| Objective: To investigate the role of arachidonic acid(AA)and its metabolities and bacteria in the pathogenesis of secretory otitis media(SOM),the concentrations of AA and AA metabolities and the level of bacteria were measured in the middle ear effusion(MEE)of SOM from the ordinary patients and the nasopharyngeal carcinoma(NPC)patients after radiotherapy.From the perspective of inflammatory response and bacteriological research,the course and treatments of SOM were studied.Methods: 102 cases of SOM patients with the inclusion criteria were collected.There were 77 ordinary patients and 25 NPC patients after radiotherapy among them.Every patient’s MEE were collected by tympanic membrane puncture therapy.Enzyme-linked immunosorbent assay(ELISA)were used to measure the concentrations of AA and its metabolities in MEE.At the same time,matrix-assisted laser desorption/ionization time-of-flight mass spectrometry(MALDI-TOF MS)was used to identify bacteria and then drug susceptibility test was done.Metabolities of AA such as leukotriene B4(LTB4),leukotriene D4(LTD4),leukotriene E4(LTE4),6-ketoprostaglandin F1α(6-keto-PGF1α)were measured.The results of tests was used to compare the difference in radiation therapy,different course of SOM and positive germiculture of the concentration of AA and its metabolites in MEE by Mann-Whitneytest method of analysis.Results: 1.AA and its metabolites: The detective rate of AA and its metabolites in MEE was 100% by ELISA method.(1)Compared with the ordinary group,the concentrations of AA and its metabolites in MEE from the post-radiotherapy group were generally lower.And the concentration of LTB4 was significantly differrent(p <0.05).(2)Compared with the ordinary group,the course of SOM of fthe post-radiotherapy group were longer.The concentration of LTB4 in MEE between acute and non-acute stages of disease was significantly different(p<0.05).2.Bacterial culture and drug sensitivity:(1)The positive rate of bacterial culture was 15.1%.The positive rate in postradiotherapy group was 21.4%.The ordinary group was 12.8%.The positive rate in post-radiotherapy group was 1.67 times than the ordinary group,but there was no statistical difference.All of the bacteria were Gram-positive bacteria,and the Staphylococcus caused the most infections(40%).There were not only Hemolytic Staphylococcus,oral Streptococcus,hemolytic Streptococcus and other aerobic bacteria but also Propionibacterium acnes,Bacillus pumilus and other anaerobic bacteria.(2)The drug-sensitive experiments in four kinds of staphylococcus aureus : Staphylococcus epidermidis was sensitive to benzyl penicillin and oxacillin,but it was resistant to evofloxacin;while Staphylococcus Petencoccus,Staphylococcus capitis and hemolytic Staphylococcus were all sensitive to quinolones such as levofloxacin,but hemolytic Staphylococcus was resistant to oxacillin;Staphylococcus Petencoccus and hemolytic Staphylococcus were resistant tobenzyl penicillin.(3)There were no significantly different between the positive rates and the concentrations of AA and its metabolites in MEE(p > 0.05).Conclusions: AA and its metabolites may participate in the occurrence of SOM.It is speculated that it is participate in the inflammatory reaction of SOM.LTB4,a metabolite of AA,can be used as a marker to distinguish acute phase and no-acute phase of SOM in clinic.Radiotherapy may reduce the expression of AA and its metabolites in MEE,especially LTB4.Compared with the ordinary group,the positive rate of bacterial culture in the post-radiotherapy group was higher,but there was no statistical differrence.The bacterial culture and drug sensitivity of middle ear effusion are of meaningful to clinical precise treatment of SOM.Targeted use of antibiotics drugs and anti-inflammatory drugs can be used as the treatment for SOM clinically. |
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