mb w11 (pathways of cross infect)

Nosocomial Infection* (will test on parameters)

• infectious disease contracted during dental apt or hosp stay

• if first appear 48hr+ after hosp admit

• if within 72hr after discharge

• if 30 days after surgery

causes (provides portal of entry for environ microorgs)

• surg trauma

• intubation

• cathertization

microorgs that cause nosocom disease may be known pathogens, normal flora, cross infect in dental (AKA HC-assoc infections HAI)

Nosocomial Examples

Streptococcus pyogenes

• Strep throat

• Scarlet fever

• Tonsillitis

• Rheumatic fever

• Septicemia (bloodstream infection)

Healthcare-assoc pneumonia may be cause by…

• Staphylococcus aureus

• Klebsiella pneumoniae

• Haemophilus influenzae

• Streptococcus pyogenes (less common)

Nosocomial Infect(know what and percent)

common bacterial isolates from nosocoms are…

3 gram-pos cocci

• resp for approx 34% nosocomials

1. Coagulase-negative staphylococci

2 Staphylococcus aureus

3. Enterococcus spp.

4 gram-neg bacilli

• resp for approx 32% nosocomials

1. Enterobacter aerogenes

2. Escherichia coli

3. Klebsiella pneumonia

4. Pseudomonas aeruginosa

other

• legionella pneumophilia & clostridium difficile (common org of colon)

Opportunistic diseases (nosocom)

infect disease caused by microorgs usually…

• live in harmony w host

• nonpathogenic environ orgs

• pathogens that take advantage of weakened hosts

Can cause either prim or second disease

• ∴ opportunistic can also be nosocomial

• approx 70% of nosocomial involve drug-resistant bact

Ex of difficult treat healthcare-assoc infects

1. Pseudomonas aeruginosa infections

2. Multidrug-resistant organisms (MDROs):

– MRSA (Methicillin-resistant Staphylococcus aureus)

– VRE (Vancomycin-resistant Enterococcus)

– Drug-resistant Mycobacterium tuberculosis

3. Opportunistic fungal infections:

– Candida species

4. Some viral infections may require long-term management:

– HIV

will be q on quiz identifying one of these so know.

Which of the following best defines a nosocomial infection?

A. An infection acquired before admission to a healthcare facility

B. An infectious disease contracted during a dental appointment or hospital stay

C. An infection caused only by antibiotic-resistant bacteria

D. An infection transmitted only through airborne routes

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According to the definition of a nosocomial infection, an infection may be considered

healthcare-associated if it first appears:

A. Within 24 hours of admission only

B. At any time during hospitalization

C. 48 hours or more after admission, within 72 hours after discharge, or within 30 days after surgery

D. Only after discharge from the hospital

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Which of the following Gram-positive cocci is commonly associated with nosocomial

infections?

A. Escherichia coli

B. Pseudomonas aeruginosa

C. Staphylococcus aureus

D. Mycobacterium tuberculosis

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Which of the following is considered a multidrug-resistant organism commonly

associated with healthcare settings?

A. Candida albicans

B. Vancomycin-resistant Enterococcus (VRE)

C. Influenza virus

D. Streptococcus pyogenes

Approximately what percentage of nosocomial infections involve drug-resistant bacteria?

A. 20%

B. 35%

C. 50%

D. 70%

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A patient receiving chemotherapy develops an infection from microorganisms that

normally live harmlessly on the body. This is an example of:

A. Cross-contamination

B. A nosocomial infection

C. An opportunistic infection

D. Airborne transmission

Dental environ sources of infect

Parenteral exposure

• injury to lips (incl piercings), gingiva, or oral mucosa from needles/contam instrument

Inhalation

• expose to droplet/aerosols w oral/resp microorgs

Contam instuments/handpieces

DUWLs

Environ surfs

• counters, chairs, light handles, other clinical surfs

Contam clothing/PPE of dental personell

q relating to article on immunocomp infection from duwls from mt will be on quiz

Definition Review

Direct contact: blood, saliva, other body fluids, or infectious lesions.

