(174 days)
The Sofia Strep A+ FIA detects Group A Streptococcal antigens from patients with signs and symptoms of pharyngitis, such as sore throat. All negative test results should be confirmed by either bacterial culture or an FDA-cleared molecular assay because negative results do not prection and should not be used as the sole basis for treatment. The test is intended for professional and laboratory use as an aid in the diagnosis of Group A Streptococcal infection.
The Sofia Strep A+ FIA may be used with Sofia or Sofia 2.
The Sofia Strep A+ FIA involves the extraction of the antigenic components of the Group A Streptococcus (GAS) bacteria. The patient's Swab sample is placed in the Reagent Tube containing the Reagent Solution, during which time the bacterial antigens are extracted, making them more accessible to the specific antibodies. An aliquot of the extracted sample is dispensed into the Test Cassette sample well. From the sample well, the sample migrates through a test strip containing various unique chemical environments. If Group A Streptococcal antigens are present, they will be bound by antibodies coupled to fluorescent microparticles that migrate through the test strip. The fluorescent microparticles containing bound antigen will be captured by antibodies at a defined location on the test strip where they are detected by Sofia or Sofia 2. If antigens are not present, the fluorescent microparticles will not be trapped by the capture antibodies nor detected by Sofia or Sofia 2.
Depending upon the user's choice, the Test Cassette is either placed inside of Sofia or Sofia 2 for automatically timed development (WALK AWAY Mode) or placed on the counter or bench top for a manually timed development and then placed into Sofia 2 to be scanned (READ NOW Mode).
Sofia or Sofia 2 will scan the test strip and measure the fluorescent signal by processing the results using method-specific algorithms. Test results will be displayed (Positive, or Invalid) on the screen. The results can also be automatically printed on an integrated printer if this option is selected.
Sofia 2 is a microprocessor-controlled device about the size of a desk top telephone and weighs less than 3 pounds. Sofia 2 uses a fluorescent tag that is illuminated by an Ultraviolet (UV) light source to generate specific results.
The Sofiea Strep A+ FIA is a device intended to detect Group A Streptococcal antigens from throat swabs of patients with signs and symptoms of pharyngitis. All negative test results must be confirmed by either bacterial culture or an FDA-cleared molecular assay.
As this is a 510(k) submission, the device does not have explicit acceptance criteria mentioned, but rather demonstrates substantial equivalence to a predicate device. The performance data section of the document describes several studies undertaken to document the performance characteristics of the Sofia 2 and the Sofia Strep A+ assay, as well as to compare performance between Sofia and Sofia 2.
Here's the information about the studies presented:
1. Table of Acceptance Criteria and Reported Device Performance:
| Study | Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|---|
| Limit of Detection (LoD) | LoD on Sofia 2 is equivalent to LoD on Sofia. | Confirmed that the LoD generated for the Sofia Strep A+ FIA on Sofia 2 is equivalent to the LoD generated on Sofia. |
| Precision | Equivalent qualitative results between Sofia and Sofia 2 for negative and positive concentrations near threshold | Confirmed that Sofia and Sofia 2 generated equivalent qualitative results for negative and positive concentrations near the positivity threshold, across multiple operators, device lots, days, and two calibration cycles. |
| Assay Development Time | Development time of 5-10 minutes is acceptable for Sofia 2 in Read Now mode. | Confirmed that when running Sofia 2 in Read Now mode, a development time of five (5) to ten (10) minutes is acceptable. |
| Method Comparison | Comparable performance between Sofia and Sofia 2 using a panel of clinical samples. | Demonstrated that Sofia and Sofia 2 have comparable performance when using a panel of clinical samples. |
| Reproducibility | Intra- and inter-operator, and intra- and inter-laboratory reproducibility with various antigen concentrations. Comparable performance between Sofia and Sofia 2. | Demonstrated intra- and inter-operator reproducibility and intra- and inter-laboratory reproducibility with a panel of test samples at various Group A Streptococcal antigen concentrations. Also demonstrated comparable performance between Sofia and Sofia 2. |
2. Sample Size Used for the Test Set and Data Provenance:
The document does not explicitly state the sample sizes used for each test set in these studies, nor does it specify the country of origin of the data or whether the studies were retrospective or prospective. It refers to "a panel of clinical samples" for the Method Comparison study and "a panel of test samples" for the Reproducibility study.
3. Number of Experts Used to Establish Ground Truth for the Test Set and Their Qualifications:
This information is not provided in the document. The nature of the device (antigen detection) likely implies a microbiological gold standard (e.g., bacterial culture), rather than expert consensus on interpretation.
4. Adjudication Method for the Test Set:
This information is not provided in the document.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study:
A MRMC comparative effectiveness study involving human readers and AI assistance is not mentioned. The studies focus on the performance of the device itself and its equivalence to a predicate device.
6. Standalone Performance Study:
Yes, standalone performance studies were done. All the studies listed in the "Performance Data" section (LoD, Precision, Assay development time, Method Comparison, Reproducibility) assess the performance of the Sofia Strep A+ FIA on Sofia 2 (and its comparison to Sofia) as a standalone algorithm/device without explicit human-in-the-loop performance measurement.
7. Type of Ground Truth Used:
The document mentions that negative test results "should be confirmed by either bacterial culture or an FDA-cleared molecular assay." This implies that bacterial culture or an FDA-cleared molecular assay would serve as the ground truth for determining the presence or absence of Group A Streptococcal infection in the clinical sample studies.
8. Sample Size for the Training Set:
The document does not provide information about a specific training set or its sample size. This is common for this type of in vitro diagnostic device, where performance is evaluated against known concentrations or clinical samples with confirmed status, rather than training a machine learning model in the conventional sense.
9. How the Ground Truth for the Training Set Was Established:
As there is no mention of a traditional training set for a machine learning model, the method for establishing ground truth for a training set is not applicable or described in this document. The "ground truth" for the performance evaluation studies would be established using validated methods like bacterial culture or FDA-cleared molecular assays, as mentioned in the indications for use.
§ 866.3740
Streptococcus spp. serological reagents.(a)
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 identifyStreptococcus spp. from cultured isolates derived from clinical specimens. The identification aids in the diagnosis of diseases caused by bacteria belonging to the genusStreptococcus 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.(b)
Classification. Class I (general controls). The device is exempt from the premarket notification procedures in subpart E of part 807 of this chapter subject to § 866.9.