novel approach to antimicrobial drug resistance
				ultrasound applied directly to the body for epidermal, mucosal infections and biofilms
		Martin L. Lenhardt, Au.D., Ph.D. Professor of Biomedical Engineering

		ultrasonic antibiotic
		Tested on Staphylococcus Epidermidis Low level low frequency ultrasound Antibiotic effect not due to: heating or cavitation Safe levels for topical treatment of skin and mucosal infections of the head, neck and trunk.

		Staphylococcus Epidermidis
		primary hospital-acquired infection mortality rate of 10-37%, result in increased hospital stay of 7 - 19 days, and costs an estimated $6,000 per case. antibiotic resistance rising as is morbidity and mortality can only be treated with vancomycin no vaccine over 75% infections associated with implanted biomaterial or intravascular catheters. colonizes skin and mucosal surfaces spreads to blood in breaks in mucosal membranes and skin

					culture
		apply ultrasound

		Method: broth of staphylococcus epidermidis diluted 1: 107                    placed on trypticase soy agar                    vibrator attached to lower surface of glass plate with gel                    incubated for 24 hours at 350C

			Cross section of human legs with two unit array
				Treat deep infections, reduce even resistant strains
					Targeted tissue is in center of the beam

		Antimicrobial ultrasonic array
				applications over the entire body

			Effects of very low power ultrasound for 24 hrs on Staphylococcus growth
			Staph reduction after ultrasonification
		Staphylococcus epidermidis is reduced an average of 29% with application of low power ultrasound. Frequency range of 34-50 kHz is effective. Effect not due to thermal or cavitation prosperities of ultrasound Suitable for skin application

			Preliminary Results
		control (no sound)                            ~ 30 % reduction with ultrasound
		S. Epidermidis spherical in shape with diameters of 0.5-1.5 mm Cell death likely from cell wall resonance to rupture or displacement Effective in less controlled (temperature) study with Escherichia coli

			mechanism of operation
		Bacterium growth retardation not due to:                 heat or                 cavitation Bacterium could resonate and oscillation could disrupt cell membranes. Bacterium could oscillate which in turn could disrupt normal metabolic function Both mechanisms are possible

		wearable antimicrobial ultrasound
	DSP swept tone piezo amplifier

			Hand application
		No sensation or vibration; safe even on the skin of the head or neck.

Page Content and Design : Dr Martin L. Lenhardt WebMaster: Alan G. Madsen Last update: Sunday, January 27, 2002