Dataset Information

Minor environmental concentrations of antibiotics can modify bacterial virulence in co-infection with a non-targeted parasite.

ABSTRACT: Leakage of medical residues into the environment can significantly impact natural communities. For example, antibiotic contamination from agriculture and aquaculture can directly influence targeted pathogens, but also other non-targeted taxa of commensals and parasites that regularly co-occur and co-infect the same host. Consequently, antibiotics could significantly alter interspecific interactions and epidemiology of the co-infecting parasite community. We studied how minor environmental concentrations of antibiotic affects the co-infection of two parasites, the bacterium Flavobacterium columnare and the fluke Diplostomum pseudospathaceum, in their fish host. We found that antibiotic in feed, and particularly the minute concentration in water, significantly decreased bacterial virulence and changed the infection success of the flukes. These effects depended on the level of antibiotic resistance of the bacterial strains. Antibiotic, however, did not compensate for the higher virulence of co-infections. Our results demonstrate that even very low environmental concentrations of antibiotic can influence ecology and epidemiology of diseases in co-infection with non-targeted parasites. Leakage of antibiotics into the environment may thus have more complex effects on disease ecology than previously anticipated.

SUBMITTER: Sundberg LR

PROVIDER: S-EPMC6303518 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Minor environmental concentrations of antibiotics can modify bacterial virulence in co-infection with a non-targeted parasite.

Sundberg Lotta-Riina LR Karvonen Anssi A

Biology letters 20181201 12

Leakage of medical residues into the environment can significantly impact natural communities. For example, antibiotic contamination from agriculture and aquaculture can directly influence targeted pathogens, but also other non-targeted taxa of commensals and parasites that regularly co-occur and co-infect the same host. Consequently, antibiotics could significantly alter interspecific interactions and epidemiology of the co-infecting parasite community. We studied how minor environmental concen ...[more]

PMID: 30958249

Similar Datasets

Project description:The nucleoid-associated proteins Hha and YdgT repress the expression of the toxin ?-hemolysin. An Escherichia coli mutant lacking these proteins overexpresses the toxin ?-hemolysin encoded in the multicopy recombinant plasmid pANN202-312R. Unexpectedly, we could observe that this mutant generated clones that no further produced hemolysin (Hly(-)). Generation of Hly(-) clones was dependent upon the presence in the culture medium of the antibiotic kanamycin (km), a marker of the hha allele (hha::Tn5). Detailed analysis of different Hly(-) clones evidenced that recombination between partial IS91 sequences that flank the hly operon had occurred. A fluctuation test evidenced that the presence of km in the culture medium was underlying the generation of these clones. A decrease of the km concentration from 25 mg/l to 12.5 mg/l abolished the appearance of Hly(-) derivatives. We considered as a working hypothesis that, when producing high levels of the toxin (combination of the hha ydgT mutations with the presence of the multicopy hemolytic plasmid pANN202-312R), the concentration of km of 25 mg/l resulted subinhibitory and stimulated the recombination between adjacent IS91 flanking sequences. To further test this hypothesis, we analyzed the effect of subinhibitory km concentrations in the wild type E. coli strain MG1655 harboring the parental low copy number plasmid pHly152. At a km concentration of 5 mg/l, subinhibitory for strain MG1655 (pHly152), generation of Hly(-) clones could be readily detected. Similar results were also obtained when, instead of km, ampicillin was used. IS91 is flanking several virulence determinants in different enteric bacterial pathogenic strains from E. coli and Shigella. The results presented here evidence that stress generated by exposure to subinhibitory antibiotic concentrations may result in rearrangements of the bacterial genome. Whereas some of these rearrangements may be deleterious, others may generate genotypes with increased virulence, which may resume infection.

Project description:Phage treatment is suggested as an alternative to antibiotics; however, there is limited knowledge of how phage treatment impacts resident bacterial community structure. When phages induce bacterial lysis, resources become available to the resident community. Therefore, the density of the target bacterium is essential to consider when investigating the effect of phage treatment. This has never been studied. Thus, we invaded microcosms containing a lake-derived community with Flavobacterium columnare strain Fc7 at no, low or high densities, and treated them with either the bacteriophage FCL-2, the antibiotic Penicillin or kept them untreated (3 × 3 factorial design). The communities were sampled over the course of one week, and bacterial community composition and density were examined by 16S rDNA amplicon sequencing and flow cytometry. We show that phage treatment had minor impacts on the resident community when the host F. columnare Fc7 of the phage was present, as it caused no significant differences in bacterial density α- and β-diversity, successional patterns, and community assembly. However, a significant change was observed in community composition when the phage host was absent, mainly driven by a substantial increase in Aquirufa. In contrast, antibiotics induced significant changes in all community characteristics investigated. The most crucial finding was a bloom of γ-proteobacteria and a shift from selection to ecological drift dominating community assembly. This study investigated whether the amount of a bacterial host impacted the effect of phage treatment on community structure. We conclude that phage treatment did not significantly affect the diversity or composition of the bacterial communities when the phage host was present, but introduced changes when the host was absent. In contrast, antibiotic treatment was highly disturbing to community structure. Moreover, higher amounts of the bacterial host of the phage increased the contribution of stochastic community assembly and resulted in a feast-famine like response in bacterial density in all treatment groups. This finding emphasises that the invader density used in bacterial invasion studies impacts the experimental reproducibility. Overall, this study supports that phage treatment is substantially less disturbing to bacterial communities than antibiotic treatments.

Project description:There is a clear need to understand the effect of human intervention on the evolution of infectious disease. In particular, culling and harvesting of both wildlife and managed livestock populations are carried out in a wide range of management practices, and they have the potential to impact the evolution of a broad range of disease characteristics. Applying eco-evolutionary theory we show that once culling/harvesting becomes targeted on specific disease classes, the established result that culling selects for higher virulence is only found when sufficient infected individuals are culled. If susceptible or recovered individuals are targeted, selection for lower virulence can occur. An important implication of this result is that when culling to eradicate an infectious disease from a population, while it is optimal to target infected individuals, the consequent evolution can increase the basic reproductive ratio of the infection, R0, and make parasite eradication more difficult. We show that increases in evolved virulence due to the culling of infected individuals can lead to excess population decline when sustainably harvesting a population. In contrast, culling susceptible or recovered individuals can select for decreased virulence and a reduction in population decline through culling. The implications to the evolution of virulence are typically the same in wildlife populations, that are regulated by the parasite, and livestock populations, that have a constant population size where restocking balances the losses due to mortality. However, the well-known result that vertical transmission selects for lower virulence and transmission in wildlife populations is less marked in livestock populations for parasites that convey long-term immunity since restocking can enhance the density of the immune class. Our work emphasizes the importance of understanding the evolutionary consequences of intervention strategies and the different ecological feedbacks that can occur in wildlife and livestock populations.

Dataset Information

Minor environmental concentrations of antibiotics can modify bacterial virulence in co-infection with a non-targeted parasite.

Publications

Minor environmental concentrations of antibiotics can modify bacterial virulence in co-infection with a non-targeted parasite.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets