Diagnostic Bacteriology Exam 1
correctly answered 100%
Trypticase soy agar with 5% sheep blood - correct answer ✔✔- most common in medical lab
- contains:
- pancreatic digest of casein, papaic digest of soy bean meal, NaCl, agar, growth factors, defibrinated
sheep blood
Gram Positive Cocci - correct answer ✔✔- staphylococcus
- streptococcus
Gram positive bacilli - correct answer ✔✔- bacillus
- clostridium
- corynebacterium (pleomorphic)
- listeria (small, even)
- actinomyces
Gram Negative Cocci - correct answer ✔✔- Neisseria/Moraxella (coffee-bean arrangement)
- Veillionella
Gram Negative Bacilli - correct answer ✔✔- huge variations on size, shape, morphology
Enriched media - correct answer ✔✔- supports growth of fastidious organisms
- e.g. pathogenic Neisseria
Enriched: Chocolate Agar - correct answer ✔✔- contains lysed RBCs that release nutrients leading to the
brown colored agar
- contains:
,- pancreatic digest of casein, selected meat peptones
- corn starch
- phosphate buffers (dipotassium and monopotassium)
- NaCl, agar, hemoglobin
- IsoVitaleX enrichment
Chocolate Agar: function of corn starch - correct answer ✔✔- neutralizes toxic fatty acids
Chocolate Agar: hemoglobin factor X function - correct answer ✔✔- supports Haemophilus growth
Chocolate Agar: IsoVitaleX function - correct answer ✔✔- has ferric ion for Neisseria
- factor V for Haemophilus
Enriched: Buffered Charcoal Yeast Extract (CYE) - correct answer ✔✔- specifically for Legionella
- contains:
- yeast extract for nutrients, L-cysteine, ferric pyrophosphate, alpha-keto glutarate, activated charcoal,
ACES buffer (maintains pH)
CYE: L-cysteine, ferric pyrophosphate, and alpha-keto glutarate function - correct answer ✔✔- specific
growth requirements for Legionella
CYE: activated charcoal function - correct answer ✔✔- neutralizes HOOH
Enriched: Brucella blood agar - correct answer ✔✔- contains:
- pancreatic digest, peptic digest of animal tissue, yeast extract, dextrose, NaCl, agar, hemin, vitamin k,
defibrinated sheep blood (5%)
Brucella blood agar: vitamin K function - correct answer ✔✔- supports the growth of anaerobic
organisms
, Selective Media - correct answer ✔✔- never use it alone - it may inhibit your desired organism
- favors one organism over another
- contains antibiotics or inhibitory chemicals
Selective: MacConkey Agar - correct answer ✔✔- inhibits gram positive bacteria
- favors non-fastidious GNRs (e.g. enterobacteriaciae, as well as non-glucose fermenting bacilli -
pseudomonas)
MacConkey Agar Contains - correct answer ✔✔- pancreatic digest of casein/gelatin
- peptic digest of animal tissue, NaCl, lactose, neutral red
- bile salts and crystal violet - inhibit gram + growth
Selective: Columbia Colistin Nalidixic Acid Agar (CNA) - correct answer ✔✔- inhibits gram - and favors
gram + growth
- colistin - antibiotic which disrupts cell membrane of gram neg organisms
- nalidixic acid - quinolone antibiotic - disrupts DNA gyrase activity in gram neg
Selective: Eosin Methylene Blue Agar - correct answer ✔✔- not used much because Mackonkey is more
selective
- inhibits gram positive bacteria
- favors non-fastidious GNRs
- eosin and methylene blue are inhibitory agents
Selective: Martin Lewis Agar (brown) - correct answer ✔✔- used for genital specimens
- inhibits gram positive and GNRs
- favors pathogenic Neisseria
- contains 4 antimicrobials
*Chocolate agar should be used in conjunction as a non-selective alternative
Martin Lewis Agar: 4 antimicrobials/functions - correct answer ✔✔- vancomycin - inhibits gram +
