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The Steris Verify Spore Test Strip for S40 is intended to provide users with a means to assess spore kill by the S40 sterilant at its use dilution in the System 1E Liquid Chemical Sterilant Processing System. A "no growth" result from the Steris Verify Spore Test Strip for S40 after 24 hours of incubation indicates that the liquid chemical sterilization process achieved the conditions necessary to kill at least 1 x 10 viable spores (5 logs) on the test strip. The Steris Verify Spore Test Strip for S40 does not confirm the expected full performance of the SYSTEM 1E Liquid Chemical Sterilization Cycle.

Device Description

The Steris Verify Spore Test Strip for S40 consists of a 1 3/8 in x ¼ in filter paper-based strip inoculated with Geobacillus stearothermophilus spores and is enclosed in a glassine envelope. The Spore Test Strips are provided with media vials containing a modified tryptic soy broth with phenol red pH indicator, and a transfer clip. The transfer clip holds the Spore Test Strip in a single location during a processing cycle in the System 1E Liquid Chemical Sterilant Processing System (System 1E processor; cleared under K090036) and enables aseptic transfer of the Strip from the processor into the growth media vial. Using the clip, the Spore Test Strip is secured on the available post located in the tray of the System 1E processor.

AI/ML Overview

Here's an analysis of the acceptance criteria and study details for the Steris Verify Spore Test Strip for S40, based on the provided text:

Evaluation of Automatic Class III Designation (De Novo) for the STERIS VERIFY SPORE TEST STRIP FOR S40

1. Table of Acceptance Criteria and Reported Device Performance

Acceptance Criteria Category	Specific Acceptance Criteria	Reported Device Performance
Spore Test Strip Specifications (Table 1)
Population (At manufacture)	≥1.5 x 10^5 cfu/strip	All initial spore populations were ≥1.5 x 10^5 cfu/strip (e.g., Lot 1: 1.8 x 10^5, Lot 2: 2.6 x 10^5, Lot 3: 2.3 x 10^5).
Population (After wash-off - end of cycle)	≥1.0 x 10^5 cfu/strip	All recovered populations after processing in Builders-Only were ≥1.0 x 10^5 cfu/strip.
D-value	12-26 sec at 1635 ppm PAA	D-values for 3 lots were 23 sec, 24 sec, and 18 sec respectively, all within 12-26 sec. Mean D-value of 19 sec with SD of 2.4 sec.
Survival Time	≥38 seconds	All strips in Survival/Kill study survived at 41 seconds (50/50 for all 3 lots).
Kill Time	≤239 seconds	All strips in Survival/Kill study were killed at 225 seconds (0/50 for all 3 lots).
Reduced Incubation Time	≥97.0% growth correspondence with 7 day growth (for growth between 30-80%)	All lots and time points (0-12 months for 18/24hr RIT) showed ≥97.8% growth correspondence with 7-day growth. Many were 100%.
Viable Spore Population (Pre/Post Builders-Only - Table 3 & 8)
Averaged recovered post-processing population	>1.0 x 10^5 cfu/Spore Test Strip	All lots (except 6-month Lot 1 explained by petitioner) showed >1.0 x 10^5 cfu/strip post-processing (e.g., Lot 1 initial: 1.4 x 10^5).
Calculated initial population of each sample (average cfu)	±50% of calculated mean sample population	Not explicitly detailed for individual samples, but Table 3 shows % Difference from Manufacturer Stated Population within this range.
Recovered average population of unprocessed Spore Test Strips	-50% to +300% of manufacturer's stated population	Table 3 shows initial recovered populations are within this range relative to manufacturer's stated (e.g., Lot 2: -18.2%).
Strips must not show any signs of damage	Not explicitly quantified, qualitative observation	"No visible signs of damage to the strip material" after two 6-minute cycles with S40 Sterilant.
Growth Inhibition
Strip material does not inhibit growth	Growth of G. stearothermophilus within 24 hrs.	All vials with autoclaved/processed strips inoculated with G. stearothermophilus showed growth within 24 hrs.
Transfer clip does not inhibit growth	Growth of G. stearothermophilus within 24 hrs.	All samples with processed transfer clip showed growth within 24 hrs.
Media Validation	Media support growth of low number of test organisms	Both solid and liquid media supported growth of low numbers of organisms under various conditions.
Effectiveness of Neutralization Method	Equivalent growth in all inoculated tubes	All inoculated tubes showed equivalent growth, validating the method.
Stability of Color	Inoculated samples demonstrate growth by color change, maintained for 7 days	All inoculated vials showed growth and color change within 24 hrs, maintained for 7 days.
	Negative controls maintain same color for 7 days	All uninoculated vials showed no growth and no color change for 7 days.
D-value Determination (Shelf-Life - Table 9)	D-value: 12-26 sec	All D-values across all lots and time intervals (0-12/15 months) were within 12-26 sec.
	±20% of initial calculated D-value for Spore Test Strip lot	All D-values (except for 12mo Lot 2 at -33.6%, explained by the petitioner) were within ±20% of initial (e.g., Lot 1: -23.6%, Lot 2: -19.6% at 3mo, Lot 3: 15.6%).
Survival/Kill Times (Shelf-Life)	All survive: 38 sec	All samples exposed for 41 seconds showed growth.
	All kill: 239 sec	All samples exposed for 225 seconds showed no growth.
Processor Performance (Simulated Use & Shelf-Life)	All strips processed with S40 Sterilant Concentrate must not show growth for 7 days	0/80 strips showed growth after Pass cycle. All strips processed with Sterilant were killed at each stability time point.
	All strips exposed to S40 Builders only should show growth within 7 days	80/80 strips showed growth after Builders Only cycle. All strips processed with Builders Only showed growth within 1 day.
	All in situ tests must complete a full cycle	Not explicitly reported as a pass/fail metric in results, but implied by successful cycle runs.

