(242 days)
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.
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.
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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EVALUATION OF AUTOMATIC CLASS III DESIGNATION (DE NOVO) FOR THE STERIS VERIFY SPORE TEST STRIP FOR S40
REGULATORY INFORMATION
FDA identifies this generic type of device as:
SPORE TEST STRIP: The spore test strip consists of a carrier or strip with a known number of spores, at least 5 log10 per strip, of known resistance to a particular liquid chemical sterilant in a liquid chemical sterilant processing system. A "no growth" result from the spore test strip after the specified predetermined incubation period indicates that the liquid chemical sterilization process achieved the conditions necessary to kill the specified minimum number of viable spores on the test strip which is 5 log10 spores/strip; it does not confirm the expected full performance of the liquid chemical sterilant processing cycle because full performance is a 6 log10 spore kill in a full liquid chemical sterilization cycle.
NEW REGULATION NUMBER: 880.6887
CLASSIFICATION: II
PRODUCT CODE: OVY
BACKGROUND
DEVICE NAME: Steris Verify Spore Test Strip for S40 for use in the Steris System 1E Liquid Chemical Sterilant Processing System
510(K): K100049
DATE OF 510(K) NSE (NOT SUBSTANTIALLY EQUIVALENT) DECISION: JULY 7, 2011
DATE OF DE NOVO PETITION: AUGUST 01, 2011
PETITIONER CONTACT: STERIS CORPORATION 5960 HEISLEY ROAD MENTOR, OHIO 44060-1834
PETITIONER'S RECOMMENDED CLASSIFICATION: CLASS II
INDICATIONS FOR USE
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
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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.
LIMITATIONS
Please refer to the labeling for a more complete list of warnings, precautions and contraindications.
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. The Spore Test Strip specifications are shown in Table 1.
| Value | Spore Test Strip for S40 |
|---|---|
| Population | |
| At manufacture | ≥1.5 x 105 cfu*/strip |
| After wash-off (end of cycle) | ≥1.0 x 105 cfu/strip |
| Resistance | |
| D-value | 12-26 sec at 1635 ppm* |
| PAA* | |
| Survival Time | ≥38 seconds |
| Kill Time | ≤239 seconds |
| Reduced Incubation Time | 24 hours |
Table 1. Spore Test Strip Specifications
*cfu = colony forming units, ppm = parts per million, PAA = peracetic acid
For use, the Spore Test Strip is removed from the glassine envelope and secured in the System 1E processor along with the items to be liquid chemically sterilized. The liquid chemical sterilization cycle is initiated. At the end of the full cycle, the Spore Test Strip is removed and placed into the vial of growth medium for incubation under the specified conditions that will promote spore growth for at least 24 hours. If the media remains red and non-turbid, the user interprets the results as a pass. If the media color turns yellow or is turbid, the user interprets the result as a fail.
The Spore Test Strip is incubated at 55-60°C for a minimum of 24 hours, but may be incubated for up to 7 days. The shelf life is 12 months when stored at 2-24°C and 30-80% relative humidity (RH) away from sterilizing agents and excessive heat.
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Use of the Verify Spore Test Strip for S40 with the System 1E Liquid Chemical Sterilant Processing System
The Verify Spore Test Strip for S40 is intended to be used with the System 1E Liquid Chemical Sterilant Processing System (System 1E), which was cleared under K090036. The System 1E Processor dilutes the S40 Sterilant Concentrate to its use dilution (>1820 mg/L peracetic acid), liquid chemically sterilizes the load during a controlled 6-minute exposure at 46 to 55°C. and rinses the load with extensively treated potable water. The processed load should be used immediately. In the 510(k) submission, K090036, for the System 1E processor and the S40 Sterilant, simulated use testing demonstrated a 6 log kill of spores on devices by the end of the 6-minute liquid chemical sterilization cycle.
Limitations to use of liquid chemical sterilants (LCS) for device sterilization | The information available in the literature suggests that sterilization processes based on LCSs, in general, may not convey the same sterility assurance level (SAL) as sterilization achieved using thermal or physical methods. The data indicate that the survival curves for a LCS may not exhibit log-linear kinetics and the shape of the survivor curve may vary depending on the formulation, chemical nature and stability of the LCS. It is not possible to directly measure an SAL at the half cycle point of a LCS cycle as it is with thermal sterilization methods using a Biological Indicator. Therefore, the FDA recommends that LCSs be limited to reprocessing only semi-critical and critical devices that are heat-sensitive and incompatible with other sterilization methods.
Assessing Spore Kill by a Liquid Chemical Sterilant
The Verify Spore Test Strip for S40 is an optional accessory that provides users with a means to test the sporicidal activity of the S40 Sterilant use dilution in the System 1E. A "no growth" result after 24 hours of incubation from the Spore Test Strip holding 1 x 10 cfu of viable spores indicates that the liguid chemical sterilization process achieved the conditions necessary to kill at least 1 x 105 viable spores (5 logs) on the test strip by the end of the cycle. It does not confirm the expected full performance of the liquid chemical sterilization cycle, which kills at least 1 x 10° viable spores.
