Effect Of Low-frequency Ultrasound In Combination With Antibiotics On Penetration Of Staphylococcus Epidermidis Biofilm

Objective To study the effect of low-frequency ultrasound combinedwith antibiotics on penetration of S．epidermidis RP62A strain biofilm(BF)．Methods Mature biofilm model of48h of S．epidermidis RP62Astrain was established in vitro，the BF structures were confirmed andobserved by scanning electron microscope(SEM); Viable counts weredetermined by drop plating after suspending the biofilm cells; Thepenetration of antibiotics （gentamicin; cefotaxime; vancomycin;levofloxacin）through the biofilms or not was established, after1h、3h withultrasonication interventions, the diameter of zones of growth inhibitionwere measured.Results The model of S．epidermidis biofilm in vitro culture andpenetration of antibiotics was established successfully. The average numberof bacteria per membrane was （3.33±0.11）×108cfu. Presence of biofilmreduced the transport of any antibiotics. The penetration of gentamicin (aminoglycoside antibiotics), cefotaxime (β-lactam antibiotics) andvancomycin (glycopeptide antibiotic) were significantly decreased throughthe biofilms (P<0.05) whereas that of ciprofloxacin (a fluoroquinolone)was unaffected. Most importantly, Low-frequency ultrasonic significantlyincreased the transport of gentamicin and cefotaxime through the biofilm.Cefotaxime combined with low-frequency ultrasound(1h,3h) andGentamicin combined with low-frequency ultrasound(3h) showedsignificant difference in comparison with the CB control group (P<0.05);Vancomycin was also moderately increased with time of ultrasound to3h.Conclusions Low-frequency ultrasonic can enhance the penetrationof antibiotics through the S．epidermidis biofilm in varying degrees.