Due to the inappropriate use of florfenicol in agricultural practice, florfenicol resistance has become increasingly serious. In this work, we studied the novel florfenicol resistance mechanism of an animal-derived Leclercia adecarboxylata strain R25 with high-level florfenicol resistance. A random genomic DNA library was constructed to screen the novel florfenicol resistance gene. Gene cloning, gene knockout, and complementation combined with the minimum inhibitory concentration (MIC) detection were conducted to determine the function of the resistance-related gene. Sequencing and bioinformatics methods were applied to analyze the structure of the resistance gene-related sequences. Finally, we obtained a regulatory gene of an RND (resistance-nodulation-cell division) system, ramA, that confers resistance to florfenicol and other antibiotics. The ramA-deleted variant (LA-R25ΔramA) decreased the level of resistance against florfenicol and several other antibiotics, while a ramA-complemented strain (pUCP24-prom-ramA/LA-R25ΔramA) restored the drug resistance. The whole-genome sequencing revealed that there were five RND efflux pump genes (mdtABC, acrAB, acrD, acrEF, and acrAB-like) encoded over the chromosome, and ramA located upstream of the acrAB-like genes. The results of this work suggest that ramA confers resistance to florfenicol and other structurally unrelated antibiotics, presumably by regulating the RND efflux pump genes in L. adecarboxylata R25.

• MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• Enterobacteriaceae účinky léků   genetika   metabolismus   MeSH
• Escherichia coli genetika   MeSH
• genový knockout MeSH
• klonování DNA MeSH
• mikrobiální testy citlivosti MeSH
• mnohočetná bakteriální léková rezistence účinky léků   genetika   MeSH
• RNA ribozomální 16S MeSH
• sekvenování celého genomu MeSH
• thiamfenikol analogy a deriváty   MeSH
• trans-aktivátory genetika   MeSH
• výpočetní biologie MeSH
• Publikační typ
• časopisecké články MeSH

Limited data regarding the susceptibility of Actinobacillus pleuropneumoniae to antimicrobials has been published during recent years. Accordingly, the aim of the present study was to investigate the distribution of MICs for the isolates of A. pleuropneumoniae from diseased pigs in the Czech Republic between 2007 and 2009. A total of 242 isolates were tested for susceptibility to 16 antimicrobial agents by a broth microdilution method. A low degree of resistance was observed for florfenicol (0.8%), amoxicillin and clavulanic acid (0.8%), tilmicosin (1.2%), tiamulin (1.7%) and ampicillin (3.3%), whereas resistance to tetracycline was detected more frequently, 23.9% of isolates. Interestingly, resistance to florfenicol has not yet been reported in any study investigating antimicrobial resistance of A. pleuropneumoniae. By PCR the presence of the floR gene was confirmed in all florfenicol resistant isolates.

• MeSH
• Actinobacillus pleuropneumoniae účinky léků   izolace a purifikace   MeSH
• amoxicilin farmakologie   MeSH
• ampicilin farmakologie   MeSH
• antibakteriální látky farmakologie   MeSH
• bakteriální geny MeSH
• diterpeny farmakologie   MeSH
• kyselina klavulanová farmakologie   MeSH
• mikrobiální testy citlivosti MeSH
• nemoci prasat epidemiologie   mikrobiologie   MeSH
• prasata mikrobiologie   MeSH
• tetracyklin farmakologie   MeSH
• thiamfenikol analogy a deriváty   farmakologie   MeSH
• tylosin analogy a deriváty   farmakologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Geografické názvy
• Česká republika MeSH