Infection (Class 6)

Chain of Infection

Chain of Infection

A sequence of events that describes how a pathogen gets from where it is to infecting a susceptible host.

Infectious Agent

Microorganisms capable of causing disease or illness. Ex:

• Bacteria

• Fungi

• Parasites

• Prions

Reservoirs

Places where infectious agents live, grow, and reproduce. Ex:

• People

• Water

• Food

Portal of Exit

Ways in which infectious agents leave the reservoir. Ex:

• Blood

• Secretions

• Excretions

• Skin

Mode of Transmission

Ways in which the infectious agents is spread from the reservoir to the susceptible host. Ex:

• Contact

• Droplets

• Airborne

Portal of Entry

Ways in which the infectious agent enters the susceptible host. Ex:

• Mucous membranes

• Respiratory system

• Digestive system

• Broken skin

Susceptible Host

Individuals may have traits that affect their susceptibility and severity of disease. Ex:

• Immune Deficiency

• Diabetes

• Burns

• Surgery

• Age

Direct Contact

Person-to-person

Direct Contact Example

Oral, fecal

Indirect Contact

Contaminated object-to-person

Indirect Contact Example

Contaminated stethoscopes or BP cuffs.

Droplet

Coughing or sneezing drops that are >5-10 um

Droplet Disease Example

Influenza

Airborne

Droplets <5 um suspended in the air.

Airborne Disease Example

Tuberculosis

Vehicles

Contaminated items entering a person.

Vehicle Example

Water, drugs, blood, food

Vector

Living organisms that transmit diseases. (External/internal)

Vector Examples

Mosquitos, ticks, flea bites

Localized Infection

Infection at a specific site. Ex:

• Wounds

• Pressure

• Injuries

• Lesions

• Absecess

Localized Infection Symptoms

• Edema

• Pain

• Tenderness

• Warmth

• Erythema

• Yellow, green, and/or brown drainage

Systemic Infection

Infection affecting the entire body, usually occurs when treatment of local infection was unsuccessful, and can be fatal if untreated.

Systemic Infection Symptoms

• Fever

• Fatigue

• Malaise

• Enlarged, tender lymph nodes

• Other, more specific, symptoms related to body systems

Stages of Infection

1. Incubation period

2. Prodromal stage

3. Illness stage

4. Convalescence

Incubation Period

Entrance of a pathogen → When the first symptoms appear

True

True or False: The prodromal sage is the most infectious stage.

Prodromal Stage

Nonspecific S/S → Specific S/S

Illness Stage

Start of the S/S → End of them.

Convalescence Stage

Acute S/S disappear (recovery)

Exogenous

Microorganisms from outside the individual. Ex:

• Salmonella

• C. diff

Endogenous

Microorganisms from altered normal flora. Ex:

• Yeast infections

Iatrogenic

From an invasive or diagnostic procedure. Ex:

• CAUTI

• CLABSI

Healthcare-Associated Infections

Infections resulting from the delivery of healthcare services in healthcare agencies.

Populations most at risk for HAI’s

• Elderly

• Infants

• Patients with recent surgeries or procedures

Examples of potential HAI’s sites

Wounds, lesions, and abscesses

False

True or False: Hospitals are reimbursed by insurance for HAI’s.

Risk factors for infection in older adults

• Deteriorating immune system (less thymus function and less lymphocytes)

• Poorer nutrition

• Sedentary lifestyle

• Greater likelihood of multiple comorbidities

Ways to decrease HAI’s

• Hand hygiene

• Immunization

• Nutrition

• Rest and exercise (balanced lifestyle)

Asepsis

The absence of pathogens or disease-producing microorganisms. Techniques break the chain of infection and should be done on all patients.

Medical Asepsis

Used for everyone. Cleaning, disinfecting, and sterilizing equipment.

Surgical asepsis is used for:

• Perforations in the skin

• Broken skin integrity

• Invasive procedures

Disinfection

Eliminates many or all microorganisms with the exception of bacterial spores.

Sterilization

Eliminates all forms of microbial life including spores.

True

True or False: Steam, dry heat, hydrogen peroxide, and ethylene oxide are all ways to disinfect or sterilize equipment.

