Atypical Aeromonas salmonicida causes furunculosis infections of non‐salmonid fish, which requires antibiotic therapy. However, antibiotics may induce biofilm in some bacteria, which protects them against hostile conditions while allowing them to persist on surfaces, thus forming a reservoir for infection. The aim of this study was to determine whether atypical isolates of A. salmonicida increased biofilm in the presence of two antibiotics, florfenicol and oxytetracycline. A microtitre plate assay was used to quantify biofilm in the presence and absence of each antibiotic. Fifteen of 28 isolates formed biofilms under control conditions, while 23 of 28 isolates increased biofilm formation in the presence of at least one concentration of at least one antibiotic. For oxytetracycline, the most effective concentration causing biofilm to increase was one‐quarter of that preventing visible bacterial growth, whereas for florfenicol it was one‐half of this value. This is the first study to demonstrate that a bacterial pathogen of fish increases biofilm in response to antibiotics. Biofilm formation may increase the risk of re‐infection in culture systems and this lifestyle favours the transmission of genetic material, which has implications for the dissemination of antibiotic‐resistance genes and demonstrates the need for enhanced disease prevention measures against atypical A. salmonicida.

中文翻译：

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抗生素调节非典型鲑鱼气单胞菌病原菌中生物膜的形成。

不典型的鲑鱼气单胞菌引起非鲑鱼的呋喃菌感染，需要抗生素治疗。但是，抗生素可能会在某些细菌中诱导生物膜，从而保护它们免受敌对条件的侵害，同时使它们在表面上持久存在，从而形成了用于感染的蓄水池。本研究的目的是确定鲑鱼曲霉是否非典型分离株在两种抗生素，氟苯尼考和土霉素的存在下，生物膜增加。使用微量滴定板测定法定量存在和不存在每种抗生素的生物膜。28个分离物中的15个在控制条件下形成了生物膜，而28个分离物中的23个在至少一种浓度的至少一种抗生素存在下增加了生物膜的形成。对于土霉素，引起生物膜增加的最有效浓度是防止可见细菌生长的浓度的四分之一，而对于氟苯尼考，则是该值的一半。这是第一项证明鱼类细菌病原体会增加对抗生素的反应的生物膜的研究。生物膜的形成可能会增加培养系统中再次感染的风险，这种生活方式有利于遗传物质的传播，沙门氏菌。