Ultrasound frequency of sonication applied in microbiological diagnostics has a major impact on viability of bacteria
Piotr Dudek1, Aleksandra Grajek2, Jacek Kowalczewski1
1Centre of Postgraduate Medical Education, Department of Orthopaedics and Rheumoorthopaedics, Warsaw, Poland.
Objectives:
Sonication of explanted prosthesis constitutes an element of microbiological diagnostics. The aim of performing this procedure is to remove biofilm and to increase sensitivity of diagnostics. Ultrasound used in medical purposes are low-frequency and low-intensity. With this wide range of frequency which can be used in sonication process it is necessary to find the golden mean between biofilm dislodging and planktonic bacteria sparing.
Materials And Methods:
The aim of this study was to determine the least harming low-intensity ultrasound frequency (35 kHz, 40 kHz or 53 kHz) used during sonication process with other parameters constant. Four bacteria species were examined: S. aureus, E. faecalis, E. coli, K. pneumoniae. Number of microbiological studies (n) for each group (g) counted 40 specimens (based on scheme 1 bacteria type - 4 groups, 40 studies each).
Results:
A detailed analysis of gathered data was conducted. Based on study findings following conclusions were drawn. Sonication has a significant and negative impact on survival of sonicated planktonic bacteria. Part of bacteria in planktonic state are damaged/killed by ultrasound, which is demonstrated by lower CFU count in sonicated samples versus control group.
Conclusions:
Optimal ultrasound frequencies for sonication of S. aureus, P. aeruginosa and E. coli are 35 kHz and 40 kHz. Ultrasound frequencies used in sonication process (35 kHz, 40 kHz, 53 kHz) of E. coli showed same impact on bacteria survival. It is crucial to perform further assessment of ultrasound parameters on clinical effects of sonication used in PJI diagnostics.
Insights
Lower ultrasound frequencies (35 kHz and 40 kHz) are optimal for sonication in prosthetic joint infection diagnostics, as higher frequencies negatively impact planktonic bacteria survival.
Area of Science:
- Microbiology
- Biophysics
- Medical Diagnostics
Background:
- Sonication is crucial for microbiological diagnostics of explanted prostheses.
- The procedure aims to dislodge biofilm and enhance diagnostic sensitivity.
- Optimizing ultrasound parameters is key to balance biofilm removal and planktonic bacteria survival.
Purpose of the Study:
- To determine the least harmful low-intensity ultrasound frequency for sonication.
- Investigate the impact of 35 kHz, 40 kHz, and 53 kHz ultrasound frequencies on bacterial survival.
- Assess bacterial response to sonication for improved prosthetic joint infection (PJI) diagnostics.
Main Methods:
- Four bacterial species (S. aureus, E. faecalis, E. coli, K. pneumoniae) were tested.
- Sonication was performed at constant low intensity across different frequencies.
- Microbiological studies (n=40 per group) analyzed bacterial survival post-sonication.
Main Results:
- Sonication significantly reduces the survival of planktonic bacteria.
- Lower colony-forming unit (CFU) counts in sonicated samples indicate bacterial damage or death.
- Ultrasound frequencies tested negatively impact planktonic bacteria viability.
Conclusions:
- Optimal ultrasound frequencies for sonication of S. aureus, P. aeruginosa, and E. coli are 35 kHz and 40 kHz.
- All tested frequencies (35 kHz, 40 kHz, 53 kHz) similarly impacted E. coli survival.
- Further research is needed to assess ultrasound parameters' clinical effects in PJI diagnostics.