correctly answered 100%
Trypticase soy agar with 5% sheep blood - correct answer ✔✔- most common in medical lab
- contains:
- pancreatic digest of casein, papaic digest of soy bean meal, NaCl, agar, growth factors, defibrinated
sheep blood
Gram Positive Cocci - correct answer ✔✔- staphylococcus
- streptococcus
Gram positive bacilli - correct answer ✔✔- bacillus
- clostridium
- corynebacterium (pleomorphic)
- listeria (small, even)
- actinomyces
Gram Negative Cocci - correct answer ✔✔- Neisseria/Moraxella (coffee-bean arrangement)
- Veillionella
Gram Negative Bacilli - correct answer ✔✔- huge variations on size, shape, morphology
Enriched media - correct answer ✔✔- supports growth of fastidious organisms
- e.g. pathogenic Neisseria
Enriched: Chocolate Agar - correct answer ✔✔- contains lysed RBCs that release nutrients leading to the
brown colored agar
- contains:
,- pancreatic digest of casein, selected meat peptones
- corn starch
- phosphate buffers (dipotassium and monopotassium)
- NaCl, agar, hemoglobin
- IsoVitaleX enrichment
Chocolate Agar: function of corn starch - correct answer ✔✔- neutralizes toxic fatty acids
Chocolate Agar: hemoglobin factor X function - correct answer ✔✔- supports Haemophilus growth
Chocolate Agar: IsoVitaleX function - correct answer ✔✔- has ferric ion for Neisseria
- factor V for Haemophilus
Enriched: Buffered Charcoal Yeast Extract (CYE) - correct answer ✔✔- specifically for Legionella
- contains:
- yeast extract for nutrients, L-cysteine, ferric pyrophosphate, alpha-keto glutarate, activated charcoal,
ACES buffer (maintains pH)
CYE: L-cysteine, ferric pyrophosphate, and alpha-keto glutarate function - correct answer ✔✔- specific
growth requirements for Legionella
CYE: activated charcoal function - correct answer ✔✔- neutralizes HOOH
Enriched: Brucella blood agar - correct answer ✔✔- contains:
- pancreatic digest, peptic digest of animal tissue, yeast extract, dextrose, NaCl, agar, hemin, vitamin k,
defibrinated sheep blood (5%)
Brucella blood agar: vitamin K function - correct answer ✔✔- supports the growth of anaerobic
organisms
, Selective Media - correct answer ✔✔- never use it alone - it may inhibit your desired organism
- favors one organism over another
- contains antibiotics or inhibitory chemicals
Selective: MacConkey Agar - correct answer ✔✔- inhibits gram positive bacteria
- favors non-fastidious GNRs (e.g. enterobacteriaciae, as well as non-glucose fermenting bacilli -
pseudomonas)
MacConkey Agar Contains - correct answer ✔✔- pancreatic digest of casein/gelatin
- peptic digest of animal tissue, NaCl, lactose, neutral red
- bile salts and crystal violet - inhibit gram + growth
Selective: Columbia Colistin Nalidixic Acid Agar (CNA) - correct answer ✔✔- inhibits gram - and favors
gram + growth
- colistin - antibiotic which disrupts cell membrane of gram neg organisms
- nalidixic acid - quinolone antibiotic - disrupts DNA gyrase activity in gram neg
Selective: Eosin Methylene Blue Agar - correct answer ✔✔- not used much because Mackonkey is more
selective
- inhibits gram positive bacteria
- favors non-fastidious GNRs
- eosin and methylene blue are inhibitory agents
Selective: Martin Lewis Agar (brown) - correct answer ✔✔- used for genital specimens
- inhibits gram positive and GNRs
- favors pathogenic Neisseria
- contains 4 antimicrobials
*Chocolate agar should be used in conjunction as a non-selective alternative
Martin Lewis Agar: 4 antimicrobials/functions - correct answer ✔✔- vancomycin - inhibits gram +
