BASIC MICROBIOLOGY
Definition Microbiology is the science that studies living organisms that cannot be seen with the naked eye (microorganisms or microbes) microorganisms are commonly known as germs
Nature of Microorganisms Pathogens: microorganisms that cause disease most microorganisms are harmless some microorganisms found in the body are beneficial to us when a microorganism enters a part of the body other than where it is intended to be, it can be harmful eg. E. coli from the colon (breaks down waste/makes vitamin K) can enter the urinary tract and cause an infection
Factors that Influence Microbial Growth 5 factors affect the growth of microorganisms: temperature pH (only a few live in acidic environments) moisture food oxygen these factors must be favorable if microorganisms are to live different microorganisms require different conditions for survival eg. aerobic microorganisms grow best with high levels of oxygen, while anaerobic microorganisms grow best in the absence of oxygen Type of food varies: living matter or tissue or dead matter Most pathogens prefer a warm, dark environment
Methods that Destroy Microorganisms 3 common methods destroy microorganisms: Antiseptics (eg. alcohol and betadine) used on the skin slow or prevent the growth of pathogens Disinfection (eg. bleach solution & zephirin) not used on skin because irritation may result Sterilization autoclaves use steam under pressure to kill ALL microorganisms (first two methods are not effective against spores) other methods include the use of chemicals, radiation, and gas Spores are cells produced by bacteria either to reproduce or to be resistant to a harsh environment
Types of Microorganisms 5 major types are: Bacteria Fungi Protozoa (protists) Parasites (rickettsiae) Viruses
Bacteria most familiar of the microbes that infect humans classified by their shape and arrangement Type Shape Arrangement Diplococci Round in pairs Staphylococci in groups or clusters Streptococci in chains Bacilli Rod-shaped in pairs, single, or in chains Spirilla Cork-screw or spiral single