Working with Microbial Pathogens (infectious microorganisms)

Definition of a Microorganism

A living organism (such as a bacteria, fungi or virus), too small to be seen by the naked eye but visible under the microscope.

Approach to Working with Microorganisms

The basic approach to working with microorganisms is to regard them all as potential pathogens and to handle them with standard microbiological techniques to minimise the risk to laboratory staff and the environment.

AS/NSZ 2243.3:2010 Safety in Laboratories Part 3: Microbiological safety and containment, outlines requirements for laboratories handling microorganisms. The Standard specifies different containment requirements for facilities depending on the type of microorganisms being handled. Compliance with the relevant sections of AS/NZS 2243.3 is considered as a minimum requirement for anyone handling microorganisms.

Classification of Microorganisms - Risk Groups

The World Health Organisation (WHO) suggests each country draw up risk groups according to the microorganisms encountered within its boundaries. The following classification has been drawn up for Australia and New Zealand and is based on the pathogenicity of the agent, the mode of transmission and host range of the agent, the availability of effective preventive measures, and the availability of effective treatment.

Risk Group 1 (low individual and community risk)

A microorganism that is unlikely to cause human, plant or animal disease.

Risk Group 2 (moderate individual risk, limited community risk)

A microorganism that is unlikely to be a significant risk to laboratory workers, the community, livestock or the environment; laboratory exposures may cause infection, but effective treatment and preventive measures are available, and the risk of spread is limited.

Risk Group 3 (high individual risk, limited to moderate community risk)

A microorganism that usually causes serious human or animal disease and may present a serious a significant risk to laboratory workers. It could present a limited to moderate risk if spread in the community or the environment, but there are usually effective preventive measures or treatment available.

Risk Group 4 (high individual and community risk)

A microorganism that usually produces life-threatening human or animal disease, represents a significant risk to laboratory workers and may be readily transmissible from one individual to another. Effective treatment and preventive measures are not usually available.

A list of examples of organisms classified into their Risk Group is provided in AS2243.3*. The list includes examples of bacteria, fungi, viruses and prions. In addition to the Risk Group classification in AS/NZS 2243.3, Pathogen Safety Data Sheets (SDS) are available through other sources, in most cases the information and grouping is the same as in Australia:

• PHAC (Public Health Agency of Canada) Pathogen Safety Data Sheets and Risk Assessments;
• American Biological Safety Association webpage listings of micro-organisms including risk groupings; and
• AS/NZS 2243.3 2010 -  available via the UNE online library database

It is recommended that before starting work with any potentially infectious microorganism that you download a Pathogen SDS and use this to help you conduct a risk assessment of your work.

Classification of Laboratories

AS/NZS 2243.3 specifies four levels of physical containment for laboratories.

Physical Containment Level 1 (PC1)

A Physical Containment Level 1 laboratory is suitable for work with microorganisms where the hazard levels are low, and where laboratory or facility personnel can be adequately protected by standard laboratory practice. The organisms used should generally be classified as Risk Group 1. Specimens that have been inactivated or fixed may be handled in PC1 facilities.

There is no formal certification procedure required for PC1 facilities where Risk Group 1 microorganisms are handled. Facilities must comply with the requirements for the relevant type of PC1 facility as described in AS/NZS 2243.3*, i.e.

• PC1 Laboratory Containment Facility;
• PC1 Animal Containment Facility;
• PC1 Plant Containment Facility; and
• PC1 Invertebrate Facility.

Physical Containment Level 2 (PC2)

A Physical Containment Level 2 laboratory is suitable for work with material likely to contain microorganisms that are classified as Risk Group 2 microorganisms. If working with specimens containing microorganisms transmissible by the respiratory route or if the work produces a significant risk to humans or the environment from the production of infectious aerosols, a biological safety cabinet must be used. It is highly recommended that you view the "Working Safely in Class II Biological Safety Cabinets DVD" produced by the Victorian Infectious Diseases Reference Laboratory (VIDRL).

There is no formal certification procedure required for PC2 facilities where Risk Group 2 microorganisms are handled. Facilities must comply with the requirements for the relevant type of PC2 facility as described in AS/NZS 2243.3* i.e.

• PC2 Laboratory Containment Facility;
• PC2 Animal Containment Facility;
• PC2 Plant Containment Facility; and
• PC2 Invertebrate Facilty (pg 92-95).

Please note that there is a formal PC2 certification procedure for facilities undertaking certain types of gene technology work. Click here for details.

In any facility where Risk Group 2 microorganisms are handled a “PC2 Microbiological Laboratory” sign must be displayed on the entrance door to the facility. Click here for an example of suitable signage.

The “PC2 Microbiological Laboratory” signage is separate from OGTR PC2 signage which designates that approved work with genetically modified organisms is undertaken in the facility. Some facilities will require both forms of signage, while some will only require one or the other.

Physical Containment Levels 3 and 4

UNE has no PC3 or PC4 facilities and work with risk category 3 or 4 organisms may not be undertaken at the present time.

Categorising the Risk

To summarise, the requirements set out for risk groupings of microorganisms and the physical containment requirements of facilities are as follows:

• Both infectious microorganisms and GMOs are classified into 4 levels of risk categories (risk group 1-4).
• The risk categories must be contained in the equivalent containment facility (physical containment 1-4).

* to get access to Australian Standards please visit the UNE Library web site. Click on AT-AU, scroll down to 'Australian Standards' and click on the link. Search the database.