The aim of the research was to explore possibilities for the use of bacteriophage K for the detection of Staphylococcus spp. in sonicate fluid (SF) of infected prosthetic joints (PJI). Specificity testing results of bacteriphage K showed that it is able to recognize and lyse only staphylococci. The optimal time for bacterial detection with the method of ATP detection after staphylococcal lysis with bacteriophage (ATP method) was 120 min after infection with bacteriophage K and 180 min with the method of bacteriophage K DNK detection with qPCR (qPCR method). The limit of detection for the ATP method was in the range of 10^3 CFU/mL and 6.8 × 10^2 CFU/mL for the qPCR method. After the induction of the viable but non-culturable (VBNC) state of bacteria, the optimized methods were tested for the possibility of detection. The ATP method did not allow the detection of VBNC bacteria, because lysis did not occur. However, the detection of VBNC bacteria with the qPCR method was successful based on the adsorption of added bacteriophages. With the use of bacteriophage K for the detection of bacteria within 104 tested SF, the same sensitivity of staphylococcal determination was achieved compared to standard microbiological methods. However, the detection time was significantly reduced. The results open up the possibility for further exploration of bacteriophages in order to expand the detection spectrum of methods and thus approach the development of a fast and specific method for accurate and inexpensive diagnosis of PJI.