The System 1E is computer controlled and continually monitors the cvcle, including the fill time, exposure time, temperature range of the exposure time, and the conductivity of the use dilution. The system provides printed documentation of each cycle. In addition, the Verify System 1E Chemical Indicator is available for routine monitoring of the peracetic acid concentration of the S40 Sterilant use dilution.
SUMMARY OF NONCLINICAL/BENCH PERFORMANCE TESTING
Non-clinical performance data were provided to address the following areas:
Spore Strip Characterization
1 FDA Guidance Document, Guidance for Industry and FDA Reviewers: Content and Format of Premarket Notification [510(k)] Submissions for Liquid Chemical Sterilants/High Level Disinfectants, released January 3, 2000
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Viable spore population pre-processing and post-processing with Builders only: Testing was conducted to demonstrate that the viable spore population on the Spore Test Strip meets its specification for the starting spore population of at least 1.5 x 10° cfu prior to processing and of at least 1.0 x 10° cfu following processing through a complete System 1E liquid chemical sterilization cvcle under simulated use conditions in the absence of the active ingredient. Samples from 3 lots of Spore Test Strips were processed in the System 1E processor through a complete cycle with Builders only solution (no peracetic acid) or left unprocessed. Note: In the System 1E processor, the active ingredient in the S40 sterilant, peracetic acid (PAA), is combined with inert ingredients (Builders) to form a use dilution. Testing was conducted with the C1220 container/tray, which was modified with the addition of multiple posts attached to the bottom of the container to which the Spore Test Strips were attached with the transfer clips. Thirteen Spore Test Strips were processed in each run. The viable spore population was determined for each sample. Ten of the 13 Spore Test Strips were macerated and then cultured. The other 3 Spore Test Strips were transferred to growth media for comparison. The testing is summarized in Table 2.
| Sample | Processing | Recovery and Culture |
|---|---|---|
| 10 Spore TestStrips/Lot | No processing | Macerated in Sterile Water forIrrigation (SWFI), cultured 48 hrs, thenenumerated |
| 10 Spore TestStrips/Lot | Processing in System1Ewith Builders Only cup | Macerated in SWFI, cultured 48 hrs,then enumerated |
| 3 Spore TestStrips/Lot | Processing in System 1Ewith Builders Only cup | Transferred to growth media andcultured 7 days, then enumerated |
| Table 2. Summary of Testing for Viable Spore Population | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| -- | -- | -- | -- | --------------------------------------------------------- | -- | -- | -- | -- | -- | -- | -- |
The acceptance criteria were as follows:
-
- The averaged recovered post-processing population will be > 1.0 x 10° cfu/Spore Test Strip.
-
- The calculated initial population of each sample (average cfu) must be ± 50% of the calculated mean sample population.
-
- The recovered average population of unprocessed Spore Test Strips will be within -50% to +300% of the manufacturer's stated population.
The results are shown in Table 3. All Spore Test Strips showed growth. Incubation of the Media alone showed no growth through 7 days of incubation. During the processing cycle, the PAA concentration was measured at the 3 min exposure time and recorded.
| Lot | Manu. StatedPopulation | Recovered InitialPopulation | %Difference | RecoveredPopulation afterProcessing | |
|---|---|---|---|---|---|
| 1 | Average | $1.8 x 10^5$ cfu | $1.8 x 10^5$ cfu | 0.0 | $1.4 x 10^5$ cfu |
| 1 | Range | NA | $1.5-2.2 x 10^5$ cfu | -- | $1.1-1.7 x 10^5$ cfu |
Table 3. Viable Spore Population
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| Lot | Manu. StatedPopulation | Recovered InitialPopulation | %Difference | RecoveredPopulation afterProcessing | |
|---|---|---|---|---|---|
| 2 | Average | 2.2 x 105 cfu | 2.6 x 105 cfu | -18.2% | 1.8 x 105 cfu |
| Range | NA | 2.3-3.0 x 105 cfu | -- | 1.4-2.4 x 105 cfu | |
| 3 | Average | 2.1 x 105 cfu | 2.3 x 105 cfu | -9.5% | 1.4 x 105 cfu |
| Range | NA | 1.9-3.1 x 105 cfu | -- | 1.1-1.9 x 105 cfu |
NA — Not Applicable
The initial population of all Spore Test Strip samples tested was >1.5 x 10° cfu. The population on each of the Spore Test Strip samples after processing was ≥1.0 x 10° cfu.
The firm also evaluated the compatibility of the strip material with the S40 Sterilant. Ten Spore Test Strips were exposed to two 6 minute cvcles in the System 1E processor with the S40 Sterilant with the PAA concentration at 1845-2374 ppm. The results showed no visible signs of damage to the strip material. In addition, as described below, the strip material was shown not to inhibit growth of the B. stearothermophilus spores.
