MICRO PARA

• The history of microbiology began with the availability of the microscope during the mid-1600s, and an English scientist named Robert Hooke made key observations.
• Robert Hooke is reputed to have observed strands of fungi among the specimens of cells he viewed.
• In the 1670s, a Dutch merchant named Anton van Leeuwenhoek made careful observations of microscopic organisms, which he called animalcules.
• Spontaneous generation, which stated that microorganisms arise from lifeless matter such as beef broth, was disputed by Francesco Redi, who showed that fly maggots do not arise from decaying meat if the meat is covered to prevent the entry of flies.
• Louis Pasteur performed numerous experiments to discover why wine and dairy products became sour, and he found that bacteria were to blame.
• Robert Koch provided the proof by cultivating anthrax bacteria apart from any other type of organism.
• Bacteriology is a branch of microbiology that involves the identification, classification, and characterization of bacterial species.
• Taxonomy is an area of biologic science comprising three distinct, but highly interrelated, disciplines that include classification, nomenclature and identification.
• The science of classification is known as taxonomy, and taxon is an alternative expression for a classification category.
• The generally accepted classification of living things was devised by Robert Whittaker of Cornell University in 1969, who suggested a five-kingdom classification.
• The five kingdoms are Monera (Prokaryotae), Protista, Fungi, Plantae, and Animalia.
• If the bacterial suspension initially does not match the standard’s turbidity, the suspension may be diluted, or supplemented with more organisms, as needed.
• Matching turbidity using the unaided eye is facilitated by holding the bacterial suspension and MacFarland tubes side by side and viewing them against a black-lined background.
• Disk Diffusion Method involves placing filter paper disks impregnated with various antimicrobial agents of specific concentrations on an agar plate previously inoculated with the bacterium being tested.
• Turbidity standard for Disk Diffusion Method is 0.5% McFarland Turbidity Standard.
• Susceptibility standard medium for Disk Diffusion Method is Mueller Hinton Agar (MHA).
• Standard inoculum size for Disk Diffusion Method is 1 x 10 8 CFU/mL.
• The diameter of the zone of inhibition around disk is measured in millimeters using a caliper.
• Pure inoculate (cultures) are obtained by selecting 4 - 5 colonies of the same morphology, inoculating them into broth medium and incubating for 3 - 5 hours to achieve a turbid suspension.
• The zone of inhibition is inversely related to MIC - the larger the zone of inhibition, the lower the MIC.
• Alternatively, 4 - 5 colonies 6 - 24 hours of age may be selected from an agar plate and suspended in broth or 0.85% NSS to achieve a turbid suspension.
• Factors affecting zone of inhibition include the growth rate of the test organism, the pH of the medium, the number of disk per plate, and the concentration of divalent cations (calcium and magnesium).
• Ba2SO4 causes turbidity in the Disk Diffusion Method.
• Disk Diffusion Method (Kirby - Bauer Test) is limited to aerobic and facultative anaerobic bacteria.
• MHA containing 5% sheep’s blood is used for testing streptococci and other fastidious organisms.
• Reference method for anaerobes: Brucella agar with laked blood and vitamin K (Wadsworth method).
• Microbiology involves the study of microorganisms that share similar morphologic, physiologic and genetic traits into specific groups or taxa.
• Passive Immunization is the artificially acquired passive immunity that provides protection without the participation of the recipient’s immune system.
• Gonococcus involves deep tissues.
• A carrier is a person or animal who harbors and spreads a microorganism that causes disease but who does not become ill.
• Epidemiology is the study of occurrence, distribution, and causes of disease and injury.
• Routes of Transmission include airborne transmission, transmission by food and water, and transmission by arthropods and cuts and bites.
• Exotoxins are secreted or excreted by living bacteria and their toxicity is due to a simple protein.
• A chronic carrier remains infected for a relatively long time, sometimes throughout life.
• Endotoxins represent diseases such as meningitis, septicemia, pneumonia, and gonococcal infections.
• Antigenic shift is a major genetically determined change in the antigenic character of a pathogen which may result in not being recognized by the host’s immune system; responsible for most of the pandemic infection.
• Antigenic drift is the minor antigenic changes as a result of mutation in pathogen strains and facilitate the pathogen avoid host immune responses; responsible for most of the epidemic infections.
• Exotoxins represent diseases such as gas gangrene, tetanus, botulism, diphtheria, scarlet fever, typhoid fever, UTI, meningococcal infection, meningitis.
• Endotoxins are secreted or excreted by dead bacteria and their toxicity is due to lipid A (LPS).
• Infectious Agent Factors include adherence, proliferation, secretory antibody, lactoferrin, lysozyme, tissue damage, exotoxins, and endotoxins.