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CORYNEBACTERIUM DIPHTHERIAE

Corynebacterium diphtheriae is a Gram-positive, non-spore forming, aerobic, rod-shaped and motile bacterium that causes diphtheria, an upper respiratory tract illness. They are pleomorphic organisms exhibiting different characteristic morphological shapes including V-shapes, irregular shapes and club-shapes.C. diphtheriae and other species in the genera Corynebacteria grow on the mucous membrane of the upper respiratory tract, skin, nares […]

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BacteriologyCORYNEBACTERIUM, CORYNEBACTERIUM DIPHTHERIAE, DIPHTHERIA, diphtheria toxoid, DTaP, Loeffler serum medium, Tellurite blood agar, tetanus toxoid

VIBRIO CHOLERAE

DrChika

Vibrio cholerae is a Gram-negative, oxidase positive, spiral, non-spore forming, facultative, motile, curved or straight rod bacterium that causes severe diarrheal disease known as cholera in humans. Cholera, which is one of the leading causes of waterborne infections in developing countries, is a profuse watery diarrheal disease that is associated with extreme dehydration following excessive

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BacteriologyCholera, TCBS agar, thiosulphate-citrate bile salt sucrose (TCBS) agar, thiosulphate-citrate bile salt sucrose agar, VIBRIO, Vibrio cholerae, waterborne infection

NEISSERIA GONORRHOEAE

DrChika

Neisseria gonorrhoeae is a Gram-negative, oxidase-positive, non-motile, non-sporulating, non-capsulate, diplococcus found asymptomatically in humans. N. gonorrhoeae is found in the family Neisseriaceae and genus Neisseria which contains two important human pathogens viz: N. gonorrhoeae and N. meningitidis (which causes meningococcal meningitis, an inflammation of the meninges of the brain and spinal cord). Though the syndromes

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BacteriologyGONORRHEA, MNYC medium, Modified New York City (MNYC) medium, Modified New York City medium, NEISSERIA, NEISSERIA GONORRHOEAE

Bacillus anthracis

DrChika

Bacillus anthracis is a mesophilic, Gram-positive, aerobic, catalase-positive, rod-like and spore-forming bacterium that causes anthrax in both humans and animals (e.g. goats, cattle and sheep). Due to their ubiquity in the soil, microbes in the genus Bacillus are often referred to as a normal flora of the soil. B. anthracis is very unique amongst other

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Bacteriologyanthrax, anthrax toxin, Bacillus, Bacillus anthracis, bioterrorism

MICROBIAL HAEMOLYSIS IN BLOOD AGAR

DrChika

Haemolysis is the breakdown of red blood cells (RBCs). Certain bacterial species including Streptococcus and Staphylococcus species produce extracellular enzymes that lyse or breakdown the red blood cell component of whole blood. Such bacteria require additional growth factors for growth; and when such bacterial species are cultured in vitro in culture media (e.g. blood agar),

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Bacteriology, Biochemical Tests in Microbiology LabBLOOD AGAR, HAEMOLYSIS, MICROBIAL HAEMOLYSIS, MICROBIAL HAEMOLYSIS IN BLOOD AGAR

PATHOGENICITY ISLANDS

DrChika

Pathogenicity islands (PAIs) are the regions of bacterial chromosome (usually of foreign origin) that contain clusters of genes that provoke virulence in the microbe. They are usually acquired by pathogenic bacteria by horizontal gene transfer in the environment; and only pathogenic bacteria harbour PAIs as they are normally absent in non-virulent bacteria of the same

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BacteriologyPATHOGENICITY, PATHOGENICITY ISLANDS

BACTERIAL ENZYMES THAT EXCITE PATHOGENICITY

DrChika

Pathogenic bacteria produce numerous enzymes that help to increase their pathogenicity and/or virulence during an infection. These enzymes are extracellularly produced, and they are unique features of some pathogenic bacteria that help in their pathogenicity and virulence in their host. Extracellular enzymes help in the disease forming process of pathogenic bacteria even though they may

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BacteriologyBACTERIAL ENZYMES, BACTERIAL ENZYMES THAT EXCITE PATHOGENICITY

ENDOTOXIN PRODUCING BACTERIA

DrChika

Endotoxins are microbial toxins which are produced only on cell lysis i.e. on cell death. They are lipopolysaccharide (LPS) components of the outer membrane of Gram-negative bacteria. Endotoxins produce their effect in a host by activating the complement system by the alternative pathway. They also activate the production of macrophages and B cells; and exotoxins

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BacteriologyENDOTOXIN PRODUCING BACTERIA, toxin

EXOTOXIN PRODUCING BACTERIA

DrChika

Exotoxins are extracellular toxins produced by living bacterial cells. They are protein molecules excreted by growing bacteria into the surrounding medium where the bacterium grows or into the tissues, cells and circulatory system of their human host. Exotoxins are diffusible in nature, and they are produced by both Gram-positive and Gram-negative bacteria. They are known

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BacteriologyEXOTOXIN, EXOTOXIN PRODUCING BACTERIA, TOXINS

BACTERIAL TOXINS

DrChika

Toxins are specific microbial products or secretions which at very low concentrations can act specifically on the cells and tissues of other organisms including humans to cause a local or systemic damage. Toxins which are found in both Gram-positive and Gram-negative bacteria help to increase the pathogenicity and virulence of a given pathogen once they

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BacteriologyBACTERIAL TOXINS, ENDOTOXIN, EXOTOXIN, TOXINS