Viable Spore Population on the Spore Test Strip pre- and post-rinse phase: Testing was conducted to demonstrate that the loss of spores from the Spore Test Strip by physical wash-off occurs prior to the rinse phase of the System 1E liquid chemical sterilization cycle. The firm evaluated the recoverable viable spore population from the Spore Test Strip before and after exposure to the rinse phases in the System 1E processor. Testing was conducted with 10 strips from each of three lots of the Spore Test Strip. The spore population on the test strips was evaluated under the following conditions:
-
Unprocessed
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Exposure to a full System 1E sterilization cycle with Builders-only (no PAA)
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Exposure to a the System 1E exposure phase only (no rinses) with Builders-only
The spore population of each strip was determined and then the average population for the lot was calculated by calculating the mean of the 10 individual strip populations. The results showed a statistically significant loss of viable spores from the strip during the Builders only exposure phase. However, the loss of viable spores from the strip during the subsequent rinse phases was not statistically significant.
Characterization of the spores on the test strip: Testing was conducted to compare the characteristics of the spores on the test strip with the spores remaining on the test strip following processing in the System 1E with Builders-only.
-
The spores on the strip were evaluated by Scanning Electron Microscopy. The micrographs showed that the spores are imbedded in the matrix of the strip and do not sit on the surface of the strip. The spores do not physically attach themselves to the matrix.
-
The kill kinetic properties of the Spore Test Strips were evaluated before and after
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exposure to the Builders-only cycle. A total of 30 strips were exposed to the full Builders-only cycle and then evaluated for kill kinetics using a beaker of the S40 Sterilant use dilution in a 43°C water bath. A single strip was removed at each of 6 time points (40-140 sec) and immediately neutralized. Unexposed Strips were similarly evaluated. The results were the same for both sets of Spore Test Strips. The results demonstrate that the spores maintain the same kill kinetic properties whether or not they are exposed to the Steris System 1E processor.
Growth inhibition: The strip material used for the Spore Test Strip was evaluated for its potential to inhibit growth of the organism. G. stearothermophilus, either before processing or after processing in the System 1E processor with the S40 Sterilant. Testing after processing is intended to demonstrate that the strip does not retain significant levels of the Sterilant that may hinder the outgrowth of the organism. Testing was conducted with three different lots of media. Six strips were autoclaved and then clipped in a tray in the System 1E processor and exposed to a full cycle with the S40 Sterilant (2004-2045 ppm PAA, pH 6.35-6.72) and then transferred to growth media. 2 strips were placed in each vial of media. Six additional strips, which had also been autoclaved, but were not processed through the System 1E processor were similarly transferred to growth media. After 2 hrs incubation, each tube was inoculated with an average of 18.7 cfu G. stearothermophilus and then incubated at 55-60°C for 7 days. The vials were evaluated daily for growth. All vials showed growth within 24 hrs of incubation. The results demonstrate that the strip material does not inhibit growth, either before or after processing in the System 1E processor. Positive and negative controls showed that the growth media can support growth of low numbers of organisms and that the strip and the media were sterile prior to use.
Because the transfer clip contacts the Spore Test Strip, the firm evaluated the growth inhibition potential of the transfer clip following exposure in the System 1E processor with the S40 sterilant use dilution. The processed clip was placed in growth media and then inoculated with low numbers of G. stearothermophilus spores and examined for growth. All samples showed growth within 24 hrs. The results show that the clip does not have inhibitory effects on the G. stearothermophilus outgrowth.
Media Validation: Testing was conducted to demonstrate that both the solid and liguid culture media used in the performance studies are capable of supporting growth of a low number of test organisms. Testing was conducted under the following conditions:
-
10% variation in volume
-
10% variation in pH indicator
- A Presence or absence of pH indicator
The results show that both the solid and liquid culture media support growth of low numbers of test organisms under the above conditions.
Effectiveness of Neutralization Method: Testing was conducted to demonstrate ability of the method of neutralization (dilution with 0.048% sodium thiosulfate) to effectively
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neutralize the PAA and not adversely affect the growth of the organisms. Testing was conducted under the following conditions:
Sodium thiosulfate with Spore Test Strip - strip exposed to S40 Sterilant
-
10 vials inoculated with approximately 10 cfu/ml
-
1 vial not inoculated (Negative control)
Sodium thiosulfate with Spore Test Strip - strip exposed to deionized water
-
10 vials inoculated with approximately 10° cfu/ml
-
1 vial not inoculated (Negative control)
Sodium thiosulfate with Spore Test Strip - strip exposed to S40 Sterilant
-
1 vial not inoculated test strip used to check for presence of detectable PAA the results were negative
Sterile deionized water with Spore Test Strip -
10 vials inoculated with approximately 103 cfu/ml
-
1 vial not inoculated (Negative control)
The PAA concentration was 1487-1588 ppm over the results show equivalent growth in all inoculated tubes. The study validates the neutralization method.
Stability of Color
Testing was conducted to demonstrate that the culture medium maintains a stable color or color change following growth for a minimum of 7 days at 55-60°C. A color change from red to yellow during incubation indicates microbial growth. Three lots of Spore Test Strips and 30 vials of media from each of 3 lots of media were evaluated. The samples were incubated at 55-60°C and monitored daily for growth or color change for 7 days.
