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close this bookBasic Laboratory Procedures in Clinical Bacteriology (WHO; 1991; 128 pages)
View the documentPreface
View the documentIntroduction
open this folder and view contentsQuality assurance in microbiology
close this folderPart I. Bacteriological investigations
open this folder and view contentsBlood
open this folder and view contentsCerebrospinal fluid
open this folder and view contentsUrine
open this folder and view contentsStool
open this folder and view contentsLower respiratory tract infections
open this folder and view contentsUpper respiratory tract infections
open this folder and view contentsSexually transmitted diseases
open this folder and view contentsPurulent exudates, wounds, and abscesses
close this folderAnaerobic bacteriology
View the documentIntroduction
View the documentDescription of bacteria in relation to oxygen requirement
View the documentBacteriology
open this folder and view contentsAntimicrobial susceptibility testing
open this folder and view contentsPart II. Essential media and reagents for isolation and identification of clinical pathogens
View the documentSelected further reading
View the documentSelected WHO publications of related interest
View the documentBack Cover
 

Description of bacteria in relation to oxygen requirement

A perhaps over-simplistic, but operationally acceptable, description of medically important bacteria in relation to their oxygen requirements is as follows:

 

Obligate aerobic bacteria require gaseous oxygen to complete their energy -producing cycle; these organisms cannot grow without a source of oxygen. Examples of obligate aerobic bacteria are Micrococcus spp and Nocardia asteroides.

Obligate anaerobic bacteria do not require oxygen for metabolic activity, and in fact oxygen is toxic to many of them. Energy is derived from fermentation reactions, which may produce foul-smelling end-products. Examples of such anaerobic bacteria are Bacteroides fragilis and Peptostreptococcus magnus.

Facultative anaerobic bacteria are those for which there is no absolute requirement for oxygen for growth or energy production; they can either utilize oxygen or grow by anaerobic mechanisms. Such bacteria are most versatile, and are usually able to adapt to their environment, creating energy for growth and multiplication by the most effective mechanism. E. coli and S. aureus are examples of facultative anaerobic organisms.

• There are, in addition to the above, microaerophilic bacteria that grow best at reduced oxygen tensions. Campylobacter jejuni is an example of a microaerophilic bacterium.

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