The Infectious Disease Model

The Infectious Disease Model

and Breaking the ChainOf Infection

MSIPCFundamentals of Infection, Prevention, Control

and Epidemiology2015

Ruth Anne Rye, RN, BS

The Infectious Disease ModelThe Infectious Disease Model

The Chain of Infection helps to explain the infection process. Each link represents a component or element in the cycle, and must be present in sequential order for infection transmission to occur. Understanding the characteristics of each link and the relation to the other links is important to determine interventions and strategies to break the chain and prevent infection. Breaking the chain of infection is the responsibility of every healthcare professional.

Chain ofInfection

Exit

Transmission

Entry

SusceptibleHost

InfectiousAgent

Reservoir

Chain ofInfectio

n

Infectious AgentInfectious Agent

• Exogenous: from outside the body

• Endogenous: from inside the body

• Bacteria– Bacilli– Cocci– Spirochetes

• Virus

• Fungi

• Rickettsia

• Protozoa

• Bacteria– Bacilli– Cocci– Spirochetes

• Virus

• Fungi

• Rickettsia

• Protozoa

Chain ofInfectio

n

ReservoirReservoir

Storage site for growth and reproduction

Humans: Patient’s own flora - transient or chronically colonized

• Incubating• Active disease • Convalescent Animals Environment

• Food, beverages, soil, • Healthcare equipmento Contaminatedo Handlingo Storage

Chain ofInfectio

n

Mode of ExitMode of Exit

Organism leaves the Reservoir– Respiratory tract

• Cough, sneeze, talking– Gastrointestinal tract

• Saliva, vomitus, feces– Skin, mucous membranes– Genitourinary tract

• Urine, semen, vaginal secretions– Blood– Mother to unborn child– Artificial openings

Chain ofInfectio

n

Mode of TransmissionMode of Transmission

• Contact– Direct– Indirect– Droplet

• Airborne

• Other sources of infection– Example: vector

Chain ofInfectio

n

Mode of EntryMode of Entry

Infectious agent enters the new host– Respiratory tract

• Breathing contaminated air droplets– Gastrointestinal tract

• Eating, drinking, hand-to-mouth (fecal-oral route)– Skin, mucous membranes

• Non-intact skin• Hand-to-eye and nose

– Genitourinary tract• Urinary tract, sex

– Blood– Placenta-to-baby

Chain ofInfectio

n

Susceptible HostSusceptible Host

Immune system, e.g.transplant, extremes of age, chemotherapy

Barrier compromised, e.g. abrasion, burn, device use, surgical procedure

Additional factors, e.g. underlying disease, medications, nutrition, stress

Chain ofInfectio

n

Breaking the ChainBreaking the Chain

Medical Asepsis Medical Asepsis

Definition: Purposeful Prevention of infection by• Reducing the number of organisms and• Preventing their spread

Practices that …….Practices that …….

Keep environment free from contamination

+Keep patient free of colonization by facility

microbes=

ASEPSIS

* Also protects healthcare workers

Asepsis: Know What Is Clean

Asepsis: Know What Is Clean

• Clean, laundered Linen• Dishes and utensils after running

through dishwasher or cleaned + sanitized

• Employee hands following hand hygiene

• Item thoroughly washed and/or disinfected

Asepsis: Know What Is Dirty

Asepsis: Know What Is Dirty

“Dirty” – contaminated (e.g. visible soil), used item

• Examples:• Any obviously soiled item• The floor• Any patient’s body fluid• Soiled/used dressing materials• Toilet seat soiled with patient’s body fluids• Gloved hands following personal care

                                                                                                                                                                                                                        

Asepsis: Know What Is Sterile

Asepsis: Know What Is Sterile

Sterile = Absence of all microbes

• Sterile field • Use sterile supplies – labeled sterile

* Example – delivered in sealed package,

e.g. gauze 4x4, urinary catheter, intravevenous fluids

Asepsis: Separation & Preventing Contamination

Asepsis: Separation & Preventing Contamination

Keep the three conditions separate•Don’t allow clean or disinfected items to come in contact with dirty items•Clean linen falls on floor – floor considered dirty Place in laundry for washing

Remedy the contamination immediately•When you see that dirty, clean, and sterile not kept apart, do something immediately•Report any observed breach in technique

Surgical Asepsis(sterile technique)Surgical Asepsis

(sterile technique)

Practices that keep an area or objects free from all microorganisms

Surgical Asepsis Principles

Surgical Asepsis Principles

• Only sterile items are used withint the sterile field• Sterile persons are gowned and gloved• Tables are serile ony at table level• Sterile persons touch only sterile items or areas• Unsterile persons avoid reaching over the sterile

field• The edges of anything that encloses sterile

contetns are considered unsterile• The sterile field is created as close as possible

to the time of use

Principles, continuedPrinciples, continued

• Sterile areas are continuously kept in view• Sterile person keep well within the sterile

area• Sterile persons keep ontact with sterile

areas to a minimum

PracticesSurgical scrub – gowning - gloving

Precautions to Prevent Transmission Precautions to Prevent Transmission of Infectious Agentsof Infectious Agents

Precautions to Prevent Transmission Precautions to Prevent Transmission of Infectious Agentsof Infectious Agents

Two tier system (HICPAC 2007)Two tier system (HICPAC 2007)

Standard PrecautionsStandard PrecautionsTransmission-Based PrecautionsTransmission-Based PrecautionsDesigned to Supplement Standard Precautions in patients with documented or suspected infection/colonization of highly transmissible or epidemiological important pathogens.

