Clostridium
USDA (food safety) Introduction The genus Clostridium is comprised of gram-positive, anaerobic, spore-forming bacilli. The natural habitat of these organisms is the environment and the interstinal tracts of humans and other…
Bacillus anthracis
Bacillus anthracis is a spore-forming bacterium that causes anthrax in humans and animals. It is a zoonaotic disease in that it is normally transmitted by handling of animal carcases. Human…
Gram positive bacteria
Gram positive bacteria are a diverse group. The most clinically important gram ositive pathogens include Staphylococcus, Streptococcus and Entercocci. Gram-positive cocci Enterococcus: are gram positive cocci to elongated cocci in single…
Biochemical or differential tests
Microbiologists have differentiated bacterial based on their biochemical diversity using various biochemical tests. Such tests often include differential medial which are artificial mixtures of chemicals and organic substrates intended to…
Selective media
Selective media can be used to inhibit unwanted bacterial and thereby differentiate bacterial types. Media for isolating intestinal pathogens (MacConkey agar, Hektoen enteric (HE) agar) contain bile salts as a selective…
Motility assays
Motility Test: The motility test uses a semisolid medium. Agar is typically 1.5% to 0.4% which is just enough to maintain its form while allowing movement of motile bacteria. A tetrazolium…
Enterobacteria
Generally Enterobacteriaceae are the largest group of medically important bacteria which comprise a family of Gram negative rods that mostly inhabit the intestinal tract. The port of entry into the human…
Classification & detection
Bacteria are classified according to 1) morphology 2) gram stain as well as 3) growth requirements. (1) Morphology See right hand column (2) Gram stain: is the most important tool for…
Medically important bacteria
Medically Important Gram + Genus--species Shape Metabolism Diagnosis Symptoms Virulence factors location transmission Therapy Staphylococci cocci clusters facultative anaerobes beta lactams --S. aureus alpha…
Gram +/- comparison
See also medically important gram + bacteria organisms and Medically Important Gram Negative Bacteria Differences between Gram Negative and Gram Positive Bacteria Gram-negative bacteria organisms have thinner cell walls which differ in…