Green fluorescent protein-fused bacteriophage cellular wall-binding domain as broad-spectrum signal probe for fluorimetry of methicillin-resistant Staphylococcus aureus strains

As a "superbug", methicillin-resistant Staphylococcus aureus (MRSA) has long been one of the most ubiquitous drug-resistant bacteria inducing numerous nosocomial infections. To achieve effective diagnosis and following treatment decision of infectious diseases induced by MRSA, it is highly desired to establish rapid analysis and antibiotic susceptibility test methods for this pathogen. In this study, we successfully expressed a bifunctional protein by fusing green fluorescent protein and cellular wall-binding domain of bacteriophage P108. The bifunctional protein can be employed as a signal probe for broad-spectrum fluorimetry of MRSA strains because it can both bind with the target pathogen and emit intensive fluorescence. By using it as the signal probe and porcine IgG as the capture agent, MRSA can be analyzed within a dynamic range of 1.0 × 103-2.0 × 107 CFU mL-1 with a sandwich mode. The fluorimetry was also applied to test antibiotic susceptibility of this pathogen to five antibiotics, and all results are conformable with those obtained with a standard micro broth dilution method. The above results demonstrate the attractive perspective of the bifunctional protein for rapid diagnosis and effective medication of infectious diseases induced by MRSA.