Molecular determination of oxytetracycline-resistant bacteria and their resistance genes from mariculture environments of China

Abstract

Aims: To assess the diversity of antibiotic‐resistant bacteria and their resistance genes in typical maricultural environments. Methods and Results: Multidrug‐resistant bacteria and resistance genes from a mariculture farm of China were analysed via cultivation and polymerase chain reaction (PCR) methods. Oxytetracycline (OTC)‐resistant bacteria were abundant in both abalone and turbot rearing waters, accounting for 3·7% and 9·9% of the culturable microbes. Multidrug resistance was common, with simultaneous resistance to OTC, chloramphenicol and ampicillin the most common resistance phenotype. 16S rDNA sequence analyses indicate that the typical resistant isolates belonged to marine Vibrio, Pseudoalteromonas or Alteromonas species, with resistance most common in Vibrio splendidus isolates. For OTC resistance, tet(A), tet(B) and tet(M) genes were detected in some multidrug‐resistant isolates, with tet(D) being the most common molecular determinant. For chloramphenicol resistance, cat II was common, and floR was also detected, especially in marine Pseudoalteromonas strains. Conclusions: There is the risk of multidrug‐resistant bacteria contamination in mariculture environments and marine Vibrio and Pseudoalteromonas species serve as reservoirs of specific antibiotic resistance determinants. Significance and Impact of the Study: This paper and similar findings from Korea and Japan indicate the potential for widespread distribution of antibiotic resistance genes in mariculture environments from the East Asian region of the world.