-
10 vials negative control; no inoculation
-
10 vials inoculated
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10 vials inoculated with <100 cfu G. stearothermophilus
The results indicate that all inoculated vials show growth and color change to yellow within 24 hrs with no reversion for the duration of the 7-day incubation. All of the uninoculated vials show no growth and no color change over the same period of time and conditions.
Reduced Incubation Time
Testing to support a reduced incubation time (RIT) of 24 hrs for the Spore Test Strips following exposure to the S40 Sterilant was conducted per the FDA recommended protocol. Testing was conducted with newly manufactured Spore Test Strips and with Spore Test Strips at intervals following storage of 3 months, 6 months, and 12 months. The Acceptance Criteria were:
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-
30-80% Spore Test Strips show growth
-
≥97.0% growth correspondence with 7 day growth per the FDA guidance
For the 0 and 3 month time points, the samples were exposed to the sterilant in the Use Dilution Vessel at 43°C and about 1635 ppm PAA. Media color was recorded at 18. 24. 48, 72, 96, 120, 144, and 168 hours. One hundred Spore Test Strips were tested per lot per time point. The exposure cycle times varied per lot of Spore Test Strip. The test results in the Use Dilution Vessel for the 0 month samples are summarized in Table 4.
| Lot | TimeInterval | Incubation Time | % Growthafter 18hrs | % Growthafter 7days | % GrowthCorrespondence | |
|---|---|---|---|---|---|---|
| 18 hrs | 7 days | |||||
| 1 | 0 mos | 65/100 | 65/100 | 65% | 65% | 100% |
| 3 mos | 46/100 | 47/100 | 46% | 47% | 97.8% | |
| 2 | 0 mos | 47/100 | 48/100 | 47% | 48% | 97.9% |
| 3 mos | 45/100 | 45/100 | 45% | 45% | 100% | |
| 3 | 0 mos | 54/100 | 54/100 | 54% | 54% | 100% |
| 3 mos | 49/100 | 49/100 | 49% | 49% | 100% |
Table 4. Reduced Incubation Time of Strips Exposed in the Use Dilution Vessel
Temperature and pH were recorded prior to addition of PAA, after the addition of PAA, and then again at the end of the run. PAA concentration was recorded after the addition of PAA and then again at the end of the run. The data indicate that the PAA concentration range for the 100 runs was 1454-1712 ppm after the addition of PAA and 1348-1579 ppm at the end of the run. The results of the RIT testing support reduced incubation times of 18 hours and 24 hours.
For the 6 month, 9 month, and 12 month time points, the samples were exposed to the S40 sterilant in the System 1E processor. For testing in the System 1E processor, the C1140 container/tray was modified with the addition of a stainless steel rod attached across the tray. This configuration was intended to allow 10 Spore Test Strips to experience sterilant contact for an equivalent time period. The trav is kidney shaped and fits snugly into the well of the square trav that fits into the chamber of the System 1E processor chamber. One hundred Spore Test Strips from each of 3 lots and 100 vials of media from 3 lots were used for testing in the System 1E processor with the S40 Sterilant cup using fractional cycles to obtain 30-80% growth. Ten Spore Test Strips were clipped to the stainless steel rod that is attached across the C1140 tray for each run. The cycle was aborted to achieve the partial cycle times. The retrieved Spore Test Strips were incubated at 56±2℃. The test results are summarized in Table 5. The results of the RIT testing support a reduced incubation time of 18 hours and 24 hours over 12 months of storage.
| Table 5. Reduced Incubation Time of Spore Strips Exposed in the System 1E | |||||
|---|---|---|---|---|---|
| Lot | Time | Incubation Time | % Growth | % Growth | % Growth |
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| Interval | 18 hrs | 7 days | after 18hrs | after 7days | Correspondence | |
|---|---|---|---|---|---|---|
| 1 | 6 mos | 74/100 | 74/100 | 74% | 74% | 100% |
| 9 mos | 71/100 | 71/100 | 71% | 71% | 100% | |
| 12 mos | 69/100 | 69/100 | 69% | 69% | 100% | |
| 2 | 6 mos | 73/100 | 73/100 | 73% | 73% | 100% |
| 9 mos | 50/100 | 50/100 | 50% | 50% | 100% | |
| 12 mos | 62/100 | 62/100 | 62% | 62% | 100% | |
| 3 | 6 mos | 63/100 | 63/100 | 63% | 63% | 100% |
| 9 mos | 68/100 | 68/100 | 68% | 68% | 100% | |
| 12 mos | 76/100 | 76/100 | 76% | 76% | 100% |
Spore Resistance Characteristics
Testing was conducted to determine the resistance characteristics of the spores on the Spore Test Strip to the S40 Sterilant use dilution using a "Use Dilution Vessel" under static conditions below the minimum recommended concentration (MRC) of 1800 ppm PAA. The firm conducted the following tests with the Spore Test Strip in a Use Dilution Vessel:
- A D-value characterization
-
Survival/Kill Window
- A Reduced Incubation Time validation testing (see section above)
The Spore Test Strips used in these studies were manufactured from three different G. stearothermophilus spore crops. Three different media lots also were used. One of the media lots was replaced with a fourth lot at the 6 month interval because of an insufficient supply of the original lot remaining to complete the shelf life study. The original media lot had been damaged by a water leak into the interior storage compartment of the environmental chamber which soaked the media samples and containers. Numerous vials were soaked with water or showed signs of mold growth. Therefore, approximately half of the vials put up for the shelf life study were removed and disposed. The firm decontaminated the chamber. Inconsistent results were obtained with the remaining media, which was subsequently replaced with the backup lot, which had been stored under the similar conditions. Lots were of similar age.
