Suspected bacterial contamination
By the end of this lesson
- Separate suspected contamination from identification
- Trace possible common pathways
- Use containment procedures for suspect cultures
See it
Bacterial contamination can present in many ways, including cloudiness, colonies, films, or subtle reduced culture performance. Some bacteria can be internal or latent, so visual appearance alone is not enough for species-level identification.
Understand it
Separate suspected contamination from identification
Separate ‘suspected bacterial contamination’ from confirmed identification.
Appearance can support suspicion, but it cannot establish species-level identification on its own.
Trace possible common pathways
Trace shared source material, media, tools, and handling events.
Shared source and handling history helps evaluate potential contamination pathways.
Use containment procedures for suspect cultures
Follow the lab's containment/disposal procedure for suspect cultures.
Record the observed feature and preserve uncertainty about its cause and identity.
Worked example
Several cultures show cloudiness after a shared handling session. Record cloudiness and suspected contamination, trace common sources and handling, and follow containment procedures. The observation does not identify a bacterial species.
Explain your decision before opening the worked reasoning below.
Show the worked reasoning
Containment protects other work; unnecessary manipulation can spread risk rather than clarify the record.
Some contamination is subtle or delayed, so appearance at one moment has limited evidential scope.
Do not keep manipulating a suspect culture simply to see what happens if that risks spreading contamination.
Try it
What should be recorded in the example?
Use the worked example above to explain your answer in your own words before taking the quiz.
Lesson quiz
Assessment version: 2026-10-15-v2. Previous reading-completion markers are retained. This revised quiz has its own result.
Apply it
Use the worked example to write a short decision record: what did you observe, which rule did you apply, and what would you check before acting?
Completion marks reading progress, not a quiz pass or professional certification.