Nature of Microorganisms Pathogens are microorganisms that cause disease. Non-pathogens are microorganisms that do not cause disease.

Factors That Influence Microbial Growth Following factors influence microbial growth:  Temperature.  pH, or the values used in chemistry to express the degrees of acidity of a substance.  Food.  Moisture.  Oxygen.

Factors That Influence Microbial Growth (cont.) Aerobic microbes – live only in the presence of oxygen. Anaerobic microbes – grow best in the absence of oxygen.

Methods That Destroy Microorganisms Antiseptics – solutions applied directly to the skin that prevent or inhibit the growth of pathogens. Disinfection – using strong chemicals, such as bleach to destroy pathogens, usually on objects, not skin. Sterilization – the most effective way to destroy all microorganisms.

Microorganisms Microorganism (microbe)  Small living organism  Need a microscope to see it Pathogens  Can cause disease or infection Normal flora  Microbes that are beneficial when present  Not all microbes are pathogens

Microorganisms Bacteria  One-celled  Multiply rapidly  Cocci = round  Bacilli = rod-shaped  Spirilla = spiral  Antibiotics kill bacteria  Gonorrhea, strep throat, tetanus, botulism

Bacteria Cocci Spirilla Bacilli

Types of Microorganisms Bacteria  One-celled microorganisms that are classified according to their shape and arrangement.  Cause diseases such as strep throat, pneumonia, and tuberculosis. (Table 3-4)  Some bacteria produce spores, which help them reproduce. A. B. C.D. E. F. G. H. I. Name the microorganisms A to I. Click HERE to see answers.HERE

Types of Microorganisms (Answers) A. Streptococci B. Staphylococci C. Diplococci D. Micrococci E. Flagellated forms F. Bacilli G. Vibrios H. Spirilla I. Spirochetes BACK

Microorganisms Protozoa  One-celled animal-like organism  Many flagella – aids in movement  Malaria, amebic dysentery Fungi  Plant-like  Live on dead organic matter  Yeasts and molds are common forms  Ringworm, athlete’s foot, thrush

Types of Microorganisms (cont.) Fungi  A plantlike organism that lives on dead matter.  Cause conditions such as ringworm, athlete’s foot, yeast infections, and thrush. Protozoa  Tiny animals found in contaminated water.  Cause diseases such as malaria, trichomoniasis, and amebic dysentery.

Types of Microorganisms (cont.) Rickettsiae  Parasites that live inside the cells of other living organisms.  Transmitted to humans by fleas, lice, and ticks.  Cause diseases such as Rocky Mountain spotted fever.

Viruses  Smallest of all microorganisms.  Live inside cells.  Spread by contact with blood and other body fluids.  Difficult to destroy.  Associated with diseases such as the common cold, chicken pox, herpes, hepatitis B, and acquired immune deficiency syndrome (AIDS). Types of Microorganisms (cont.)

Microorganisms Rickettsiae  Parasitic – live inside other living organisms  Live in fleas, lice, ticks – whose bite transmits disease to humans  Rocky Mountain Spotted Fever Viruses  Smallest, seen with electron microscope  Reproduce inside other living cells  Spread by blood and other body secretions  Common cold, measles, mumps, chicken pox, AIDS

Microorganisms Most grow best in environment that is:  Warm  Moist  Dark Aerobic  Require oxygen to live Anaerobic  Live and reproduce without oxygen

Pathogens Cause infection in different ways  Some produce toxins (poison)  Some cause allergic reaction in the body  Some attack and destroy living cells Nosocomial infections  Transmitted in a health care facility Opportunistic infections  Occur when body defenses are weak

Pathogens Transmission of disease  Person-to-person contact  Contaminated hands!!!  Contaminated substances Food Soil Insects Equipment  Droplets in the air (cough, sneeze)

Infection Control Asepsis  Absence of pathogens Aseptic technique  Handwashing  Good personal hygiene  Disposable gloves  Proper cleaning of equipment and environment

Handwashing Most effective way to prevent the spread of infection Wash your hands:  Whenever they become contaminated.  Before and after lab procedures.  After personal use of the bathroom.  After you cough, sneeze or use a tissue.  Before and after eating, drinking, and using contact lenses.

Handwashing Soap Warm water Friction Clean all surfaces Fingertips pointed down Dry paper towel for turning the faucet on and off

Alcohol-Based Handrub Used in healthcare facilities Used between patients when hands not soiled