CHAPTER 5: INFECTION CONTROL IN SURGICAL PRACTICE

oral surgery

breaches the epithelial barrier and exposes dental personnel and equipment to the patient’s blood and saliva, creating a significant risk of infection transmission

communicable pathogenic organisms due to bacteria

non-maxillofacial

maxillofacial skin

upper respiratory tract

communicable pathogenic organisms due to viral organisms

HIV

hepatitis

mycobacterial

gram-positive aerobic in normal oral flora

Streptococcus → primary

gram-positive anaerobic in normal oral flora

Actinomyces

gram-negative anaerobic in normal oral flora

Prevotella multiformis

gram-negative anaerobic in fungus

Candida

gram-positive aerobic in nasal sinus flora

Streptococcus [and anaerobes]

nasal sinus flora in children

Haemophilus influenza

nasal sinus flora in adults

Staphylococcus aureus

four main processes in checking total number of oral organisms in the upper respiratory tract

salivary flow dilution

salivary immunoglobulin A

competition among microorganisms

rapid epithelial turnover/desquamation

organisms of normal flora in maxillofacial skin (facial skin)

Staphylococcus epidermidis

Corynebacterium diphtheriae

Staphylococcus aureus → spread from nose

Propionibacterium acnes → in pores and hair follicles

—highlighted in red are the predominants!

skin flora is altered by:

antimicrobial agents → disturb microbial balance

dirt or dried blood → provide nutrients and niches

occlusive dressings → prevent desiccation and desquamation

organisms in nonmaxillofacial (areas below the clavicles-hands)

Staphylococcus epidermidis

gram-negative

anaerobic enteric organisms

Corynebacterium diphtheriae

gram-negative aerobes bacterias in nonmaxillofacial (areas below the clavicles)

Escherichia coli

Klebsiella species

Proteus species

spp. → means multiple species

anaerobic organism in nonmaxillofacial (areas below the clavicles)

Bacteroides fragilis

important considerations for viral organisms

hardiness of the virus

mode of transmission

clinical suspicion for carriers

most problematic viruses towards dentistry

tuberculosis (TB)

hepatitis B virus (HBV)

hepatitis C virus (HCV)

human immunodeficiency virus (HIV)

hepatitis A (HAV)

fecal–oral

self-limiting

hepatitis B (HBV)

antivirals

bloodborne

[in partner with HDV]

hepatitis C (HCV)

bloodborne

direct-acting antivirals

hepatitis D (HDV)

bloodborne

pegylated interferon-alpha

hepatitis E (HEV)

fecal–oral

supportive care

hepatitis B

most serious risk for dental personnel

as it can be transmitted via saliva or tiny amounts of blood

extremely resistant to desiccation & chemical disinfectants

desiccations that HBV is resistant to:

alcohol, phenols

quaternary ammonium compounds

prevention of HBV

universal precautions

vaccination, barrier protection

careful handling of sharps, cleaning/disinfection

means of inactivation of HBV

iodophors

hypochlorite

formaldehyde

2% glutaraldehyde

ETO & heat sterilization & irradiation

—highlighted in red are halogen-containing disinfectants, green are aldehydes

human immunodeficiency virus (HIV)

requires direct contact of infected blood or secretions

unstable outside the host and loses infectivity when desiccated

has far fewer infectious particles than hepatitis blood (10⁶/mL vs. 10¹³/mL)

saliva is not a significant source → very low viral levels and no proven transmission

—this low viral load explains why healthcare workers have a very low risk of contracting from exposure to blood or body fluids

CD4 level

refers to the number of CD4+ T lymphocytes per microliter (cells/mm³) of blood

normal CD4 count

500–1,600 cells/mm³

immunocompromised CD4 count

<400 cells/mm3

acquired immunodeficiency syndrome CD4 count

<200 cells/mm³

highly active anti-retroviral therapy (HAART)

a combination of anti-HIV drugs taken for life

suppresses HIV, allowing the immune system to recover

there is no cure, but ART can make viral load undetectable and prevent progression

transmission of HIV

unprotected sexual contact

• vaginal or anal

mother-to-child transmission

• pregnancy, breastfeeding, delivery

exposure to infected blood

• needlestick injury, needle sharing

• transfusion with unscreened blood

exposure types

receptive anal intercourse

insertive anal intercourse

receptive penile-vaginal intercourse

insertive penile-vaginal intercourse

percutaneous (needlestick)

