Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers
- Published
- Accepted
- Subject Areas
- Ecology, Microbiology, Infectious Diseases
- Keywords
- ABC complex, ESKAPE, MDRO, competition, calcoaceticus, pittii, Phylomark
- Copyright
- © 2017 Heitkamp et al.
- Licence
- This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, reproduction and adaptation in any medium and for any purpose provided that it is properly attributed. For attribution, the original author(s), title, publication source (PeerJ Preprints) and either DOI or URL of the article must be cited.
- Cite this article
- 2017. Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers. PeerJ Preprints 5:e2973v1 https://doi.org/10.7287/peerj.preprints.2973v1
Abstract
Antibiotic-resistant bacteria complicate many infections and can be difficult to eradicate from hospitals. The population dynamics and ecology of these organisms in the hospital setting, however, is not well understood. Here, we report extensive strain-based antagonistic interactions occurring in military clinical isolates of Acinetobacter baumannii, a bacterial species that causes many drug-resistant hospital-associated infections. Sequence-based phylogenetic analysis of isolates allowed for differentiation to two major clades, with one of the clades representing two closely related genetic groups. Antagonistic activity was detected using a spot-plate assay to test pairwise interactions of all isolates. Isolates exhibited extensive and diverse patterns of antagonism against other isolates. One major clade of isolates had a distinct change in antagonism phenotype between isolates that differed by one base pair out of ~1500bp sequenced, with consistent antagonism of one group of isolates by the other. Both the antagonistic and the sensitive group exhibited extensive drug resistance. The first isolate of the antagonistic group was cultured in May 2010. The proportion of isolates from the antagonistic group collected before and after July 2010 increased from 2% to 76%. The results of this early study of the ecology of hospital-associated bacterial populations are discussed in the context of the species ecology of bacteria in natural environments. This work is a potential starting point for investigations into ecological interventions for infection control in hospitals.
Author Comment
This is a submission to PeerJ for review.
Supplemental Information
Isolate aliases and published genomic sequences
Additional data on isolates in this study for correlation with other studies or further investigation.
Sequences used to construct phylogenetic tree
DNA sequences in phylip format used for parsimony tree building after trimming, alignment, gblocks processing and concatenation. Concatenated in the following order: L2, L3 (lowercase), L1.
Pairwise antagonism counts
Matrix of raw data collected during pairwise antagonism tests. Counts of positive antagonistic interaction of test isolate against sensitive isolate out of six total replicates performed per pair.
Schematic of antagonism methodology and photo
Flowchart of experimental methodology used to generate antagonism counts. Any size clearing of indicator isolate was interpreted as antagonism. Isolates were replicated twice on each plate, and each plate was replicated three times, for a total of six replicates. The location of isolates on the left half of the plate were randomized for placement on the right side of the plate in an attempt to control for local environmental effects on phenotype expression.
