Infection Control and Isolation

A sequence of interconnected factors necessary for an infectious process to take place.

Chain of infection

Six components of the chain of infection

Infectious agent
reservoir,
portal of exit
mode of transmission,
portal of entry
susceptible host.

Key strategy for preventing infection

Breaking at least one link in the sequence required for disease transmission.

Resident flora as an infectious agent

Microorganisms naturally present on or in the body that protect against infection, but can cause disease if translocated to an improper body site (such as GI tract flora moving elsewhere).

The habitat where an infectious agent lives, grows, and multiplies, encompassing both animate hosts (humans, animals, insects) and inanimate objects (soil, water, equipment).

Reservoir

The route by which an infectious agent leaves its reservoir.

Portal of exit

The mechanism by which an infectious agent travels from the reservoir to a new host.

Mode of transmission

The site through which an infectious agent gains access into a host.

Portal of entry

Factors that increase host susceptibility

Advanced or young age
underlying disease (HIV/AIDS, malignancy),
immunosuppressive medications
radiation therapy
invasive indwelling devices
and poor nutrition or sleep.

Invasive indwelling devices are medical tools that are surgically or non-surgically introduced into the body—either through a body surface (skin break) or a natural body orifice—and remain in place for a prolonged period

The degree of pathogenicity or efficiency with which an infectious pathogen can produce disease in a host.

Virulence

Physical movement of microorganisms directly from an infected individual to another host without an intervening contaminated object or person.

Direct contact transmission

Transfer of microorganisms from an infected individual to a host via an intermediate contaminated object or person, such as shared medical equipment, bed rails, or unwashed gloves.

Indirect contact transmission

Dispersal of large infectious respiratory particles over short distances ($3\text{ to }6\text{ feet}$) through coughing, sneezing, or talking onto host mucous membranes.

Droplet transmission

Dispersal of fine infectious particulates that remain suspended in the air over long distances, requiring negative-pressure isolation rooms.

Airborne transmission

Spread of pathogens to multiple individuals through contaminated media such as food, water, or commercial products.

Vehicle transmission

Transfer of microorganisms carried from host to host or place to place by living organisms such as mosquitoes or rodents.

*A mosquito bites a person infected with malaria and picks up the parasite and transmits to tothers *

Vector-borne transmission

What is the regeneration timeline of the stratum corneum
(the outermost layer of your skin's epidermis)

The skin's protective lipid layer restores half of its barrier in $6\text{ hours}$ and achieves complete recovery in $5\text{ to }6\text{ days}$.

General immune protection driven by phagocytic cells (neutrophils and macrophages) that engulf and destroy microorganisms during inflammation.

Nonspecific immunity

* AKA INATE IMMUNITY : the natural defense system you are born with that fights all germs and foreign substances in the same way*

Targeted body defense mediated by lymphocytes and antibodies(immunoglobulins) that recognize and neutralize specific infectious agents.

[this is in response to a pathogen that has invaded the body before and the body remembers and uses markers (antibodies) to recognize them if they return]

Specific immunity (also known as adaptive or acquired immunity)

The body's natural defense mechanism activated when tissue is injured, foreign substances are present, or an infectious agent attacks.

Inflammatory response

Four basic steps of the inflammatory pathway

1. Recognition of harmful stimuli by pattern receptors

2. Activation of the inflammatory pathway

3. Release of inflammatory markers

4. Recruitment of inflammatory cells

Five cardinal local manifestations of inflammation

1. 🔴 Redness — increased blood flow to the area

2. 🔥 Heat — increased blood flow and local metabolic activity

3. 🫧 Swelling — fluid moves from blood vessels into the tissues

4. 😣 Pain — inflammatory chemicals stimulate nerve endings

5. 🚫 Loss of function — caused by pain, swelling, and tissue damage

R-H-S-P-L
→ Red, Hot, Swollen, Painful, Loss of function

Five stages of infection in chronological order

1. Incubation

2. Prodromal stage

3. Acute illness

4. Period of decline

5. Period of convalescence

The initial period extending from exposure to the pathogen until the appearance of the first symptom, during which pathological changes occur without visible manifestations.