needle sharing (injection drug use)

blood transfusion

receptive anal intercourse

1.38% prevalence

138 per 10k exposures

[ang mudawat, ang gisudlan]

insertive anal intercourse

0.11% prevalence

11 per 10k exposures

receptive penile-vaginal intercourse

0.08% prevalence

8 per 10k exposures

insertive penile-vaginal intercourse

0.04% prevalence

4 per 10k exposures

[ang nisud, ang nihatag]

percutaneous (needlestick)

0.23% prevalence

23 per 10k exposures

needle sharing (injection drug use)

0.63% prevalence

63 per 10k exposures

HIV is not transmitted by:

casual contact, insects

saliva, sweat, tears, air, water

tuberculosis

caused by Mycobacterium tuberculosis

resistant to drying and to many disinfectants

spreads mainly thru airborne droplets & thru dental instruments

protection / precautions for tuberculosis

should wear N95 respirators

instruments must be sterilized

special considerations for tuberculosis

dental staff should undergo regular TB skin testing to monitor exposure

elective dental care for untreated TB should be postponed until medical treatment begins

treatment for TB

rifampicin

isoniazid

pyrazinamide

ethambutol

streptomycin

effects of rifampicin

bactericidal

orange-red discoloration of body fluids

effects of isoniazid

most potent anti-TB drug

peripheral neuropathy → damage of peripheral nerves causing numbness, tingling, weakness, or pain in the hands and feet

effects of pyrazinamide

arthralgia → joint pain without inflammation

hyperuricemia → higher uric acid level in the blood

effects of ethambutol

optic neuritis

effects of streptomycin

ototoxicity

sepsis

breakdown of living tissue caused by microorganisms, usually with inflammation

presence of microorganisms alone (e.g., bacteremia) does not mean sepsis

medical asepsis

keeping people & objects as free as possible from infection-causing agents

surgical asepsis

preventing microorganisms from entering surgically created wounds

antiseptics

used on living tissue to inhibit microbial growth

examples of antiseptics

chlorhexidine

hexachlorophene

hydrogen peroxide

alcohol, iodophors

quaternary ammonium compounds

disinfectants

used on inanimate objects only

examples of disinfectants

phenols

formaldehyde

2% glutaraldehyde

ethylene oxide gas

sodium hypochlorite

hydrogen peroxide (high concentration)

sterility

complete absence of viable microorganisms (absolute, no degrees)

sanitization

not equivalent to sterilization

reducing microorganisms to levels considered safe by public-health standards

decontamination

reducing microorganisms, similar to sanitization but not linked to public health standards

chemical agents to reduce microbes

ethylene oxide gas

antiseptics, disinfectants

physical agents to reduce microbes

heat, irradiation

mechanical dislodgment

bacterial endospores

most resistant microbe

so sterilization/disinfection methods that kill this means it can eliminate bacteria, viruses, mycobacteria, fungi, mold, and parasites

dry heat sterilization

oxidizes cell proteins

principal antimicrobial effect

uses high temperature under dry conditions

for glassware, heat-resistant items, prone to rust (low)

100°C for 1.5 hours

cycle of dry heat that destroys vegetative bacteria

140°C for 3 hours

cycle of dry heat needed to destroy spores of anthrax

standard cycle of dry heat sterilization

160°C (320F) for 2 hours

alternative cycles of dry heat sterilization

180°C for 20 minutes

170°C (340F) for 1 hour

advantages of dry heat sterilization

simple to use

low tendency to rust instruments

safe for heat-resistant instruments

disadvantages of dry heat sterilization

very slow, limits turnover

not for heat-sensitive items

susceptible to rust and heat (handpiece, glassware)

moist heat sterilization (autoclaving)

denatures cell proteins, principal antimicrobial effect

uses the combined effects of heat, moisture, and pressure

more efficient than dry heat because:

• water at 100°C kills microbes faster than dry heat at the same temperature because water transfers heat more efficiently

• boiling water stores extra heat as steam; when steam condenses on an object, it releases this heat quickly, causing a rapid protein denaturation (steam under pressure)

