8. "Defensive Working"

After risk assessment and adopting a policy to prevent laboratory infections have been completed, comes the "practical" stage: executing the theoretical approach and implementing actions for "defensive working." The tools for the prevention of laboratory infection can be categorized into four groups:

• Safety procedures and techniques
• Safety equipment
• Containment laboratories
• Biological containment

A combination of the four groups provides the worker with the appropriate protection necessary for the prevention of laboratory infection.

Two other concepts in safety are primary and secondary barriers:

• Primary barriers, which include all the physical safety devices that prevent direct contact between the agent and the worker. They include personal protective equipment like gloves, coats, respirators, etc., and biological safety cabinets or stainless steel sealed containers.

• The secondary barrier provides a second defense line to block the infectious agent from escaping into the environment if the primary barrier has collapsed. Secondary barriers consist of a variety of safety devices, such as the air filtration system, decontamination and sterilization system, impermeable walls, etc.

8.1 Safety Instruction

As has already been mentioned, the human factor is predominant in causing accidents and laboratory infections.

In order to minimize the risk from the human factor, efforts must be made in instructing all employees involved in the bioindustry. Instruction should begin at the universities and technical schools, and should continue in the workplace in the research institute, the industrial plants, etc.

The responsibility lies with management, which has to develop the appropriate safety procedures and practices.

8.2 Good Laboratory Practices (GLP)

GLP aims to minimize the occurrence of most common accidents caused by human error, poor laboratory practice, or the misuse of equipment. It consists of a set of instructions about the use of various laboratory equipment such as pipettes, bacterial loops, hypodermic needles, centrifuges and homogenizers.

These practices are based on sterile techniques, which are learned in every bacteriological course. They are intended to protect the experiment from contamination on one hand, and the worker and the environment on the other. Basically, they prevent the production and dissemination of aerosols, and some of them are cited here:

• Bacteriological loops should be heated from the far end of the loop.
• Loops must be cooled before touching the inoculum.
• Mixing, blending and centrifuging should be done in airtight tubes.
• The last drop from the pipette should not be blown out.
• Lyophilized cultures should be opened and wrapped in cloth soaked with decontaminant, preferably in a biological safe cabinet.
• Cultures should be poured slowly.
• Needles should be wrapped before withdrawing from bottles.

GLP is based on years of experience and studying accidents and laboratory-acquired infections, and appears in the form of regulations. These regulations must be obeyed, preferably after instructing and explaining the rationale behind each regulation.

8.3 Good Manufacturing Practices (GMP)

GMP describes the manufacturing, processing, packing, or holding of drugs and finished pharmaceuticals. GMP deals with organization and personnel, buildings and facilities, equipment, written procedures, laboratory controls, records, and reports.

GMP is essential not only for product uniformity, quality control and assurance; it is also good for safety. Written standard operating procedures (SOP) do not allow much leeway for improvisation and short cuts, which usually lead to unforeseen conditions and accidents. SOP is intended to insure the quality and integrity of the data generated in the course of a study or production process. Deviations in the study or production processes from standard operating procedures must be authorized by the study director, and must be documented in the raw data. Significant changes in SOP have to be properly authorized in writing by the management.

8.4 Code of Practice (COP)

The code of practice is a listing of the most essential laboratory procedures that are basic to safe laboratory practice. In many laboratory programs, the code may be given the status of "rules" for laboratory operation.

Each worker should read, sign, and even be tested on his knowledge of this code. There is a code for basic laboratories and a special one for containment laboratories. Again, these rules, as with GLP and GMP, are derived from accumulated experience and are based on sources and causes of accidents and infection. In order to work safely, as well as to produce a good product, one must follow them to the letter.

Some examples of these rules:

• Mouth pipetting is prohibited.
• Eating, drinking, and smoking are prohibited in the laboratory work area.
• Gloves and laboratory gowns must be worn for procedures that may involve direct contact with infectious materials.
• All contaminated materials should be decontaminated before disposal.
• Work surfaces should be decontaminated at least once a day and after every spill of infectious material.