Co-diversification of Enterococcus faecium Core Genomes and PBP5: Evidences of pbp5 Horizontal Transfer

• Published in: Frontiers in microbiology Vol. 7; p. 1581
• Main Authors: Novais, Carla, Tedim, Ana P, Lanza, Val F, Freitas, Ana R, Silveira, Eduarda, Escada, Ricardo, Roberts, Adam P, Al-Haroni, Mohammed, Baquero, Fernando, Peixe, Luísa, Coque, Teresa M
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 06-10-2016
• Subjects: Ampicillin Resistance; chromosomal transfer; Microbiology; PBP5 mutations; phylogenomic diversification; PONA; phylogenomic diversification; PBP5 mutations; chromosomal transfer; PonA; ampicillin resistance
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2016.01581

Ampicillin resistance has greatly contributed to the recent dramatic increase of a cluster of human adapted
lineages (ST17, ST18, and ST78) in hospital-based infections. Changes in the chromosomal
gene have been associated with different levels of ampicillin susceptibility, leading to protein variants (designated as PBP5 C-types to keep the nomenclature used in previous works) with diverse degrees of reduction in penicillin affinity. Our goal was to use a comparative genomics approach to evaluate the relationship between the diversity of PBP5 among
isolates of different phylogenomic groups as well as to assess the
transferability among isolates of disparate clonal lineages. The analyses of 78 selected
strains as well as published
genomes, suggested that the diversity of
mirrors the phylogenomic diversification of
. The presence of identical PBP5 C-types as well as similar
genetic environments in different
lineages and clones from quite different geographical and environmental origin was also documented and would indicate their horizontal gene transfer among
populations. This was supported by experimental assays showing transfer of large (≈180-280 kb) chromosomal genetic platforms containing
alleles,
(transglycosilase) and other metabolic and adaptive features, from
donor isolates to suitable
recipient strains. Mutation profile analysis of PBP5 from available genomes and strains from this study suggests that the spread of PBP5 C-types might have occurred even in the absence of a significant ampicillin resistance phenotype. In summary, genetic platforms containing
sequences were stably maintained in particular
lineages, but were also able to be transferred among
clones of different origins, emphasizing the growing risk of further spread of ampicillin resistance in this nosocomial pathogen.