Abstract:[Objective] To analyze the antibiotic-resistant bacteria and antimicrobial-resistant genes in Penaeus monodon (African).[Methods]We collected P.monodon from Beihai New Area,Binzhou,Shandong,and then tested the number,proportion,and species of antibiotic-resistant bacteria in the intestine.Meanwhile,we analyzed the distribution of genes related to the resistance to four antibiotics by quantitative reverse transcription PCR (qRT-PCR).[Results] The total number of culturable bacteria in the intestine was about 1.45x105-2.13x106 CFU/g,and bacteria resistant to tetracycline,nalidixic acid,florfenicol,and gentamicin were all detected,among nalidixic acid-resistant bacteria (35.00%) and gentamicin-resistant bacteria took up the largest and smallest proportion,respectively.The sensitivity to 10 antibiotics was analyzed and the result showed that the intestinal bacteria were highly susceptible to six antibiotics such as gentamicin and florfenicol,moderately susceptible to tetracycline and kanamycin and resistant to nalidixic acid,penicillin,and amoxicillin.The culturable antibiotic-resistant bacteria mainly belonged to Vibrio,and the species of bacteria resistant to different antibiotics varied.Moreover,species of the same genus may be resistant to multiple antibiotics.The abundance of genes related to the resistance of the four antibiotics was different.Significant correlation between the relative copy number of tetA gene and the proportion of tetracycline-resistant bacteria and between the relative copy number of floR gene and the proportion of florfenicol-resistant bacteria was detected (P<0.01),but no significant correlation was observed between the relative copy number of qnrA gene and the proportion of nalidixic acid-resistant bacteria,and between the relative copy number of aadA gene and the proportion of gentamicin-resistant bacteria (P>0.01).[Conclusion] The intestine of P.monodon (African) harbors antibiotic-resistant bacteria and antimicrobial-resistance genes.
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