Otitis externa (OE) is a frequently reported disorder in dogs associated with secondary infections by Staphylococcus, Pseudomonas and yeast pathogens. The presence of biofilms may play an important role in the resistance of otic pathogens to antimicrobial agents. Biofilm production of twenty Staphylococcus pseudintermedius and twenty Pseudomonas aeruginosa canine otic isolates was determined quantitatively using a microtiter plate assay, and each isolate was classified as a strong, moderate, weak or nonbiofilm producer. Minimum biofilm eradication concentration (MBEC) of two ionophores (narasin and monensin) and three adjuvants (N-acetylcysteine (NAC), Tris-EDTA and disodium EDTA) were investigated spectrophotometrically (OD570nm ) and quantitatively (CFU/ml) against selected Staphylococcus and Pseudomonas biofilm cultures. Concurrently, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of planktonic cultures were assessed. 16/20 of the S. pseudintermedius clinical isolates were weak biofilm producers. 19/20 P. aeruginosa clinical isolates produced biofilms and were distributed almost equally as weak, moderate and strong biofilm producers. While significant antibiofilm activity was observed, no MBEC was achieved with narasin or monensin. The MBEC for NAC ranged from 5,000-10,000 µg/ml and from 20,000-80,000 µg/ml against S. pseudintermedius and P. aeruginosa, respectively. Tris-EDTA eradicated P. aeruginosa biofilms at concentrations ranging from 6,000/1,900 to 12,000/3,800 µg/ml. The MBEC was up to 16-fold and eightfold higher than the MIC/MBC of NAC and Tris-EDTA, respectively. Disodium EDTA reduced biofilm growth of both strains at concentrations of 470 µg/ml and higher. It can be concluded that biofilm production is common in pathogens associated with canine OE. NAC and Tris-EDTA are effective antibiofilm agents in vitro that could be considered for the treatment of biofilm-associated OE in dogs.

中文翻译：

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与犬中耳炎有关的病原体产生生物膜，以及离子载体和抗菌助剂的抗生物膜活性。

外耳炎（OE）是犬中经常报告的疾病，与葡萄球菌，假单胞菌和酵母菌病原体继发感染有关。生物膜的存在可能在耳部病原体对抗菌剂的耐药性中起重要作用。使用微量滴定板测定法定量测定了二十个假单胞菌葡萄球菌和铜绿假单胞菌犬耳分离株的生物膜产量，每个分离株被分类为强，中，弱或非生物膜生产者。用分光光度法（OD570nm）和定量（CFU / ml）对选定的葡萄球菌和双歧杆菌分别测定了两个离子载体（柚皮苷和莫能菌素）和三种佐剂（N-乙酰半胱氨酸（NAC），Tris-EDTA和二钠EDTA）的最小生物膜清除浓度（MBEC）。假单胞菌生物膜培养。同时，评估了浮游培养的最小抑菌浓度（MIC）和最小杀菌浓度（MBC）。假单胞菌临床分离株的16/20是弱的生物膜生产者。19/20铜绿假单胞菌临床分离株产生生物膜，并且几乎与弱，中和强生物膜生产者一样分布。虽然观察到了显着的抗生物膜活性，但用萘乐菌素或莫能菌素未达到MBEC。NAC的MBEC相对于假单胞菌和铜绿假单胞菌的范围分别为5,000-10,000 µg / ml和20,000-80,000 µg / ml。Tris-EDTA消除了铜绿假单胞菌生物膜的浓度范围为6,000 / 1,900至12,000 / 3,800 µg / ml。MBEC分别比NAC和Tris-EDTA的MIC / MBC高出16倍和8倍。EDTA二钠在470 µg / ml或更高的浓度下会降低两种菌株的生物膜生长。可以得出结论，与犬OE相关的病原体中生物膜的产生是常见的。NAC和Tris-EDTA是体外有效的抗生物膜剂，可以考虑用于治疗犬中与生物膜相关的OE。