The Use Dilution Vessel consists of a 150 ml sterile beaker and a sterile stir bar in a water bath held at 43 ± 2℃. The solution temperature was below the minimum in the System 1E of 46°C. Prewarmed Builders solution (100 ml) was added and then a volume of S40 Sterilant concentrate was added to achieve the desired final PAA concentration. The Spore Test Strip was exposed to the PAA in the Use Dilution Vessel , during which the PAA concentration and pH were determined. The Spore Test Strip was removed from the vessel just prior to the full 6 minute exposure and then neutralized in sodium thiosulfate. The Spore Test Strip was then cultured. The Use Dilution Vessel reduces the significant kill that occurs during the fill and warm/mix phases of processing in the Steris System1E processor. It is intended to minimize loss of spores from the test strip due to wash-off and thus permit determination of resistance for the Spore Test Strip to the S40
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Sterilant use dilution. An ANOVA analysis of the mean Spore Test Strip population with exposure to the Builders only and with no exposure shows that there is no statistical difference between populations of unexposed Spore Test Strips and those exposed in the Use Dilution Vessel. Eight different tests were run to show the reproducibility and consistency of the PAA concentration and pH in the Vessel during the 6 minute exposure period.
D-value characterization: The D-value specification for the System 1E Spore Test Strip was originally set at > 15 seconds. A survivor curve was constructed using a PAA concentration of 1635 ppm, which is below the MRC of 1800 ppm PAA for the 6 minute cycle in the System 1E processor. The curve shows linearity over 70 seconds. Therefore, the Holocomb-Spearman-Karber (HSK) calculation was used to determine the D-value. Using this method, the D-value is determined as the negative reciprocal of the slope of the survival curve. In comparison, the Stumbo-Murphy-Cochran (SMC) method uses a single time point for calculation of the D-value.
Three lots of Spore Test Strips were used in the study. Five Spore Test Strips were placed in the Use Dilution Vessel with a PAA concentration of about 1635 ppm. Temperature and pH were recorded prior to addition of PAA and temperature, pH and PAA concentration were recorded after the addition of PAA and then again at the end of the run. The data indicate that the PAA concentration range for the twenty runs was 1459-1712 ppm after the addition of PAA and 1413-1551 ppm at the end of the run. One Spore Test Strip was retrieved at each time point as follows: 41 seconds - all survive; 92 seconds and 98 seconds - mixed survival/kill; and 225 seconds and 300 seconds - all killed. Following exposure, the Spore Test Strips were placed in neutralizer and then transferred to growth media and incubated at 55-60°C for 7 days. Samples were scored daily for growth. 20 Spore Test Strips were evaluated per lot per time point for a total of 100 Spore Test Strips evaluated per lot. The results of the study are shown in Table 6 along with a comparison to the D-value determined using the SMC method at 2 different quantal times. All D-values meet the initial specification for the System 1E Spore Test Strip of > 15 seconds.
| Lot | HSK | SMC | |
|---|---|---|---|
| 1.53 min | 1.63 min | ||
| 1 | 23 sec | 18 sec | 18 sec |
| 2 | 24 sec | 19 sec | 18 sec |
| 3 | 18 sec | 16 sec | 17 sec |
Table 6. D-value Determination - Comparison of Two methods
The D-values was calculated for each lot of S40 Sterilant use dilution and then averaged to establish a mean D-value of 19 sec with a standard deviation of 2.4 sec. The limits of the D-value were set using the following formula: Mean D-value ± 3 x standard deviation. Therefore, the D-value limits were established as 12-26 sec.
Survival/Kill Window: For the survival/kill study, 2 Spore Test Strips were placed in the Use Dilution Vessel with a PAA concentration of about 1635 ppm. One Spore Test Strip was removed at 41 seconds and the other was removed at 225 seconds. The results of
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testing with 3 lots of Spore Test Strips are in Table 7. Temperature and pH were recorded prior to addition of PAA; temperature, pH and PAA concentration were recorded after the addition of PAA and then again at the end of the run. The data indicate that the PAA concentration range for the 50 runs was 1445-1712 ppm after the addition of PAA and 1348-1579 ppm at the end of the run. A total of 100 Spore Test Strips were evaluated per lot. Samples were scored daily for growth.