2. Sample Sizes and Data Provenance

Test Set (Reduced Incubation Time - RIT):
- Use Dilution Vessel (0 and 3 month time points): 100 Spore Test Strips per lot per time point (3 lots = 600 strips).
- System 1E processor (6, 9, and 12 month time points): 100 Spore Test Strips from each of 3 lots (300 strips per time point, total 900 strips).
- Provenance: Retrospective, derived from laboratory testing conducted by STERIS Corporation (implied by manufacturer's submission). Country of origin is not specified but is a US-based company.
Test Set (Viable Spore Population - Builders Only):
- Initial Characterization: 10 Spore Test Strips/Lot (for maceration), 3 Spore Test Strips/Lot (for growth media) - total 39 strips (13 per lot).
- Shelf-Life: 10 Spore Test Strips per lot per time point (3 lots * 5 time points = 150 strips).
- Provenance: Retrospective, laboratory testing.
Test Set (D-value characterization):
- 100 Spore Test Strips evaluated per lot (for 3 lots = 300 strips).
- Shelf-Life: Not explicitly stated but "10 Spore Test Strips per lot per 5 exposure times" for D-value study in shelf-life section implies significant numbers.
- Provenance: Retrospective, laboratory testing.
Test Set (Survival/Kill Window):
- 100 Spore Test Strips evaluated per lot (for 3 lots = 300 strips).
- Shelf-Life: "50 Spore Test Strips per lot per survival time or kill time" implies 300 strips total.
- Provenance: Retrospective, laboratory testing.
Test Set (Simulated Use Testing in System 1E - Pass/Fail):
- 80 Spore Test Strips per lot (for 3 lots = 240 strips).
- Provenance: Retrospective, laboratory testing.
Other tests (Growth Inhibition, Media Validation, Neutralization, Color Stability): Sample sizes varied, typically small numbers of strips or media vials (e.g., 6 strips for growth inhibition, 10 vials for color stability).

3. Number of Experts and Qualifications for Ground Truth

The ground truth in this submission is not established by human experts in the medical field (like radiologists). Instead, it is based on objective biological and chemical measurements and observations using established laboratory protocols.
The "experts" are the laboratory personnel who conducted these tests, but their specific qualifications are not detailed beyond being able to perform the described scientific studies (e.g., microbiology techniques, chemical analysis).

4. Adjudication Method for the Test Set

There appears to be no adjudication method in the traditional sense of multiple human readers independently assessing results.
The ground truth is determined by direct scientific measurement and observation of biological phenomena (spore growth/kill, color change, spore count) and chemical properties (PAA concentration, pH). Results are quantitative or clearly qualitative (growth/no growth) and are not subject to expert interpretation requiring adjudication.

5. If a Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study was done

No, an MRMC comparative effectiveness study was not done. This device is a biological indicator (spore test strip) for a sterilization process, not an imaging or diagnostic device that involves human interpretation of complex data. Therefore, the concept of "human readers improve with AI vs without AI assistance" is not applicable here. The device itself provides a direct biological outcome.

6. If a Standalone (i.e., algorithm only without human-in-the-loop performance) was done

Yes, the studies are essentially standalone performance evaluations of the device itself. The device provides a direct, objective result (growth or no growth, spore count, D-value) that is then interpreted according to established acceptance criteria. There isn't an "algorithm" in the sense of artificial intelligence, but rather a set of physical and biological processes designed to yield a clear outcome. Human involvement is primarily in executing the protocol and observing/recording the predetermined biological response (e.g., color change indicating growth).

7. The Type of Ground Truth Used

The ground truth used is primarily based on:

Biological Activity and Quantitative Microbiology: Direct measurement of viable spore populations (colony forming units, cfu), observation of bacterial growth (colony formation, turbidity, color change), and calculation of resistance parameters like D-value and survival/kill times.
Chemical Analysis: Measurement of peracetic acid (PAA) concentration and pH to define test conditions.
Physical Observation: Assessment of strip material integrity.
Reference Standards: Comparison against manufacturer's stated population and pre-defined acceptable ranges for specifications.

8. The Sample Size for the Training Set

This submission describes a de novo classification for a medical device (spore test strip), not an AI/ML algorithm. Therefore, there is no "training set" in the context of machine learning. The studies described are validation and performance testing of the physical and biological properties of the device.

9. How the Ground Truth for the Training Set was Established

As there is no "training set" for an AI/ML algorithm, this question is not applicable. The device's performance is intrinsically linked to the physical and biological characteristics of the Geobacillus stearothermophilus spores, the filter paper strip, and the chemical sterilant system, all validated through direct laboratory experimentation.

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