| Aquaculture is the crucial economic industry in the coastal regions in Jiangsu Province as there are a quite number of aquaculture ponds. Bacteriosis have been ubiquitous in aquaculture in these regions, and caused great loss. The fishing antibacterial agents are introduced and have performed quite well in precaution and control such bacteria disease. Because of the unscientific usage of the antibacterial agents, antibiotic resistance has emerged after it was applied to aquaculture. It hinders the industry sustainable development, at the same time it poses a threat to the quality and safety of aquatic products and the aquatic ecological environment.To figure out the pathogenic bacteria resistance of aquaculture in the coastal regions in Jiangsu Province, we have isolated 377 strains of original bacteria from the aquatic product in these coastal regions, identified them with morphology, physiology and biochemistry and alignment of 16 S r RNA sequence methods. There are 274 strains out of them, which have been reported pathogenic in aquaculture, including 90 strains of Aeromonas, 54 Vibrio, 22 Pseudoalteromonas, 7 Photobacterium damsela and 14 Acinetobacter. And out of them, there are 46 strains came from Lianyungang region, 89 came from Yancheng region, 116 came from Nantong region. 64 strains are seawater bacteria, the others are plain-water bacteria, and 150 strains came from the fish and the others came from the crustacea.We have adopted K-B paper-spread method and micro-scale broth dilution method to analyze the antibiotic resistance of the above selected strains. The paper-spread method results showed that the pathogenic bacteria which were from Jiangsu coastal regions had high antibiotic resistance to sulfisoxazole, penicillin,doxycycline and tetracycline, the drug resistance rates are 66.06%, 64.23%, 32.12%and 30.66% respectively; and low antibiotic resistance to ciprofloxacin, ofloxacin,enrofloxacin, neomycin, ceftriaxone, erythromycin, norfloxacin and florfenicol, the drug resistance rates are 5.84%, 3.65%, 6.57%, 5.11%, 6.57%, 8.03% and 9.49%respectively. The broth dilution method results showed that the MIC of 79.07% of the pathogenic bacteria to amoxicillin had reached or exceeded to 32 μg/m L, the MIC of96.12% of the pathogenic bacteria to dimethyl sulfate pyrimidine had reached or exceeded 128 μg/m L, which were highly antibiotic resistant. The multi-tier of resistance is very universal, and the rates of 2-tier-resistance, 3-tier-resistance,4-tier-resistance and 5-tier-resistance are 22.3%, 13.5%, 10.9% and 6.6% respectively,even there exists 11-tier-resistance of bacteria. The antibiotic resistance increases from south to north, plain-water strain has higher resistance than the seawater strain,and which from the fish has higher resistance than that of the crustacea.We have amplified the drug resistance gene of the 90 strains of Aeromonas isolated from Jiangsu coastal areas with PCR methods, studied the relevance ratio of the drug resistance gene and analyzed their gene-types of drug resistance in these areas, and preliminarily explored the relationship between the gene-types and corresponding drug-resistant phenotypes. The findings showed that the relevance ratio of gene-types of TEM, IMP, Amp C, OXA-23, OXA-24 in β-lactam drug resistance of the tester strain is 0, 6.67%, 41.11%, 4.44% and 24.44% respectively, and there are 8gene-types for drug resistance, among which 75%of IMP is drug-resistant to penicillin,92.86%of Amp C and OXA-24 is drug resistant, and the rest are 100% drug-resistant.The relevance ratio of gene-types of aph(3’)-Ia, aac(6’)-Ib, ant(3’’)-Ia and ant(3’’)-Ia resistant to aminoglycosides is 28.89%, 67.78%, 32.22% and 8.89% respectively, and there are 11 gene-types for drug resistance. All stains are sensitive to penicillin. It suggests that the resistance to mediate aminoglycosides may concurrently result from multiple genes.The carrying rate of sul1,sul2 and sul3, the genes of drug resistance to sulfonamides, are 34.44%, 28.89%and45.56% and there are 7 gene-types, namely sul1,sul2, sul3, sul1/sul2, sul1/sul3, sul2/sul3, sul1/sul2/sul3. And their resistance to sulfisoxazole is 90%, 60%, 48%, 90%, 77.78%, 75% and 100% respectively. And drug resistance of the genes tet A, tet C and tet M to tetracyclines is 32.22%, 34.44%and 60% repectively, with 7 gene-types. Though the relevance ratio of the flo R gene which is resistant to florfenicol is 76.67%, it does not show resistance to florfenicol with flo R gene. Therefore we inferred that the flo R gene had low drug resistance to florfenicol. The genes resistant to quinolones are qnr A, qnr B, qnr B-24, qnr S and qep A, with relevance ratio of 3.33%, 52.22%, 46.67%, 26.67% and53.33% and 14gene-types of quinolones resistance. But we have not figured out the relation between the drug-resistant phenotype and their gene-types and it suggests that the quinolones resistance may be related to other genes.In conclusion,aquaculture conditions caused by bacteria to antibacterial agents produced different degrees of resistance in coastal area of Jiangsu Province,especially resistant to penicillin,sulfa isoxazole,doxycycline and tetracycline is very serious,drug resistance in freshwater fish species performance is particularly prominent.It is suggested that the area should use in the process of preventing and treating aquatic bacterial diseases and preventing the unreasonable application of drugs.There are more drug-resistant genes and gene-types of Aeromonas in the coastal areas in Jiangsu,and their corresponding drug-resistant phenotype is complicated,and the mediate drug-resistance is concurrently caused by multiple genes.It is recommended to apply neomycin sulfate powder,quinolones antibacterial agents and florfenicol powder to bacterial disease in aquaculture the coastal regions in Jiangsu Province. |
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