| Spore TestStrip Lot | # Growers/# Tested | |
|---|---|---|
| 41 sec | 225 sec | |
| 1 | 50/50 | 0/50 |
| 2 | 50/50 | 0/50 |
| 3 | 50/50 | 0/50 |
Table 7 Survival/Kill Results
The survival and kill times were calculated based on the specifications for a manufacturing population of 1.5 x 10 cfu and the D-value limits. The specifications were calculated as all survive at 38 seconds and all kill at 239 seconds when tested at 1635 ppm PAA using the following formulas:
Survival Time = [log (minimum population) -2] x minimum D-value = [log (1.5 x 103) - 2] x 12 sec = 38 sec
Kill Time = [log (minimum population) + 4] x maximum D-value = [log (1.5 x 103) + 4] x 26 sec = 239 sec
SIMULATED USE TESTING IN STERIS SYSTEM 1E
Simulated use testing with the Spore Test Strips was conducted in the System 1E processor under pass and fail conditions to demonstrate the expected performance of the Spore Test Strips. Testing in the System 1E processor was conducted without use of an instrument load in the final finished System 1E processor. The empty load represents worst case conditions because, with no load present, the sterilant concentrate is diluted to its minimum PAA concentration. Testing was conducted with the C1220 container/tray. which was modified with the addition of multiple posts attached to the bottom of the container to which the Spore Test Strips were attached with the transfer clips. This container/tray was used for post processing the builders-only population testing, inprocessor testing and growth inhibition testing. The shape of the tray is a long oval and fits snugly into the well of the square tray that fits into the System 1E processor chamber.
Eighty Spore Test Strips per lot were evaluated for growth following exposure to a Pass cycle with the S40 Sterilant cup (at >1800 ppm PAA) and following exposure to a cycle with a Builders only cup (no PAA). The Spore Test Strips were clipped to posts in a modified 1220 trav. Ten Spore Test Strips were processed in each run in the System 1E processor. The PAA concentration and pH were measured at 3 minutes after the start of the exposure phase. The PAA concentration was 1995-2410 ppm during processing of
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the Spore Test Strips in the Pass cycle with the Sterilant. Prior to running the test cycles, the transfer clips were processed through a sterilization cycle in the System 1E with the Sterilant. The transfer clips were then used to attach the Spore Test Strips to the posts in the tray and then to transfer the Spore Test Strips to the growth media. In the results, 0/80 Spore Test Strips show growth following exposure in the Pass cycle and 80/80 Spore Test Strips show growth following exposure to the Builders Only cycle with a 6 minute exposure phase. The Spore Test Strips performed as expected under pass and fail conditions in the System 1E liquid chemical sterilization cycle.
SHELF LIFE/STABILITY
The subject device is not sterile and is not reusable. Shelf life/stability testing was conducted to support a shelf life of 12 months when stored at 2-24°C and 30-80% RH away from sterilizing agents and excessive heat. Three lots of Spore Test Strips from 3 different lots of G. stearothermophilus and 3 lots of media were evaluated in the study. The Spore Test Strips and media were stored at 24±2℃ at 80%±10% RH. Samples were tested at 3 month intervals - 0, 3, 6, 9, and 12 months. Spore Test Strips and media were randomly selected, although Spore Test Strips and media were paired up before storage. Samples were evaluated, as shown below, according to the criteria described for the performance and characterization studies.
- a. Viable spore population pre and post processing with builders only (10 Spore Test Strips per lot)
- b. D-value characterization study (10 Spore Test Strips per lot per 5 exposure times)
- c. Survival/Kill window (50 Spore Test Strips per lot per survival time or kill time)
- d. Performance in the System 1E (100 Spore Test Strips per lot)
- e. Stability of Read
In addition, Reduced Incubation Time was assessed for Spore Test Strips exposed in the Use Dilution Vessel and for Spore Test Strips processed in the System 1E processor. See Reduced Incubation Time section above.
As shown in Table 8, all Spore Test Strips passed the test criteria to support a shelf life of 12 months.
