DISINFECTION: Destruction of pathogenic and other kinds of microorganisms by physical or chemical means. Disinfection is less lethal than sterilization, because it destroys the majority of recognized pathogenic microorganisms, but not necessarily all microbial forms (e.g., bacterial spores).
Disinfection is a process of removing or killing most, but not all, viable organisms.(MIMS-PLAYFAIR).
Disinfection refers to the destruction of pathogenic organisms.(Ronald B Luftig).
Hand hygiene (e.g., handwashing, hand antisepsis, or surgical hand antisepsisis) considered the single most critical measure for reducing the risk of transmitting organisms to patients and health care professionals.
The microbial flora of the skin, consist of transient and resident microorganisms . Transient flora, which colonize the superficial layers of the skin, are easier to remove by routine handwashing.
The purpose of surgical hand antisepsis is to eliminate transient flora and reduce resident flora to prevent introduction of organisms in the operative wound, if gloves become punctured or torn.
Skin bacteria can rapidly multiply under surgical gloves if hands are washed with soap that is not antimicrobial . Thus, an antimicrobial soap or alcohol hand rub with persistent activity should be used before surgical procedures.
CHLORHEXIDINE BASED – these contain 2- 4% chlorhexidine gluconate with 4% isopropyl alcohol in a detergent solution with a pH of 5.0 to 6.5. They have broader activity for special cleansing(e.g: for surgery, glove leaks, or when clinician experiences injury). But it can be hazardous to eyes.
POVIDONE IODONE – contain 7.5-10% povidone iodine, used as a surgical hand scrub.
When airborne infection isolation precautions are necessary (e.g., for TB patients), a National Institute for Occupational Safety and Health (NIOSH)-certified particulate-filter respirator (e.g., N95, N99, or N100) should be used.
N95 refers to the ability to filter 1-µm particles in the unloaded state with a filter efficiency of >95% (i.e., filter leakage <5%), given flow rates of < 50 L/min (i.e., approximate maximum airflow rate during breathing).
Work-practice controls for needles and other sharps include placing them in appropriate puncture-resistant containers located as close as feasible to where the items were used.
Sharp end of instruments must be pointed away from the hand
Avoid handling large number of sharp devices.
Work-practice controls include removing burs before disassembling the handpiece from the dental unit, restricting use of fingers in tissue retraction during suturing and administration of anesthesia, and minimizing uncontrolled movements of sharp instruments.
Used needles should never be recapped or otherwise manipulated by using both hands, or any other technique that involves directing the point of a needle toward any part of the body.
A one-handed scoop technique, a mechanical device designed for holding the needle cap to facilitate one-handed recapping, or an engineered sharps injury protection device (e.g., needles with resheathing mechanisms) should be employed for recapping needles.
Counseling of the exposed worker regarding bloodborne pathogens.
Source patient testing for HBV,HCV and HIV (consent required).
Documentation of the incident and review.
Postexposure assessment and prophylaxis for the health care worker.
Baseline and follow up serology of the worker.
IF AND THEN Source pt is +ve for HBsAG Exposed worker not vaccinated
Worker should receive vaccine series
should receive single dose of HB immunoglobulin within 7 days.
Exposed worker has been vaccinated Should be tested for anti-HBs & given 1 dose of vaccine & 1 dose of HBIG if < 10 IU
IF AND THEN Source pt is –ve for HBsAg Exposed worker not vaccinated Worker should be encouraged to receive hepatitis B vaccine. Exposed worker has been vaccinated No further action is needed. Source pt refuses testing or not identified Exposed worker not vaccinated
Should receive HB series
HBIG should be considered
Exposed worker has been vaccinated Management should be individualized.
IF THEN AND Source pt has AIDS OR Source pt is HIV+ve OR Source Pt refuses to be tested
Exposed worker should be counseled about risk of infection.
Should be tested for HIV infection immediately
Should be asked to seek medical advice for any febrile illness within12 weeks
Refrain from blood donation & take appropriate precautions
Exposed worker testing –ve initially should be retested 6 weeks, 12 weeks & 6 months after exposure.
IF THEN AND Source pt is tested & found -ve Baseline testing of the exposed worker with follow up testing 12 weeks later Source cannot be identified Serological testing must be done & decisions must be individualized
In the dental operatory, environmental surfaces (i.e., a surface or equipment that does not contact patients directly) can become contaminated during patient care. Certain surfaces, especially ones touched frequently (e.g., light handles, unit switches, and drawer knobs) can serve as reservoirs of microbial contamination, although they have not been associated directly with transmission of infection to either personnel or patients.
Almost 40 years ago, Dr. E. H. Spaulding proposed a classification system for disinfecting and sterilizing medical and surgical instruments. This system, or variations of it, has been used in infection control over the years.
