Combination of therapeutic ultrasound with antibiotics interfere with the growth of bacterial culture that colonizes skin ulcers: An in-vitro study

• Published in: Ultrasonics sonochemistry 2016-09, Vol.32, p.284-289
• Main Authors: Guirro, Elaine Caldeira de Oliveira, Angelis, Dejanira de Franceschi de, Sousa, Natanael Teixeira Alves de, Guirro, Rinaldo Roberto de Jesus
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - therapeutic use; Bacteria; Escherichia coli; Microbial Sensitivity Tests; Physical therapy; Skin Ulcer - mortality; Skin Ulcer - therapy; Staphylococcus aureus; Ultrasonic Therapy
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2016.03.024

•S. aureus and E. coli are among the major bacterial species which colonize skin ulcers.•The action of phonophoresis in bacteria that colonize ulcers is not well grounded.•Phonophoresis was performed by adding nalidixic acid (S. aureus) and tetracycline (E. coli).•Phonophoresis was able to inhibit completely the growth of both bacteria.•The action of ultrasound on S. aureus and E. coli is dependent on frequency and intensity. Staphylococcus aureus and Escherichia coli are among the major bacterial species that colonize skin ulcers. Therapeutic ultrasound (TUS) produces biophysical effects that are relevant to wound healing; however, its application over a contaminated injury is not evidence-based. The objective of this research was to analyze the effect of TUS on in vitro-isolated S. aureus and E. coli, including the combination of ultrasound and antibiotics, in order to assess their antibiotic action on bacterial susceptibility. For the experiments, the bacterial strains were suspended in saline, then diluted (104CFU/mL) for irradiation (at 1 and 3MHz, 0.5 and 0.8W/cm2 for 0 and 15min) and the combination treatment of ultrasonication and antibiotics was administered by adding nalidixic acid (S. aureus) and tetracycline (E. coli) at concentrations equivalent to 50% of the minimum inhibitory concentration (MIC). The experiments were carried out in duplicate with six repetitions. The suspensions were inoculated on to Petri plates and incubated at 37°C and the colony forming units (CFUs) were counted after 24h. The results were subjected to the Shapiro–Wilk normality test, followed by parametric ANOVA and Tukey’s post hoc test at a significance level of 1%. The results demonstrated that the action of TUS at 1MHz inhibited bacterial growth while at 3MHz, bacterial growth was observed in both species. However, the synergistic combination of ultrasound and antibiotics was able to inhibit the growth of both bacteria completely after 15min of ultrasonication. The results suggest that the action of ultrasound on S. aureus and E. coli are dependent on the oscillation frequency as well as the intensity and time of application. The combination of ultrasound with antibiotics was able to inhibit bacterial growth fully at all frequencies and doses in both species.