Study On Antibiotic Resistant Bacteria In Mariculturing Water And Their Resistant Genes

Since many misuses (e.g. the intensive and multi-drug use of antibiotics) occurred, more mutations have been selected in bacterial pathogens of mariculturing water under a high antibiotic pressure, leading to a seriously antibiotic resistance. At the same time, more multi-drug resistant bacteria have appeared as a result. This phenomenon has caused even higher level of difficulty and failure in aquacultural disease control and treatment. Based on the isolation of multiple resistant bacteria from sea cucumber, sea urchin, abalone and turbot mariculturing water in Dalian, tetracycline resistant genes and chloramphenicol resistant genes as well as florfenicol resistant genes were detected using molecular methods in this study. Based on 16S rRNA gene sequences analysis and construction of phylogenetic tree, these multidrug-resistant bacteria were assinged mostly to genus Vibrio, and a few of them to Pseudoalteromonas and Alteromonas. The most common species in genus Vibrio were V. tasmaniensis and V. splendidus. Through multiplex PCR, the tet gene was detected. Totally, five types of tet gene were detected in these 80 multidrug-resistant strains. the dominant resistant gene types were tet(B), tet(D) and tet(M), accounting for 33.8%, 42.5% and 41.3% of the total respectively. Both cat II and cat IV types were detected in these 80 multidrug-resistant strains, accounting for 37.5% and 18.8% of the total respectively. There were 36 floR harboring multidrug-resistant strains, accounting for 45.0% of the total. Most of the antibiotic-resistant bacteria carried resistant genes, indicating that the antibiotic resistance of them was mainly defined by the resistant genes.