Prevention

Broken slides and used slides must be disposed of in a sharps container. Containers for sharps disposal must be puncture-proof, have a fitted lid, and must not be filled to capacity. When they are three quarters full, they should be placed in containers for infectious waste and incinerated. Containers for sharps disposal must not be discarded in a landfill unless they have been incinerated or autoclaved. Used slides must not be reused.

A system for identifying and separating infectious materials and their containers should be adopted. Categories may include:

• uncontaminated (non-infectious) waste that can be reused, recycled or disposed of in the same way as general household waste;
• contaminated (infectious) sharps, such as broken glass, syringes and slides;
• contaminated infectious material to be disposed of by burying, incinerating or autoclaving.

The killing action of disinfectants depends on the population of organisms to be killed, the concentration used, the duration of contact, and the presence of organic debris.

Proprietary disinfectants recommended as suitable for use in TB laboratories are those containing phenols, chlorine or alcohol. These are usually selected depending on the material to be disinfected.

Phenol

Separate autoclaves should be used to sterilize solutions or glassware (clean materials), and to decontaminate infectious materials.

The following materials are suitable for autoclaving:

To incinerate hazardous waste properly requires an efficient means of controlling the temperature, and a secondary burning chamber. Many incinerators, especially those with a single combustion chamber, are unsatisfactory for dealing with infectious materials or plastics. If this type is used, such materials may not be completely destroyed, and the effluent from the chimney may pollute the atmosphere with microorganisms, toxic chemicals and smoke. However, there are many satisfactory configurations for combustion chambers.

Waste-management procedures must comply with all pertinent local or national requirements and regulations. Waste is anything that is to be discarded. The overriding principle in minimizing risks from waste is that all infectious materials should be decontaminated, incinerated, prepared to be buried or autoclaved. Discard bags should be used to segregate waste. Most glassware, instruments and laboratory clothing will be reused or recycled.

The principal questions to be asked before any objects or materials are removed from a laboratory are:

Human error and poor technique can compromise the best safeguards put in place to protect laboratory workers. Well informed, competent and safety-conscious staff are essential for preventing laboratory-acquired infections, incidents and accidents.

The proper design and construction of laboratory facilities contributes to the protection of all laboratory workers and provides a barrier that protects the community from TB aerosols that may be created with the laboratory. Specific features of the laboratory, including separated laboratory areas and a ventilation system, are secondary containment measures. The secondary barriers that are recommended for a laboratory depend on the procedures conducted and their associated risk of transmission.

Equipment should be selected to take certain general principles into account – that is equipment should be:

• The laboratory should be divided into “functionally clean” and “potentially contaminated” areas, with the clean areas reserved for administrative and preparatory work. Access to the clean areas and the contaminated areas must be controlled and enforced by the laboratory’s manager.
• The laboratory should be kept neat, clean and free of materials and equipment not used for performing routine work.