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
Incubation period
Prodromal stage
Illness stage
Convalescence
Incubation Period
Entrance of a pathogen â When the first symptoms appear
True
True or False: The prodromal sage is the most infectious stage.
Prodromal Stage
Nonspecific S/S â Specific S/S
Illness Stage
Start of the S/S â 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 HAIâs
Elderly
Infants
Patients with recent surgeries or procedures
Examples of potential HAIâs sites
Wounds, lesions, and abscesses
False
True or False: Hospitals are reimbursed by insurance for HAIâs.
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 HAIâs
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
Donât 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 patientâs 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
Donât 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 personâs 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 patientâs 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 bodyâs 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 patientâs 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
Patientâs family or caregiver