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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Bacteriology
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),
MICROBIAL HAEMOLYSIS IN BLOOD AGAR Read More »
Bacteriology, Biochemical Tests in Microbiology Lab
Over the past 70 years, antibiotics have saved countless number of lives across the globe and enabled the further development of modern medicine as well as antimicrobial agents of diverse types with putative activity against pathogenic microorganisms. Despite the current state of antimicrobial resistance (AMR) globally, these antibiotics are currently used to counter the nefarious
HISTORY OF ANTIBIOTICS – a synopsis on how it all started Read More »
Pharmaceutical Microbiology
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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Bacteriology
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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Bacteriology
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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Bacteriology
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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Bacteriology
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
Bacterial pathogens that cause infections in humans have innate characteristic mechanisms with which they use to suppress the immune response of their host in their bid to establish a disease process. Initiation of an infectious process leads to the development of signs and symptoms in the human host, and these syndromes helps to announce the
Characteristics of Pathogenic Microorganisms (Bacteria) Read More »
Bacteriology
Inoculum size is defined as the number of invading pathogenic microorganisms that is sufficient enough to initiate an infectious process (i.e. an infection) in a susceptible human host. Pathogens must reach or exceed a particular threshold before they will be able to produce clinical signs which are unique to a given disease process. Normally, the
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Bacteriology