Incubation stage of infection

Prodromal stage of infection

The second stage of infection characterized by non-specific initial manifestations (such as fever, aches, malaise, and poor appetite) as the pathogen replicates.

Acute illness stage

The third stage of infection where specific, severe manifestations of the disease process become clearly obvious.

Local vs. systemic infection

Local infections are confined to a single area and treated with topical or oral antibiotics, whereas systemic infections spread into the bloodstream and require intravenous antibiotics and continuous monitoring.

Expected reference range for total white blood cell count

$$5{,}000\text{ to }10{,}000\,\text{mm}^{-3}$$

Nonspecific blood markers of inflammation

C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and procalcitonin (PCT).

Sequential order of the inflammatory response in a wound

1. Bacteria invade an open wound

2. Histamine, kinins, and prostaglandins arrive at the site

3. Plasma from the blood enters the site

4. Phagocytosis occurs

5. Pus develops

Priority order of assessment for post-operative surgical site inflammation

First assess for signs of infection (warmth, erythema, edema, chills), then check peripheral pulses to evaluate circulation.

Period of decline in infection

The stage where disease manifestations begin to subside as the number of infectious agents in the body decreases.

Period of convalescence

The final stage where the client returns to a previous or new balanced state of health.

Anatomical sites to touch during a throat culture swab

The surface of the tonsils, tonsillar pillars, or back of the pharyngeal wall (avoiding other areas of the mouth and pharynx).

serves as the first responder to injury and ingests bacteria via phagocytosis. Immature forms are called bands or stabs.

Neutrophil
expected percentage $55\%\text{ to }70\%$ of total WBCs

fights chronic bacterial infections and acute viral infections, divided into T cells and B cells.

Lymphocyte
expected percentage $20\%\text{ to }40\%$ of total WBCs

phagocytizes damaged tissue from injury or infection and produces interferon.

Monocyte
expected percentage $2\%\text{ to }8\%$ of total WBCs

active in allergic reactions, parasitic infections, and inflammatory responses.

Eosinophil
expected percentage $1\%\text{ to }4\%$ of total WBCs

releases histamine, serotonin, and heparin. (also called mast cells)

Basophils
expected percentage $0.5\%\text{ to }1\%$ of total WBCs

Key laboratory requirement when drawing sequential nonspecific inflammatory markers (CRP, ESR, PCT)

Sequential blood samples must be processed by the same laboratory because these test values are not standardized across different facilities.

Novel CBC ratio markers for chronic inflammation status

Neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and systemic immune inflammation index (SII).

Medical asepsis

Clean technique designed to reduce the number and transfer of disease-causing microorganisms.

Surgical asepsis

Sterile technique that completely eliminates all microorganisms, including spores, from equipment and sterile fields.

Primary indication for soap and water handwashing over alcohol-based hand rub

When hands are visibly soiled or when caring for clients with spore-forming pathogens like Clostridioides difficile.

Recommended duration for hand rubbing with soap or alcohol-based sanitizer

$20\text{ to }30\,\text{seconds}$ (equivalent to singing 'Happy Birthday' twice).

Minimum alcohol concentration required for effective alcohol-based hand rub

$60\%$ alcohol concentration.

Hand hygiene protocol when caring for clients with Clostridioides difficile

Wear gloves during client contact and wash hands with soap and water immediately after glove removal, as alcohol-based rubs do not destroy spores.

Fingernail and polish guidelines for nurses in high-risk areas (e.g., OR, ICU)

Fingernails must be kept short with no chipped polish, and artificial or gel nails are strictly prohibited due to bacterial retention.

Required jewelry removal prior to performing surgical hand antisepsis

All rings, watches, and bracelets must be removed.

Sterilization

The complete destruction and elimination of all microbial life, including bacterial spores.

Three primary methods of sterilization

1. Thermal (autoclaving dry steam)

2. Chemical (ethylene glycol or hydrogen peroxide gas)

3. Radiation (gamma rays)

High-level vs. low-level disinfection

High-level disinfection eradicates almost all microorganisms except a few spores (used for endoscopes), whereas low-level disinfection destroys most vegetative bacteria on non-critical surfaces.

