infection control guidelines for dentists

29/04/2013 at 5:55 pm #16546

drsnehamaheshwari

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Discharging Blood or Other Body Fluids to Sanitary Sewers or Septic Tanks

All containers with blood or saliva (e.g., suctioned fluids) can be inactivated in accordance with state-approved treatment technologies, or the contents can be carefully poured down a utility sink, drain, or toilet. Appropriate PPE (e.g., gloves, gown, mask, and protective eyewear) should be worn when performing this task. No evidence exists that bloodborne diseases have been transmitted from contact with raw or treated sewage. Multiple bloodborne pathogens, particularly viruses, are not stable in the environment for long periods, and the discharge of limited quantities of blood and other body fluids into the sanitary sewer is considered a safe method for disposing of these waste materials. State and local regulations vary and dictate whether blood or other body fluids require pretreatment or if they can be discharged into the sanitary sewer and in what volume.

Dental Unit Waterlines, Biofilm, and Water Quality

Studies have demonstrated that dental unit waterlines (i.e., narrow-bore plastic tubing that carries water to the high-speed handpiece, air/water syringe, and ultrasonic scaler) can become colonized with microorganisms, including bacteria, fungi, and protozoa. Protected by a polysaccharide slime layer known as a glycocalyx, these microorganisms colonize and replicate on the interior surfaces of the waterline tubing and form a biofilm, which serves as a reservoir that can amplify the number of free-floating (i.e., planktonic) microorganisms in water used for dental treatment. Although oral flora and human pathogens (e.g., Pseudomonas aeruginosa, Legionella species, and nontuberculous Mycobacterium species), have been isolated from dental water systems, the majority of organisms recovered from dental waterlines are common heterotrophic water bacteria. These exhibit limited pathogenic potential for immunocompetent persons.

Clinical Implications

Certain reports associate waterborne infections with dental water systems, and scientific evidence verifies the potential for transmission of waterborne infections and disease in hospital settings and in the community. Infection or colonization caused by Pseudomonas species or nontuberculous mycobacteria can occur among susceptible patients through direct contact with water or after exposure to residual waterborne contamination of inadequately reprocessed medical instruments. Nontuberculous mycobacteria can also be transmitted to patients from tap water aerosols. Health-care–associated transmission of pathogenic agents (e.g., Legionella species) occurs primarily through inhalation of infectious aerosols generated from potable water sources or through use of tap water in respiratory therapy equipment. Disease outbreaks in the community have also been reported from diverse environmental aerosol-producing sources, including whirlpool spas, swimming pools, and a grocery store mist machine. Although the majority of these outbreaks are associated with species of Legionella and Pseudomonas, the fungus Cladosporium has also been implicated.

Researchers have not demonstrated a measurable risk of adverse health effects among DHCP or patients from exposure to dental water. Certain studies determined DHCP had altered nasal flora or substantially greater titers of Legionella antibodies in comparisons with control populations; however, no cases of legionellosis were identified among exposed DHCP. Contaminated dental water might have been the source for localized Pseudomonas aeruginosa infections in two immunocompromised patients. Although transient carriage of P. aeruginosa was observed in 78 healthy patients treated with contaminated dental treatment water, no illness was reported among the group. In this same study, a retrospective review of dental records also failed to identify infections.

Concentrations of bacterial endotoxin <1,000 endotoxin units/mL from gram-negative water bacteria have been detected in water from colonized dental units. No standards exist for an acceptable level of endotoxin in drinking water, but the maximum level permissible in United States Pharmacopeia (USP) sterile water for irrigation is only 0.25 endotoxin units/mL. Although the consequences of acute and chronic exposure to aerosolized endotoxin in dental health-care settings have not been investigated, endotoxin has been associated with exacerbation of asthma and onset of hypersensitivity pneumonitis in other occupational settings.

Dental Unit Water Quality

Research has demonstrated that microbial counts can reach <200,000 colony-forming units (CFU)/mL within 5 days after installation of new dental unit waterlines, and levels of microbial contamination <10⁶ CFU/mL of dental unit water have been documented. These counts can occur because dental unit waterline factors (e.g., system design, flow rates, and materials) promote both bacterial growth and development of biofilm.

Although no epidemiologic evidence indicates a public health problem, the presence of substantial numbers of pathogens in dental unit waterlines generates concern. Exposing patients or DHCP to water of uncertain microbiological quality, despite the lack of documented adverse health effects, is inconsistent with accepted infection-control principles. Thus in 1995, ADA addressed the dental water concern by asking manufacturers to provide equipment with the ability to deliver treatment water with <200 CFU/mL of unfiltered output from waterlines. This threshold was based on the quality assurance standard established for dialysate fluid, to ensure that fluid delivery systems in hemodialysis units have not been colonized by indigenous waterborne organisms.

Standards also exist for safe drinking water quality as established by EPA, the American Public Health Association (APHA), and the American Water Works Association (AWWA); they have set limits for heterotrophic bacteria of <500 CFU/mL of drinking water. Thus, the number of bacteria in water used as a coolant/irrigant for nonsurgical dental procedures should be as low as reasonably achievable and, at a minimum, <500 CFU/mL, the regulatory standard for safe drinking water established by EPA and APHA/AWWA.