Novel Immunosensor via Dual-Species Antibody Synergy: Guinea Pig Immunoglobulin G (IgG)/Chicken Immunoglobulin Y (IgY)-Mediated Specific Determination of Staphylococcus aureus

Traditional immunoassays for Staphylococcus aureus (S. aureus) suffer from significant limitations, particularly owing to cross-reactivity with protein G-producing Streptococcus species. To address this issue, here is reported an innovative colorimetric strategy that depended on the unique binding characteristics of guinea pig immunoglobulin G (IgG) toward staphylococcal protein A (SPA), a highly expressed epitope on S. aureus. Unlike conventional monoclonal or polyclonal antibodies, guinea pig IgG exhibits high specificity for SPA, while demonstrating negligible affinity for protein G. The method also integrated horseradish peroxidase (HRP)-conjugated chicken anti-protein A immunoglobulin Y (IgY) (HRP–IgY) in a sandwich immunoassay format, enabling the catalytic oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) and hydrogen peroxide. The signal intensity correlated linearly with S. aureus concentration over a dynamic range of 7.8 × 102 CFU/mL–1.0 × 105 CFU/mL, achieving a detection limit of 6.9 × 102 CFU/mL. Notably, the assay demonstrated exceptional specificity, with no cross-reactivity with other common foodborne pathogens. Compared with mainstream methods, this assay completed the entire analytical process within 90 min-shorter than polymerase chain reaction (PCR) and traditional enzyme-linked immunosorbent assay (ELISA). It eliminated the need for complex DNA extraction or strict anti-cross-contamination controls and maintained stable performance in real samples. This advantage outperforms PCR (often susceptible to matrix inhibitors) and ELISA (typically exhibits reduced sensitivity in complex matrices). By offering significant improvements over conventional techniques, this strategy holds great promise for enhancing the efficiency and reliability of S. aureus detection in practical applications.