STANDARD PRECAUTIONS (SP)

STANDARD PRECAUTIONS (SP)

• Principle that all blood, body fluids, secretions (except sweat), excretions, non-intact skin, and mucous membranes may contain transmissible microbes

• Group of prevention practices that apply to all patients, regardless of suspected or confirmed infection status, in any setting in which healthcare is delivered.

• Application of SP: determined by:– the nature of the HCW-resident interaction,

and – the extent of anticipated blood, body fluid, or

pathogen exposure (e.g. only gloves for drawing blood vs gown + gloves to dress a wound with excess drainage)

Standard Precautions Standard Precautions

• Hand hygiene• Personal protective equipment (PPE)

– Gloves, gown, face protection• Patient resuscitation• Environmental measures

– Cleaning and disinfection– Soiled patient-care equipment– Textiles and laundry

• Safe injection practices• Patient placement• Respiratory hygiene/cough etiquette

Recommendations chart: http://www.cdc.gov/ncidod/dhap/pdf/guidelines/isolation2007.pef (Table 4, pp 125, 126)

Hand Hygiene: Why?Hand Hygiene: Why?

• Single most important practice to reduce the transmission of infectious agents in healthcare settings

• Reduce risk of morbidity, mortality and cost associated with healthcare-associated infections

• Eliminate transient organisms and reduce resident hand flora

EvidenceEvidenceChain ofInfectio

n

The relationship betweenhand hygiene and HAI’s

• Substantial evidence that hand hygiene reduces the incidence of infections

• Historical study: Semmelweis• More recent studies: rates lower when

antiseptic hand hygiene was performed

Hand Hygiene Methods Hand hygiene is a general term that applies to eitherhandwashing, antiseptic handwash, alcohol-based handrub, orsurgical hand hygiene/antisepsis.

• Handwashing:Washing hands with plain soap and water.

• Antiseptic handwash:Washing hands with water and soap or other detergents containing an antiseptic agent

• Alcohol-based handrub (ABHR):Rubbing hands with an alcohol-containing preparation

• Surgical hand hygiene/antisepsisHandwashing or using an alcohol-based handrub before operations by

surgical personnel

Guideline for Hand Hygiene in Health-care Settings. MMWR 2002; vol. 51, no. RR-16.

Which Method Kills Bacteria Better?

Good Better Best

Plain Soap Antimicrobial soap

Alcohol-based handrub

• Handwashing (HW) with water and soap requires 40–60 seconds from

start to finish 7 times / shift = 56 min.

• Alcohol-based handrubbing (ABHR): 20–30 seconds total; 7 times / shift = 18 min.

• If HCW used hand hygiene for every indication in an 8 hr shift:– HW = 16 hours ! – ABHR = 5 hours

Time constraint major obstacle for hand hygiene

Time constraint major obstacle for hand hygiene

Voss A and Widmer AF, Infect Control Hosp Epidemiol 1997:18;205-208.

Indications for ABHRIndications for ABHR

All situations where soap and water are not required

Dispenser Placement and Storage

Dispenser Placement and Storage

• CMS encourages use of alcohol-based hand rubs– Dispensers in patient rooms, dining rooms and,

as determined, in all settings• Placement in corridors and rules for storage

should follow CMS regulations – Based on NFPA standards published in Federal

Register March 25, 2005, effective May 2005 – (Criteria pg FR 15237)

MSIPC website provides specific directions for locations, e.g. distances between dispensers, distance from electrical plates http://www.msipc..org/advocacy.html

Recommended Hand Hygiene Technique

• Handrubs

– Apply to palm of one hand, rub hands together covering all surfaces until dry

• Handwashing

– Wet hands with water, apply soap, rub hands together for at least 15 seconds

– Rinse and dry with disposable towel

– Use towel to turn off faucet

Guideline for Hand Hygiene in Health-care Settings. MMWR 2002; vol. 51, no. RR-16.

Indications for Hand HygieneIndications for Hand Hygiene

NOTE: This list is too prescriptive for inclusion in a policy;

may be useful when teaching risk reduction/taskidentification

• When coming on-duty and at shift completion• Before and after patient contact • Between all patient contacts• Before performing invasive procedure• Before medication preparation• Before and after eating• Before donning/after removing gloves • Before and after personal restroom use

HH Indications, contHH Indications, cont• When moving from a contaminated body site to

a clean body site• After touching inanimate objects that are likely

to be contaminated with pathogenic microorganisms– Urine measuring/collecting containers

• After contact with objects (including equipment) located in the patient’s environment