According to the CDC, patient-care items (eg, dental instruments, devices, and equipment) are categorized as critical, semicritical, or noncritical, based on the potential risk of transmitting infection if the item becomes contaminated during use.
Instruments that contact cut tissues or penetrate tissues are considered to be critical items that require thorough clean i ng and sterilization for reuse. E.g dental burs, endodontic files etc.
Semicritical items that touch mucosa are the air/water syringe tip, suction tips, prophy angle, and handpieces. Others (air/water syringe handle etc) are handled or touched interchangeably with treatment instruments that become contaminated with blood and saliva.
High-level disinfection : Disinfection process that inactivates vegetative bacteria, mycobacteria, fungi, and viruses but not necessarily high numbers of bacterial spores. FDA further defines a high-level disinfectant as a sterilant used for a shorter contact time.
Intermediate-level disinfection : Disinfection process that inactivates vegetative bacteria, the majority of fungi, mycobacteria, and the majority of viruses (particularly enveloped viruses) but not bacterial spores.
Low-level disinfectant : Liquid chemical germicide registered with EPA as a hospital disinfectant. OSHA requires low-level hospital disinfectants also to have a label claim for potency against HIV and HBV.
Nonporous surfaces should be cleaned and then decontaminated with either an hospital disinfectant effective against HBV and HIV or an disinfectant with a tuberculocidal claim (i.e., intermediate-level disinfectant).
However, if such products are unavailable, a 1:100 dilution of sodium hypochlorite (e.g., approximately ¼ cup of 5.25% household chlorine bleach to 1 gallon of water) is an inexpensive and effective disinfecting agent .
Regulated medical waste is only a limited subset of waste: 9%-15% of total waste in hospitals and 1%-2% of total waste in dental offices.
Examples of regulated waste found in dental-practice settings are solid waste soaked or saturated with blood or saliva (e.g., gauze saturated with blood after surgery), extracted teeth, surgically removed hard and soft tissues, and contaminated sharp items (e.g., needles, scalpel blades, and wires.
All containers with blood or saliva (e.g., suctioned fluids) can be carefully poured down a utility sink or drain.
Adding 5% hypochlorite in water to suctioned fluids is recommended before disposing into the drain.
Multiple bloodborne pathogens, are not stable in the environment for long periods, and the discharge of limited quantities of blood into the sanitary sewer is considered a safe method for disposing of these waste materials.
Ultrasonic cleaning is the safest and most efficient way to clean sharp instruments.
An ultrasonic cleaning device should provide fast and thorough cleaning without damage to instruments; have a lid, well-designed basket, and audible timer; and be engineered to prevent electronic interference with other electronic equipment
Various new methods of sterilization are under investigation and development.
Peroxide vapor sterilization - an aqueous hydrogen peroxide solution boils in a heated vaporizer and then flows as a vapor into a sterilization chamber containing a load of instruments at low pressure and low temperature
Ultraviolet light - exposes the contaminants with a lethal dose of energy in the form of light. The UV light will alter the DNA of the pathogens. Not effective against RNA viruses like HIV.
Mechanical techniques for monitoring sterilization include assessing cycle time, temperature, and pressure by observing the gauges or displays on the sterilizer and noting these parameters for each load . Correct readings do not ensure sterilization, but incorrect readings can be the first indication of a problem with the sterilization cycle.
Chemical indicators , internal and external, use sensitive chemicals to assess physical conditions (e.g., time and temperature) during the sterilization process.
External indicators applied to the outside of a package (e.g., chemical indicator tape or special markings) change color rapidly when a specific parameter is reached, and they verify that the package has been exposed to the sterilization process.
Internal chemical indicators should be used inside each package to ensure the sterilizing agent has penetrated the packaging material and actually reached the instruments inside.
Biological indicators (BIs) (i.e., spore tests) are the most accepted method for monitoring the sterilization process because they assess it directly by killing known highly resistant microorganisms (e.g., Geobacillus or Bacillus species), rather than merely testing the physical and chemical conditions necessary for sterilization.
Spores dried on absorbent paper strips are calibrated to be killed when sterilization conditions are reached and maintained for the necessary time to kill all pathogenic microorganisms.
Tests can be evaluated in the office. However, by sending the strip to a licensed reference laboratory for testing, the dentist obtains independent documentation of monitoring frequency and sterilization effectiveness .
STERILIZATION METHOD SPORE TYPE INCUBATION TEMPERATURE AUTOCLAVE Baccilus stearothemophilus 56 °C CHEMICAL VAPOR DRY HEAT Baccilus subtilis 37 °C ETHYLENE OXIDE