Recent studies have shown that ampicillin resistance has increased steadily over the past 3 decades within U.S. Enterococcus faecium isolates.
Analysis of the predicted PBP5 protein of 41 isolates showed a consensus PBP5 pattern for the 9 isolates with MICs of <4 μg/ml that is distinctly different from the PBP5 consensus of the 32 isolates with MICs of >4 μg/ml with ∼5% difference between these; however, there were no consistent amino acid changes that correlated with specific increases in the MICs of ampicillin within the latter group.
Analysis of three other genes encoding cell wall/surface proteins also showed that there are two distinct evolutionary groups for each gene, but with occasional mixing of genes, consistent with a species that evolves by recombination.
2011-06-17
Eng.
Antimicrobial agents and chemotherapy
Division of Infectious Disease, Department of Medicine, Center for the Study of Emerging and Re-emerging Pathogens, University of Texas Medical School, Houston, Texas 77030, USA.
Antimicrob Agents Chemother. 2011 Jul;55(7):3272-7
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