Acquired Antibiotic Resistances in Enterococci

Vivek Kak; Joseph W. Chow

doi:10.1128/9781555817923.ch9

Chapter 9 : Acquired Antibiotic Resistances in Enterococci

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Affiliations: 1: Division of Infectious Diseases, B321 Life Sciences Building, Michigan State University, East Lansing, MI 48824; 2: Division of Infectious Diseases (11W), John D. Dingell VA Medical Center and Wayne State University, Detroit, MI 48201-1932

Content Type: Monograph

Publication Year: 2002

Category: Bacterial Pathogenesis

Book DOI: 10.1128/9781555817923

Chapter DOI: 10.1128/9781555817923.ch9

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Abstract:

This chapter provides an overview of the most clinically relevant acquired antibiotic resistance mechanisms in enterococci. Enterococci possess a natural, intrinsic resistance to β-lactam antibiotics that is due to the low affinity of their penicillin-binding proteins (PBPs) for the β-lactam agents. Enterococci possess at least five and at times more than nine different PBPs. Enterococci intrinsically possess a low level of resistance to aminoglycosides by limiting transport of the drugs across the cell membrane. The glycopeptide antibiotics vancomycin and teicoplanin are used to treat serious infections due to resistant gram-positive organisms. The most common acquired resistance mechanism among enterococci to the macrolide antibiotics is the production of an enzyme that methylates an adenine residue in the 23S ribosomal RNA of the 50S ribosomal subunit. The high prevalence of multidrug-resistant enterococci in many hospitals has led to an interest in using chloramphenicol as an alternative therapeutic agent. There are two major mechanisms of tetracycline resistance in enterococci: (i) active efflux of the drug across the cell membrane, and (ii) ribosomal protection. The oxazolidinones are a new class of antimicrobial agents developed for use against multidrug-resistant gram-positive bacteria. Evemimicin is an oligosaccharide antimicrobial agent that has shown excellent in vitro activity against enterococci. Ciprofloxacin's activity against enterococci is moderate at best, and quinolone resistance is common among clinical enterococcal isolates.

Citation: Kak V, Chow J. 2002. Acquired Antibiotic Resistances in Enterococci, p 355-383. In Gilmore M, Clewell D, Courvalin P, Dunny G, Murray B, Rice L (ed), The Enterococci. ASM Press, Washington, DC. doi: 10.1128/9781555817923.ch9

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Acquired Antibiotic Resistances in Enterococci

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Figure 1

Vancomycin resistance operons. Adapted from reference 67 .

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Figure 1

Vancomycin resistance operons. Adapted from reference 67 .

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Figure 2

Induction of VanA/VanB type of resistance. Adapted from reference 14 .

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Figure 2

Induction of VanA/VanB type of resistance. Adapted from reference 14 .

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Figure 3

Biochemical overview of vancomycin resistance. Adapted from reference 67 .

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Figure 3

Biochemical overview of vancomycin resistance. Adapted from reference 67 .

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Tables

Acquired Antibiotic Resistances in Enterococci

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Table 1

Overview of vancomycin resistance genotypes a

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Table 1

Overview of vancomycin resistance genotypes a

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Table 2

Overview of gene functions in vanA operon a

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Table 2

Overview of gene functions in vanA operon a