Flowflex® Plus Strep A Rapid Test Cassette; Flowflex® Plus Strep A Rapid Test Strip

K251697 · ACON Laboratories, Inc. · GTY · Nov 26, 2025 · Microbiology

Device Facts

• Record ID: K251697
• Device Name: Flowflex® Plus Strep A Rapid Test Cassette; Flowflex® Plus Strep A Rapid Test Strip
• Applicant: ACON Laboratories, Inc.
• Product Code: GTY · Microbiology
• Decision Date: Nov 26, 2025
• Decision: SESE
• Submission Type: Dual Track
• Regulation: 21 CFR 866.3740
• Device Class: Class 1

Intended Use

Flowflex® Plus Strep A Rapid Test Cassette: The Flowflex® Plus Strep A Rapid Test Cassette is a rapid chromatographic immunoassay for the qualitative detection of Group A Streptococcus antigen from throat swab specimens from symptomatic patients. The test is used to aid in the diagnosis of Group A Streptococcal infection. All negative test results should be confirmed by bacterial culture because negative results do not preclude infection with Group A Streptococcus and should not be used as the sole basis for treatment. Flowflex® Plus Strep A Rapid Test Strip: The Flowflex® Plus Strep A Rapid Test Strip is a rapid chromatographic immunoassay for the qualitative detection of Group A Streptococcus antigen from throat swab specimens from symptomatic patients. The test is used to aid in the diagnosis of Group A Streptococcal infection. All negative test results should be confirmed by bacterial culture because negative results do not preclude infection with Group A Streptococcus and should not be used as the sole basis for treatment.

Device Story

The Flowflex Plus Strep A Rapid Test (Cassette and Strip formats) is a lateral flow chromatographic immunoassay for qualitative detection of Group A Streptococcus (GAS) antigen in throat swab specimens. The device is intended for use by healthcare professionals in clinical settings. The test process involves extracting GAS antigen from a patient throat swab using provided reagents (2M Sodium Nitrite and 0.2M Acetic Acid). The extracted sample is applied to a test strip (either standalone or housed in a cassette) coated with anti-Strep A antibodies. If GAS antigen is present, it binds to antibody-coated particles and migrates to the test line, forming a visible pink-red line. A control line confirms proper sample volume and wicking. Results are read visually after 5 minutes. The test aids in the diagnosis of pharyngitis; however, negative results do not rule out infection and must be confirmed by culture. The device provides rapid point-of-care diagnostic information to assist clinicians in determining appropriate treatment pathways for patients with suspected streptococcal pharyngitis.

Clinical Evidence

Prospective clinical study (Aug 2022–Mar 2024) at 5 US sites with 397 subjects (all ages) presenting with pharyngitis symptoms. Performance compared to bacterial culture and latex agglutination. Strip format: 97.2% sensitivity (95% CI: 92.2%–99.1%), 95.8% specificity (95% CI: 92.9%–97.6%). Cassette format: 98.2% sensitivity (95% CI: 93.6%–99.5%), 95.1% specificity (95% CI: 92.0%–97.1%). Study included 16 untrained operators.

Technological Characteristics

Rapid chromatographic immunoassay; lateral flow technology; qualitative visual readout; manual test procedure; no electronic components or software.

Indications for Use

Indicated for symptomatic patients requiring qualitative detection of Group A Streptococcus antigen from throat swab specimens to aid in diagnosis of infection. Negative results require confirmation by bacterial culture.

Regulatory Classification

Identification

Streptococcus spp. serological reagents are devices that consist of antigens and antisera (excluding streptococcal exoenzyme reagents made from enzymes secreted by streptococci) used in serological tests to identify Streptococcus spp. from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by bacteria belonging to the genus Streptococcus and provides epidemiological information on these diseases. Pathogenic streptococci are associated with infections, such as sore throat, impetigo (an infection characterized by small pustules on the skin), urinary tract infections, rheumatic fever, and kidney disease.

