Infections (germs) spread via various routes, but germs don’t move on their own—people move them. The core goal is to break the chain of infection using evidence-based practice (EBP) in healthcare settings.
Clinical Application: EBP guides policies on hand hygiene, PPE use, and environmental cleaning, leading to a measurable reduction in healthcare-associated infections (HAIs).
The chain of infection (conceptual model):
\text{Chain of infection: }\text{agent} \rightarrow \text{reservoir} \rightarrow \text{portal of exit} \rightarrow \text{mode of transmission} \rightarrow \text{portal of entry} \rightarrow \text{susceptible host}
Clinical Scenario: If a healthcare worker (mode of transmission) fails to perform hand hygiene after caring for a patient with C. difficile (agent in reservoir: gut), they can transfer the spores to the next patient (susceptible host), leading to a new infection. Breaking any link, such as proper hand hygiene, prevents this.
Why break the chain: to prevent transmission, protect patients (especially those with weak immune systems), and reduce illness and complications.
The Chain of Infection and the Role of People
Germs need a host to survive; people move germs between hosts.
Hand hygiene, PPE, and adherence to aseptic techniques are primary tools to interrupt transmission.
Clinical Application: A nurse wearing gloves and gown while attending to a patient with a draining wound (contact precautions) effectively prevents the spread of pathogens from the wound to themselves or other surfaces.
Hand Hygiene Practices
When to perform hand hygiene:
Before touching the patient
After touching the patient
Before entering the room
After leaving the room
After contact with blood, body fluids, or contaminated areas
Before an aseptic task (e.g., preparing medications, wound dressing)
Essentially, hand hygiene should be done almost all the time during patient care
Types of hand hygiene:
Alcohol-based hand sanitizer (gel in and out) for routine cleaning
Soap and water when hands are visibly soiled or contaminated with something visibly dirty
Choosing the right method:
If hands look visibly dirty or are soiled, wash with soap and water for at least 20 seconds. This is critical for removing C. difficile spores, which are not effectively killed by alcohol-based sanitizers.
If hands are not visibly soiled, use alcohol-based hand sanitizer (containing at least 60\% alcohol).
Asepsis and Gloving: Medical vs Surgical (Sterile) Techniques
Medical asepsis (clean technique):
Use clean gloves; aim to reduce the number of pathogens
Most routine healthcare tasks fall under medical asepsis (e.g., administering oral medications, routine patient assessments, emptying urine drainage bags).
Surgical asepsis (sterile technique):
Use sterile gloves, sterile fields, and sterile equipment
Required for procedures that require sterility (e.g., inserting an indwelling catheter, obtaining sterile cultures, central line dressing changes, certain suctioning, surgical procedures).
Maintaining a Sterile Field: Always keep sterile items within vision, do not turn your back on a sterile field, and avoid reaching across it. Any object that falls below waist level or becomes wet is considered contaminated.
Key rationale:
These patients are not healthy; often immunocompromised, so strict sterile technique is reserved for when the risk of infection is highest.
Clinical Consequence: Failure to maintain surgical asepsis during a central line insertion can introduce bacteria directly into the bloodstream, leading to a life-threatening central line-associated bloodstream infection (CLABSI).
Contamination and disposal:
Items must be disposed of in appropriate containers (e.g., biohazard bags) to prevent cross-contamination.
Personal Protective Equipment (PPE) and Attire
Types of PPE and usage context:
Non-sterile gloves (for routine contact with patients, blood, body fluids, secretions, excretions, and contaminated surfaces; removed immediately after use)
Sterile gloves (for sterile procedures, as described above)
Gowns (various types depending on risk level: fluid-resistant for general contact, impervious for heavy fluid exposure like surgery)
Masks (e.g., regular surgical mask for droplet precautions; N95 respirator for airborne precautions, requiring fit-testing)
Example context: a healthcare provider may rotate through PPE levels depending on the procedure and precautions in place (e.g., standard precautions, or transmission-based precautions such as airborne, droplet, or contact).
Clinical Application: Before entering the room of a patient with tuberculosis (airborne precautions), a nurse must don an N95 respirator. Prior to a sterile procedure, such as placing a Foley catheter, sterile gloves are essential.
Practical note from the transcript:
Airborne and other transmission-based precautions require appropriate PPE and room assignments (see the sections below).
Donning and Doffing: Proper sequence, especially doffing (gloves first, then gown, then mask), is crucial to prevent self-contamination after exposure.
