Chapter 9 and 10: Patient Care in Radiography

Microorganisms

Bacteria

Viruses

Fungi

Prions

Protozoa

Normal Flora

Microorganisms that live on or inside the body without causing infections or diseases

Pathogens

Microorganisms that cause infections and diseases

Bacteria

Very small, single-celled organisms with a cell wall and an atypical nucleus that lacks a membrane

Most bacteria have one of three distinct shapes

Spherical

Rod-shaped

Spiral

Spherical

Cocci

Rod-shaped

Bacilli

Spiral

Spirilla or spirochetes

Bacteria are also grouped by their

Oxygen requirements

Obligate Aerobes

Require oxygen to grow

Anaerobes

Will not grow in the presence of oxygen

Bacteria are often referred to simply by the

Name of their class or subclass

Some types of bacteria can generate

Endospores

Endospores

Bacteria forms that are resistant to destruction and can remain viable for many years

Significant diseases caused by bacteria

TB

Strep

Necrotizing fasciitis

Necrotizing fasciitis

Skin eating bacteria

Viruses

Subcellular organisms and are among the smallest known disease-causing organisms

A fully developed viral particle is called

Virion

Virion

Is made up of genetic material, either DNA or RNA

Viruses cannot survive

Independently

Viruses must have a

Host cell

Enveloped viruses are

Influenza

Human immunodeficiency virus (HIV)

Hepatitis B

Other common viruses include the

Epstein- Barr virus

Varicella

Epstein -Barr Virus

Causes infectious mononucleosis

Varicella

Causes chicken pox and herpes zoster

Fungi

Occur as single-celled yeasts or as long, branched, filament-like structures

Molds

Branched, filament-like structures

In humans, fungi cause

Skin infections

Respiratory infections

Opportunistic infections

Skin infection such as

Athletes foot and ring worm

Respiratory infections such as

Histoplasmosis and Coccidiodomycosis

Opportunistic infections

caused by usually nonpathogenic organisms

Opportunistic infections such as

Pneumocystis carinii pneumonia and Pharyngeal and Esophageal candidiasis in individuals with compromised immune systems

Prions

The smallest and least understood of all pathogens

Prions was discovered in

1988

Scientists believe that prions

May be infectious proteins

Prions occurs when

Someone is exposed to contaminated products

Prions examples

Corneal transplant, Consumption of infected meat

Protozoa

Complex single-celled animals that generally exist as free-living organisms

A few protozoa are

Parasitic and live within the human body

Protozoa may be classified as

Motile and Nonmotile

Motile

Moving

Nonmotile

Not moving

Protozoa can infect

GI, Genitourinary, Respiratory and Circulatory systems

Common protozoal diseases

Amebiasis, Giardiasis, Trichomoniasis, and Toxoplasmosis

Cycle of infection

Infectious organisms

Reservoir of infection

Portal of exit

Susceptible host

Portal of entry

Transmission of disease

Pathogenic organisms

Microorganisms capable of causing disease

Virulence Factors

Distinguish them from nonpathogenic organisms or normal flora

The reservoir or source of infection may be any place where

Pathogens can thrive in sufficient numbers to pose a threat

Reservoir of infection must provide

Moisture, nutrients, and a suitable temperature, all which are found in the human body

Reservoir of infection may be

Human or nonhuman

(food, water, animals)

Portal of Exit from the human body

May be any route through which blood, body fluids, excretions, or secretions leave the body

Examples of Portal of exit

The respiratory, urinary, and gastrointestinal tracts; an infected wound; and the bloodstream

Susceptible Host

Patients who have a reduced natural resistance to infection

Nosocomial infection

Hospital-acquired infection or Healthcare-associated infections

Nosocomial infections are also called

HAI

Hospital workers are exposed to

Many Pathogens

Portal of Entry

The route microorganisms gain access into the susceptible host

Portal of entry example

Respiratory tract

Urinary tract

GI tract

Open wound or break in skin

Mucous membranes of the eyes, nose, or mouth

Bloodstream

Transmission of Disease

The most direct way to intervene in the cycle of infection is to prevent transmission of the infectious organism from the reservoir to the susceptible host

There are 6 main routes of transmission

1. Direct contact

2. Fomites

3. Vectors

4. Vehicles

5. Droplet contamination

6. Airborne transmission

Direct contact requires

That the host be touched by an infected person and that the organisms be placed in direct contact with susceptible tissue

Direct contact examples

Syphilis, HIV infections, and Staph infections

Fomites

An object that has been in contact with pathogenic organisms

Fomites examples

Contaminated gloves, X-ray tube, and Positioning sponges

Vectors

An arthropod in whose body an infectious organism develops or multiplies before becoming infectious to a new host

What can transmit disease to humans

Bites from infected insects

Vectors examples

Mosquitos and Ticks

Mosquitos

Malaria

Ticks

Lyme disease

Vehicles

Any medium that transports microorganisms

Vehicle example

Contaminated food, Water, Drugs, and Blood

Droplet Contamination

Occurs when an infectious individual coughs, sneezes, speaks, or sings in the vicinity of a susceptible host

Droplet transmission involves

Contact of the mucous membranes of the eyes, nose, or mouth of a host with large droplets that contain microorganisms

Large droplets

Greater than 5 um

How long do droplets travel

3 feet or less

Droplet contamination examples

Influenza, Meningitis, Diphtheria, Pertussis, Streptococcal Pneumonia

Airborne

Occurs from dust that contains spores or by means of droplet nuclei

Droplet nuclei are particles of

Evaporated droplets containing microorganisms and measuring 5 microns or smaller

How long can airborne stay in the air

For long periods of time

Airborne examples

TB, Varicella viruses, and Rueobella

TB

Tuberculosis

Varicella viruses

Also transmitted via direct contact

The body's defense against infection

Natural Resistance

Acquired Immunity

Passive Immunity

Natural Resistance

Provides by mechanical barriers of intact skin and mucous membranes

Acquired Immunity

Occurs when an individual develops antibodies to a particular organism as a result of either infection or immunization

Passive Immunity

Occurs following an injection of performed antibodies to a particular infection

Infectious Diseases

Emerging diseases

Healthcare- associated infections

Bloodborne pathogens

Tuberculosis

Emerging diseases are

New diseases, Existing diseases, and Resurgent or recurrent old diseases

New diseases are

Appearing in the population

Existing diseases that are

Rapidly increasing in incidence or geographic range

Resurgent or recurrent old diseases caused by

An old or mutated pathogen

Infection-control department of hospital responsible for keeping up-to-date

CDC recommendations

WHO data

CDC

Centers for Disease Control and Prevention

WHO

World Health Organization

Disease emergence is precipitated by many factors

1. Increased human exposure to vectors in nature

2. Population growth and migration to crowded cities

3. Bioterrorism

4. Rapid international travel and transportation of goods

5. Contact with new strains of dangerous pathogens

6. Pathogen mutations caused by over utilization of antimicrobial agents

7. Breakdowns in public health measures

8. Climate change

Healthcare- associated infections

HAIS

When does HAIS occur

More than 48 hours after patient is admitted to the hospital

Of greatest concern are those that are multi drug-resistant

MRSA

VRE

Another very common HAI is

Clostridium Difficile Colitis

Clostridium Difficile Colitis

C Diff