Bacillus stearothermophilus

this spore is used to test sterilization reliability bc it is extremely heat-resistant spore, killing this indicates the sterilization is effective for all types of spores

if spores do not grow in culture after sterilization, the process is successful

after 6 months

possibility of contamination increases when storing sterilized instru

6–12 months

recommended expiration date of stored sterilized instru

alternative in storing sterilized instru

double-wrapped cassettes sterilized for single-patient use

typical temperatures of autoclaving

5 psi → 109°C

10 psi → 115°C

15 psi → 121°C (250F) for 15 mins

20 psi → 126°C

30 psi → 134°C (270F) for 3 mins

—highlighted in red are the mostly used

advantages of autoclaving

effective, fast

widely available in dental offices

mostly used for surgical instruments

disdvantages of autoclaving

cost of autoclaves

can dull or rust instruments

1:10

immerse in this ratio of 5%–6% sodium hypochlorite for 5 minutes

ethylene oxide

most commonly used gas

highly flammable → mixed with CO₂ or nitrogen for safety

gas at room temperature → penetrates porous materials (plastic, rubber)

effective at 50°C for 3 hours against all organisms, including spores

gas-sterilized equipment must be aerated:

50–60°C for 8–12 hours

4–7 days at room temperature

advantages of ethylene oxide

for heat/moisture-sensitive items

effective for porous materials & large equipment

disadvantages of sterilization with gas

impractical in dental offices

requires specialized equipment

long sterilization + aeration time

low-level disinfectants

effective against vegetative bacteria and lipid viruses

intermediate-level disinfectants

effective against all microbes except bacterial spores

high-level disinfectants

biocidal for all microbes

acceptable disinfectants for dental surgical instrument

iodophors

formaldehyde

0.2% chlorine compounds

2% glutaraldehyde → most commonly used

alcohols

not suitable disinfectants for dental surgery

evaporate too quickly (except for anesthetic cartridge disinfection)

quaternary ammonium compounds

not suitable disinfectants for dental surgery

ineffective against hepatitis B virus; inactivated by soap/anionic agents

disposable materials

sutures, anesthetics

scalpel blades, syringes

handling sterile materials

outer wrapper handled non-sterile; inner wrapper remains sterile

ungowned/ungloved individual may transfer inner sterile material onto sterile field

scalpel blades handled similarly → can be dropped onto sterile field or picked up in sterile manner

set-up of sterilized/disinfected instruments

use flat platform (ex: mayo stand)

cover with two layers of sterile towels or waterproof paper

place instrument pack carefully

maintain sterility when opening edges

avoid excessive moisture → prevents bacteria wicking from undersurface

clean technique (medical asepsis)

achieves sanitization or disinfection, not sterility

reduce number of microorganisms & prevent spread

reduces contamination using antiseptics and disinfectants

used for routine dental care where absolute sterility is not required

methods used in clean technique

hand hygiene

long-sleeved lab coat

clean gloves and barriers

eye, face, and hair protection

use of antiseptics on living tissue

surface disinfection (not sterilization)

sterile technique (surgical asepsis)

creates an absolutely sterile field

achieve complete absence of viable microorganisms

used for procedures requiring full asepsis those entering deeper tissues

eliminates all microorganisms using sterilization methods (moist heat, dry heat, gas)

methods used in sterile technique

use of sterile gloves, drapes, and instruments

sterilized instruments (autoclave, gas sterilization)

prevention of microbes from entering surgically created wounds

patient prioritization

non-infectious patients seen first

patients with draining abscesses seen afterward

sharps management

use auto-resheathing needles

use one-handed scoop technique

use a hemostat to hold the cap when needed

never remove a scalpel blade by hand—use an instrument

dispose of blades/needles in rigid, labeled sharps containers

contaminated waste must be placed in biohazard bags and removed by licensed hazardous-waste services

self-gloving and handling sterile gloves

procedure ensures fingertips only touch sterile surfaces:

• open inner wrapper with outer side non-sterile

• pull folds to expose gloves

• fold glove cuffs; insert fingers carefully

• stabilize and unfurl cuff without touching outside

• gloves now ready, fingertips fully in glove tips, touching only sterile surfaces