Transmission-Based Precautions: Airborne, Droplet, and Contact
Airborne precautions:
Pathogens spread through the air via small particles (aerosols) that remain suspended for longer periods; require a private, negative-pressure room with 6-12 air changes per hour.
Core idea: protect others from airborne transmission; typically requires an N95 respirator mask for healthcare workers and a dedicated/private room for the patient.
Clinical Scenario: A patient presenting with a persistent cough and fever might be suspected of having TB. They would immediately be placed in an airborne isolation room, and staff would wear N95 respirators. The patient should wear a surgical mask if transported.
Droplet precautions:
Pathogens spread via droplets when coughing, sneezing, or talking within close proximity (typically less than 3 feet).
Patient isolation involves a private room (or cohorting with another patient with the same infection) and standard precautions plus droplet precautions.
Mask use:
The patient should wear a surgical mask when being transported or when in proximity to others, and healthcare workers should wear a surgical mask when within close contact of the patient.
Example focus: diseases spread by droplets include influenza, pertussis (whooping cough), adenovirus, mumps, and some types of meningitis.
Cough etiquette is an important educational component.
Clinical Scenario: A patient admitted with confirmed influenza would be placed on droplet precautions. Healthcare staff would wear surgical masks and eye protection when providing care within 3 feet of the patient.
Contact precautions:
Pathogens spread by direct contact with the patient (e.g., skin-to-skin) or via contaminated surfaces/items in the patient's environment.
Indications include: multidrug-resistant organisms (MDROs) like MRSA, VRE, CRE; respiratory infections (e.g., RSV in infants); skin/wound infections (e.g., herpes simplex, impetigo, scabies, draining wounds not covered); enteric infections, and eye infections (e.g., conjunctivitis).
Enteric infections specifically involve the gut (example: C. difficile, Norovirus).
Key phrase from the transcript: enteric means "gut"
Practical implication: patients with enteric infections like C. diff require contact precautions; emphasize cleaning and hand hygiene with soap and water (after glove removal) after contact with the patient or environment.
Clinical Vignette: A patient with abdominal cramps, diarrhea (e.g., 4-5 liquid stools per day) and recent antibiotics (e.g., amoxicillin) may have an enteric infection, most commonly C. difficile. Appropriate precaution is stringent contact precautions: private room, gown and gloves upon entry, dedicated equipment (e.g., stethoscope, blood pressure cuff) or disinfection after use, and handwashing with soap and water.
Cough etiquette and education:
Educate patients and visitors about covering coughs/squeezes with a tissue or elbow to minimize droplet spread.
Exam-style scenario (from transcript):
A nurse preparing a sterile field is asked which action would contaminate the field (e.g., reaching across the field, allowing a non-sterile item to touch it, turning away from it); this represents a common testing scenario on sterile technique and contamination risk.
Practical Scenarios, Examples, and Implications
Metaphor to remember concept:
Germs don’t move by themselves; people move them. To protect patients, break the chain of infection with proper hand hygiene, aseptic technique, and adherence to PPE and precautions.
Real-world relevance:
In healthcare settings, strict adherence to standard and transmission-based precautions reduces healthcare-associated infections (HAIs) and protects vulnerable patients, leading to better patient outcomes and reduced healthcare costs.
Ethical and practical implications:
Failure to adhere to infection control can cause harm to patients (e.g., increased morbidity/mortality), increase costs (e.g., longer hospital stays, additional treatments), and erode trust in healthcare systems. It also risks staff well-being.
Key recall points:
Always perform hand hygiene before touching a patient and after contact, use the appropriate hand hygiene method based on soil and context.
Use medical asepsis for most care and sterile technique for high-risk procedures.
Select PPE based on the transmission risk and the precautions in place (airborne, droplet, contact).
Recognize and implement standard precautions plus transmission-based precautions when indicated.
Understand that enteric infections require contact precautions, while airborne and droplet infections require corresponding precautions.
Quick Reference: Summary of Precautions
Standard Precautions (baseline for all patient care)
Airborne Precautions: private negative-pressure room + standard precautions + N95 respirator; example agents include measles, TB, chickenpox.
Droplet Precautions: private room (or cohort) + standard precautions + surgical mask for close contact; protect others from droplet transmission; patients may require masks when transported.
Contact Precautions: private room (or cohort) + standard precautions + gown and gloves; used for MDROs, enteric infections (e.g., C. diff, Norovirus), skin/wound infections, and eye infections.
Common actions to support all precautions:
Hand hygiene every time.
Proper donning and doffing of PPE.
Proper disposal of contaminated materials (e.g., in biohazard waste).
Clear patient and family education about infection control