Culture media: Difference between revisions

From IDWiki
(β†’β€: added thio broth)
m (Text replacement - " species]]" to "]]")
Β 
(4 intermediate revisions by the same user not shown)
Line 1: Line 1:
== Bacterial ==
==Bacterial==

* Primary media (i.e. those onto which samples are directly inoculated) vary by specimen
*Primary media (i.e. those onto which samples are directly inoculated) vary by specimen
** Most commonly include blood, chocolate, and MacConkey agars
**Most commonly include blood, chocolate, and MacConkey agars
** For anaerobic cultures, pre-reduced Brucella agar
**For anaerobic cultures, pre-reduced Brucella agar


{| class="wikitable"
{| class="wikitable"
! Media !! Abbr !! Description
!Media!!Abbr!!Description
|-
|-
| 5% sheep's blood || SBA || A general, non-selective media; allows for identification of hemolysis patterns
|5% sheep's blood||SBA||A general, non-selective media; allows for identification of hemolysis patterns
|-
|-
| Chocolate || CHOC || Enriched media for difficult-to-grow bacteria
|Chocolate||CHOC||Enriched media for difficult-to-grow bacteria
|-
|-
| MacConkey || MAC || Selective for Gram-negative bacteria, with an indicator for lactose fermentation
|MacConkey||MAC||Selective for Gram-negative bacteria, with an indicator for lactose fermentation
|-
|-
| Sorbitol-MacConkey || SMAC || Used to identify sorbitol-negative strains of ''E. coli'' such as O157:H7
|Sorbitol-MacConkey||SMAC||Used to identify sorbitol-negative strains of ''E. coli'' such as O157:H7
|-
|-
| Mueller-Hinton || || Used for antibiotic susceptibility testing
|Mueller-Hinton|| ||Used for antibiotic susceptibility testing
|-
|-
| BCSA || BCSA || For isolation of [[Burkholderia cepacia]], incubated at 30ΒΊC
|BCSA||BCSA||For isolation of [[Burkholderia cepacia]], incubated at 30ΒΊC
|-
|-
| Columbia naladixic acid || CNA || Selective for Gram-positive bacteria
|Columbia naladixic acid||CNA||Selective for Gram-positive bacteria
|-
|-
| Bile esculin || || Selective for [[Enterococcus species]]
|Bile esculin|| ||Selective for [[Enterococcus]]
|-
|-
| Brucella blood || BRUC || General anaerobic medium
|Brucella blood||BRUC||General anaerobic medium
|-
|-
| Neomycin || NEO || Selective plate for anaerobes
|Neomycin||NEO||Selective plate for anaerobes
|-
|-
| CHROMagar ''Staph. aureus'' || CSA || Selective and chromogenic for [[Staphylococcus aureus]]
|CHROMagar ''Staph. aureus''||CSA||Selective and chromogenic for [[Staphylococcus aureus]]
|-
|-
| [[Bacteroides species|Bacteroides]] bile esculin || BBE || Increases sensitivity for [[Bacteroides species]] (which grow black)
|[[Bacteroides species|Bacteroides]] bile esculin||BBE||Increases sensitivity for [[Bacteroides]] (which grow black)
|-
|-
| Egg yolk || || Enriched media for [[Clostridium species]]
|Egg yolk|| ||Enriched media for [[Clostridium]]
|}
|}


=== Blood agar ===
===Blood Agar===

* Most common medium used
*Most common medium used
* Allows for differentiation of hemolysis pattern:
*Allows for differentiation of hemolysis pattern:
** Partial hemolysis (Ξ±): [[Streptococcus pneumoniae]], [[Enterococcus species]], [[Streptococcus bovis]], [[Viridans-group streptococci]]
** Full hemolysis (Ξ²): [[Streptococcus pyogenes]], Group B, C, and G streptococci, some [[Streptococcus anginosus]], and rare [[Enterococcus species]]
**Partial hemolysis (Ξ±): [[Streptococcus pneumoniae]], [[Enterococcus]], [[Streptococcus bovis]], [[Viridans group streptococci]]
** No hemolysis (Ξ³): [[Viridans-group streptococci]]
**Full hemolysis (Ξ²): [[Streptococcus pyogenes]], Group B, C, and G streptococci, some [[Streptococcus anginosus]], and rare [[Enterococcus]]
**No hemolysis (Ξ³): [[Viridans-group streptococci]]

===Mueller-Hinton Agar===

*Standardized pH and solute content that are used for antimicrobial susceptibility testing

===Bile Esculin Agar===

*Selects for bacteria that can grow in 40% bile and can hydrolyze esculin
*E.g. [[Enterococcus]] and [[Streptococcus bovis]]

===Chocolate Agar===

*Sheep's blood that has been lysed
*Used most commonly to identify [[Haemophilus influenzae]] and [[Neisseria]]

===MacConkey Agar===

*Uses bile salts and crystal violet to inhibit Gram-positive and some fastidious Gram-negative bacteria
*Uses an indicator to identify lactose fermentation
**Lactose fermenters turn pink or red
**Non-lactose fermenters stay yellow

