Estimation of Staphylococcus total viable count in different contamination states of central venous catheters in hemodialysis centers based on tunable diode laser wavelength-modulation spectroscopy

The surveillance and assessment of the total viable count (TVC) of Staphylococcus under different levels of catheter contamination are crucial for the prevention and evaluation of catheter-related infections in hemodialysis (HD). This paper demonstrates the noninvasive and accurate measurement of the TVC of Staphylococcus using wavelength-modulated tunable diode laser absorption spectroscopy (WMAS). The tunable distributed feedback laser with a central wavelength of 2004 nm was employed and the detection limit of 22.5 ppm for carbon dioxide (CO₂) produced by Staphylococcus epidermidis was obtained. The growth of Staphylococcus under different medium concentrations was studied, and the results indicated a strong correlation between the growth rate and final TVC of S. epidermidis with the medium concentration. When the degree of catheter contamination was low, resulting in minimal residual nutrient concentration within the catheter, the bacterial growth rate and TVC were effectively suppressed. Therefore, it is proven that WMAS is a user-friendly, noninvasive, and high signal-to-noise ratio technique for monitoring Staphylococcus, making it an effective tool for assessing Staphylococcus growth in HD catheter surveillance.