Ch. 4 Principles of Infection and Control

What % of hospitalized patients develop a health-care associated infection (HAI)?

4%

Community Onset

infections that develop outside of the hospital

Hospital-Onset or Nosocomial

infections that develop in the hospital

What is HAI?

Healthcare Associated Infection

• infections that develop in a patient during the course of medical treatment

What are IP programs?

Infection Prevention programs

• charged with reducing the risk of HAIs

  • protects patients, employees, and visitors

  • provide guidance to their organizations

What do IP procedures do?

• eliminate the sources of infectious agents

• create barriers to their transmission

• monitor and evaluate the effectiveness of control

What 3 elements must be present for transmission of infection within a healthcare setting?

1. a source (or reservoir) of pathogens

2. a route of transmission for the pathogen

3. a susceptible host

What is the primary source of infectious agents in the healthcare setting?

Humans

What are the sources of infectious agents?

• people

• inanimate objects

• patient’s environment

• people via endogenous flora

Host factors increasing the risk of infection

• poorly controlled diabetes mellitus

• extremes of ages

• underlying acquired infections (HIV)

• Iatrogenic

  • chemotherapy

  • placement of tubes and catheters

What are the 3 major routes for transmission of human pathogens?

1. contact (direct and indirect)

2. droplets

3. airborne

What are the 5 modes of transmission?

1. contact (direct and indirect)

2. droplet

3. vehicle

4. airborne

5. vector borne

Examples of each mode of transmission

Direct Contact - Hepatitis A

Indirect Contact - Pseudomonas Aeruginosa

Droplet - Influenza

Vehicle - Salmonellosis

Airborne - Tuberculosis

Vector Borne - Lyme Disease

What is the most common route of transmission?

indirect contact

Direct Contact

• occurs when a pathogen is transferred directly from one person to another

• occurs less frequently than indirect

Indirect Contact

• involves transfer of a pathogen through a contaminated intermediate object or person

• most frequent mode of transmission

Endogenous Flora

bacteria that is normally present in the body

What are immunocompromised patients?

• more susceptible to infection

• ex. cancer, HIV, and old patients

Fomite

inanimate objects that may serve to transfer pathogens from one person to another

What is the most common indirect contact transmission?

healthcare workers not washing their hands

Transmission Involving Fomites

can occur when instruments haven’t been adequately cleaned between patients

How can respiratory droplets be spread

• coughing, sneezing, talking

• procedures: suctioning, bronchoscopy, and cough induction

• propelled ≤3 feet through the air

Droplet Transmission

occurs via respiratory droplets

Airborne Transmission

• occurs via the spread of airborne droplet nuclei

What are airborne droplet nuclei?

• particles ≤5 μm of evaporated droplets containing infectious microorganisms

• can remain suspended in air for long periods of time

• can travel further distances than droplets

How is airborne transmission prevented?

• special air handling and ventilation/respiratory protection is required

• airborne infection isolation (AII) rooms

• N-95 or higher respirators

NIOSH

National Institute for Occupational Safety and Health

Obligate Transmission

under natural conditions, disease occurs after transmission of the microorganism only through airborne (droplet nuclei) aerosols

• ex. tuberculosis

Preferential Transmission

Natural infection results from transmission through multiple routes, but airborne transmission predominates

• ex. measles

Opportunistic Transmission

microorganisms that cause disease through other routes—droplet or contact—but under certain environmental conditions, may be transmitted via airborne transmissions

• ex. SARS transmission via an aerosol plume that originated from sewage

Vehicle Transmission

exposure to pathogens in contaminated food, water, or medications

• ex. heparin solution

Vector-borne Transmission

infectious diseases from insects and rats

• less significant in US

Comprehensive Unit-Based Safety Program

• “stop the line”

• shared commitment to patient and healthcare worker safety

Infection prevention strategies for employees

• employee immunization

• don’t come to work if you have a fever

  • makes it harder to perform tasks and poses a threat to patients

• Occupational Safety and Health Administration (OSHA) - requires hep B vaccine

What immunization should all health care workers undergo

• hep B and varicella (if not immune)

• pertussis booster

• annual influenza vaccination

Tuberculosis, Varicella Zoster (Chicken Pox), and Rubeola (Measles)

• diseases able to be aerosolized as respiratory droplet nuclei

• if people are in a room with someone with this disease, they could become infected, without ever coming into contact with the infected person

Negative Pressure Rooms

• for the isolation of patients

  • ex. Measles patients

Standard infection prevention procedures include

• efforts to eliminate pathogens

• recommended practices for cleaning and disinfecting noncritical surfaces in patient care areas

2 major categories of procedures designed to remove environmental pathogens

1. general sanitation measures

2. specialized equipment processing

Generalized Sanitation Measures

• helps keep the overall environment clean

• aims to reduce the number of pathogens to a safe level

• achieved through sanitary laundry management, food preparation, and housekeeping

• environmental control of air (through specialized ventilation systems) and water

Specialized Equipment Processing

• decontamination of equipment capable of spreading infection

• involves, cleaning, disinfecting, and sterilization (when necessary)

