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mBio

Title:		Multidrug-resistant enterococci lack CRISPR-cas
Author(s):		Palmer KL; Gilmore MS;
Address:		"Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts, USA"
Journal Title:		mBio
Year:		2010
Volume:		20101012
Issue:		4
Page Number:		-
DOI:		10.1128/mBio.00227-10
ISSN/ISBN:		2150-7511 (Electronic)
Abstract:		"Clustered, regularly interspaced short palindromic repeats (CRISPR) provide bacteria and archaea with sequence-specific, acquired defense against plasmids and phage. Because mobile elements constitute up to 25% of the genome of multidrug-resistant (MDR) enterococci, it was of interest to examine the codistribution of CRISPR and acquired antibiotic resistance in enterococcal lineages. A database was built from 16 Enterococcus faecalis draft genome sequences to identify commonalities and polymorphisms in the location and content of CRISPR loci. With this data set, we were able to detect identities between CRISPR spacers and sequences from mobile elements, including pheromone-responsive plasmids and phage, suggesting that CRISPR regulates the flux of these elements through the E. faecalis species. Based on conserved locations of CRISPR and CRISPR-cas loci and the discovery of a new CRISPR locus with associated functional genes, CRISPR3-cas, we screened additional E. faecalis strains for CRISPR content, including isolates predating the use of antibiotics. We found a highly significant inverse correlation between the presence of a CRISPR-cas locus and acquired antibiotic resistance in E. faecalis, and examination of an additional eight E. faecium genomes yielded similar results for that species. A mechanism for CRISPR-cas loss in E. faecalis was identified. The inverse relationship between CRISPR-cas and antibiotic resistance suggests that antibiotic use inadvertently selects for enterococcal strains with compromised genome defense"
Keywords:		"Anti-Bacterial Agents/pharmacology Base Sequence *Drug Resistance, Multiple, Bacterial Enterococcus faecalis/classification/drug effects/*genetics Genome, Bacterial *Inverted Repeat Sequences Molecular Sequence Data Phylogeny Plasmids/genetics;"
Notes:		"MedlinePalmer, Kelli L Gilmore, Michael S eng R01AI072360/AI/NIAID NIH HHS/ R01 AI072360/AI/NIAID NIH HHS/ P01 AI083214/AI/NIAID NIH HHS/ T32EY007145/EY/NEI NIH HHS/ T32 EY007145/EY/NEI NIH HHS/ P01AI083214/AI/NIAID NIH HHS/ Research Support, N.I.H., Extramural 2010/11/10 mBio. 2010 Oct 12; 1(4):e00227-10. doi: 10.1128/mBio.00227-10"