection)?
    • Staph aureus
    • Pseudomonas aeruginosa
  30. What organism is commonly the cause of boils and bedsores?
    Staph aureus
  31. What organisms are commonly the cause of Impetigo?
    • Strep pyogenes (Group A)
    • Staph aureus
  32. What organisms are commonly the cause of Erysipelis?
    • Strep pyogenes (Group A)
    • Erysipelothrix rhusiopathiae (less common)
  33. What organisms are commonly the cause of Deep wounds, surgical wounds, and abscesses?
    Anaerobes from normal body sites
  34. What organisms does the Catalase test identify?
    • POS - Staphlococcus
    • NEG - Streptococcus
  35. What organism does the Coagulase test identify?
    • POS - Staph aureus (also S. intermedius and S. hyicus)
    • More specific agglutination tests are now performed
  36. What does the PYR test for?
    Detects the enzyme L-pyrrolidonyl arylamidase
  37. What organism does PYR differentiate?
    • NEG - Staph aureus
    • POS - S. lugdensis, S. schleiferi, Strep pyogenes (Group A), and Enterococcus species
  38. What organism does the Bile solubility test identify?
    • Strep pneumoniae
    • In the presence of bile at 37 degrees celcius, colonies will autolyse within 30 min and disappear from the agar surface
  39. What does the Hippurate Hydrolysis test for?
    Detects the bacterial enzyme hipuricase - which hydrolyzes hippurate to glycine and benzoic acid
  40. What organism does the Hippurate hydrolysis test differentiate?
    • POS - Group B Strep, Campylobacter jejuni
    • NEG - Most other beta-hemolytic Streps, Campylobacter species
  41. What does the Oxidase test for?
    Detects chytochrome oxidase that is used in the electron transport system
  42. What organism does the Oxidase test differentiate?
    POS - Pseudomonas species, Neisseria gonorrheae
  43. What does the Indole test for?
    Detects the bacterial enzyme tryptophanase (tryptophan is broken down by tryptophanase into pyruvic acid, ammonia, and indole)
  44. What does the Urease test for?
    Urease breaks down urea to form ammonia (NH3)
  45. What does the Triple sugar iron agar (TSI) test for?
    TSI will show the pattern of glucose, lactose, and sucrose fermentation in addition to H2S and gas production
  46. What organisms does the TSI differentiate?
    • Alkaline slant/alkaline deep (K/K) - Nonfermentor, NOT Enterobacteriaceae
    • Alkaline slant/acid deep (K/A) - Nonlactose and nonsucrose fermenter, glucose fermenter
    • Acid slant/acid deep (A/A) - Lactose and/or sucrose fermenter, and glucose fermenter
    • Black deep, production of H2S gas - production of hydrogen sulfide (H2S) from sulfer-containing molecules in the medium
    • Lead acetate - added to filter paper strips and one end is held in place by the cap.  If H2S gas is produced, a black color will form
  47. What does the TSI result of K/K mean?
    • Nonfermentor
    • NOT Enterobacteriaceae
  48. What does the TSI result of K/A mean?
    • Nonlactose and/or Nonsucrose fermenter
    • Glucose fermenter
  49. What does the TSI result of A/A mean?
    • Lactose and/or sucrose fermenter
    • Glucose fermenter
  50. What does Methyl Red (MR) test for?
    • pH indicator
    • Yellow at acid pH (indicating glucose fermentation)
    • Red is NEG
  51. What does Voges-Proskauer (VP) test for?
    • Detects the metabolism of glucose to acetyl-methyl-carbinol (acetoin)
    • Bacteria are usually MR or VP POS
  52. What does Citrate test for?
    Determines if citrate is used as a sole carbon source
  53. What does ONPG (o-nitrophenyl-beta-D-galactopyranoside) test for?
    • Detects the presence of beta-galactosidase, an enzyme that cleaves ONPG and lactose
    • Test is useful in detecting delayed (late) lactose fermenters that lack or are deficient in beta-galactoside permease
  54. What does the Amino acid degradation test for?
    Detects bacterial enzymes that break down various amino acids
  55. What does the Deaminase reaction test for?
    Detects the ability of an organism to remove the amino group from specific amino acids
  56. What does the Decarboxylation reaction test for?
    Detects the ability of bacteria to remove the carboxyl group from a specific amino acid
  57. What are the reactions in an Amino acid degradation test?
    • Deaminase reaction
    • Decarboxylation reaction
  58. What are some examples of bacterial enzymes that will turn positive for the Amino acid degradation test?
    • Tryptophan (tryptophan deaminase)
    • Lysine (lysine decarboxylase)
    • Ornithine (ornithine dihydrolase)
  59. What does the carbohydrate fermentation test for?
    Detects the ability of bacteria to produce organic acids by the fermentation of various carbs
  60. What does the Nitrate reduction test for?
    Determines the ability of an organism to reduce nitrate (NO3) to nitrite (NO2) and nitrogen gas (N2)
  61. What does the Sherlock Microbial Identification System identify?
    The fatty acid composition of the bacterial cell wall as determined by gas chromatography
  62. How are the fatty acids in mycobacteria identified?
    • The fatty acids in mycobacteria have a larger molecular weight
    • Identified via high-performance liquid chromatography in the Sherlock Mycobacteria Identification System
Card Set
Procedures and Biochemical Identification of Bacteria
Plating Procedures, Biochemical ID