INTENDED USE

The Strep B Rapid Test is a rapid, visual immunoassay for the qualitative, presumptive
detection of group B Streptococcus (GBS) antigens in specimens collected from vaginal or rectal swab. Ear or throat swabs from newborns collected directly after birth can also be used. The test is intended as an aid in diagnosing the presence of GBS in sample material that may either be a sign of colonisation or infection. This test provides epidemiological information about infections caused by GBS. The Strep B Rapid Test is designed for professional use only. The detection limit of the assay is 1×105 bacteria/swab and does not depend on viability of organisms.

SUMMARY AND EXPLANATION

Group B Streptococci (GBS) or Streptococcus agalactiae are among the most frequent causes of life-threatening infections in neonates. Up to 30% of all pregnant women are
colonised with GBS. Some recent studies have shown that the intrapartum antibiotic prophylaxis of GBS-colonised women significantly reduces the incidence of GBS-caused sepsis in newborns. Routine examination for GBS is frequently recommended between the 35th and the 37th week of pregnancy. A CDC study has shown that this screening approach is 50% more effective than the use of antibiotics for pregnant women identified by clinical risk approach.
Standard culture methods require 24 to 48 hours, and the results may not be available soon enough for efficient treatment. Thus, methods utilising more rapid screening techniques are required. The Strep B Rapid Test is especially suitable if time and/or availability of culture methods are limited. It enables the detection of GBS directly from swabs, helping physicians make a presumptive diagnosis and decide whether a therapy should be indicated.

PRINCIPLE 

The Strep B Rapid Test detects group B Streptococcus antigens through visual interpretation of colour development on the internal test strip. Anti-streptococcus B antibodies are immobilised in the test line region of the membrane. During testing, the specimen reacts with further polyclonal anti-streptococcus B antibodies conjugated to coloured particles and precoated onto the conjugate pad of the internal test strip. The mixture then migrates along the membrane by capillary action and interacts with reagents on the membrane.
If there are sufficient streptococcus B antigens in the specimen, a coloured line will form in the test line region of the membrane. The presence of this coloured line indicates a positive result, while its absence indicates a negative result. The appearance of a coloured line in the control line region serves as a procedural control, indicating that the proper volume of specimen has been added and membrane wicking has occurred.