Required clearance distance between a sterile field surface and surrounding walls or objects

$$12\text{ to }18\,\text{inches}$$

Contaminated border dimension on a sterile drape field

The outer $1\,\text{inch}$ border of the field.

Correct sequence for opening a sterile package

1. Open the first flap away from the body

2. Open the side flaps one at a time

3. Open the final flap closest to the body

Prerequisite step required prior to performing sterilization or disinfection on medical equipment

Thorough cleaning to remove all visible soil and organic or inorganic material manually or mechanically.

Essential package checks prior to setting up sterile supplies

Verifying package integrity for damage or breaches and confirming the item has not passed its expiration date.

Recommended positioning for a sterile field work surface

A flat surface positioned close to the client to minimize unnecessary movement and contamination risk.

Correct sequence for opening flaps on a sterile drape or package

1. Flap furthest away.
   
   

2. Side flaps.
   
   

3. Flap closest to the nurse

Rationale for opening the flap furthest away first

Prevents reaching directly over the open sterile field, which could introduce contaminants and compromise sterility.

Primary objective of maintaining proper sequence and outer wrapper technique when opening a sterile field

To prevent contamination and preserve overall asepsis.

Health care–associated infections (HAIs)

Infections acquired by a client while receiving treatment in a health care facility, such as a hospital, nursing home, or ambulatory care center.

Four major types of health care-associated infections (HAIs)

1. Central line–associated bloodstream infections (CLABSIs)
   2. Catheter-associated urinary tract infections (CAUTIs)
   3. Surgical-site infections (SSIs)
   4. Ventilator-assisted pneumonias (VAPs)

Mechanism by which invasive medical devices increase HAI risk

Invasive devices create an artificial portal of entry, allowing pathogens from contaminated surfaces, hands, or client skin flora to enter internal body sites.

Primary benefit of maintaining asepsis with invasive devices beyond preventing infection

Reduces the need for antibiotic therapy, thereby decreasing the development of antibiotic resistance.

Infection control bundles

Evidence-based practice guidelines grouped together to systematically prevent HAIs and improve client safety and mortality rates.

Key components of a Ventilator-Assisted Pneumonia (VAP) bundle

Hand hygiene, specific client positioning, avoiding frequent ventilator circuit changes, mouth care, nutrition guidelines, and preventing cross-contamination.

Key strategies for Catheter-Associated Urinary Tract Infection (CAUTI) prevention

Preventing unnecessary urinary catheterization, ensuring prompt/early removal, and maintaining an aseptic closed drainage system.

Maximal sterile barrier requirements during central line insertion

Cap, mask, sterile gown, sterile gloves, and a full-body sterile drape.

Preferred skin antiseptic solution and concentration prior to central line insertion

A solution containing greater than $0.5\%$ chlorhexidine with alcohol.

Central line insertion site to avoid in adult clients who are obese or overweight

The femoral site, due to an increased risk of infection and complications.

Dressing guidelines for central line insertion sites

Cover with sterile gauze or a transparent semipermeable dressing; apply a chlorhexidine-impregnated dressing for clients age $18$ years and older.

Daily skin hygiene protocol for intensive care clients older than $2\text{ months}$ with central lines

Daily bathing with a chlorhexidine preparation.

Replacement schedule for central line dressings

Gauze dressings every $2\text{ days}$ and transparent semipermeable dressings every $7\text{ days}$, or sooner if wet, dislodged, or soiled.

Protocol for accessing a central line hub or port

Perform hand hygiene, use sterile supplies, and scrub the access port with friction using chlorhexidine, iodophor, $70\%$ alcohol, or povidone-iodine prior to use.

Tubing change frequency for propofol infusions

Every $6\text{ to }12\,\text{hr}$ or whenever the drug vial is changed.

Tubing change frequency for fat emulsions or blood products

Every $24\,\text{hr}$.

Tubing change frequency for standard continuous IV infusions

At least every $7\text{ days}$, but no more frequently than every $4\text{ days}$.

Multidrug-resistant organisms (MDROs)

Bacteria that display resistance to one or more classes of existing antimicrobial medications.

Primary challenge in treating multidrug-resistant organisms (MDROs)

They typically respond to only one or two remaining medications, making infections difficult to treat.

