Co-occurrence of resistance to different antibiotics among aquatic bacteria

Abstract

BackgroundAntibiotic resistance is not confined to pathogens, but is also widespread in various natural environments. In nature the microbes producing antibiotic compounds have been around for millions of years. Heavy use of antibiotics in medicine and veterinary practice may lead to the accumulation of resistance genes in microbial populations, followed by a rise in multiresistant bacteria.ResultsTo test the extent of resistance among aquatic bacteria, we have collected 760 isolates resistant to at least one antibiotic. The phylogeny of the isolates covers a wide range of Proteobacteria, Actinobacteria and Bacteroidetes. In order to determine the extent of multiresistance, the isolates were tested on six antibiotics. As the growth rate of the different bacteria was highly variable, the classical medical resistance tests could not be used, and an alternative method considering the full growth curve was developed. In general, the overall resistances to different antibiotics could be explained by random, independent distribution. An exception to this was the resistances against tetracycline and chloramphenicol, which tended to occur in pairs.ConclusionsWe conclude that there is no massive spread of multiresistance determinants in the studied environment, although some specific cases can be found, awaiting for molecular characterization of the resistance mechanisms.

Isolation and Molecular Characterization of Multidrug-Resistant Enterobacteriaceae Strains from Pork and Environmental Samples in Xiamen, China

“…Almost all selected isolates were resistant to three or more kinds of antibiotics, which indicated that this method was a fast and effective way to screen MDR isolates. Similar methods have been used previously to select ART bacterial isolates from various samples (31,53,57).…”

Aeromonas and Pseudomonas Species Carriers of ampC FOX Genes in Aquatic Environments

“…Forty-five FOX-positive isolates were isolated from ampicillin-containing media; these isolates made up 31% of the total number of isolates that were isolated from ampicillin-containing media. The other 3 FOX-positive isolates were isolated from tetracycline-containing media but were confirmed as ampicillin resistant (5).…”

“…We used a collection of antibiotic-resistant (AR) isolates originating from freshwater ecosystems in Estonia (5) and carried out assays on selective medium with single-AB (ampicillin, chloramphenicol, kanamycin, norfloxacin, and tetracycline) or double-AB (ampicillin and kanamycin; tetracycline and chloramphenicol) plates as previously described (5).…”

The multi-omics promise in context: from sequence to microbial isolate

“…Antimicrobial compounds play a major role in the environment, not only as defence mechanisms against competing organisms, but also as intra-species signalling molecules (Goh et al 2002;Yim et al 2006;Yim et al 2007;Voolaid et al 2012). Therefore, antibiotic resistance genes are also widespread; they can be extracted from multi-omics data (Medema & Fischbach 2015) and have recently been shown to be expressed in a broad range of different natural environments (Versluis et al 2015).…”