===Hektoen Agar===

*Contains lactose, sucrose, salicin, and a high concentration of bile salts (intended to inhibit Gram-positive and coliform Gram-negative bacteria)
*Black colonies suggests [[Salmonella]], from hydrogen sulfide production
*Bright orange to pink colonies suggests rapid lactose fermenters like [[Escherichia coli]]
*Green colonies include [[Salmonella]] and [[Shigella]]

===Sorbitol-MacConkey Agar===


*The lactose in MacConkey is replaced with sorbitol
=== Bile esculin ===
*Common strains of [[Escherichia coli]] ferment sorbitol
* Selects for bacteria that can grow in 40% bile and can hydrolyze esculin
*[[Escherichia coli]] O157:H7 is a sorbitol non-fermenter
* E.g. [[Enterococcus species]] and [[Streptococcus bovis]]
*However, many other enterohemorrhagic strains are fermenters


=== Chocolate agar ===
===Columbia Naladixic Acid Agar===
* Sheep's blood that has been lysed
* Used most commonly to identify [[Haemophilus influenzae]] and [[Neisseria species]]


*Uses [[colistin]] and naladixic acid to inhibit the growth of Gram-negative bacteria
=== MacConkey ===
* Uses bile salts and crystal violet to inhibit Gram-positive and some fastidious Gram-negative bacteria
* Uses an indicator to identify lactose fermentation
** Lactose fermenters turn pink or red
** Non-lactose fermenters stay yellow


=== Hektoen ===
===Chromogenic Urine Plates===
* Contains lactose, sucrose, salicin, and a high concentration of bile salts (intended to inhibit Gram-positive and coliform Gram-negative bacteria)
* Black colonies suggests [[Salmonella species]], from hydrogen sulfide production
* Bright orange to pink colonies suggests rapid lactose fermenters like [[Escherichia coli]]
* Green colonies include [[Salmonella species]] and [[Shigella species]]


*In the HRLMP:
=== Sorbitol-MacConkey ===
*Pink colonies are definitive for [[Escherichia coli]]
* The lactose in MacConkey is replaced with sorbitol
*Blue colonies suggest [[Klebsiella]], [[Enterobacter]], or [[Serratia]]
* Common strains of [[Escherichia coli]] ferment sorbitol
* [[Escherichia coli]] O157:H7 is a sorbitol non-fermenter
* However, many other enterohemorrhagic strains are fermenters


===Thioglycolate Broth===
=== Columbia naladixic acid ===
* Uses [[colistin]] and naladixic acid to inhibit the growth of Gram-negative bacteria


*Thio broth is much more sensitive for both aerobes and anaerobes
=== Thioglycolate broth ===
*Useful only with specimens from sterile sites
* Thio broth is much more sensitive for both aerobes and anaerobes
*If an organism grows from broth only, it may be a fastidious organism, a very small inoculum, or a contaminant
* Useful only with specimens from sterile sites
* If an organism grows from broth only, it may be a fastidious organism, a very small inoculum, or a contaminant


== Fungal ==
==Fungal==
* '''Sabouraud with and without antibacterials:''' originally made for dermatophyte growth, also useful for yeasts. Not good for dimorphics.
** '''Chloramphenicol and gentamicin''' added to inhibit growth of bacteria.
** '''Cycloheximide''' added to inhibit growth of rapidly-growing contaminating molds.
*** However, will inhibit Mucorales, so always need media with and without cycloheximide.
** Inhibitory antimicrobials not needed if collected from a sterile site.
* '''BHI (blood-heart infusion) with blood:''' enriched medium. Good for yeasts, including ''Cryptococcus'', and dimorphic fungi. Non-selective medium. Used for saprophytic and dimorphic fungi (cycloheximide inhibits saprophytes).
* '''Sabouraud’s BHI (SABHI):''' also exists, good for fastidious fungi.
* '''Littman:''' selective medium for fungi. Crystal violet and streptomycin inhibit bacterial growth.
* '''Inhibitory Mould Agar (IMA):''' used to grow dimorphic fungi. Saprophytic and dermatophytic fungi will not grow. Can be used instead of SAB.
* '''Potato flake agar:''' used for fastidious and slow-growing strains.
* '''Cycloheximide''' in primary media: prevents growth of rapidly-growing molds that are frequently contaminants. However, it does inhibit some pathogenic fungi including Mucorales, ''Cryptococcus'', ''Candida krusei'', other ''Candida'' spp., ''Trichosporon'' spp., ''P. boydii'', and ''Aspergillus'' spp.