Indirect Contact: involves an intermediate material or inanimate

(non-living) object that has had contact with an infected host or

their body fluids.

• water & food can both be resevoir + mode of transmit

Fomites: inanim objects resp for transmit of infect agents

• ex: instruments, needles, counters, clothing, dental trays, pens

Aerosols: invisible particles suspended in air that remain airborne for extended periods

• can be inahled

Definitions

Sterilization - destruct/removal of all microorgs in/on object

Disinfection - reducing # pathogenic orgs, therby elim potential for disease transmission

1. disinfectants applied to inanimate objects

2. antiseptics applied to living tissues

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will test

Splatter - droplets greater than 100 µm diam. that settle quick (contam clinicial & operatory surfs

Droplets/particles - betw 20 µm & 100 µm fall from airborne suspension within secs

Aerosols - small (>5 µm) remain suspend in air

Infectious Agents

• Bacteria

• Viruses

• Protozoa

• Fungi

• Prions

Prions = proteinaceous infectious particle

• unique elements in nature

• agents of group of chronic diseases called “prion diseases” or transmissible spongiform encephalopathies (TSEs)

• no DNA/RNA

• normal prion protein (PrPᶜ) can be convert > abnorm form (PrPˢᶜ)

• abnorm protein accum in nervous tissue (cause spongey appearance in brain)

• can self-propagate by convert normal p abnormal prots

• very long incubation periods (sometimes years)

• ex: scrapie in sheep, Creutzfeldt–Jakob disease (CJD)

• highly resistant to heat, chem agents & irradation (need special autoclaving procedures)

• have been reports of transmit thru instruments

review

Which of the following particles remains suspended in the air for the longest

period of time?

A. Splatter

B. Droplet

C. Aerosol

D. Saliva

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A particle measuring 50 µm in diameter would be classified as a:

A. Aerosol

B. Droplet

C. Splatter

D. Fomite

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Which statement about splatter is correct?

A. It remains suspended in the air for hours.

B. It measures less than 5 µm in diameter.

C. It settles quickly onto nearby surfaces.

D. It is not involved in cross-contamination.

Which characteristic makes prions particularly challenging for infection control?

A. They contain DNA that mutates rapidly.

B. They reproduce only inside bacteria.

C. They are highly resistant to heat and many sterilization methods.

D. They survive only in water.

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Which statement about prions is TRUE?

A. Prions contain DNA but no RNA.

B. Prions contain RNA but no DNA.

C. Prions are infectious proteins that contain neither DNA nor RNA.

D. Prions are bacteria that invade nervous tissue.

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The disease-causing prion protein (PrPSc) causes disease primarily by:

A. Producing toxins that destroy nerve cells.

B. Converting normal prion proteins (PrPC) into abnormal forms.

C. Replicating its DNA inside host cells.

D. Triggering an autoimmune response.

Chain of infection

Cross-Contam

transfer of oral fluids & debris from client > surfs, equip, mats, hands, other client

• saliva’s invisible & high # bact & virus (so problematic in oral hc)

• microorgs have potential survive on surfs for days/weeks/months (if left untreated w germicidal agent)

route of transmission (review)

disease transmit = contact w/ infected person/animal/carrier

• survival of pathogens is dep upon transfer to suscept human/anim host

direct

• skin-skin (herpes type 1)

• mucous-mucous (sti)

• across placenta (toxoplasmosis)

• breast milk (HIV)

• sneeze-cough (influenza)

indirect

• food-borne (salmonella)

• water-borne (hep A)

• vector-borne (malaria)

• air-brone (chickenpox)

Cross Infection

transmit of infectious agents betw. patient>patient(or staff) in clinical environ

orgs capable of cause cross-infect in humans derived from…

• other human sources (MOST IMPORT)

• animal sources (ie. vectors LESS IMPORT)

• inanimate objects (ie. fomites LEAST IMPORTANT)

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bact & virus can survive on surfs for long time (remember)

1. C. difficile = 5 months on hospital floors

2. MRSA = 2 days on plastic

3. VRE = 58 days on countertops

4. Norovirus = 12 days on carpets

review

A dental hygienist treats a patient with an undiagnosed respiratory infection and later provides care to several other patients without following appropriate infection prevention protocols. This scenario best illustrates:

A. A vector-borne infection originating from an animal source

B. Cross-infection involving the most significant source of infectious agents

C. Transmission from a fomite, the most important source of infection

D. An example of indirect transmission from an environmental reservoir only

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Why is environmental cleaning and disinfection important in dental settings?

