Anaerobic Culture Methods - Microbiology Notes

         ANAEROBIC CULTURE METHOD 

Hello, doctor vanakam, 

The topic of discussion for today is anaerobic culture methods as informed in the previous post on the healing of tissues https://www.stencildent.com/2020/07/healing-of-tissue-repairprocess.html if you haven't checked the previous post do check it out using this link without any further ado lets get started.

 CONTENT :

 1) INTRODUCTION
 2)CLASSIFICATION OF ANAEROBE
 3)METHODS TO ACHIEVE ANAEROBIOSIS

1) INTRODUCTION :

• Anaerobic bacteria have grown only in the absence of oxygen
• These conditions are called as anaerobiosis
• Anaerobic media are used for cultivation of anaerobic bacteria
• Types of anaerobes:

1. Obligate, eg: Clostridium tetani,
2. Aero-tolerant, eg: clostridium histolyticum
3. Facultative 

2) CLASSIFICATION OF ANEROBE:

                                                            ANAEROBIC BACTERIA 

BACILLI                                                                                                 COCCI

GRAM POSITIVE   GRAM NEGATIVE                           GRAM POSITIVE     GRAM NEGATIVE 

CLOSTRIDIUM         FUSOBACTERIUM                 PEPTOSTREPTOCOCUS          VELIONELLA 

                                     SPECIES                             

C.PERFRINGEN

C.TETANI

C.BOTULINUM 

3) METHODS TO CULTIVATE ANEROBEIC BACTERIA:

• 1) CULTIVATION IN VACCUM
• 2)DISPLACEMENT OF OXYGEN WITH GASES
• 3)CHEMICAL, BIOLOGICAL METHOD 
• 4)REDUCTION OF OXYGEN IN THE MEDIUM   

1) CULTIVATION IN VACCUM:

• It is an unsatisfactory method and is not in use now
• Fluid culture may over boil over the media may get detached from plates in the vacuum produced 

2)DISPLACEMENT OF OXYGEN WITH GAS:

• Gases : hydrogen,nitrogen,helium ,carbon dioxide 
• They rarely produce complete anaerobiosis 
•  It is an ineffective method is candle and jar method

• PROCEDURE:

1. In an airtight container inoculated plates are placed inside 
2. Lighted candle kept in it before the lid is sealed
3. Before candle extinguish, it uses up all the oxygen inside and some amount of oxygen is left behind
4. The jar provides a concentration of carbon dioxide to stimulate  the growth of bacteria

3) CHEMICAL, BIOLOGICAL METHOD:

• This method was introduced by Buchner 
• In an airtight jar: pyrogallic acid and sodium hydroxide this reaction result in a small amount of carbon monoxide to get produced but this might be inhibitory to some bacteria 

• ROSENTHAL METHOD:

• In this method instead of pyrogallol, a mixture of chromium and sulphuric acid is used 

• MC INTOSH FILDE ANAEROBIC JAR METHOD:

• CONSISTS OF: 

1.  stout glass/metal jar
2.  metal lid
3. inlet
4. outlet 
5. electric terminal
6. catalyst
7. indicator

• PROCEDURE:

1. In an airtight container, culture plate inoculated with specimen are placed with an indicator 
2. The lid is clamped tight the outlet tube connected to a vacuum pump, and the inlet tube is closed.
3. The air inside is evacuated and the outlet tube is closed
4. Hydrogen gas is passed through inlet tube till reduced atmospheric pressure =normal atmospheric pressure 
5. Electric terminal are switched on to heat the catalyst
6. Catalyst help to combine hydrogen and residual oxygen to form water

• GAS PAK METHOD:

• It is a simple effective method in eliminating the need for drawing a vacuum  and adding hydrogen
• 
  
  

 4) REDUCTION OF OXYGEN IN THE MEDIUM:

• Reducing agents: 1% glucose,0.1%thioglycolate
• Thioglycolate broth with hemin and vitamin k is an enriched medium

Robertson cooked meat medium is used for culture 
Fastidious anaerobe in culture quantitative, anaerobic chamber 

Upcoming post :

The next post is about hypersensitivity reaction and in detail about type 1 hypersensitivity reaction and mediators of reaction.

I hope you all liked the post if u understood do let me know in the comment section as this will motivate me to post more such content.

NOTE: For classification of anaerobe refer the picture I have added while viewing on mobile there might be some changes hope you understand.