*'''Sabouraud with and without antibacterials:''' originally made for dermatophyte growth, also useful for yeasts. Not good for dimorphics.
**'''Chloramphenicol and gentamicin''' added to inhibit growth of bacteria.
**'''Cycloheximide''' added to inhibit growth of rapidly-growing contaminating molds.
***However, will inhibit Mucorales, so always need media with and without cycloheximide.
**Inhibitory antimicrobials not needed if collected from a sterile site.
*'''BHI (blood-heart infusion) with blood:''' enriched medium. Good for yeasts, including ''Cryptococcus'', and dimorphic fungi. Non-selective medium. Used for saprophytic and dimorphic fungi (cycloheximide inhibits saprophytes).
*'''Sabouraud’s BHI (SABHI):''' also exists, good for fastidious fungi.
*'''Littman:''' selective medium for fungi. Crystal violet and streptomycin inhibit bacterial growth.
*'''Inhibitory Mould Agar (IMA):''' used to grow dimorphic fungi. Saprophytic and dermatophytic fungi will not grow. Can be used instead of SAB.
*'''Potato flake agar:''' used for fastidious and slow-growing strains.
*'''Cycloheximide''' in primary media: prevents growth of rapidly-growing molds that are frequently contaminants. However, it does inhibit some pathogenic fungi including Mucorales, ''Cryptococcus'', ''Candida krusei'', other ''Candida'' spp., ''Trichosporon'' spp., ''P. boydii'', and ''Aspergillus'' spp.


[[Category:Microbiology]]
[[Category:Microbiology]]

Latest revision as of 08:38, 9 February 2022

Bacterial

  • Primary media (i.e. those onto which samples are directly inoculated) vary by specimen
    • Most commonly include blood, chocolate, and MacConkey agars
    • For anaerobic cultures, pre-reduced Brucella agar
Media Abbr Description
5% sheep's blood SBA A general, non-selective media; allows for identification of hemolysis patterns
Chocolate CHOC Enriched media for difficult-to-grow bacteria
MacConkey MAC Selective for Gram-negative bacteria, with an indicator for lactose fermentation
Sorbitol-MacConkey SMAC Used to identify sorbitol-negative strains of E. coli such as O157:H7
Mueller-Hinton Used for antibiotic susceptibility testing
BCSA BCSA For isolation of Burkholderia cepacia, incubated at 30ΒΊC
Columbia naladixic acid CNA Selective for Gram-positive bacteria
Bile esculin Selective for Enterococcus
Brucella blood BRUC General anaerobic medium
Neomycin NEO Selective plate for anaerobes
CHROMagar Staph. aureus CSA Selective and chromogenic for Staphylococcus aureus
Bacteroides bile esculin BBE Increases sensitivity for Bacteroides (which grow black)
Egg yolk Enriched media for Clostridium

Blood Agar

Mueller-Hinton Agar

  • Standardized pH and solute content that are used for antimicrobial susceptibility testing

Bile Esculin Agar

Chocolate Agar

MacConkey Agar

  • Uses bile salts and crystal violet to inhibit Gram-positive and some fastidious Gram-negative bacteria
  • Uses an indicator to identify lactose fermentation
    • Lactose fermenters turn pink or red
    • Non-lactose fermenters stay yellow

Hektoen Agar

  • Contains lactose, sucrose, salicin, and a high concentration of bile salts (intended to inhibit Gram-positive and coliform Gram-negative bacteria)
  • Black colonies suggests Salmonella, from hydrogen sulfide production
  • Bright orange to pink colonies suggests rapid lactose fermenters like Escherichia coli
  • Green colonies include Salmonella and Shigella

Sorbitol-MacConkey Agar

  • The lactose in MacConkey is replaced with sorbitol
  • Common strains of Escherichia coli ferment sorbitol
  • Escherichia coli O157:H7 is a sorbitol non-fermenter
  • However, many other enterohemorrhagic strains are fermenters

Columbia Naladixic Acid Agar

  • Uses colistin and naladixic acid to inhibit the growth of Gram-negative bacteria

Chromogenic Urine Plates

Thioglycolate Broth

  • Thio broth is much more sensitive for both aerobes and anaerobes
  • Useful only with specimens from sterile sites
  • If an organism grows from broth only, it may be a fastidious organism, a very small inoculum, or a contaminant

Fungal

  • Sabouraud with and without antibacterials: originally made for dermatophyte growth, also useful for yeasts. Not good for dimorphics.
    • Chloramphenicol and gentamicin added to inhibit growth of bacteria.
    • Cycloheximide added to inhibit growth of rapidly-growing contaminating molds.
      • However, will inhibit Mucorales, so always need media with and without cycloheximide.
    • Inhibitory antimicrobials not needed if collected from a sterile site.
  • BHI (blood-heart infusion) with blood: enriched medium. Good for yeasts, including Cryptococcus, and dimorphic fungi. Non-selective medium. Used for saprophytic and dimorphic fungi (cycloheximide inhibits saprophytes).
  • Sabouraud’s BHI (SABHI): also exists, good for fastidious fungi.
  • Littman: selective medium for fungi. Crystal violet and streptomycin inhibit bacterial growth.
  • Inhibitory Mould Agar (IMA): used to grow dimorphic fungi. Saprophytic and dermatophytic fungi will not grow. Can be used instead of SAB.
  • Potato flake agar: used for fastidious and slow-growing strains.
  • Cycloheximide in primary media: prevents growth of rapidly-growing molds that are frequently contaminants. However, it does inhibit some pathogenic fungi including Mucorales, Cryptococcus, Candida krusei, other Candida spp., Trichosporon spp., P. boydii, and Aspergillus spp.