A. Most microorganisms die immediately after leaving the body.

B. Only viruses can survive on surfaces for extended periods.

C. Some pathogens can survive on surfaces for days to months and contribute to

disease transmission.

D. Cross-contamination occurs only through direct patient contact.

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Which statement best describes cross-contamination in the dental setting?

A. The growth of microorganisms inside dental unit water lines

B. The transfer of microorganisms from a patient to surfaces, equipment, healthcare

workers, or another patient

C. The destruction of all microorganisms on an instrument

D. The removal of microorganisms through sterilization

Oral HC Workers (OHCW)

health history

1. Obtain, review, update health history (all visits)

2. Assess

• Current health status

• Medical conditions

• Hospitalizations or surgeries

• Medications

• Allergies

• Physician care

• Oral health concerns

3. health history alone can’t identify all infectious patients

• some infect may be asymptomatic (dont know)

• client may suppress info (ex: HBV, hepC HCV, HIV) from discrim fear

4. health histories help identif patients who may require…

• additional diagnostic testing

• med consultation

• modified treatment plans

• antibiotic prophylaxis when indicated by current guidelines

• dental procs may introd oral bact > blood (bacteremia)

• can inc risk in suscept patient

• transient bacteremia?

Interviewing Skills

• thorough med history = essential part of infections control

• med hist provide baseline data to help identif specif human needs (protection from heatlh risks, freedom from fear/stress ect..) — form basis of dh diagnosis

• health history provide baseline info for treat plan & safety

• safe environ for discuss + verbal/nonverbal communic.

• build rapport

Immunizations

Universal/Standard Precautions

standard precautions (prev universal)

• min. infection prevention practices that apply to all patient care

• regardless of suspect/confirm infect status

• all clinical proced on patient should be conduct w this

main features

• hand hygiene

• use of personal protective equip (ex., gloves, masks, eyewear)

• respiratory hygiene/cough etiquette

• sharps safety (engineering & work practice controls)

• safe injection practices (ex., aseptic technique for parenteral meds)

• sterile instruments and devices

• clean and disinfected environmental surfaces

• education, lifelong learning and training.

skincare

• gloves don’t replace handwash

• wash exposed skin after contact w/ blood, saliva, spatter

• hands can transfer microorgs betw things

• microorgs collect under nails

• cuts/broken skin allow pathogens enter body

Occupational risks for HIV & HBV

• skin integrity is compromised if evidence of chapped skin, dermatitis, abrasion, or open wound

• combo of severity factors (ex: large-bore hollow needle, deep puncture, visible blood on device, or needle used in vessel

• ^contrib to elev risk of transmit (if person pos)

CDC Reccs for Hand Hygiene

1. Perform hand hygiene when…

• hands visibly soiled

• after barehand touch equipment/stuff likely to be contam by anything

• before/after patient

• before putting on glove + after

2. Use soap + water when hands soiled OTHERWISE use alcohol rub

3. for surg procedure, perform surgical hand scrub before putting on

Standard precaution Cont

thorough medical history & update every visit!

hygienist should…

• review every visit

• conduct approp screening exams

• recog that patients may be harbouring a pathogen, asymptomatic, in a carrier state

why is this important?