Submission Summary (Full Text)

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FDA U.S. FOOD & DRUG ADMINISTRATION

November 26, 2025

ACON Laboratories, Inc.
% James Mullally
Vice President, In-Vitro Diagnostic Regulatory Affairs
MCRA
803 7th street NW
Washington, District of Columbia 20001

Re: K251697
Trade/Device Name: Flowflex® Plus Strep A Rapid Test Cassette; Flowflex® Plus Strep A Rapid Test Strip
Regulation Number: 21 CFR 866.3740
Regulation Name: Streptococcus Spp. Serological Reagents
Regulatory Class: Class I
Product Code: GTY
Dated: May 21, 2025
Received: June 2, 2025

Dear James Mullally:

We have reviewed your section 510(k) premarket notification of intent to market the device referenced above and have determined the device is substantially equivalent (for the indications for use stated in the enclosure) to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976, the enactment date of the Medical Device Amendments, or to devices that have been reclassified in accordance with the provisions of the Federal Food, Drug, and Cosmetic Act (the Act) that do not require approval of a premarket approval application (PMA). You may, therefore, market the device, subject to the general controls provisions of the Act. Although this letter refers to your product as a device, please be aware that some cleared products may instead be combination products. The 510(k) Premarket Notification Database available at https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm identifies combination product submissions. The general controls provisions of the Act include requirements for annual registration, listing of devices, good manufacturing practice, labeling, and prohibitions against misbranding and adulteration. Please note: CDRH does not evaluate information related to contract liability warranties. We remind you, however, that device labeling must be truthful and not misleading.

If your device is classified (see above) into either class II (Special Controls) or class III (PMA), it may be subject to additional controls. Existing major regulations affecting your device can be found in the Code of Federal Regulations, Title 21, Parts 800 to 898. In addition, FDA may publish further announcements concerning your device in the Federal Register.

U.S. Food & Drug Administration
10903 New Hampshire Avenue
Silver Spring, MD 20993
www.fda.gov

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Additional information about changes that may require a new premarket notification are provided in the FDA guidance documents entitled "Deciding When to Submit a 510(k) for a Change to an Existing Device" (https://www.fda.gov/media/99812/download) and "Deciding When to Submit a 510(k) for a Software Change to an Existing Device" (https://www.fda.gov/media/99785/download).

Your device is also subject to, among other requirements, the Quality System (QS) regulation (21 CFR Part 820), which includes, but is not limited to, 21 CFR 820.30, Design controls; 21 CFR 820.90, Nonconforming product; and 21 CFR 820.100, Corrective and preventive action. Please note that regardless of whether a change requires premarket review, the QS regulation requires device manufacturers to review and approve changes to device design and production (21 CFR 820.30 and 21 CFR 820.70) and document changes and approvals in the device master record (21 CFR 820.181).

Please be advised that FDA's issuance of a substantial equivalence determination does not mean that FDA has made a determination that your device complies with other requirements of the Act or any Federal statutes and regulations administered by other Federal agencies. You must comply with all the Act's requirements, including, but not limited to: registration and listing (21 CFR Part 807); labeling (21 CFR Part 801 and Part 809); medical device reporting (reporting of medical device-related adverse events) (21 CFR Part 803) for devices or postmarketing safety reporting (21 CFR Part 4, Subpart B) for combination products (see https://www.fda.gov/combination-products/guidance-regulatory-information/postmarketing-safety-reporting-combination-products); good manufacturing practice requirements as set forth in the quality systems (QS) regulation (21 CFR Part 820) for devices or current good manufacturing practices (21 CFR Part 4, Subpart A) for combination products; and, if applicable, the electronic product radiation control provisions (Sections 531-542 of the Act); 21 CFR Parts 1000-1050.

