Disease Transmission and Infection Control

Medical Foundations

Objectives• Introduce microorganisms• Become familiar with infections and

control measures• Introduce the need for standards and

precautions• Become familiar with sterile

environments

Introduction to Microorganisms

Pathogenic microorganisms: cause illness, infection, or disease

Nonpathogenic microorganisms: help keep a balance in the environment and in the body

Microorganism Survival• Most microorganisms that cause disease

– Thrive in warm temperatures• How warm is the human body?

– Need moisture• How much of the human body is made up of

water?– Prefer a dark area to grow in– Need food

• Some live on dead tissue (saprophytes), some live on live tissue

• Some need oxygen (aerobic), some do not need oxygen (anaerobic)

Nonpathogenic Microorganisms

“Good” microorganisms are used in a variety of ways: examples? (P. 489)

Buttermilk, fermenting alcohol, making bread rise

Where do nonpathogenic microorganisms live in your body

and what do they do?

Types of Pathogens

• Bacteria–One celled plants–Classified by shape

and arrangement–Causes strep throat,

staph infections, syphilis

• Protozoa– One celled animals– Found in water and soil environments

• decayed material and contaminated water– Cause amebic dysentery and malaria

Types of Pathogens

• Fungi– Simple, low form of

plant life– May live on dead matter– Yeasts, molds– Causes athlete’s foot,

thrush, vaginitis, and serious lung diseases

Types of Pathogens

Types of Pathogens

Rickettsiae • Parasitic microorganism

– Transmitted to humans through the bite of lice, fleas, ticks, and mites

– Responsible for some of the world’s worst epidemics

– Rocky Mountain spotted fever

– Typhus

• Viruses– Smallest microorganism,

smaller than bacteria– Can only reproduce inside

humans cells– Causes common cold,

upper respiratory infections, smallpox, chickenpox, measles, mumps, influenza, fever blisters

– Also cause HIV which can lead to AIDS

Additional Classifications • Endogenous

– Originates inside the body• Exogenous

– Originates outside the body• Nonsocomial

– An infection acquired inside the hospital• Opportunistic

– Infections that occur when the body’s immune system is weak

How Microorganisms Affect the Body

• Production of toxins– Staphylococcus produces enterotoxin that causes

food poisoning = fatigue, diarrhea, vomiting– Tetanus bacilli produces a toxin that attacks the

central nervous system = damage, possible death• Cell invasion

– A protist can enter red blood cells, making them rupture = chills and fever

• Allergic reactions– Allergies = runny nose, watery eyes, sneezing

Chain of Infection

How Microorganisms and Viruses Spread

• Direct Contact• Indirect Contact• Airborne• Oral Route• Insects and Pests

(Pg. 493)

Disease Prevention• Standard Precautions and Transmission-Based

Precautions were created to provide guidelines that prevent the spread of microorganisms.

• Signs and Symptoms—Which is which?– Infections can be generalized or localized

• Affecting all of the body• Affecting one area of the body

– Give signs and symptoms of each