Chapter 26




Appendix D. Good Microbiological Practice

D.1  Introduction and Scope

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Good and standard microbiological practices. Source: Berkeley Lab EHS.
Good and standard microbiological practices. Source: Berkeley Lab EHS.

This appendix describes (1) customary principles of good microbiological practice (GMP) and (2) explains the differences between GMP and laboratory biosafety practices defined by the Centers for Disease Control and Prevention (CDC) and the National Institutes of Health (NIH) and provided in Appendix C, Laboratory Biosafety Level 1 and Biosafety Level 2 Criteria, of this manual. These GMP principles are guidelines that may be used to control the biosafety and research quality aspects of laboratory work. These guidelines are not biosafety requirements unless other sections of this manual describe them as biosafety requirements.


The first and most important element of control for research product protection and laboratory containment is strict adherence to (1) GMP and (2) standard microbiological practices and special practices. These sets of practices have different main objectives, but include many overlapping practices and secondary objectives. Both sets of practices should be used when conducting work.



D.2  Good Microbiological Practice

GMP involves the use of aseptic techniques and other good microbiological practices. These practices and techniques prevent:

Both objectives are important, but the first objective is primarily important for the safety of the worker, while the second objective is mostly important for the quality of the research.


The principles of GMP should generally be applied to all types of work involving microorganisms and tissue cultures, regardless of containment level.

D.2.1  Aseptic Technique

An aseptic technique is a procedure used to grow a microorganism or culture of interest in a clean micro-environment isolated from the outside world. This micro-environment is usually some sort of culture or holding container such as a flask, bottle, or petri dish. The organisms or cells can either be on a solid agar medium or be suspended in a broth, diluent, or other fluid medium.


Examples of aseptic techniques include ensuring all components of the system are sterile prior to use (e.g., container interior, growth medium, and any items used in manipulation) and using special care and techniques to avoid cross-contamination during the inoculation, incubation, and processing steps. They also include:


In addition to aseptic techniques, GMP includes a wide range of other working methods that minimize the cross-contamination of the work and workplace. Examples of these methods are provided in the remaining sections of this appendix.

D.2.2  Personal Hygiene and Dress

D.2.3  Area Cleanliness and Organization

Keep the laboratory and work area clean and organized, such as in the following examples:

D.2.4  Biosafety Cabinets and Airborne Contamination

D.2.5  Manipulation Techniques for Minimizing Aerosols

Manipulation techniques should be used to minimize the possibility of producing aerosols. Examples include:

D.2.6  Worker Qualifications

Workers who handle microorganisms and cultures should have sufficient technical competence, training, and experience in GMP and containment practices. In addition, workers should use GMP and biosafety containment in anticipation of unexpected hazards when handling microorganisms and cultures (including Risk Group 1). Workers should conservatively approach their safety by assuming, for example, that an unexpected pathogen may exist or contaminate the culture; a pathogen may be unintentionally cultured; the disease potential of the agent may be altered under laboratory conditions; or exposure to an RG1 agent may cause an opportunistic infection.

D.2.7  Microbial Contamination Checks

Routine microbial contamination checks should be incorporated into protocols and undertaken at various stages of experiments. Examples of contamination checks include:


The purity of a liquid culture can also be obtained by microscopic examination. This is done by placing a loopful of the culture on a microscope slide. The slide is then examined wet either by phase contrast microscopy, or by fixed or Gram staining. Contaminant organisms should be instantly and clearly visible.


Contamination checks are particularly useful in evaluating GMP competence. Workers with poor aseptic techniques will have frequent contamination problems, while workers skilled in GMP will have problems only occasionally. It is important to recognize that poor practices not only result in contaminated cultures, but may also result in spreading biological materials and contamination to work surfaces and workers in the laboratory.


D.3 References

University of Edinburgh, Health and Safety, Good Microbiological Practice and Containment,” Web page information from the Health and Safety Department, August 2003.




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