Abstract In this study, we evaluated whether ultrasound instruments are important in the spread of nosocomial staphylococcal infections. Following genomic typing by pulsed-field gel electrophoresis, it was apparent that ultrasound procedures transferred colonizing staphylococci from a patient's skin to the ultrasound instruments. Staphylococcus aureus survived in the transmission medium for longer than in water. Furthermore, S. aureus was more resistant to the ultrasonic medium than Pseudomonas aeruginosa, also a significant cause of hospital-acquired infections. To prevent staphylococcal transmission by ultrasound equipment, we recommend disinfection of the probe and removal of the medium after each examination.