Methods for enhancing specificity and sensitivity of group a

1. A method for detecting the presence of at least one Group A Streptococcus species in a biological sample comprising:

(a) contacting the biological sample with a polyclonal antibody that specifically targets a Group A streptococcus -specific antigen and an amount of N-propionyl-D-glucosamine; or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide; and

(b) detecting binding of the polyclonal antibody to the Group A streptococcus -specific antigen, if present, in the sample;

wherein detection of binding of the polyclonal antibody to the Group A streptococcus -specific antigen indicates the presence of at least one Group A Streptococcus species in the sample, and,

wherein the amount of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide is an amount effective to reduce a false positive signal in the presence of mucin in the sample.

2. The method of claim 1 , wherein the polyclonal antibody comprises a gold nanoparticle label, a chemiluminescent label, a radioactive label, a bioluminescent label, a fluorescent label, a chromogenic label, a spectroscopic label, a photochemical label, or an electrochemiluminescent label.

3. The method of claim 2 , wherein the chemiluminescent label is selected from the group consisting of β-galactosidase, horseradish peroxidase (HRP), and alkaline phosphatase.

4. The method of claim 2 , wherein the bioluminescent label is selected from the group consisting of aequorin, firefly luciferase, Renilla luciferase, red luciferase, luxAB, or nanoluciferase.

5. The method of claim 2 , wherein the radioactive label is selected from the group consisting of 3 H, 14 C, 32 P, 35 S, 36 Cl, 57 Co, 131 I and 186 Re.

6. The method of claim 1 , wherein the biological sample is urine, saliva, sputum, mucous, a throat swab sample, whole blood, plasma, serum, amniotic fluid, semen, wound secretions, vaginal secretions, tears, or spinal fluid.

7. The method of claim 1 , wherein binding of the polyclonal antibody to the Group A streptococcus -specific antigen is detected via enzyme-linked immunosorbent assay (ELISA) or Enzyme multiplied immunoassay technique (EMIT).

8. The method of claim 1 , wherein the Group A streptococcus -specific antigen is selected from the group consisting of capsular polysaccharide (C-substance), cell wall peptidoglycan, lipoteichoic acid (LTA), M protein, fimbrial proteins, fibronectin-binding proteins, and cell-bound streptokinase.

9. The method of claim 1 , wherein the biological sample is obtained from a subject suffering from or suspected of having a bacterial infection.

10. The method of claim 9 , wherein the subject is human.

11. The method of claim 1 , wherein the Group A Streptococcus species is Streptococcus pyogenes or Streptococcus dysgalactiae.

12. The method of claim 1 , wherein contacting the biological sample with a polyclonal antibody that specifically targets a Group A streptococcus -specific antigen comprises applying the biological sample to a sample receiving zone of an immunoassay device comprising the sample receiving zone and a labeling zone, wherein the labeling zone comprises the antibody or antigen binding fragment that specifically targets a Group A streptococcus -specific antigen.

13. The method of claim 12 , wherein the immunoassay device comprises a lateral flow device.

14. The method of claim 12 , wherein the immunoassay device comprises N-propionyl-D-glucosamine, or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide.

15. The method of claim 14 , wherein the sample receiving zone comprises N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide.

16. The method of claim 14 , wherein the labeling zone comprises N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide.

17. The method of claim 1 , wherein contacting the biological sample with an effective amount of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide comprises adding an effective amount of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide directly to the biological sample.

18. The method of claim 17 , wherein adding an effective amount of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide directly to the biological sample comprises adding N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide to an extraction reagent and combining the biological sample with said extraction reagent.

19. The method of claim 1 , wherein the biological sample comprises epithelial cells originating from the tongue, cheek or teeth.

20. The method of claim 1 , wherein the addition of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide reduces false positive results.

21. The method of claim 1 , wherein the addition of N-propionyl-D-glucosamine or Bis-(2-(D-2-deoxy-glucosaminyl))-PEG3-amide does not increase false negative results.

22. A method for detecting the presence of Streptococcus pyogenes in a biological sample comprising:

(a) applying a throat swab sample or saliva sample to a sample receiving zone of a lateral flow immunoassay device comprising the sample receiving zone and a labeling zone, wherein the labeling zone comprises a polyclonal antibody that specifically targets a Group A streptococcus capsular polysaccharide (C-substance), wherein the antibody or antigen binding fragment comprises a gold nanoparticle label, and wherein the sample receiving zone or labeling zone comprises an amount of N-propionyl-D-glucosamine; and

(b) detecting binding of the antibody or the antigen binding fragment to the Group A streptococcus capsular polysaccharide (C-substance), if present, in the sample;

wherein detection of binding of the polyclonal antibody indicates the presence of Streptococcus pyogenes in the sample, and

wherein the amount of N-propionyl-D-glucosamine is an amount effective to reduce a false positive signal in the presence of mucin in the sample.