-
a. Viable spore population pre and post processing with builders only (no PAA):
Test samples were evaluated in the 1220 tray. The acceptance criteria were: -
Average recovered post processing population is ≥1.0 x 10 cfu/Spore Test Strip
-
The strips must not show any signs of damage after being exposed to two consecutive liquid chemical sterilization cycles
-
Calculated initial population of each sample must be ±50% of the calculated mean sample population
-
Average recovered population will be -50% to +300% of stated manufacturing population
Table 8. Stability of Viable Spore Population
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| Lot | TimeInterval | Manu. StatedPopulation | Recovered InitialPopulation | Recovered PopulationPost Processing |
|---|---|---|---|---|
| 1 | 0 mo | 1.8 x 105 cfu/Strip | 1.8 x 105 cfu/Strip | 1.4 x 105 cfu/Strip |
| 3 mo | 1.7 x 105 cfu/Strip | 1.1 x 105 cfu/Strip | ||
| 6 mo | 1.1 x 105 cfu/Strip | 8.3 x 104 cfu/Strip* | ||
| 9 mo | 1.6 x 105 cfu/Strip | 1.3 x 105 cfu/Strip | ||
| 12 mo | 2.1 x 105 cfu/Strip | 1.1 x 105 cfu/Strip | ||
| 2 | 0 mo | 2.2 x 105 cfu/Strip | 2.6 x 105 cfu/Strip | 1.8 x 105 cfu/Strip |
| 3 mo | 1.9 x 105 cfu/Strip | 1.3 x 105 cfu/Strip | ||
| 6 mo | 2.3 x 105 cfu/Strip | 2.1 x 105 cfu/Strip | ||
| 9 mo | 1.8 x 105 cfu/Strip | 1.4 x 105 cfu/Strip | ||
| 12 mo | 2.5 x 105 cfu/Strip | 2.0 x 105 cfu/Strip | ||
| 3 | 0 mo | 2.1 x 105 cfu/Strip | 2.3 x 105 cfu/Strip | 1.4 x 105 cfu/Strip |
| 3 mo | 1.9 x 105 cfu/Strip | 1.8 x 105 cfu/Strip | ||
| 6 mo | 2.3 x 105 cfu/Strip | 1.8 x 105 cfu/Strip | ||
| 9 mo | 1.9 x 105 cfu/Strip | 1.7 x 105 cfu/Strip | ||
| 12 mo | 1.6 x 105 cfu/Strip | 1.5 x 105 cfu/Strip |
The data for lot 1 at the 6 month time point* did not meet the specifications. The petitioner explained that the agar used in the population assay was too hot when used and concluded that because the results at the 9 and 12 month time points met specifications, the low populations at the 6 month time point were artificially low due to loss in viable spores on the strips because the agar was too hot. With this explanation, it was shown that all three lots of the Spore Test Strip meet the acceptance criteria after 12 months under the label storage conditions.
- b. D-value determinations by fraction negative method: PAA concentration was ≤1800 ppm and the temperature was 43±2℃ for all runs. The acceptance criteria were:
-
D-value: 12-26 min
-
±20% of initial calculated D-value for Spore Test Strip lot The results are summarized in Table 9.
| Lot | Time Interval | D-value | % Difference fromInitial Value |
|---|---|---|---|
| 1 | 0 mo | 23.0 sec | NA |
| 1 | 3 mo | 21.1 sec | -8.3% |
| 1 | 6 mo | 21.3 sec | -7.4% |
| 1 | 9 mo | 17.6 sec | -23.6% |
| 1 | 12 mo | 19.8 sec | -13.9% |
| 2 | 0 mo | 23.5 sec | NA |
| 2 | 3 mo | 18.9 sec | -19.6% |
| 2 | 6 mo | 19.5 sec | -17.0% |
| 2 | 9 mo | 19.6 sec | -16.6% |
Table 9. D-Value Determined by Fraction Negative Method
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| Lot | Time Interval | D-value | % Difference fromInitial Value |
|---|---|---|---|
| 12 mo | 15.6 sec | -33.6%* | |
| 15 mo | 21.1 sec | -10.3% | |
| 3 | 0 mo | 18.0 sec | NA |
| 3 mo | 19.5 sec | 8.3% | |
| 6 mo | 20.8 sec | 15.6% | |
| 9 mo | 20.8 sec | 15.6% | |
| 12 mo | 17.0 sec | -5.6% |
- Extra point added to evaluate whether D-value had really dropped
During incubation, one heating block was at 24°C at the 12 mo time point for lot 2. * The samples were transferred to another heating block at the proper temperature and incubated for an time point of 15 mo. The results did not change and that there was no negative impact on the study.
- c. Survival/Kill Times: Spore Test Strip samples were exposed in the System 1E processor to a PAA concentration of <1800 ppm. The results showed all samples exposed for 41 seconds showed growth and all samples exposed for 225 sec showed no growth. The acceptance criteria were:
-
All survive: 38 sec
-
All kill: 239 sec
-
Although the specifications are 38 seconds survival time and 239 seconds kill time, testing was conducted at a longer survival time and a shorter kill time.
- d. Processor Performance: Testing was conducted with the C1220 tray in the System 1E processor as previously described. The firm indicates that the PAA concentration was >1800 ppm for these cycles. The acceptance criteria were:
-
All Spore Test Strips processed with S40 Sterilant Concentrate must not show growth for 7 days of incubation time.
- All Spore Test Strips exposed to S40 Builders only should show growth A within 7 days incubation time.
-
All in situ tests must complete a full cycle.
-
All Spore Test Strips processed with the Sterilant were successfully killed at each stability time point and all Spore Test Strips processed with the Builders only (no PAA) showed growth within 1 day of incubation.
- Stability of Media Color: Testing was conducted to assess the stability of the media e. color change and turbidity. The samples were observed daily for color. The Acceptance Criteria were:
-
All inoculated samples demonstrate growth by color change and maintenance
-
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of that color change
-
All negative controls should maintain the same color for the 7 days of incubation
All media samples inoculated with a Spore Test Strip or suspension indicated growth within 24 hrs of incubation at 55-60°C. The color change was maintained throughout the remainder of the incubation period. All negative controls maintained the red color.
BIOCOMPATIBILITY/MATERIALS
The Verify Spore Test Strip for S40 does not come in contact with patients or with devices that come in contact with patients. The Indicators are handled by healthcare personnel with gloves.
