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Antibiotic Resistance in Aquaculture Production
Başlık:
Antibiotic Resistance in Aquaculture Production
Yazar:
Huang, Ying, author.
ISBN:
9780438091023
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (128 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Hua Wang Committee members: John Litchfield; Gireesh Rajashekara; Zhongtang Yu.
Özet:
The rapid emergence of antibiotic resistance (AR) has become a major public health concern. Recent findings provided solid evidences suggesting that multiple risk factors contributed to AR development, enrichment, dissemination and persistence, and a comprehensive understanding of AR ecology is essential for targeted mitigation. Following the investigation of AR in aquaculture products from China, a study on AR in fish and aquaculture production-related samples from a U.S. fish farm with controlled practices and no history of antibiotic applications was further conducted to better understand the potential impact of aquaculture production practice on the prevalence of antibiotic resistant (ART) bacteria in the aquaculture ecosystem.
Phenotypic resistant populations against sulfamethoxazole with trimethoprim (Sul/Tri), tetracycline (Tet), erythromycin (Erm) or cefotaxime (Ctx) were screened by conventional plating with the corresponding antibiotics, followed by population assessments with denaturing gradient gel electrophoresis (DGGE) and 16S rDNA next generation sequencing (NGS). Despite the absence of antibiotic application in the farm, our results showed that antibiotic resistant (ART) bacteria were abundant in all samples examined, including fish intestine, surface rinsing water, feed, pond water and mud samples. By NGS, a total of 569 genera were identified in Tetr and Ctx r bacteria from five types of samples. Certain correlations of ART bacteria between different types of samples were observed. Various AR genes measured by quantitative PCR (qPCR) were significantly more abundant in fish intestine and feed than farm environmental samples. Certain dominant ART bacteria subpopulations in feed and pond water were also identified in fish intestine.
About 79% of 4747 ART isolates from aquaculture samples showed resistance to more than one antibiotic. Some ART isolates showed MIC of Sul/Tri, Tet, Erm or Ctx no less than 512 microg/ml. Various AR genes were detected in ART isolates including sul1, sul2, tetS, tetL, tetM, ermB or ermC. Identified AR gene carriers belong to 18 genera. In addition, the AR traits in many isolates were quite stable, even in the absence of selective pressure.
A fosmid genomic library generated from a pooled DNA of 6 ART isolates was used to screen for new AR genes against tetracycline. Tetr clones were further subjected to subcloning using pBluescript vector, followed by DNA sequence analysis. A 4.7-kb fragment from a Tetr subclone T61 contained two divergently transcribed open reading frames (ORFs). The larger ORF encoded a 398-amino-acid protein with 88% identity to a major facilitator superfamily (MFS) transporter and 87% identity to class D tetracycline/H+ antiporter. The smaller ORF encoded a 199-amino-acid protein with 86% identity to TetR family transcriptional regulator. Deletion mutagenesis confirmed the involvement of the two ORFs in Tetr. The original host of the new tetD variant, designated tetD(Y), was identified as Providencia sp.
Our results suggested that additional risk factor(s), rather than direct exposure to antibiotics, are responsible for AR in aquaculture production. Results would contribute to an improved understanding of AR ecology in the aquaculture production system.
Notlar:
School code: 0168
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(686979.1) | 686979-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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