• After touching an animal or animal waste, e.g. therapy dog, bird

• After touching garbage• After smoking

WHEN? “My 5 Moments for Hand Hygiene” WHO 2009

WHEN? “My 5 Moments for Hand Hygiene” WHO 2009

Hand Hygiene: Patients, Visitors,

Volunteers

Hand Hygiene: Patients, Visitors,

Volunteers • PATIENTS

– Expected minimally to perform hand hygiene before meals and after personal toilet use

– Nursing staff to review other indications with patient

• VISITORS– Expected minimally to perform hand hygiene before

meals and after personal restroom use – If participating in personal patient care, nursing staff

will review product use and indications for hand hygiene

Additional Considerations

Additional Considerations

• Hand lotion• Nails• Jewelry• Glove use• Adherence

HP Barriers to adherenceHP Barriers to adherence

• Lack of knowledge that guidelines for

hand hygiene exist• Not recognizing opportunities during

the performance of one’s duties• Lack of awareness for the risk of

cross-contamination of organisms

Best PracticeBest Practice• Facility decision regarding hand hygiene• Input into evaluation and selection of

products• Educate – proper HH, product safety, how

and when to use• Competency evaluation and monitoring:

observations, quizzes, skills lab, electronic monitoring systems, data collection forms,

• Encourage patient/family empowerment

References/ResourcesReferences/Resources

• Strategies to Prevent Healthcare-Associated Infections Through Hand Hygiene. SHEA August, 2014

• Canada’s Hand Hygiene Challenge 2012

• Implementing AORN Recommended Practices for Hand Hygiene 2012

• WHO Guidelines on Hand Hygiene in Healthcare, 2009

• Guideline for Hand Hygiene in Health Care Settings, 2002 (HICPAC)

(SP) Personal Protective Equipment (PPE)

(SP) Personal Protective Equipment (PPE)

Facewear

Personal Protective Equipment

GownGloves

GlovesGloves

• Body substance – fluid and solids• Mucous membrane contact – oral,

nasal, conjunctival, rectal, genital• Non-intact skin – burns, surgical

incisions, open skin lesions• Device insertion site• Contaminated items

41

Donning gloves• If wearing gown, extend to

cover wrist of gownRemoving gloves - Remember outside of

gloves are contaminated• Grasp outside of glove with

opposite gloved hand; peel off

• Hold removed glove in gloved hand

• Slide fingers of ungloved hand under remaining glove at wrist

Gloves Gloves

Additional BarriersAdditional Barriers

• Gown: protect arms and exposed body areas– Example: if soiling of clothes probable,

procedure likely to generate splashes

• Facewear (mask/goggles/eyewear): protect conjunctiva, nasal mucosa and mouth– Example: if procedure likely to generate splash, unprotected cough, suctioning

• Resuscitation device: Use Standard Precautions

43

Gown: protect arms and exposed body areas• Example: if soiling of clothes

probable, procedure likely to generate splashes

Removing gown:• Unfasten neck, then waist ties• Remove gown using a peeling

motion; gown will turn inside out• Hold removed gown away from

body, roll into a bundle and discard in room

GownsGowns

How to DecideHow to Decide

• Based on nature of task• Anticipated degree of contact

with potentially infectious substance (anything wet)

• Level of protection needed to prevent fluid penetration

For healthcare personnel (HP) – perorganization policy (all decisions are

local)

STOPSTOPSTOPSTOP

PPE: Donning and removing

PPE: Donning and removing

How hard can it be?A learned skill?Does it matter?

Practice makes perfect!

(S.P.) ENVIRONMENTAL MEASURES

(S.P.) ENVIRONMENTAL MEASURES

• Cleaning and disinfection– Daily room cleaning– Periodic cleaning– “High touch” surfaces - bedrails,

bedside tables, IV poles, call bells, door handles, BR surfaces, computer keyboards

• Care of soiled equipment• Textiles and laundry

(SP) Safe injection practices

(SP) Safe injection practices

• Use safer needle/sharp technologies, e.g. needles/syringes, lancets (glucometers)

• Do not recap, bend, break or hand-manipulate used needles

• Must recap? Use 1-handed scoop• Place used sharps in puncture-resistant

containerResources: MIOSHA, CMS, APIC, and othersCDC: http://www.cdc.gov/injectionsafety/

(S.P.) - Patient Placement

(S.P.) - Patient Placement

Prioritize for single-patient room if patient

• is at increased risk of transmission • is likely to contaminate the environment • does not maintain appropriate hygiene• is at increased risk of acquiring infection• developing adverse outcomes following

infection

(SP) Respiratory hygiene/cough etiquette

(SP) Respiratory hygiene/cough etiquette

Defined: Source containment of infectious respiratory secretions in symptomatic patients, beginning at initial point of encounter, e.g. triage and reception areas in emergency depts. and physician offices

• Cover nose/mouth when sneezing/coughing• Use tissues and dispose in no-touch receptacle• Practice HH after soiling with respiratory

secretions• Wear surgical mask or maintain spatial

separation more than 3 ft (six feet?) if possible

Examples: Application of SPExamples: Application of SP

• Practices that reduce or eliminate organisms– Hand hygiene– Clean uncontaminated supplies– PPE/barriers– Sterile solutions– Sterile field when indicated– Preparation of skin

Any questions?Any questions?