Risk of infection

Working with infectious agents always involves a risk of transmission and infection. Different infectious agents have different routes of transmission, infection rates and abilities to tolerate different methods of disinfection and killing. The risk of infection from a particular infectious agent can vary based on the route of infection, method of use, volume and concentration.

The normal infection route of an infectious agent can be affected by the methods, tools and techniques used. This may mean a changed or increased risk of infecting those who use the infectious agent.

Risks with sharp objects

Employees may need to use sharp objects (sharps) when preparing materials or cultures of micro-organisms. If there are infectious agents or bodily fluids from people or animals on sharps, the risk of infection in a wound increases.

Sharps that have been used on people or animals must be handled safely and placed immediately after use in a container that is made for the purpose and marked "sharps waste".

It is not just needles and lancets that can cause injuries. Also keep in mind that sharp splinters from broken glass or broken plastic can cause a cut.

Aerosol formation increases the risk of infection

Certain methods used when working with infectious agents can cause aerosol formation. This in turn increases the risk of infection. In the event of heavy aerosol formation, infectious agents that are not normally transmitted through the air can still be spread in this way, as they are carried in the aerosol. If the infectious agent has a low infective dose, aerosolisation may increase the risk of infection.

Examples of methods that can give rise to aerosol formation include

• centrifuging
• use of a shaking device (vortexing)
• agitation of a culture medium.

In large-scale cultivation, the risk of aerosol formation is greater when something is added to or removed from an ongoing cultivation. The risk is also greater with devices for venting the culture tank.

Endotoxins in large-scale cultivation

Endotoxins can be a problem when inhaled, either through moist aerosols or in drier dust. As endotoxins are part of the cell wall of some gram-negative bacteria, they may be present in cultures of these bacteria. The risk of occurrence is greater towards the end of a large-scale cultivation.

There is also a risk of exposure to endotoxins in the residues after a completed culture when the culture tank is cleaned.

Toxins or other volatile chemical substances that are not produced by infectious agents, such as organic dust that may contain mould and other living organisms, are covered by the Swedish Work Environment Authority's provisions and general guidelines (AFS 2023:10) on risks in the work environment, chapter 7. General provisions for chemical risk sources.

Infectious agents in animal experiments pose special risks

Infectious agents in animal experiments pose special risks for employees:

• If they are going to inject an animal with infectious agents or take samples from an infected animal, there is a risk that the animal will move. This increases the risk of them slipping and injuring themselves on the needle.
• There may be a risk of animals biting or scratching and that infectious agents getting into wounds.
• In some cases, infectious agents can be excreted from animals into the cage interior.

Working with laboratory animals