BACILLUS CEREUS
Written by Dr.ChrisBACILLUS CEREUS: They are responsible for food poisoning. They can grow in food and produce an enterotoxin that causes diarrhea by a mechanism similar to that of Escherichia coli enterotoxin.
Aerobic spore bearer having resemblance with B. anthracis are called anthracoid bacillus. They differ from each other.
Tags: bacillus, clostridium, spores, sporosarcina
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BACILLUS SUBTILUS
Written by Dr.ChrisBACILLUS SUBTILUS: It is Gram positive about 1.5,u x 4.5,u, straight occurring singly or chain, motile and non capsulated.
It grows on blood agar producing wider zone of beta hemolysis. It may grow on broth culture and nutrient agar etc.
It does not produce any toxin. Some strains may produce soluble hemolysin. They are opportunist pathogens. They […]
Tags: bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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Route of Infection in Man: Bacillus Anthrax
Written by Dr.ChrisRoute of infection in man: The persons most commonly involved are butchers, shephards, handlers of hides, hair and laboratory workers. There are three routes of infection:
(a) Through skin it results in malignant pustule. The spores enter the skin through cuts, abrasion or hair follicle. This lesion starts as papule in 1 to 3 days after infections […]
Tags: aspergillus, bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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Pathogenecity of Bacillus Anthrax
Written by Dr.ChrisPathogenecity of Bacillus Anthrax: In susceptible animals, the organisms proliferate at the site of entry. The capsules remain intact, and the organisms are surrounded by a large amount of proteinaceous fluid containing few leucocytes from which they rapidly disseminate and reach blood stream.
In resistant animals, the organisms proliferate for a few hour by which […]
Tags: aspergillus, bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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Antigenic Structure of Bacillus Anthrax
Written by Dr.ChrisAntigenic structure: 3 antigens have been recognized:
(a) Capsular antigen is found in virulent strain, It consist of poly-peptide of high molecular weight composed of D — glutamic acid. It is a hapten. Antibodies against this antigen are not protective.
(b) Somatic polysaccharides are found as a complex in cell wall. It cross reacts with capsular polysaccharide of type […]
Tags: aspergillus, bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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BACILLUS ANTHRAX: MORPHOLOLGY
Written by Dr.ChrisBACILLUS ANTHRAX: It remains in parasitic form in cattle and sheep. Infection in man is the result of accidental contact with infected animal.
Morphology: It is non motile, non acid fast, Gram positive measuring 1 x 3 to 4y. They may be arranged singly or in short chains. The entire chain may be surrounded by capsule. […]
Tags: bacillus, Blood agar, ethylene diamine, Gelatin stab, lysozyme, polymyxin
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Control of Bacterial Plaqiies
Written by Dr.ChrisControl of bacterial plaqiies: Dental caries & periodental disease could be controlled by preventing plaque formation. Mechanical removal of plaque may be achieved by tooth brushing and dental floss. Curtailment of dietary sucrose also reduces decay. Now dietary fluoride is also used prophylactically against caries. Vaccine consisting of Streptococcus mutans cells or glycosyl transferase preparations, […]
Tags: bacillus, clostridium, spores, sporosarcina
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Rickettsiae
Written by Dr.ChrisRickettsiae: They are minute organisms having properties in between bacteria and viruses. The general properties are:
(1) It contains both DNA and RNA in a ratio of 1:3.5.
(2) Contains muramic acid in the cell wall.
(3) Contains enzymes for metabolic functions.
(4) Multiplies by binary fission.
(5) It is coccobacilli 300 x 600 nm in size visible under light microscope.
(6) It is Gram negative though […]
Tags: aspergillus, bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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SUBCUTANEOUS MYCOSIS: Rhinosporodiasis
Written by Dr.ChrisSUBCUTANEOUS MYCOSIS: Rhinosporodiasis:
Etiology: Rhinosporidium seeberi Specimen: Polyp material.
Direct microscopic examination: KOH preparation of polyp material crushed between two slides shows fungal spherules (10 to 200 ,u) containing endospores.
Culture: Culture is not possible.
Histological examination: It shows number of fungal spherules (100 to 200 p) containing endospores.
Clinical picture: The infection causes the development of polyp in the […]
Tags: bacillus, clostridium, spores, sporosarcina
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OPPORTUNISTIC MYCOTIC INFECTIONS: Aspergillus
Written by Dr.ChrisOPPORTUNISTIC MYCOTIC INFECTIONS:
Aspergillus:
Etiology: Aspergillus fumigatus
Specimen:
1. Exudate
2. Sputum
3. Lung biopsy.
Direct microscopic examination: KOH preparation of the specimen shows septate filamentous hyphae.
Culture:. On Sabouraud’s, dextrose agar with chloramphenicol after 25°C incubation for 1 to 4 days, there appears grey green colored colonies. Microscopic examination of these colonies shows septate hyphae bearing conidia in chain like fashion on sterigmata of conidiophore.
Other […]
Tags: aspergillus, bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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Pneumococcus: Bacteriological Investigations
Written by Dr.ChrisBacteriological investigations:
(1) Material: Sputum, cerebrospinal fluid, pleural fluid, pericardial fluid, peritoneal fluid and pus discharge are collected in a sterile container.
(2) Smear examination: Gram staining show-flame shaped cocci arranged in pair and they are Gram positive capsulated.
(3) Culture: Material is inoculated on blood agar plates and incubated at 37°C under 5 to 10% carbon dioxide. Growth occurs after […]
Tags: bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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CONJUGATION: GENETIC MATERIAL
Written by Dr.ChrisCONJUGATION: It is the process by which a male or donor bacterium makes contacts with female or recipient bacterium and transfer genetic elements into it. The capacity of a strain to act as a donor is determined by sex or fertility factor F in the cytoplasm. Such cells are called (Ft) or male. The strain […]
Tags: bacillus, DNA, hemophilus, neisseria, pneumococci
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TRANSFORMATION: GENETIC MATERIAL
Written by Dr.ChrisTRANSFORMATION: It is the transfer of genetic information through the agency of free DNA. This process, originally discovered in pneumococcus has now been also observed in hemophilus, neisseria and bacillus. Pieces of DNA involve in transformation may carry 10 to 50 genes. The frequency and significance of transformation in bacteria is not known.
Pneumococci are capsulated […]
Tags: bacillus, DNA, hemophilus, neisseria, pneumococci
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PRECIPITATION: Antigen and Antibody Reaction
Written by Dr.ChrisPRECIPITATION: When a soluble antigen combines with its antibody in presence of electrolytes (NaC1) at a suitable temperature and pH the antigen antibody complex forms insoluble precipitate.
Uses of Precipitation Reaction
(1) Identification of bacteria e.g., detection of group specific polysaccharides substance in streptococci in Lancefield grouping etc.
(2) Identification of antigenic component of bacteria in infected animal tissue. e.g., […]
Tags: bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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METHODS FOR IDENTIFICATION OF ORGANISMS
Written by Dr.ChrisDEVELOPMENT OF RAPID METHODS FOR IDENTIFICATION OF ORGANISMS: The last few years have seen exciting advances in finding out new ways of identifying micro-organisms within a few minutes of arrival of a specimen in the laboratory. Specific microbial components may be detected by countercurrent immunoelectrophoresis also designated as CIE. Another nice method for identifications of […]
Tags: bacillus, clostridium, deamination, spores, sporosarcina, tryptophan
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