Oxidase test: Difference between revisions
From IDWiki
m (Aidan moved page Oxidase to Oxidase test) |
m (Text replacement - " species]]" to "]]") |
||
| (5 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
==Background== |
|||
= Oxidase test = |
|||
* Identifies '''cytochrome C oxidase''' by testing for the ability to oxidize tetramethyl-p-phenylenediamine to indophenols, which are purple |
|||
* The test is positive when it turns '''purple''' within 10 seconds |
|||
** Must be done from plain 5% SBA |
|||
| ⚫ | |||
The oxidase test is used to identify bacteria that produce cytochrome c oxidase, an enzyme of the bacterial electron transport chain. When present, the '''cytochrome c oxidase''' oxidizes the reagent '''(tetramethyl-p-phenylenediamine)''' to '''(indophenols)''' purple color end product. When the enzyme is not present, the reagent remains reduced and is colorless. |
|||
* All oxidase-positive bacteria are aerobic |
|||
| ⚫ | |||
| ⚫ | |||
** '''N''': [[Neisseria]] |
|||
| ⚫ | |||
| ⚫ | |||
| ⚫ | |||
===Oxidase-Positive Organisms=== |
|||
[https://i2.wp.com/microbeonline.com/wp-content/uploads/2012/12/Oxidase-test-result.gif [[File:https://i2.wp.com/microbeonline.com/wp-content/uploads/2012/12/Oxidase-test-result.gif?resize=280%2C225|Oxidase test result]]] |
|||
{{#ask: [[Oxidase::positive]] |?Stain |?Cellular shape |?Oxidase }} |
|||
===Oxidase-Negative Organisms=== |
|||
'''Note:''' All bacteria that are oxidase positive are aerobic, and can use oxygen as a terminal electron acceptor in respiration. This does NOT mean that they are strict aerobes. Bacteria that are oxidase-negative may be anaerobic, aerobic, or facultative; the oxidase negative result just means that these organisms do not have the cytochrome c oxidase that oxidizes the test reagent. They may respire using other oxidases in electron transport. |
|||
{{#ask: [[Oxidase::negative]] |?Stain |?Cellular shape |?Oxidase }} |
|||
== Further Reading == |
|||
'''Test requirements for Oxidase test:''' Moist filter paper with the substrate (1% tetramethyl-p-phenylenediamine dihydrochloride), or commercially prepared paper disk, wooden wire or platinum wire. |
|||
* Microbe Online. [https://microbeonline.com/oxidase-test-principle-procedure-and-oxidase-positive-organisms/ Oxidase Test: Principle, Procedure and Oxidase-Positive Organisms]. |
|||
[[Category:Diagnostics]] |
|||
== Procedure == |
|||
# Take a filter paper soaked with the substrate tetramethyl-p-phenylenediamine dihydrochloride |
|||
# Moisten the paper with a sterile distilled water |
|||
# Pick the colony to be tested with wooden or platinum loop and smear in the filter paper |
|||
# Observe inoculated area of paper for a color change to deep blue or purple within 10-30 seconds |
|||
=== Precautions === |
|||
# Do not use Nickel-base alloy wires containing chromium and iron (nichrome) to pick the colony and make smear as this may give false positive results |
|||
# Interpret the results within 10 seconds, timing is critical |
|||
# The oxidase test must be performed from 5% Sheep blood agar or another medium without a fermentable sugar . Fermentation of a carbohydrate results in acidification of the medium (e.g., lactose in [https://microbeonline.com/macconkey-agar-mac-composition-preparation-uses-and-colony-characteristics/ MacConkey Agar] or Sucrose in [https://microbeonline.com/thiosulfate-citrate-bile-salts-sucrose-tcbs-agarcomposition-uses-colony-characteristics/ TCBS]), and a false negative oxidase test may result if the surrounding pH is below 5.1. |
|||
# During identification of suspected ''Vibrio cholerae'' isolate, it is not possible to perform an oxidase test directly from a '''TCBS culture''' because the acid produced by the sucrose fermenting colonies will inhibit the oxidase reaction. |
|||
| ⚫ | |||
# '''Positive:''' Development of '''dark purple color''' (indophenols) within 10 seconds |
|||
# '''Negative:''' Absence of color |
|||
Bacterial genera characterized as oxidase positive include ''Neisseria'' and ''Pseudomonas''. Genera of the[https://microbeonline.com/seven-common-characteristics-family-enterobacteriaceae/ Enterobacteriaceae ]family are characterized as '''oxidase negative.''' |
|||
'''Name of Oxidase positive bacteria are:''' '''PVNCH''' |
|||
| ⚫ | |||
| ⚫ | |||
# '''N''': [https://microbeonline.com/neisseria-gonorrhoeae-properties-disease-pathogenesis-and-laboratory-diagnosis/ ''Neisseria''] spp. |
|||
| ⚫ | |||
| ⚫ | |||
| ⚫ | |||
# Alcaligens |
|||
Latest revision as of 02:52, 8 February 2022
Background
- Identifies cytochrome C oxidase by testing for the ability to oxidize tetramethyl-p-phenylenediamine to indophenols, which are purple
- The test is positive when it turns purple within 10 seconds
- Must be done from plain 5% SBA
Interpretation
- All oxidase-positive bacteria are aerobic
- P: Pseudomonas
- V: Vibrio cholerae
- N: Neisseria
- C: Campylobacter
- H: Helicobacter and Haemophilus
- Aeromonas
Oxidase-Positive Organisms
| Stain | Shape | Oxidase | |
|---|---|---|---|
| Achromobacter | Gram-negative | bacillus | positive |
| Aeromonas | Gram-negative | bacillus | positive |
| Alcaligenes faecalis | Gram-negative | bacillus | positive |
| Brucella melitensis | Gram-negative | coccobacillus | positive |
| Burkholderia pseudomallei | Gram-negative | bacillus | positive |
| Campylobacter | Gram-negative | bacillus | positive |
| Francisella tularensis | Gram-negative | coccobacillus | positive negative |
| Helicobacter pylori | Gram-negative | bacillus | positive |
| Herbaspirillum | Gram-negative | bacillus | positive |
| Micrococcus | Gram-positive | coccus | positive |
| Moraxella catarrhalis | Gram-negative | diplococcus | positive |
| Neisseria | Gram-negative | diplococcus | positive |
| Ochrobactrum anthropi | Gram-negative | bacillus | positive |
| Pasteurella | Gram-negative | bacillus | positive |
| Pseudomonas aeruginosa | Gram-negative | bacillus | positive |
| Vibrio | Gram-negative | bacillus | positive |
| Vibrio cholerae | Gram-negative | bacillus | positive |
| Vibrionaceae | Gram-negative | bacillus | positive |
Oxidase-Negative Organisms
| Stain | Shape | Oxidase | |
|---|---|---|---|
| Acinetobacter ursingii | Gram-negative | coccobacillus | negative |
| Cronobacter sakazakii | Gram-negative | bacillus | negative |
| Erysipelothrix rhusiopathiae | Gram-positive | bacillus | negative |
| Francisella tularensis | Gram-negative | coccobacillus | positive negative |
| Listeria monocytogenes | Gram-variable Gram-positive | bacillus pleomorphic | negative |
| Proteus | Gram-negative | bacillus | negative |
| Raoultella | Gram-negative | bacillus | negative |
| Raoultella ornithinolytica | Gram-negative | bacillus | negative |
| Stenotrophomonas maltophilia | Gram-negative | bacillus | negative |
Further Reading
- Microbe Online. Oxidase Test: Principle, Procedure and Oxidase-Positive Organisms.
