Functional characterization and phylogenetic analysis of acquired and intrinsic macrolide phosphotransferases in the Bacillus cereus group

Abstract

The Bacillus cereus group is composed of Gram-positive spore-forming bacteria of clinical and ecological importance. More than 200 B. cereus group isolates have been sequenced. However, there are few reports of B. cereus group antibiotic resistance genes. This study identified two functional classes of macrolide phosphotransferases (Mphs) in the B. cereus group. Cluster A Mphs inactivate 14- and 15-membered macrolides while Cluster B Mphs inactivate 14-, 15- and 16-membered compounds. The genomic region surrounding the Cluster B Mph gene is related to various plasmid sequences, suggesting that this gene is an acquired resistance gene. In contrast, the Cluster A Mph gene is located in a chromosomal region conserved among all B. cereus group isolates, and data indicated that it was acquired early in the evolution of the group. Therefore, the Cluster A gene can be considered an intrinsic resistance gene. However, the gene itself is not present in all strains and our comparative genomics analyses showed that it is exchanged among strains of the B. cereus group by the mean of homologous recombination. These results provide an alternative mechanism to intrinsic resistance.

Field‐based evidence for copper contamination induced changes of antibiotic resistance in agricultural soils

“…Actinobacteria, Proteobacteria and Cyanobacteria are among the most often predicted sources of ARGs conferring multi‐resistance in metagenomics studies of soil samples (D'Costa et al ., ; Forsberg et al ., ). ARG profiles were also positively correlated with Firmicutes and Actinobacteria during sewage sludge composting (Su et al ., ), which have been frequently associated with antibiotic resistance (Wang et al ., ). Our network analysis supported these previous findings, and further found that genes resistant to antibiotics are widespread in various bacterial taxa (Fig.…”

The Prehistory of Antibiotic Resistance

“…Modern day microorganisms found in a cave that has been isolated from the surface for four million years have also been shown to harbor functional antibiotic resistance genes (Bhullar et al 2012). A phylogenetic tree of macrolide phosphostransferases was generated using a sequence found in the genome of a cave organism (identified as Brachybacterium paraconglomeratum), and compared with a phylogeny of macrolide phosphotransferases from a terrestrial species of Brachybacterium (B. faecium DSM 4810) and environmental Bacillus cereus (Wang et al 2015). Analysis of 10 kb upstream of and downstream from the mph revealed that MPHs from Brachybacterium strains from both cave and terrestrial origin cluster together as a separate group among known MPHs (Bhullar et al 2012).…”

Application of genomic technologies to measure and monitor antibiotic resistance in animals

“…MGE‐associated ARGs can be exchanged among bacteria and pathogens via horizontal gene transfer (HGT), which contributes to the spread of ARGs . In addition, comparative genome analysis provides evidence about the determination of acquired and intrinsic resistances, as well as the hosts of the MGEs and associated ARGs …”

“…ARGs in animal feces, animal farm wastewater, and associated environments have been detected with comparatively high diversity and abundance, and ARGs can spread from animals to humans via various pathways . Although the increase in the number, diversity, and resistant phenotypes of clinical pathogens directly threatens human and animal health, many ARGs have come from environmental nonpathogenic sources, and exchange of ARGs has been observed between environmental bacteria and human pathogens . These facts illustrate the potential human health risk posed by ARGs of animal origin and reinforce the urgent need for measuring and monitoring antibiotic resistance in animals.…”