LABELING
The de novo petition contains appropriate instructions for use, examples of the Certificates of Analysis, which identifies the viable spore population, D-value, and survival and kill times for the lot of spore test strips, and labels for the device. The instructions for use include the indications for use, performance characteristics, use instructions and interpretation of the results, storage conditions, expiration date, performance limitations, appropriate caution statements, and disposal instructions in accordance with 21 CFR 807.87(e). The information provided is acceptable.
RISKS TO HEALTH
Table 10, below, identifies the risks that may be associated with use of the Spore Test Strip and the measures recommended to mitigate these risks.
| Identified Risk | Recommended Mitigation Measures |
|---|---|
| User handling error due to false failSpore Test Strip device result due totechnical malfunction | Spore Strip CharacterizationSimulated Use TestingShelf LifeLabeling |
| User handling error due to false passSpore Test Strip device result due totechnical malfunction | Spore Strip CharacterizationSimulated Use TestingShelf LifeLabeling |
Table 10. Risks to Health and Recommended Mitigation Measures
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| Identified Risk | Recommended Mitigation Measures |
|---|---|
| User handling error due tomisunderstanding Spore Test Stripdevice use instructions | Labeling |
SPECIAL CONTROLS:
In combination with the general controls of the FD&C Act, the Steris Verify Spore Test Strip for S40 for use in the Steris System 1E Liquid Chemical Sterilant Processing System is subject to the following special controls to provide reasonable assurance of the safety and effectiveness of the device type of Spore Test Strip:
- (1) Spore Strip Characterization
- Population of viable spores on strip shall be a minimum of 5 log10 after 1. physical wash-off of spores from the strip by exposure to liquid chemical sterilant in the liquid chemical sterilant processing system, which should be validated over the claimed shelf life.
- ii. The resistance characteristics of the viable spores on the strip should be defined and be validated over the claimed shelf life.
- iii. The Spore Strip description should address the carrier material, how the spores are placed on the carrier, and whether there is any feature that minimizes spore wash-off. Bacteriostasis of the Spore Strip materials should be evaluated.
- iv. Incubation time for viable spores on the strip should be validated under the specified incubation conditions over the claimed shelf life.
- (2) Simulated Use Testing: Simulated use testing should demonstrate performance of spore test strip in liquid chemical sterilant/high level disinfectant under worst case in use conditions over the claimed shelf life.
- (3) Labeling: Labeling should specify appropriate instructions, warnings, cautions, limitations, and information relating to viable spore population, resistance characteristics, and interpretation of a "no growth" result.
CONCLUSION
After review of the information submitted in the de novo petition and through interaction with the petitioner, the Steris Verify Spore Test Strip for S40 indicated to provide users with a means to assess spore kill by a liquid chemical sterilant in a liquid chemical sterilant processing system, can be classified in class II with the establishment of the special controls as outlined above.
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The special controls appropriately mitigate the identified risks of the Steris Verify Spore Test Strip for S40 and provide reasonable assurance of the safety and effectiveness of the device. Like most class II medical devices, spore test strips used in a healthcare environment are subject to the Quality Systems regulation (QS regulation) as set forth at 21 CFR Part 820. Spore test strip device manufacturers must also comply with the requirements of the Medical Device Reporting (MDR) regulation 21 CFR Part 803.
The de novo petition for the Steris Verify Spore Test Strip for S40 is granted and the device is classified under the following:
Product Code: OVY Device/Product Name: Spore Test Strip Class: II Regulation: 21 CFR 880.6887
§ 880.6887 Spore test strip.
(a)
Identification. The spore test strip consists of a carrier or strip with a known number of spores, at least 5 log10 per strip, of known resistance to a particular liquid chemical sterilant in a liquid chemical sterilant processing system. A “no growth” result from the spore test strip after the specified predetermined incubation period indicates that the liquid chemical sterilization process achieved the conditions necessary to kill the specified minimum number of viable spores on the test strip which is 5 log10 spores/strip; it does not confirm the expected full performance of the liquid chemical sterilant processing cycle because full performance is a 6 log10 spore kill in a full liquid chemical sterilization cycle.(b)
Classification. Class II (special controls). The special controls for this device are:(1)
Spore strip characterization. (i) Population of viable spores on strip shall be a minimum of 5 log10 after physical wash off of spores from the strip by exposure to liquid chemical sterilant in the liquid chemical sterilant processing system, which should be validated over the claimed shelf life.(ii) The resistance characteristics of the viable spores on the strip should be defined and be validated over the claimed shelf life.
(iii) The spore strip description should address the carrier material, how the spores are placed on the carrier, and whether there is any feature that minimizes spore wash off. Bacteriostasis of the spore strip materials should be evaluated.
(iv) Incubation time for viable spores on the strip should be validated under the specified incubation conditions over the claimed shelf life.
(2)
Simulated Use Testing. Simulated use testing should demonstrate performance of spore test strip in liquid chemical sterilant/high level disinfectant under worst case in use conditions over the claimed shelf life.(3)
Labeling. Labeling should specify appropriate instructions, warnings, cautions, limitations, and information relating to viable spore population, resistance characteristics, and interpretation of a “no growth” result.