week 4: chapter 17: Disease, Infection, and Pathogens

Disease

• Disease is any deviation or interruption of the normal structure/function of a body part, organ, or system.
• Microorganisms cause disease, the absence of health entails tissue damage with symptoms.
• Healthcare practitioners need to know what infectious diseases are, how they spread, and how to control them.

Infection

• Infection involves the establishment and growth of microorganisms on or in a host, resulting in injury.
• Pathogenic organisms cause infections
• Pathogens have 3 functions, they multiply and cause obstructions, cause tissue damage, and secrete organic exotoxins.
• Exotoxins are known to results in side effects.

Types of Pathogens

• Bacteria
• Viruses
• Fungi
• Parasitic Protozoa

Bacteria Details

• Microscopic, single-celled organisms
• Prokaryotes that lack nuclei and membrane-bound organelles.
• Bacteria reside in hosts as colonies.
• Classifications are cocci (spheres), bacilli (rods), and spirals.
• Gram staining is a staining technique used to classify bacteria.
• Exists as a colony within the host, contain both DNA and RNA.
• They Produce endospores that are internal, metabolically dormant, highly resistant to external environments, and resistant to chemical and physical agents; this functions as the bacterium's survival form.

Viruses Details

• Microscopic, single cells known as virions.
• Viruses cannot live outside a living cell because they lack the components for survival.
• Carry DNA or RNA, but never both.
• Virions use three processes: attaching to a host cell, inserting their own genetic information, and redirecting the host cell to produce new viruses.
• Viruses are not affected by antibiotics.
• Size may vary from 20-250 nm
• Direct observation requires an electron microscope.
• Viruses can lie dormant for extended periods of time and then manifest as illness.

Fungi Details

• Eukaryotic with a nucleus and membrane-bound organelles.
• Size is greater than bacteria.
• Medically important fungi are dimorphic
• They have two forms: Yeast and Molds
• Disease classifications are superficial, cutaneous, subcutaneous, and systemic.

Parasitic Protozoa Details

• Protozoa are organisms that are neither plant nor animal.
• Protozoa is larger than bacteria
• Eukaryotic
• Live on or in other organisms at the host's expense.
• Protozoa have motile functionality
• They can ingest food particles, and some have digestive systems
• Classified by their motility: ameboid, flagellum, cilia, and sporozoans.

Infectious Disease Establishment

• Encounter: infectious organism comes in contact with the host.
• Entry: organism access through a portal of entry via ingression or penetration.
• Spread: propagation, overcomes body’s immune response.
• Multiplication is the growth in microbe numbers through mitosis
• Damage is direct or indirect
• Outcome is when the host gains control and eliminates the agent, the infectious agent overcomes host immunities to cause disease, or the host and infectious agent compromise and live in a symbiotic state.

Chain of Infection

• Host
• Infectious microorganism
• Mode of transportation
• Reservoir
• Infections will not spread if any link in this chain is broken.

Routes for Disease Transmission

• Air
• Droplet
• Contact
• Transmission Avenues
  • Exogenous
  • Endogenous
• Vector versus fomite

Health Care-Associated Infections

• Infections acquired while in the care of a medical provider.
• Nosocomial Infections
  • Hospital Acquired
• Iatrogenic infections
  • Acquired through care of a practitioner
• Other risks include:
  • Compromised patients
  • Medical personnel
  • Patient flora
  • Contaminated health care environment
  • Interventional, invasive procedures
  • Blood-borne pathogens (BBPs)

Factors Encouraging Nosocomial Infections

• Environment
• Therapeutic regimen
• Equipment
• Contamination during medical procedures
• Diagnostic imaging interventional procedures
  • Indwelling vascular lines
  • Thoracostomy tubes
  • Indwelling catheters
  • Vascular catheters and guidewires
  • ET Tubes
  • Endoscopes

Patient Factors Increasing Potential for Nosocomial Infections

• Age
• Heredity
• Nutritional status
• Stress
• Inadequate rest or exercise
• Personal choice habits
• Health history
• Inadequate defenses
  • Immunocompromised

Blood-Borne Pathogens

• Disease-causing microorganisms present in human blood.
• Considered Health care acquired infections (HAI)
• Two types include HIV (human immunodeficiency virus) and HBV (hepatitis B virus).

HIV

• The virus specifically infects the immune system
  • Infects CD4+ T Cells
• Responsible for acquired immunodeficiency syndrome (AIDS).
• Symptoms include weight loss, muscle and joint pain, glandular pain and swelling, night sweats.
• Symptoms can remain latent for many years.
• May be asymptomatic after exposure for up to 10 years.
• May take up to 1 year for results of blood test to become positive for HIV antibodies.

HBV

• Primarily affects the liver, resulting in swelling, soreness, and loss of normal liver function.
• Symptoms: weakness, fatigue, anorexia, nausea, abdominal pain, fever, and headache.
• Leads to yellow skin color (jaundice).
• Major cause of viral hepatitis.
• Some patients are asymptomatic.
• Blood will test positive 2-6 weeks after symptoms develop.
• Patients can recover in 6-8 weeks, but blood tests will always show they were exposed.

Body Defense Mechanisms

• Internal mechanisms are mechanical barriers, chemical processes, and cellular processes.
• External mechanisms are normal microbial flora and physical methods, chemotherapeutic agents, and Immunizations.
  • Hand washing is a physical method.
  • Chemotherapeutic agents are bactericidal and bacteriostatic.
  • Immunizations include vaccines.

Standard Precautions

• Incorporates body fluid precautions and body substance isolation.
• Used when performing procedures that may require contact with blood, body fluids, secretions, excretions, mucous membranes, and non-intact skin.
• Practice biosafety in medical imaging.
• Follow hand washing protocols.
• Make use of gloving/ Personal protective equipment (PPE)
• Recap needles and handle biospills in line with procedures

Transmission-Based Precautions

• Used with Standard Precautions on patients with pathogenic or communicable diseases.
• There are three common ones: Airborne, Droplet, and Contact.
• Must be employed if a patient is infected with a pathologic organism or communicable disease.
• Particularly important for patients who are immuno-compromised.

Asepsis

• Asepsis implies “freedom from infection.”
• Divided into surgical and medical classifications.
• Hand washing is included in this as well
• Chemical methods use disinfectants which can be bacteriostatic or bactericidal.
• Physical methods use sterilization via autoclave.

Sterilization

• Absolute killing of all life forms.
• Heat is the most effective method such as moist heat with pressure
  • Autoclave is a moist heat under pressure.
• Ultraviolet (UV) light is also effective.

Hand Washing

• Should happen before and after each patient is handled.
• Provides the simplest method of environmental control of microbes.
• Employ hand-washing in your personal life as well.

Contact Precautions

• Use gloving and personal protective equipment
• Shielding is also a critical component of contact precautions.

Chapter Conclusions

• Infection involves the establishment and dissemination of a microorganism on or in a host.
• Infectious diseases are caused by pathogenic microorganisms.
• Nosocomial infections are acquired in the hospital setting.
• The human body uses mechanical, cellular, and chemical mechanisms to fight infection.
• Simple aseptic techniques and environmental control aids.
• Medically aseptic hand-washing techniques, standard precautions, and transmission-based precautions reduce spreading infectious diseases.
• The nature of medicine is such that patients coming into the healthcare setting are "sicker than ever", requiring careful handling.