All medical devices, including Class I and unclassified devices and combination product device constituent parts are required to be in compliance with the final Unique Device Identification System rule ("UDI Rule"). The UDI Rule requires, among other things, that a device bear a unique device identifier (UDI) on its label and package (21 CFR 801.20(a)) unless an exception or alternative applies (21 CFR 801.20(b)) and that the dates on the device label be formatted in accordance with 21 CFR 801.18. The UDI Rule (21 CFR 830.300(a) and 830.320(b)) also requires that certain information be submitted to the Global Unique Device Identification Database (GUDID) (21 CFR Part 830 Subpart E). For additional information on these requirements, please see the UDI System webpage at https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance/unique-device-identification-system-udi-system.

Also, please note the regulation entitled, "Misbranding by reference to premarket notification" (21 CFR 807.97). For questions regarding the reporting of adverse events under the MDR regulation (21 CFR Part 803), please go to https://www.fda.gov/medical-devices/medical-device-safety/medical-device-reporting-mdr-how-report-medical-device-problems.

For comprehensive regulatory information about medical devices and radiation-emitting products, including information about labeling regulations, please see Device Advice (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-assistance) and CDRH Learn (https://www.fda.gov/training-and-continuing-education/cdrh-learn). Additionally, you may contact the Division of Industry and Consumer Education (DICE) to ask a question about a specific regulatory topic. See the DICE website (https://www.fda.gov/medical-devices/device-advice-comprehensive-regulatory-

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assistance/contact-us-division-industry-and-consumer-education-dice) for more information or contact DICE by email ([e-mail]) or phone [phone] or 301-796-7100).

Sincerely,

Uwe Scherf-S

for

Ribhi Shawar, Ph.D. (ABMM)

Chief

General Bacteriology and Antimicrobial Susceptibility

Branch

Division of Microbiology Devices

OHT7: Office of In Vitro Diagnostics

Office of Product Evaluation and Quality

Center for Devices and Radiological Health

Enclosure

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FORM FDA 3881 (8/23)
Page 1 of 1
PSC Publishing Services [phone]
EF

| DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration Indications for Use | Form Approved: OMB No. 0910-0120 Expiration Date: 07/31/2026 See PRA Statement below. |
| --- | --- |
| 510(k) Number (if known) K251697 | |
| Device Name Flowflex® Plus Strep A Rapid Test Cassette; Flowflex® Plus Strep A Rapid Test Strip | |
| Indications for Use (Describe) Flowflex® Plus Strep A Rapid Test Cassette: | |
| The Flowflex® Plus Strep A Rapid Test Cassette is a rapid chromatographic immunoassay for the qualitative detection of Group A Streptococcus antigen from throat swab specimens from symptomatic patients. The test is used to aid in the diagnosis of Group A Streptococcal infection. All negative test results should be confirmed by bacterial culture because negative results do not preclude infection with Group A Streptococcus and should not be used as the sole basis for treatment. | |
| Flowflex® Plus Strep A Rapid Test Strip: | |
| The Flowflex® Plus Strep A Rapid Test Strip is a rapid chromatographic immunoassay for the qualitative detection of Group A Streptococcus antigen from throat swab specimens from symptomatic patients. The test is used to aid in the diagnosis of Group A Streptococcal infection. All negative test results should be confirmed by bacterial culture because negative results do not preclude infection with Group A Streptococcus and should not be used as the sole basis for treatment. | |
| Type of Use (Select one or both, as applicable) ☑ Prescription Use (Part 21 CFR 801 Subpart D) ☐ Over-The-Counter Use (21 CFR 801 Subpart C) | |
| CONTINUE ON A SEPARATE PAGE IF NEEDED. | |
| This section applies only to requirements of the Paperwork Reduction Act of 1995. *DO NOT SEND YOUR COMPLETED FORM TO THE PRA STAFF EMAIL ADDRESS BELOW.* | |
| The burden time for this collection of information is estimated to average 79 hours per response, including the time to review instructions, search existing data sources, gather and maintain the data needed and complete and review the collection of information. Send comments regarding this burden estimate or any other aspect of this information collection, including suggestions for reducing this burden, to: Department of Health and Human Services Food and Drug Administration Office of Chief Information Officer Paperwork Reduction Act (PRA) Staff [e-mail] | |
| "An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB number." | |