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Results for “Bacterial Capsules”

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At least 19 recordsLinked to original sources

Bacterial capsules: a simple method for demonstration under the light microscope.

It is sometimes desirable to demonstrate bacterial capsules during the routine examination of clinical isolates. Apart from the Indian ink method, methods of demonstrating bacterial capsules are not only tedious but are often non-reproducible. A combined positive-negative capsule staining procedure which is simple, rapid and reproducible is described.

Bacteria↗

Role of bacterial capsule in local and systemic inflammatory responses of mice during pulmonary infection with Klebsiella pneumoniae.

The role of bacterial capsule in inflammatory responses in experimentally induced pneumonia caused by Klebsiella pneumoniae was evaluated by comparing the host immunological responses in mice infected with capsulate strain DT-S and non-capsulate mutant strain DT-X. Anaesthetised ICR mice were infected intranasally with inocula of strain DT-S or DT-X. Mice infected with strain DT-X survived significantly longer than those inoculated with strain DT-S. Viable bacterial counts in lungs and blood increased rapidly in mice infected with strain DT-S, in contrast to the gradual decrease in their density in lungs and intermittent bacteraemia in mice infected with strain DT-X. The number of broncho-alveolar lavage (BAL) cells in mice infected with strain DT-X at 24 h after inoculation was significantly higher than in those infected with strain DT-S. In the early stages of infection, the levels of tumour necrosis factor-a and interleukin-6 in BAL fluid of mice infected with strain DT-X were significantly higher than those of mice infected with strain DT-S. In contrast, in the late stage of infection, the levels of these cytokines in serum of mice infected with strain DT-S were significantly higher than in mice infected with strain DT-X. These results suggest that K. pneumoniae capsule may suppress the host immunological responses,thus allowing the bacteria to grow, causing pneumonia, septicaemia and death.

Animals↗

Ultrastructural observation on the bacterial capsule of Bacillus anthracis seen in the spleen of a diseased cow.

The bacterial capsule of Bacillus anthracis seen in the spleen of a cow which had died of anthrax was studied electron microscopically. It was visible around bacteria which had been fixed in a ruthenium red-containing fixative. It was composed of electron-dense spikes and extended outwards from the bacterial surface. It was not found around bacteria which had been treated with a fixative devoid of ruthenium red. Bacteria were seen scattered among blood cells. They were not phagocytized by neutrophils or macrophages.

Animals↗

Bacterial capsules: no barrier against Bdellovibrio.

Bdellovibrio bacteriovorus 109J attached to both capsulated and non-capsulated Escherichia coli K29 cells. Electron microscopy revealed penetration of the thick polysaccharide capsule without any major disintegration of the neighbouring capsular matrix. The capsule remained intact during bdelloplast formation and lysis was unaffected by capsulation of the prey cell. This study shows that, in contrast to its effect on bacteriophage penetration and its protective activities against immune defence mechanisms, the capsule of E. coli does not serve as a barrier against invasion by B. bacteriovorus.

Bacterial Capsules↗