Essential nursing practices to prevent MDRO transmission

Performing hand hygiene, wearing gloves, and following contact precautions according to CDC recommendations.

Six primary examples of multidrug-resistant organisms (MDROs)

1. Methicillin-resistant S. aureus (MRSA)
   2. Vancomycin-resistant enterococcus (VRE)
   3. Vancomycin-resistant S. aureus (VRSA)
   4. Vancomycin-intermediate S. aureus (VISA)
   5. Extended-spectrum beta-lactamase (ESBL)–producing organisms
   6. Multidrug-resistant Streptococcus pneumoniae (MDRSP)

Enhanced barrier precautions

Infection control measures designed for nursing homes that mandate staff to wear gowns and gloves during specific high-contact care activities to prevent MDRO transfer.

Client care activities requiring gowns and gloves under enhanced barrier precautions

Bathing or showering, hygiene, dressing, changing linens or briefs, assisting with toileting, providing wound care, transferring the client, and caring for or using invasive devices.

Primary clinical factor increasing client infection risk in health care settings

The presence of invasive medical devices (such as IV lines, catheters, tubes, or drains) or open wounds, which provide direct portals of entry for pathogens.

Institutional factors that increase infection transmission in nursing homes

Close living proximity among institutionalized clients, frequent staff movement between clients in close quarters, and a high concentration of vulnerable older adults.

Primary bloodborne pathogens transmitted through needlestick injuries

Hepatitis B virus, hepatitis C virus, and human immunodeficiency virus (HIV).

Maximum safe fill limit for sharps disposal containers

Less than three-fourths ($\frac{3}{4}$) full.

Immediate safety actions required upon withdrawing a needle

Engage the safety device immediately and promptly deposit the needle into a puncture-resistant sharps container at the point of care.

Required institutional steps following a contaminated needlestick injury

Promptly report the occurrence, complete protocol-based follow-up testing, and conduct an investigation into the cause.

Protocol for disposing of general contaminated medical waste

Place waste in leak-resistant biohazard bags at the point of care, and apply a second bag if the initial bag is punctured or contaminated on the outside.

Rules for bagging soiled client linens

Bag and secure linens directly at the site of care, and use a second bag if needed to prevent liquid leakage, regardless of whether standard or transmission-based precautions are active.

Key actions to avoid when handling soiled linens in a client care area

Sorting linens inside the client care area and shaking or agitating linens, which can disperse microorganisms into the air.

Sequential order of steps for obtaining a throat culture

1. Assist client to a sitting position, instruct head tilt, and have them say "ah"

2. Illuminate throat with penlight (use tongue depressor if needed)

3. Insert sterile swab without touching lips, teeth, tongue, cheeks, or uvula

4. Swab tonsillar area, contacting inflamed areas or drainage

5. Withdraw swab without touching other oral structures

6. Insert swab into culture tube securely and crush preservative ampule if applicable

7. Label culture tube per policy, place in biohazard bag, ensure client safety, and perform hand hygiene

Oral structures to avoid contacting during a throat culture swab

Lips, teeth, tongue, cheeks, and uvula.

Anatomical region targeted during a throat culture swab

Tonsillar area, specifically contacting inflamed areas and/or drainage.

Preparatory assessment and personal steps before hand hygiene

• Inspect hands for cuts and abrasions

• Ensure nails are no longer than $0.6\,\text{cm}$ ($\frac{1}{4}\,\text{inch}$)

• Push watch and uniform sleeves above wrists

• Remove all rings

Body positioning and water flow parameters for soap and water handwashing

• Stand in front of sink without letting uniform touch

• Adjust water to warm flow

• Keep hands and forearms below elbows during wetting and rinsing

• Keep fingertips pointing downward so water flows off clean areas last

Soap volume and friction duration required for handwashing

Dispense $3\text{ to }5\,\text{mL}$ ($1\,\text{teaspoon}$) of liquid soap and rub hands firmly for $15\text{ to }20\,\text{seconds}$.

Anatomical surface coverage required during soap and water handwashing

Palms, backs of hands, fingers, interdigital spaces, under fingernails, and at least $2.5\,\text{cm}$ ($1\,\text{inch}$) above the wrist.