Bactericidal

methods that kill bacteria

Bacteriostatic

methods and techniques that inhibit the growth of bacteria

Sporicidal

methods that destroy spores

Virucidal

methods that destroy viruses

Healthcare Infection Control Practices Advisory Committee (HICPAC) and the Centers for Disease Control and Prevention (CDC)

provide the best practices to limit the transmission of pathogens in the hospital

Define Standard Precautions

• the simplest level of infection control

• should be used with every patient

• primary strategy for prevention of HAIs

• employ personal protective equipment (PPE)

What is PPE

Personal Protective Equipment

• gloves, gowns, masks, eye protection, and face shields

What are Standard Precautions

• hand hygiene

• gloves

• mouth, eye protection, face shields

• respiratory protection

• gowns

• patient care equipment is clean

• occupational health and blood-borne pathogens

• patient placement (isolate & group diseases)

How should you clean your hands before leaving a room with a patient?

• use soap and water

• shouldn’t use hand sanitizer because alcohol is not effective against spore-forming bacteria

When should you perform hand hygiene?

• before and after patient contact

• before and after removing gloves

• after touching blood, bodily fluids, secretions, excretions, and contaminated items

• between tasks/procedures on the same patient if cross contamination of different body sites is possible

• use an approved alcohol-based product for hand hygiene

• if hands are visibly soiled, use soap and water

Standard Precautions for Gloves

• wear clean gloves when touching blood, bodily fluids, secretions, excretions, and contaminated items

• don clean gloves just before touching mucous membranes and non-intact skin

• change gloves between tasks/procedures on the same patient after contact between infectious material

• remove gloves after use, before touching non-contaminated items/surfaces, and before going to another patient

When should you wear masks, eye protection, and face shields?

during procedures and patient care activities that are likely to generate splashes or sprays of blood, bodily fluids, secretions, and excretions to protect mucous membranes of the eyes, nose, and mouth

Standard Precautions for Gowns

• wear a gown to protect skin and prevent soiling of clothing during procedures/patient care activities that are likely to generate splashes or sprays of blood, bodily fluids, secretions, or excretions

• remove a soiled gown as promptly as possible and preform hand hygiene

Standard Precautions for Needles

• never recap needles

• do not remove used needles from disposable syringes by hands

• do not manipulate used needles

• place used disposable syringes, needles, scalpel blades, and sharp items in appropriate puncture-resistant container

What to do when resuscitation is predictable

use mouthpieces, resuscitation bags, or other ventilation devices as an alternative to mouth-to-mouth resuscitation methods

When should a private room be used

with patients who contaminate the environment or who do not/cannot be expected to assist in maintaining appropriate hygiene or environmental control

What is respiratory protection?

use of NIOSH-approved N-95 or higher level respirators intended for diseases that could be transmitted by the airborne route

• ex. tuberculosis

Steps for washing hands

1. thoroughly wet hands

2. use soap to wash around wrists and forearms

3. scrub palms of hands

4. wash between digits on back of hands

5. wash around nails

6. dry hands downward

7. use towel to turn off water

(wash for 15-30 seconds)

Cough Etiquette

1. education of health care personnel, patients, and visitors

2. posted signs to the population with instructions for patients and visitors

3. source control measures (covering the mouth and nose with a tissue when coughing or placing a surgical mask on a coughing person when possible)

4. hand hygiene after contact with respiratory secretions

5. spatial separation (≥3 feet from person with respiratory infection in common waiting areas)

Transmission-Based Precautions

• for patients who are known or suspected to be infected with pathogens that require additional control measures to prevent transmission

• 3 categories

  • Contact Precautions

  • Droplet Precautions

  • Airborne Infection Isolation (AII)

Contact Precautions

intended to reduce the risk for transmission by direct or indirect contact with the patient or the patient's environment

• requires healthcare personnel and visitors to wear gowns and gloves for all interactions with the patient

Droplet Precautions

employed for patients with presumed or confirmed infection with organisms known to be transmitted by respiratory droplets

Airborne Infection Isolation

isolation techniques intended to reduce the risk for selected infectious techniques intended to reduce the risk for selected infectious agents transmitted by small droplets of aerosol particles (ex. tuberculosis)

• N-95 respirator required

• patients should be placed in a single-patient AII room

  • room must be negative pressured, have 2 air exchanges per hour, and use HEPA filters

Cohorting

placing patients with the same disease in rooms together, used only when private rooms are unavailable

What is a Protective Environment

specialized engineering approach to protect highly immunocompromised patients

What does a Protective Environment include?

• HEPA filtration of incoming air

• directed room air flow

• positive room air pressure

• well-sealed rooms to prevent infiltration of outside air

• ventilation to provide 12 or more air changes per hour

• strategies to reduce dust

• prohibition of flowers and potted plants in rooms

What patients would need a Protective Environment?

patients with allogenic hematologic stem cell transplants to minimize the number of fungal spores in the air

When transporting a patient with a contagious disease, who needs to wear the mask?

the patient

What should you do if you have to transport a manually ventilated patient?

put a filter on the expiratory side of the manual resuscitator device

A large % of HAIs are device-related infections such as…

• ventilator-associated pneumonia (VAP)

• catheter related bloodstream infection

• catheter-associated urinary tract infection

What is the best way to reduce host susceptibility to a device-related infection?