• standard precautions assume that any patient may be capable of

  transmitting infectious microorganisms, even when no signs or

  symptoms of disease are present.

barrier protection

• use phys barriers to prevent contact w/ blood/saliva/other infectious mats

• reduc risk trasmission betw ppl

PPE (personal protective equip)

• designed to protect oral hc worker from blood-borne & other pathogens

• gloves, mask, eyewear, faceshield, protective clothing

• additional barrier measure = head & shoe cover

Surface Disinfectants

factors infu effectiveness of this…

1. Number and type of organisms present

2. Amount of bioburden (blood, saliva, andmicroorganisms.)

3. Selection of an EPA (Environmental ProtectionAgency) registered disinfectant that is tuberculocidal.

4. In Canada, once a drug has been authorized, Health Canada issues a DIN (Drug Identification Number) which permits the manufacturer to market the drug in Canada.

5. Using appropriate disinfectant concentration, use life, and contact time; follow manufacturer’s directions.

6. Pre-cleaning of surface to maximize removal of bioburden before disinfection

chem disinfectants for surface disinfect (criteria)

1. Tuberculocidal and virucidal (broad spectrum)

2. Effective within 10 minutes or less (fast acting) –a rapidly lethal action on all vegetative forms and spores of bacteria, fungi, protozoa and viruses.

3. Non-toxic and hypoallergenic

4. Odourless

5. Reasonable cost

6. Provides residual effect on treated surfaces

7. Retains stability and effectiveness in the presence of bioburden

8. Good penetrating and cleaning ability

9. Not damaging to the equipment and environmental surfaces

10. Easy to use

Categories/lvls of biocidal activity of the surface disinfectant

1. high lvl

• inactivates bact spores & all forms of bact/fungi/virus

• dep on contact time, can either be disinfectant or sterilant (agent destroying microorgs & spores)

2. interm lvl

• inactivates all forms of microorgs EXCEPT spores

• kills M. tuberculosis

3. low lvl

• inactivates vegetative bacteria & certain lipid-type (lipophilic) viruses

• DOESN’T destroy spores, tubercle bacilli, or non-lipid viruses

4. hospital lvl

• kills Staphylococcus aureus, Pseudomonas aeruginosa, & Salmonella choleraesuis

dental office = intermediate lvl disinfectant (compatib w/ office equip)

a. EPA registered (EPA/DIN number on label)

b. Labeled bacteriocidal, viricidal and fungicidal

d. Label should specifically note that the disinfectant is tuberculocidal, kills

M. tuberculosis.

e. CDC does not recommend alcohol or early generation quaternary

ammonium compounds as surface disinfectants.

f. Effectiveness and stability – shelf life, use life, and reuse life.

surface disinfectants (types)

1. chlorine compounds

• Broad-spectrum and fast acting

• Inexpensive

• Can be inactivated by organic matter

• Corrosive to some surfaces

2. iodophors

• Broad-spectrum antimicrobial activity

• May stain or discolor surfaces

• Effectiveness depends on proper dilution and contact time

• Ex: Povidone-iodine

3. synthetic phenolics

• Broad-spectrum activity

• Residual antimicrobial effect

• Compatible with many surfaces

• May damage some plastics w/ prolonged use

4. glutaraldehydes

• High-level disinfectants

• Used primarily for heat-sensitive instruments

• Not rec for routine environ surface disinfection due to toxicity

Which factor can reduce the effectiveness of a surface disinfectant if not removed before disinfection?

A. Contact time

B. Bioburden such as blood and saliva

C. EPA registration

D. Drug Identification Number (DIN)

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Which characteristic is desirable in an ideal surface disinfectant?

A. Requires more than 30 minutes of contact time

B. Damages equipment to improve disinfection

C. Effective against a broad spectrum of microorganisms and acts quickly

D. Loses effectiveness in the presence of bioburden

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Which level of disinfectant is typically recommended for environmental surfaces in the dental office?

A. High-level disinfectant

B. Intermediate-level disinfectant

C. Low-level disinfectant

D. Sterilant

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What is the key difference between intermediate-level and high-level disinfectants?

A. Intermediate-level disinfectants are less expensive.

B. High-level disinfectants can inactivate bacterial spores, while intermediate-level

disinfectants generally cannot.

C. Intermediate-level disinfectants kill viruses, while high-level disinfectants do not.

D. High-level disinfectants cannot be used in healthcare settings.

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Which characteristic is most important when selecting a disinfectant for environmental surfaces in a dental office?