Eliminating an Infectious Agent

• Clean

• Disinfect

• Sterilize

Eliminating a Reservoir

• Change dressings

• Empty drainage

• Proper storage

• Antiseptic wipes on ports or equipment

• Discard open bottles within 24 hours

Control Portal of Exit/Entry

• Cough etiquette

• Standard precautions

• Maintain skin integrity

• Wipe front to back after urinating

• Keep drainage sets intact and closed

Controlling Transmission

• Don’t share personal care items (Ex. Bedpans)

• Wipe stethoscope between patients ]Dedicated equipment for contact precautions

• Wear gloves and protective eyewear

• Biohazard bags

• Carry soiled items away from your body

• Never put clean or soiled linens on the floor

• HAND HYGIENE

Hand hygiene should be performed:

• Before touching a patient

• Before a clean/aseptic procedure

• After touching a patient

• After touching the patient’s surroundings

Protect Susceptible Hosts

• Protect normal body defenses

• Isolation precautions

Standard Precautions

Apply to all patients and any situation involving blood, blood products, all body fluids, secretion, excretions (except sweat), nonintact skin, and mucous membranes.

Necessary PPE/Precautions for Standard Precautions

• Perform hand hygiene

• Don’t wear artificial nails

• Wear gloves

• Discard all sharp instruments and needs in a puncture-resistant container.

• Proper respiratory hygiene and cough etiquette.

Airborne Precautions

• Used when droplets are <5 um

• Private room with negative-pressure airflow

• N95 Mask or respiratory protection device

• The patient only leaves room for essential reasons.

• The patient must wear a mask when leaving the room.

Droplet Precautions

• Droplets are >5 um and land within three feet of the patient.

• Private room

• Mask or respiratory device

Contact Precautions

• Direct contact with patient or indirect via environmental contact

• Patients must have a private room, but they may cohort patients with the same infection.

• Gloves

• Gown

• Disposable equipment

Protective Environment

• Used for allogeneic hematopoietic stem cell transplant patients.

• Private room with positive airflow

• Mask

• Gloves

• Gown

Airborne Diseases

• Measles

• Varicella

• Tuberculosis

• Rubeola

Droplet Diseases

• Influenza

• Pertussis

• Pneumonia

• Diphtheria

• Rubella

• Mumps

Contact Diseases

• MRSA

• C. diff

• Shigella

• Scabies

• Herpes simplex

Surgical Asepsis

Prevents contamination of an open wound, serves to isolate an operative or procedural area from an unsterile environment and maintains sterile field.

Principles of Surgical Asepsis

• A sterile object remains sterile only when touches by another sterile object.

• Only sterile objects may be placed on a sterile field. A package that is torn, punctured, wet, or open is considered unsterile.

• A sterile object or field out of the range of vision or an object held below a person’s waist is contaminated.

• A sterile object or field becomes contaminated by prolonged exposure to air.

• When a sterile surface comes in contact with a wet, contaminated surface, the sterile object or field becomes contaminated by capillary action.

• Fluid flows in the direction of gravity. A sterile object becomes contaminated if gravity causes a contaminated liquid to flow over the surface of the object.

• The edges of a sterile field or container are considered contaminated.

  • The one-inch border is considered contaminated.

Normal Flora

Good bacteria that secrete antibacterial substances within the intestine and on the skin as well as provide competition to harmful bacteria.

Inflammatory Process

A protective vascular reaction that delivers fluid, blood, and nutrient to an area of injury. It neutralizes pathogens or necrotic tissue.

Factors that influence a patient’s susceptibility to infection

• Age

• Sex

• Nutritional Status

• Stress

• Disease Process

Age

Immune responses decline as the thymus slows down.

Sex

Estrogen can promote immune responses during infection/after vaccination.

Nutritional Status

Lack of this reduces wound healing and limits the body’s defenses.

Stress

Elevated cortisol levels lead to a decreased infection resistance.

Disease Process

Diseases of the immune system compromise them as their defenses are weakened.

Drugs that compromise a patient’s immune system

• Adrenal corticosteroids

• Cytotoxic and antineoplastic drugs

Normal White Blood Cell Count

5,000-10,000/mm^3

Indication of infection

White blood cells increase during an acute infection, but decrease in certain viral or overwhelming infections.

Normal Urine, Blood, or Wound Culture

Normally sterile, no microorganism growth.

Normal Gram Stain of Wound, Sputum, or Throat

No WBCs on gram stain, but possible normal flora present.

Members of the healthcare team that collaborate to prevent infection

• Nurses

• Experts in infection control

• Case managers

• Patient’s family or caregiver