Microbiology Microbial disease transmission and mechanisms

trocket52's version from 2015-10-04 19:38

Section 1

Question Answer
Epidemiology The study of disease transmission
PathogensThese are disease-causing microbes and can be transmitted in a variety of ways: Contact, respiratory, enteric, environmental, or by vectors (living things such as ticks & mmosquitos)
Where do most pathogenic microbes come from?Other humans
ZoonosesWhen pathogenic microbes come from animals and the environment
Nosocomial InfectionsWhen pathogenic microbes come from hospitals

Section 2

Question Answer
Normal Flora(normal microbiota). Refers to those microbes that live in and on certain areas of the human body normally and are not harmful. They are in fact beneficial (Lactobacillus for example, because of this it is used as a probiotic)
Mutualistic relationship (in flora)Humans and gut bacteria. Both benefit. Humans benefit by the production of vitamins such as vitamin K by gut flora.
Exotoxins(bacterial diseases) Is due to the effect of toxins. Secreted by certain bacteria (e.g.: the tetanus toxin, pertussis toxin)
Endotoxins(bacterial diseases) Is due to the effect of toxins. Part of the cell wall of Gram-negative bacteria.
Endotoxins in small amountsLead to a protective inflammatory response.
Endotoxins in large amountsCause Disseminated Intravascular coagulation (DIC) & fatal septic shock.
Viral DiseasesThe damage viruses do while replicating inside host cells or the immune response itself are major contributors to symptoms.

Section 3

Question Answer
Controlling microbes & infections There are physical & chemical methods of doing this along with antimicrobial drugs
Heat(physical method to control microbes & infection) boiling in particular
Autoclaving(physical method to control microbes & infection) achieves sterility
Pasteurization (physical method to control microbes & infection) Reduces microbial numbers but does not achieve sterility which denature proteins
Ionizing Radiation(physical method to control microbes & infection) Such as x-rays and gamma rays which create toxic free radicals inside cells
UV radiation(physical method to control microbes & infection) Damages DNA
Chemical methodsMost chemicals denature proteins
Antiseptics(chemical method to control microbes & infection) Used on living tissues
Disinfectants(chemical method to control microbes & infection) Used on inanimate objects such as equipment or surfaces
Examples of antiseptics & disinfectantsalcohol, iodine, chlorine, & phenolics (such as Lysol & Phisohex). Hydrogen peroxide (H2O2) is the most effective against anaerobic bacteria
Antibacterial drugsThose that inhibit peptidoglycan synthesis and damage the cell wall (penicillins, cephalosporins, and bacitracin) and are most effective against Gram-positive bacteria
Antimicrobial drug (basis)They are selective toxicity. Finding a target (structure or process) that is found in the microbe and not the human host.
Protein synthesis (in terms of antibacterial drugs)Drugs such as tetracycline and erythromycin interfere with __________ and are often broad-spectrum.
Sulfa Drugs (in terms of antibacterial drugs)Block DNA & RNA synthesis by mimicking enzyme substrates (sometimes referred to as base analogs)
Antiviral drugsSuch as acyclovir (used for herpes) & reverse transcriptase inhibitors like AZT (used for HIV) work by resembling nucleotides and blocking enzymes involved in DNA synthesis
Anti-fungal drugs Such as polyenes and azoles target the plasma membrane of the fungi