摘要

在越南，密集的养虾场严重依赖各种抗生素（ABs）来治疗动物或预防疾病爆发。多重抗性细菌出现的可能性很高，伴随着用于灌溉和饮用水的相邻天然水生栖息地的污染，从而削弱了人类健康系统。在本研究中，AB多重抗性细菌的定量在来自虾养殖区和Vam Co河（越南隆安省）的污水渠道的水和沉积物样品中进行。细菌菌株，例如分离出显示多重抗性性状的肺炎克雷伯氏菌和嗜水气单胞菌。分子生物学分析显示这些菌株具有4-7种不同的AB抗性基因（ARG）（例如sul1，sul2，qnrA，ermB，tetA，aac（6）1b，dfrA1，dfr12，dfrA5），赋予多药耐药性。对这些多抗性菌株中存在的质粒的测序导致鉴定总共41个抗性基因，靶向9个AB组。对sul2基因的qPCR分析显示，在连接到Vam Co河的污水通道中存在高拷贝数。本研究的结果清楚地表明，密集虾类养殖中存在的多重抗性细菌可能在自然环境中传播。本研究首次深入了解了质粒出生的ARGs以及由于南越抗生素利用不当而可能出现的相关致病菌的影响。

In Vietnam, intensive shrimp farms heavily rely on a wide variety of antibiotics (ABs) to treat animals or prevent disease outbreak. Potential for the emergence of multi-resistant bacteria is high, with the concomitant contamination of adjacent natural aquatic habitats used for irrigation and drinking water, impairing in turn human health system. In the present study, quantification of AB multi-resistant bacteria was carried out in water and sediment samples from effluent channels connecting a shrimp farming area to the Vam Co River (Long An Province, Vietnam). Bacterial strains, e.g. Klebsiella pneumoniae and Aeromonas hydrophila, showing multi-resistance traits were isolated. Molecular biology analysis showed that these strains possessed from four to seven different AB resistance genes (ARGs) (e.g. sul1, sul2, qnrA, ermB, tetA, aac(6)lb, dfrA1, dfr12, dfrA5), conferring multidrug resistance capacity. Sequencing of plasmids present within these multi-resistant strains led to the identification of a total of forty-one resistance genes, targeting nine AB groups. qPCR analysis on the sul2 gene revealed the presence of high copy numbers in the effluent channel connecting to the Vam Co River. The results of the present study clearly indicated that multi-resistant bacteria present in intensive shrimp cultures may disseminate in the natural environment. This study offered a first insight in the impact of plasmid-born ARGs and the related pathogenic bacteria that could emerged due to inappropriate antibiotic utilization in South Vietnam.

https://www.sciencedirect.com/science/article/pii/S0301479718302068