Six germ patients are waiting for treatment. Tap a patient on the left, then tap the sterilization machine that cures it. Every cure comes with a memory anchor so the pairing sticks for exam day.
Patients cured0 of 6
Healing streak0 in a row
How to play: tap a germ patient, then tap the treatment machine that wipes it out. Watch out, the ward shuffles every round.
Germ Patients
Poor little guys. Pick one to treat.
Treatment Machines
Choose the right cure for each bug.
That was just triage.
The full Sterile Squad game has 20-question shifts pulled fresh from 1000 questions every time, plus the full practice bank.
Doctor's orders: the two organisms are the whole game. Steam, IUSS, gas plasma, and ozone all share Geobacillus stearothermophilus. EtO and dry heat share Bacillus atrophaeus. Learn that split and you cannot miss these questions.
Doctor's notes: BI organism reference
Sterilization method
BI organism
Memory anchor
Steam sterilization (gravity displacement)
Geobacillus stearothermophilus
Geobacillus lives near hot springs. Heat-loving bug for the heat-based process.
Steam sterilization (dynamic air removal / prevacuum)
Geobacillus stearothermophilus
Same cycle family, same bug. Both steam cycles use G. stearothermophilus.
Immediate-use steam sterilization (IUSS)
Geobacillus stearothermophilus
IUSS is still steam, so the BI organism does not change.
Ethylene oxide (EtO)
Bacillus atrophaeus
A for atrophaeus, A for EtO gas. The gas process gets the gas-resistant spore.
Hydrogen peroxide gas plasma
Geobacillus stearothermophilus
Plasma systems group with steam: tough bug, low-temperature cycle.
Dry heat
Bacillus atrophaeus
Dry conditions, dry-heat spore. B. atrophaeus survives the long hot drought.
BI organism questions, answered
Which biological indicator organism is used to monitor steam sterilization on the CRCST exam?
Geobacillus stearothermophilus. It is the BI organism for steam sterilization (gravity and dynamic air removal cycles), immediate-use steam sterilization, hydrogen peroxide gas plasma, and ozone sterilization on the CRCST exam.
Which biological indicator organism is used for ethylene oxide sterilization?
Bacillus atrophaeus (formerly called Bacillus subtilis var. niger). It is also the BI organism for dry heat sterilization.
Why does the CRCST exam test BI organism pairings?
Biological indicators prove a sterilization cycle worked. The CRCST exam asks which organism belongs to which process, so matching each method to its BI organism is a fast, high-yield study drill.
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