Characterization of antibiotic resistance in commensal bacteria from an aquaculture ecosystem

Abstract

The objective of the study was to improve the understanding of antibiotic resistance (AR) ecology through characterization of antibiotic-resistant commensal isolates associated with an aquaculture production system. A total of 4767 isolates non-susceptible to sulfamethoxazole/trimethoprim (Sul/Tri), tetracycline (Tet), erythromycin (Erm), or cefotaxime (Ctx), originated from fish, feed, and environmental samples of an aquaculture farm with no known history of antibiotic applications were examined. Close to 80% of the isolates exhibited multi-drug resistance in media containing the corresponding antibiotics, and representative AR genes were detected in various isolates by PCR, with feed isolates had the highest positive rate detected. Identified AR gene carriers involved 18 bacterial genera. Selected AR genes led to acquired resistance in other bacteria by transformation. The AR traits in many isolates were stable in the absence of selective pressure. AR-rich feed and possibly environmental factors may contribute to AR in the aquaculture ecosystem. For minimum inhibitory concentration test, brain heart infusion medium was found more suitable for majority of the bacteria examined than cation-adjusted Mueller Hinton broth, with latter being the recommended medium for clinical isolates by standard protocol. The data indicated a need to update the methodology due to genetic diversity of microbiota for better understanding of the AR ecology.

Evidence of Increased Antibiotic Resistance in Phylogenetically-Diverse Aeromonas Isolates from Semi-Intensive Fish Ponds Treated with Antibiotics

“…It may be suggested that additional factors beyond antibiotic concentrations such as fish density, temperature, and cyanobacterial blooms (prevalent in the July and August profiles of this study) also impact antibiotic resistance in the sampled Aeromonas strains. This is supported by a recent study that showed high levels of antibiotic resistance in bacterial isolates from aquaculture facilities that did not use antibiotics (Huang et al, 2015). …”

Pharmacokinetics, efficacy prediction indexes, and residue depletion of ribavirin in Atlantic salmon's (Salmo salar) muscle after oral administration in feed

“…Some authors have demonstrated that the antiviral resistance can occur by a selection pressure that leads to therapeutic failures after repeated administrations (Eltahla et al, 2015;Hayashi et al, 2015). Considering this information, it is necessary to think in the possible negative effects that could happen when administering ribavirin in the food and some residues remains in the pools or in the sea, being this a potential causative of the appearance of antiviral resistance to ribavirin in salmon and other aquatic species, such us nowadays is happening with the antibacterial resistance (Huang et al, 2015).…”

Biological HRPs in wastewater

“…The use of antibiotics in aquaculture system and livestock breeding could increase the potential risk of antibiotic resistance in products and ecosystems (He et al, 2016;Huang et al, 2015). Increasing studies have shown that aquaculture and animal farms are important sources of ARB and ARGs in the water environment, where ARB and ARGs are abundant and may infect humans through the food chain Jia et al, 2017).…”

“…Furthermore, strains of Escherichia coli were isolated in pigs and poultry in China which had high rates of resistance to ampicillin, tetracycline, doxycycline, trimethoprime sulfamethoxazole, amoxicillin, streptomycin, and chloramphenicol (Jiang et al, 2011). Notably, antibiotic resistance was observed in aquaculture and livestock breeding system as well as clinically isolated strains, indicating that potential antibiotic resistance could be transmitted between food and humans (Brooks et al, 2014;Huang et al, 2015). Xiong et al (2015) found a total of 15 ARG subtypes (sulI, sulII, sulIII, tet(M), tet(O), tet(W), tet(S), tet(Q), tet(X), tet(B/P), qepA, oqxA, oqxB, aac(6 0 )-Ib, and qnrS) within four ARG types (sulfonamide, tetracycline, aminoglycoside, and quinolone) in fresh water aquaculture environment and the relative abundance was up to 2.8 Â 10 À2 (ARG copy/16S rRNA copy).…”