A. Pleasant scent

B. Intermediate-level activity and tuberculocidal claims

C. Lowest purchase price

D. Ability to sterilize instruments

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Which of the following disinfectants is considered a high-level disinfectant but is nottypically used for routine environmental surface disinfection because of its toxicity?

A. Chlorine compounds

B. Iodophors

C. Synthetic phenolics

D. Glutaraldehydes

Instrument Sterilization

steam autoclave (moist heat under pressure)

• steam = deanature protein & destroy microorg (including spores)

• pressure = allow steam reach sterilizing temps

• effective sterilize depend on steam penetration + exposure time

typical cycle = 121C (250F) at psi for 15-30 min (dep on load & machine type)

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dry heat sterilization

• kill micoorg by oxidation of cellular componenets

• useful for instrum that may corrode w/ moisture

typical cycle = 160C (320F for 60-120 min)

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unsaturated chemical vapour (chemiclave)

• use heated mix of alcohols + other chem vapours under pressure

• vapour penetrate instrument + destroy microorg (include spores)

• prod less instrument corrosion than steam

typical cycle = 132C (270F) at 20-40 psi for approx 20 min

clinical considerations

• less commonly used today that steam autoclave

• personnel should understand advantages & limits of each method

• some may affect certain plastics, rubber components, handpieces

incomplete sterilization result from…

• inadeq prep of materials needed to be sterilized (cleaning/packaging)

• misuse of equip (overloading, timing, temp selection)

• inadeq maintenance

ster method must provide complete destruct of all microorg/virus/spores

& not damage instrument

types of waste

1. infectious waste

• capable of causing an infectious disease.

2. contam waste

• items that have contacted blood or other body secretions.

3. hazardous waste

• poses a risk to humans or the environment.

4. toxic waste

• capable of having a poisonous effect.

5. regulated waste

• liquid blood or saliva

• sharps contam w/ blood/saliva

• non-sharp solid waste saturated with or caked w/ liquid/semisolid blood/saliva or tissue including teeth (OSHA*).

6. biomedical waste

solid waste that is generated such as gloves, saliva ejectors, cups, surface barriers.

review

Which statement about steam autoclave sterilization is correct?

A. Pressure alone destroys microorganisms.

B. Steam sterilizes by oxidizing cellular components.

C. Moist heat denatures microbial proteins and enzymes.

D. Steam sterilization is ineffective against bacterial spores.

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What is one advantage of unsaturated chemical vapour sterilization compared with steam sterilization?

A. It does not require pressure.

B. It causes less corrosion of metal instruments.

C. It sterilizes at room temperature.

D. It is ineffective against bacterial spores.

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Which of the following is the most common cause of sterilization failure?

A. Microorganisms becoming resistant to heat

B. Inadequate cleaning and preparation of instruments before sterilization

C. Use of steam sterilization

D. Sterilization cycles that are too effective

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Which method is recommended when recapping a needle in dental practice?

A. Hold the cap with one hand and guide the needle with the other

B. Bend the needle before disposal

C. Use the one-handed scoop technique

D. Place the needle on the counter until treatment is complete

Infection control procedures for oral HC worker

Reduce microbial count in suscept persons

• use 0.12% chlorhexidine rinse before treat

• apply topical antiseptic (iodine) before inject (when indicated)

• can use antiseptic mouth rinse (ex: Listerine) may be used as pre-procedural rinse

DUWLS

biofilms can form inside when water stagnant

they supply water to….

• handpieces

• air-water syringes

• ultrasonic scalers

biofilm may contain naturally occuring water microorgs & potential pathogens

ex:

• Pseudomonas aeruginosa

• Legionella species

• Non-tuberculous Mycobacterium species

• Protozoa

• Viruses

DUWL - prevent contam

• use anti-retraction valves (to prev backflow of oral fluid into waterline)

maintain them using…

• filtration sys

• chem treatment sys

• self-contained water sys

• sterile water delivery sys