-
Gram stain [results, meaning, next test]
- Cells stained purple: cell is gram (+) - has thick peptidoglycan layer
- NEXT - microscopic morphology
- Cells stained pink: cell is gram (-) - has thin peptidoglycan layer and LPS layer
- NEXT - microscopic morphology
-
Microscopic morphology (G+) [results, meaning, next test]
- coccus:
- NEXT - catalase test
- bacillus:
- NEXT - endospore stain
-
Microscopic morphology (G-) [results, meaning, next test]
- coccus:
- NEXT - none, there are no gram negative cocci
- bacillus:
- NEXT - oxidase test
-
Catalase test [results, meaning, next test]
- bubbles form: bacteria has catalase (can break down H2O2) [positive]
- NEXT - glucose fermentation test
- no bubbles: bacteria can not break down H2O2 [negative]
- NEXT - blood agar culture
-
Glucose fermentation test [results, meaning, next test]
- Tube is yellow (gas or no gas): acid has been produced from anaerobic fermentation [positive]
- NEXT - acid from mannitol salt agar
- Tube is red (no gas): acid has not been produced from anaerobic fermentation [negative]
- NEXT - none, organism is Micrococcus luteus
-
Acid from mannitol salt agar [results, meaning, next test]
- Agar has changed from red to yellow: bacteria can ferment mannitol
- NEXT - lactose fermentation test
- Agar has remained red: bacteria cannot ferment mannitol
- NEXT - novobiocin resistance
-
Lactose fermentation test [results, meaning, next test]
- Tube is yellow (gas or no gas): acid has been produced from anaerobic fermentation [positive]
- NEXT - none, organism is Staphylococcus aureus
- Tube is red (no gas): acid has not been produced from anaerobic fermentation [negative]
- NEXT - none, organism is Staphylococcus capitis
-
Novobiocin resistance [results, meaning, next test]
- area of inhibition greater than 15mm: bacteria is resistance to novobiocin [positive]
- NEXT - none, organism is Staphylococcus saprophyticus
- area of inhibition less than 15mm: bacteria is not resistant to novobiocin [negative]
- NEXT - none, organism is Staphylococcus epidermidis
-
Blood Agar [results, meaning, next test]
- greenish color: partial breakdown of RBCs, has alpha hemolysin
- NEXT - none, no organisms
- clear area around growth: complete breakdown of RBCs, has beta hemolysin
- NEXT - none, organism is Streptococcus pyogenes
- no coloring occurs: no breakdown of RBCs, lacks hemolysin
- NEXT - Mannitol Salt Agar fermentation
-
Mannitol salt agar fermentation (after blood agar) [results, meaning, next test]
- Agar has changed from red to yellow: bacteria can ferment mannitol [positive]
- NEXT - none, organism is Enterococcus faecalis
- Agar has remained red: bacteria cannot ferment mannitol [negative]
- NEXT - none, organims is Streptococcus salivarius
-
Endospore stain [results, meaning, next test]
- Green structures can be seen amongst/within red structures: the malachite green has been absorbed by the endospores [positive]
- NEXT - VP test
- red structures only can be seen: there are no endospores present [negative]
- NEXT - acid-fast stain
-
VP test [results, meaning, next test]
- MRVP tube turns pink after addition of VP reagant I and II and being exposed to oxygen for 15 minutes: organism produces acetoin from glucose fermentation [positive]
- NEXT - none, organism is Bacillus subtilis
- MRVP tube does not turn pink after addition of VP reagant I and II and being exposed to oxygen for 15 minutes: orgaism does not produce acetoin from glucose fermentation [negative]
- NEXT - none, organism is Bacillus megaterium
-
Acid-fast stain [results, meaning, next test]
- Bacteria appears red/pink: did not release carbol-fuchsin during decolorization, IS acid-fast [positive]
- NEXT - none, organism is Mycobacterium smegmatis
- Bacteria appears blue: released carbol-fuchsin during decolorization, is not acid-fast [negative]
- NEXT - none, organism is Lactobacillus rhamnosus
-
Oxidase test [results, meaning, next test]
- Oxidase strip turns purple within 50 seconds: has cytochrome C in the ETC [positive]
- NEXT - oxidized glucose test
- Oxidase strip does not turn purple within 50 seconds: does not have cytochrome C in th ETC [negative]
- NEXT - Indole test
-
Oxidized glucose test [results, meaning, next test]
- OF glucose medium
- Exposed tube yellow at top, sealed tube still green: organism is an oxidizer [positive]
- NEXT - none, organism is Pseudomonas aeruginosa
- Both tubes completely yellow: organism is a fermenter [negative]
- NEXT - none, organism is Alcaligenes faecalis
- Exposed tube slightly blue at top, sealed tube still green: organism does not use glucose [negative]
-
Indole test [results, meaning, next test]
- Kovacs reagant turns red: indole production (organism has Tryptophanase) [positive]
- NEXT - Lactose fermentation with acid AND gas
- Kovacs reagant remains clear: no Tryptophanase [negative]
- NEXT - Ornithine decarboxylase (SAME TUBE)
-
Ornithine decarboxylase (after neg indole) [results, meaning, next test]
- If MIO tube appears purple: organism has ornithine decarboxylase [positive]
- NEXT - Urease test
- If MIO tube does not appear purple: does not have ornithine decarboxylase [negative]
- NEXT - none, organism is Klebsiella pneumoniae
-
Lactose fermentation with acid AND gas [results, meaning, next test]
- Lactose fermentation tube is yellow and has gas: positive
- NEXT - none, Escherichia coli
- Lactose fermentation tube is red or yellow w/o gas: negative
- NEXT - ornithine decarboxylase
-
Ornithine decarboxylase (after neg lactose ferm w/ gas) [results, meaning, next test]
- If MIO tube purple: positive
- NEXT - none, organism is Morganella morganii
- NEXT - none, organims is Proteus vulgaris
-
Urease test [results, meaning, next test]
- Urease slant is fuchsia: organism has urease [positive]
- NEXT - none, organism is Proteus mirabilis
- Urease slant is yellow: organism does not have urease [negative]
- NEXT - culture at 25 degrees
-
Culture at 25 degrees [results, meaning, next test]
- Organism has red pigment:
- NEXT - none, organism is Serratia marcescens
- Organism does not have red pigment:
- NEXT - none, organism is Enterobacter aerogenes
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