Study On The Effect Of Pulsed Electromagnetic Field On Staphylococcus Aureus Osteomyelitis

Background:Osteomyelitis(OM)has always been a thorny issue in orthopedic clinical treatment,and there are still many controversies about the diagnosis and treatment of this disease.Studies have shown that many different forms of microwaves have significant sterilization effects,but there is no report on pulsed electromagnetic fields.In this study,we hypothesized that Pulsed Electromagnetic Field(PEMF),which can be used to treat nonunion,also has bactericidal effects,and this was verified by in vitro and animal experiments.Methods:Vitro experiment:(1)The effect of PEMF of different durations on the growth of Staphylococcus aureus(ATCC29213):A certain amount of Staphylococcus aureus was inoculated into common nutrient broth,divided into control group and PEMF intervention group(field strength)It is 1Gs,frequency 15Hz,pulse width 5μs,pulse group width 5ms,and pulse group refractory period 62ms).Both groups are cultured in a 37℃ incubator,sampled every 2 hours and then diluted and inoculated on a Columbia blood plate,37 Incubate in an incubator at℃ and count after 24 hours.(2)The combined effect of PEM F and antibiotics on Staphylococcus aureus:The experiment is divided into control group,PEMF group,antibiotic group,PEMF+antibiotic group;the four groups are cultured in a 37℃ incubator,and sampling is diluted and inoculated after 8 hours.To the Columbia blood plate,incubate in a 37℃ incubator,and count 24 hours later.Animal experiment:1×106 CFU(Colony-Forming Units)Staphylococcus aureus suspension was injected into the right tibia marrow cavity of 40 mice to make an acute osteomyelitis model.After successful modeling,the rats were randomly divided into four groups and given corresponding treatment:group 1:control group(normal saline treatment);group 2:PEMF group(normal saline+PEMF treatment);group 3:antibiotic group(cefurfur Xin treatment);Group 4:Antibiotic+PEMF group(cefuroxime+PEMF treatment).Rats in groups 2 and 4 received PEMF irradiation for 8 hours a day.All mice were sacrificed on the 7th day after surgery,and the degree of infection of tibial osteomyelitis was evaluated by bacterial quantitative analysis.Results:Vitro experiment:(1)There was no significant difference between the two groups at 2h and 4h(P>0.05);the bacterial count in the PEMF group at 6h was 23%of the control group(P<0.01),and the bacterial count at the PEMF group at 8h 28%of the control group(P<0.01);(2)The colony counts of the PEMF group,antibiotic group,and PEMF+antibiotic group were 32%,34%,and 10%of the control group,respectively,which were significantly less than the control group;The colony count of PEMF+antibiotic group was significantly less than that of PEMF group and antibiotic group alone.Animal experiment:There was no significant difference between control group and PEMF group,antibiotic group and PEMF+antibiotic group.Conclusion:The results showed that PEMF could significantly inhibit Staphylococcus aureus in logarithmic phase in vitro,and had synergistic bacteriostatic effect with antibiotics.However,in mice,we found that PEMF did not seem to have bacteriostatic or synergistic bacteriostatic effect,but did not promote bacterial proliferation,so we also indirectly demonstrated that when PEMF was used to treat infectious bone defects,PEMF would not aggravate infection.Of course,the conclusions of in vivo experiments may be affected by the frequency and intensity of PEMF we can produce.