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Basic Laboratory Procedures in Clinical Bacteriology by Jozef Vandepitte download in pdf, ePub, iPad

The catalyst becomes

The catalyst becomes inactivated during use and should be regenerated or replaced at regular intervals, as recommended by the manufacturer. Specimen collection and transport to the laboratory This has been covered thoroughly in previous sections. Bacteroides fragilis, Peptostreptococcus magnus, and Clostridium perfringens. Rapid identification is possible with the bile stimulation test. Each colony type should be examined with Gram stain.

The broth culture should be heavily inoculated with a Pasteur pipette so as to distribute the inoculum throughout the medium in the tube. Clostridium perfringens The genus Clostridium contains many species of sporulating Gram-positive rods, some of which belong to the normal gut flora while others are found in dust and soil.

Specimen collection and transport to the

As the liquid culture is inoculated with a larger volume of pus, it may be positive when the primary plates remain sterile. These devices, however, require a palladium catalyst fixed on the underside of the lid of the jar. Gram-positive cocci that produce small, convex, white colonies on anaerobic blood agar, but do not grow in aerobic conditions, may be presumptively identified as Peptostreptococcus spp. It is commonly associated with gas gangrene and may also cause bacteraemia and other deep infections.

Establishing an anaerobic environment for incubating cultures A variety of methods exist for creating an anaerobic environment. This activates the binding of oxygen and the release of carbon dioxide.

If growth appears only in anaerobiosis, identification of a pure culture of the anaerobe should be attempted. Colonies that appear only on anaerobic agar are probable anaerobes and should be subcultured on two blood agar plates, one to be incubated anaerobically and one in a candle jar. They are involved, usually in association with other aerobic or anaerobic bacteria, in anaerobic abscesses, wound infections, and even bacteraemia.