Anaerobic Bacteriology

Anaerobic bacteria are both friend and foe for us. As a normal microbiota of exposed body surfaces and mucous membranes, they help us by digesting foodstuffs, preventing attachment of pathogens, and supplying vitamins such as vitamin K. But when they are introduced to a new site in the body they can cause infections such as liver abscess, brain abscess, lungs abscess, myonecrosis, gas gangrene, and oral anaerobic infections.

To recover anaerobic bacteria from clinical specimens appropriate collection, transport, and processing procedures must be followed.

Bacteroides fragilis: Properties, Pathogenesis, Lab Diagnosis

Bacteroides fragilis: Properties, Pathogenesis, Lab Diagnosis

Bacteroides fragilis is a gram-negative, pleomorphic anaerobe responsible for variety of anaerobic infections including peritonitis.

Clostridium perfringens: Properties, Diseases, Diagnosis

Clostridium perfringens: Properties, Diseases, Diagnosis

Commensal in the large intestine of humans and is responsible for the disease, gas gangrene.

Clostridium tetani: Properties, Pathogenesis, Lab Diagnosis

Clostridium tetani: Properties, Pathogenesis, Lab Diagnosis

Gram positive, obligate anaerobe, looks like drum-stick shaped and causes tetanus.

Clostridium botulinum: Properties, Pathogenesis, Lab Diagnosis

Clostridium botulinum: Properties, Pathogenesis, Lab Diagnosis

Gram positive, anaerobic rod which produces powerful neurotoxin "botulinum toxin".

Toxins of Clostridium perfringens and their roles

Toxins of Clostridium perfringens and their roles

Alpha (α) toxin, Beta (β) toxin, Epsilon (ε) toxin, and Iota (ι) toxin are the major toxins of Clostridium perfringens.

Anaerobic infections: Etiology, Characteristics, Diagnosis

Anaerobic infections: Etiology, Characteristics, Diagnosis

Anaerobic bacteria are part of the normal flora but can cause abscess formation and tissue necrosis when enter into sterile sites.

Robertson’s Cooked Meat (RCM) Medium

Robertson’s Cooked Meat (RCM) Medium

The most widely used anaerobic culture medium containing chopped meat particles and used for maintenance of stock cultures.

Microbes with Good and Bad Smell

Microbes with Good and Bad Smell

Odor of colonies of bacteria may help in their identification but sniffing culture plates is not a good idea and you may contract a disease.

Thioglycollate broth: Composition, Principle, and Uses

Thioglycollate broth: Composition, Principle, and Uses

Thioglycollate broth supports the growth of anaerobes, aerobes, microaerophilic, and fastidious microorganisms.

McIntosh and Fildes’ Anaerobic Jar

McIntosh and Fildes’ Anaerobic Jar

McIntosh and Fildes' anaerobic jar works on the principle of evacuation and replacement, where the air inside the chamber is evacuated and replaced with mixture of gases 

Clostridioides difficile: Characteristics, Disease, Lab Diagnosis

Clostridioides difficile: Characteristics, Disease, Lab Diagnosis

Gram positive obligate anaerobe responsible for a unique colonic disease, pseudomembranous colitis.

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Clinical Specimens for Anaerobic Culture

Sample from sites known to have anaerobes as part of the normal flora (eg mouth) is unacceptable for anaerobic culture.

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Importance of Gram Stain in Anaerobic Bacteriology

Positive gram stain with negative culture report gives information regarding the adequacy of sample collection, transport, and also of culture methods used.

Anaerobic Culture Media

Anaerobic Culture Media

Commonly used anaerobic culture media are; Robertson's cooked meat broth, anaerobic blood agar, egg-yolk agar, bacteroides bile esculin agar.