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BMC Microbiol. 2018 Dec 29;18(1):228. doi: 10.1186/s12866-018-1377-3.

Oxytetracycline reduces the diversity of tetracycline-resistance genes in the Galleria mellonella gut microbiome.

Author information

1
Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, UK.
2
Present address: School of Molecular Sciences, The University of Western Australia, 35 Stirling Highway, Crawley, Perth, 6009, Australia.
3
Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, UK. tony.maxwell@jic.ac.uk.

Abstract

BACKGROUND:

Clinically-relevant multidrug resistance is sometimes present in bacteria not exposed to human-made antibiotics, in environments without extreme selective pressures, such as the insect gut. The use of antibiotics on naïve microbiomes often leads to decreased microbe diversity and increased antibiotic resistance.

RESULTS:

Here we investigate the impact of antibiotics on the insect gut microbiome by identifying tetracycline-resistance genes in the gut bacteria of greater wax moth (Galleria mellonella) larvae, feeding on artificial food containing oxytetracycline. We determined that G. mellonella can be raised on artificial food for over five generations and that the insects tolerate low doses of antibiotics in their diets, but doses of oxytetracycline higher than sub-inhibitory lead to early larval mortality. In our experiments, greater wax moth larvae had a sparse microbiome, which is consistent with previous findings. Additionally, we determined that the microbiome of G. mellonella larvae not exposed to antibiotics carries a number of tetracycline-resistance genes and some of that diversity is lost upon exposure to strong selective pressure.

CONCLUSIONS:

We show that G. mellonella larvae can be raised on artificial food, including antibiotics, for several generations and that the microbiome can be sampled. We show that, in the absence of antibiotics, the insect gut microbiome can maintain a diverse pool of tetracycline-resistance genes. Selective pressure, from exposure to the antibiotic oxytetracycline, leads to microbiome changes and alteration in the tetracycline-resistance gene pool.

KEYWORDS:

Antibiotic resistance; Galleria mellonella; Greater wax moth; Lepidoptera; Oxytetracycline; Tetracycline-resistance elements

PMID:
30594143
PMCID:
PMC6310997
DOI:
10.1186/s12866-018-1377-3
[Indexed for MEDLINE]
Free PMC Article

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