• limit the device use

• ensure that the devices are placed and maintained appropriately

Prevention Bundles

the use of multiple different evidence-based practices to prevent device-related infection

• have been shown to decrease the incidence of HAIs significantly

Common components to VAP bundles

• maintaining the head of the bed above 30 degrees

• routine mouth care with chlorhexidine

• minimizing sedation

• appropriate assessment of a patient’s ability wean and be liberated from mechanical ventilation

Cough-inducing procedures

• endotracheal intubation and suctioning

• diagnostic sputum induction

• aerosol treatments (ex. pentamidine therapy)

• bronchoscopy

Cough-inducing procedures and Tuberculosis

• these procedures should not be preformed on patients who may have Tuberculosis, unless essential and can be performed with appropriate precautions

• procedures should be performed with using booths or special enclosures

  • if not feasible, a room that meets ventilation requirements for airborne infection isolation

Airborne Precautions used in addition to Standard Precautions

• place patient in a private negative-pressure room that has 6-12 air changes per hour

• keep the room door closed and the patient in the room

• if a private room is unavailable, cohorting is acceptable

• perform hand hygiene and don respiratory protection when entering the room of a patient with known or suspected infectious pulmonary tuberculosis

• remove respiratory protection and preform hand hygiene after leaving the room

• susceptible persons should not enter the room of patients known or suspected to have measles (rubeola) or varicella (chicken pox) if other immune caregivers are available

• limit transport

Cleaning

removal of all foreign material (ex. soil, organic material) from objects

Disinfection

Inactivation of most pathogenic organisms excluding spores

Disinfection, low level

Inactivation of most bacteria, some viruses and fungi, without destruction of resistant microorganisms such as Mycobacterium tuberculosis or bacterial spores

Disinfection, intermediate level

Inactivation of all vegetative bacteria, most viruses, most fungi, and M. tuberculosis without destruction of bacterial spores

Disinfection, high level

Inactivation of all micoorganisms except bacterial spores (with sufficient exposure times, spores may also be destroyed)

Sterilization

Complete destruction of all forms of microbial life

Critical items

devices introduced into the bloodstream or other parts of the body

• should be purchased sterile or sterilized after use

Semicritical items

come into contact with mucous membranes or nonintact skin

• this category includes most respiratory equipment

• should be free of all microorganisms before use, although small number of bacterial spores may be present

• require a high-level disinfectant using chemical disinfects

Noncritical items

come into contact with intact skin only

• items may include noncritical patient care items and environmental surfaces

• most noncritical reusable items (ex. bedpans, patient bed rails, blood pressure cuffs) may be decontaminated where they are used

• require detergent washing with low to intermediate disinfection

Personnel tasked with cleaning/disinfecting/sterilizing medical equipment must

• follow instructions provided by manufacturer

• use products reregistered with the US Environmental Protection Agency (EPA) or cleared by the FDA

• wear appropriate PPE while cleaning

Cleaning

the first step in reprocessing all equipment

• involves removing dirt and organic material

• failure to clean equipment properly can render all subsequent processing efforts ineffective

• soaps and detergents need to be used

• noncritical items (ex. commodes, intravenous pumps, and ventilator surfaces) must be thoroughly cleaned and disinfected before use with another patient

• disassemble and examine before cleaning

Enzymatic cleaners

neutral detergents with added enzymes that help to remove organic (proteinaceous) material from equipment

Disinfection

a process that destroys the vegetive form of many or all pathogenic organisms except spores

• can involve chemical or physical methods

Chemical Sterilants

a few high-level disinfectants that can kill spores with prolonged exposure times

What is the most common Physical Method of Disinfection?

Pasteurization

Chemical Disinfection

involves application of chemical solutions to contaminated equipment or surfaces

• equipment must be immersed in solution for set period of time

• ex. of disinfectants: alcohol, chlorine, hydrogen peroxide

Sterilization

destroys all microorganisms on the surface

• can be achieved by physical (via forms of heat) or chemical (via low temp. sterilization) methods

• medical devices containing sterile body tissues or fluids are critical items and should be sterile

Low Temperature Sterilization

includes ethylene oxide: a colorless and toxic gas

What is the most common form of sterilization?

steam

Immediate Use Sterilization (flash sterilization)

item is placed in an open tray to allow for rapid penetration of steam

• not recommended as a routine method

Low-Temperature Sterilization Technologies

includes ETO, hydrogen peroxide, and peracetic acid

• less than 60° C

Equipment-Handling Procedures include

• maintenance of in-use equipment

• processing of reusable equipment

• application of one-patient-use disposables

• fluid and medication precautions

Respiratory care equipment that can spread pathogens include

• nebulizers

• ventilator circuits

• bag-valve-mask devices

• suction equipment