Contamination Control in Medical Laboratories

In a medical laboratory, the risk of contamination of cell cultures is incalculable – no matter how meticulous the work. It is certainly not unheard of for risks to be miscalculated, and contamination often results in culture loss. Therefore, in this blog, we would like to shed light on how to systematically detect and avoid contamination in cell lines.

Every medical laboratory is under threat day in and day out
Microbial contamination in cell cultures—including those purchased from third parties—is not uncommon in laboratories. In fact, the opposite is true: Many cell lines grown in the laboratory are infected with mycoplasma. Tiny fungal spores are ubiquitous and can spread through the air. Of course, when working in a sterile environment, there is room for human error. It's easy to make a mistake.

Horror scenarios in cell culture labs - contamination of all types:
Microbial contamination (bacteria, mycoplasma, fungi, yeast, etc.)
virus contamination
protein contamination (prions)
Chemical contamination (leachables and extractables from plastics, heavy metals, etc.)
Cross-contamination with other cell cultures
Where does pollution come from?
1. How "clean" is the original culture?

Problems often start with the source material. Even with all possible efforts in the production of media, some materials cannot be rendered completely sterile. Therefore, there is always a risk of mycoplasma escaping the sterile filter. Prions can even survive steam sterilization at 121 °C.

2. Is the working laboratory really a sterile environment?

One of the main causes of laboratory contamination is the human body. For example, many instances of cross-contamination could be avoided if lab technicians avoided handling multiple production lines at the same time on the sterile bench. One culture can quickly infect another if the liquid is not handled properly.

Also, rushing things through is the worst enemy of dull work. The door of the laboratory incubator should not be opened without reason, and of course it should not be left open for a long time. No matter how much time pressure they may be under, lab technicians should only work on one cell line at a time. When unpacking disposable pipettes under the bench, the cap must be set aside after unscrewing.

3. Are you using the correct laboratory equipment?

Of course, even equipment used in medical laboratories is entirely possible to cause contamination in cell culture. Therefore, we recommend:

Use plasticizer-free plastic containers
Choose a suitable location for the incubator (location near the washbasin may lead to soap contamination)
Use incubator accessories made of sterilized copper
When antibiotics are used, antibiotic-free lines should be bred from time to time. (This is because antibiotics can mask the contamination and the infection can spread.)
What investigative methods can be used to track which infections?
One of the most dangerous things about mycoplasma infections is that they often go undetected for a long time. In principle, pollution events can be controlled and tracked by a variety of methods, some very sophisticated and others less so.

An experienced lab technician can tell if cross-contamination has occurred simply by looking under a microscope.
If we extract all the DNA from a cell culture, the PCR method can be used to detect its mycoplasma DNA content.
Laboratories performing viral transduction or bioassays should also check for viral contamination.
Laboratories manufacturing drugs for novel therapeutics should check for low risk of bacteria, spores, fungi, mycoplasma, HIV, HCV, and BSE.

How should pollution be dealt with?
Every instance of contamination must be documented and graded. If nothing else, medical labs that keep pollution problems under wraps are jeopardizing their good reputations.

Of course, special cleaning measures must also be taken in case of contamination: in the case of fungal infections, it is advisable to check that the laboratory is regularly disinfected with an alcohol-based agent
As a general rule, regular spray or wipe disinfection of the scientific incubator interior with an alcohol-based solution helps to avoid contamination
Monthly hot air sterilization is standard medical practice in many laboratories
For sensitive stem cells, it is only in rare cases that infected cell lines can be treated with antibiotics. In most cases the solution is expensive - the culture has to be scrapped and the work has to be started from scratch
in conclusion:
Being able to consistently detect, validate and deal with contamination is absolutely essential, especially in medical laboratories that work with highly sensitive stem cells and do not use antibiotics. Transparent monitoring is essential. Covering up contamination or allowing it to spread only increases the danger and is unnecessary. The Constant Temperature Incubator should always be the safest component of the entire process step; if a sample is contaminated, then in most cases this occurs either upstream or downstream of the cooling incubator cultivation.