Antibiotic-induced lysis of enterococci.

Storch, Gregory A.; Krogstad, Donald J.

doi:10.1172/jci110298

Cited by 38 publications

(16 citation statements)

References 34 publications

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“…Finally, these data do not address the influence of human serum on the bactericidal activity of antimicrobial agents against enterococci. Storch and Krogstad (18) have shown that antibiotic-induced lysis of enterococci is markedly decreased in human serum. Nevertheless, there are sufficient data on the bactericidal activity of deptomycin, including that obtained from this study, to warrant further evaluation of this drug as a therapeutic agent for serious enterococcal infections, including endocarditis.…”

Section: Resultsmentioning

confidence: 99%

Bactericidal activity of deptomycin (LY146032) compared with those of ciprofloxacin, vancomycin, and ampicillin against enterococci as determined by kill-kinetic studies

Stratton

Liu

Ratner

et al. 1987

Antimicrob Agents Chemother

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This study used kill-kinetic methods to provide data on the bactericidal activity of subinhibitory (1/2x MIC), inhibitory (lx MIC), and suprainhibitory (4X, 6x, and 8x MIC) concentrations of deptomycin (LY146032) against strains of enterococci compared with those of ciprofloxacin, vancomycin, and ampicillin. Deptomycin was the most active agent tested, as determined by broth microdilution methods, with all strains being inhibited at concentrations <2 ,ug/ml. The kill-kinetic studies demonstrated that deptomycin had greater activity at aDl concentrations tested than the other cell wall-active agents; regrowth was seen, however, at lower concentrations. At higher concentrations (6x and 8x MIC), all aagents tested demonstrated the same or less bactericidal activity than at 4x MIC, presumably due to the Eagle effect. Nevertheless, these results suggest that further evaluation of deptomycin as a therapeutic agent for serious enterococcal infections is warranted.Deptomycin (LY146032) is a cyclic polypeptide which by standard broth dilution techniques has been shown to be bactericidal against enterococci at concentrations near the MIC (4, 6). This suggests that deptomycin may be useful clinically as a single agent against serious enterococcal infections, including endocarditis. This study used killkinetic methods to provide data on the bactericidal activity of subinhibitory (1/2 x MIC), inhibitory (lx MIC), and suprainhibitory (4x, 6x, and 8x MIC) concentrations of deptomycin against strains of enterococci compared with those of ciprofloxacin, vancomycin, and ampicillin. MATERIALS AND METHODSMicroorganisms. Ten clinical isolates of enterococci and Streptococcus faecalis ATCC 29212 were studied. These isolates were selected from more than 200 blood culture isolates of enterococci for which the MICs of vancomycin, ampicillin, and gentamicin had been determined previously.Selection was done to provide a wide range of MICs of the three agents previously tested. Identification was performed by established methods (5), which included the ability to grow in medium containing 40% bile, to hydrolyze esculin, and to grow in broth containing 6.5% sodium chloride. All strains were identified as S. faecalis.Antimicrobial agents. Standard antimicrobial reference powders and their sources were as follows: deptomycin and vancomycin, Eli Lilly & Co., Indianapolis, Ind.; ciprofloxacin, Miles Pharmaceuticals, West Haven, Conn.; and ampicillin, Bristol Laboratories, Syracuse, N.Y. Antimicrobial agent stock solutions were prepared as specified by the manufacturers and stored at -70°C until use. Final concentrations were prepared on the day they were used.Media. Mueller-Hinton broth (BBL Microbiology Systems, Cockeysville, Md.) was used in both the broth microdilution method and the kill-kinetic method. The broth was supplemented with physiologic concentrations of calcium and magnesium to achieve a final concentration of 50 mg of (14). For this method, 10-fold dilutions were made in physiologic saline, and a calibrated micropipetter was us...

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Section: Resultsmentioning

confidence: 99%

Bactericidal activity of deptomycin (LY146032) compared with those of ciprofloxacin, vancomycin, and ampicillin against enterococci as determined by kill-kinetic studies

Stratton

Liu

Ratner

et al. 1987

Antimicrob Agents Chemother

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“…Inhibition of murein synthesis by ␤-lactam antibiotics is suggested to result in the lysis of the cell by an uncontrolled action of murein hydrolases (23). For E. coli, enterococci, and pneumococci, it has been demonstrated that a decrease in murein hydrolase activity is correlated with a lower susceptibility to penicillin G and that an increase in murein hydrolase activity results in enhanced penicillin G-induced lysis (17,49,53). Penicillin G tolerance of GBS has also been suggested to be correlated with a defect in the autolytic system (27).…”

Section: Discussionmentioning

confidence: 99%

Identification and Molecular Analysis of PcsB, a Protein Required for Cell Wall Separation of Group B Streptococcus

et al. 2001

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Group B streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis in neonates. N-terminal sequencing of major proteins in the culture supernatant of a clinical isolate of GBS identified a protein of about 50 kDa which could be detected in all of 27 clinical isolates tested. The corresponding gene, designated pcsB, was isolated from a GBS cosmid library and subsequently sequenced. The deduced PcsB polypeptide consists of 447 amino acid residues (M r , 46,754), carries a potential N-terminal signal peptide sequence of 25 amino acids, and shows significant similarity to open reading frames of unknown function from different organisms and to the murein hydrolase P45 from Listeria monocytogenes. Northern blot analysis revealed a monocistronic transcriptional organization for pcsB in GBS. Insertional inactivation of pcsB in the genome of GBS resulted in mutant strain Sep1 exhibiting a drastically reduced growth rate compared to the parental GBS strain and showing an increased susceptibility to osmotic pressure and to various antibiotics. Electron microscopic analysis of GBS mutant Sep1 revealed growth in clumps, cell separation in several planes, and multiple division septa within single cells. These data suggest a pivotal role of PcsB for cell division and antibiotic tolerance of GBS.Group B streptococcus (GBS), also known as Streptococcus agalactiae, is part of the normal human flora colonizing the respiratory, gastrointestinal, and urogenital tracts. It is also the leading cause of bacterial sepsis and meningitis in neonates in the United States and western Europe, and it is a major cause of endocarditis and fever in parturient women (2). In the last decade, the incidence of GBS infections has increased especially in the elderly and in immunocompromised persons (58), but despite its clinical importance, GBS is only poorly understood on the molecular level.Bacterial cell division is a complex interplay of topological processes, biosynthetic reactions, and cleavage mechanisms. Septum formation is initiated by the cooperative action of division inhibitors, topological specificity factors, and proteins constituting the cell division apparatus both found in gramnegative and gram-positive bacteria (reviewed in reference 5, 31, and 42). In globular cells, like streptococci, the division septum can be arranged in several orientations, resulting in the generation of two daughter cells of the same size and shape. The choice of the division plane determines the three-dimensional organization of the multicellular arrays of progeny cells that are formed. In GBS, the plane of division is approximately the same in each division cycle, resulting in the formation of frequently long chains (20). The division septum that is formed between the daughter cells is composed of newly synthesized membrane and peptidoglycan components. Peptidoglycan biosynthesis is accomplished by the insertion of peptide-carrying disaccharide units into the existing murein sacculus by transglycosylation and transpeptidation (34). Cell divi...

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“…They are either direct inhibitors of MraY, like mureidomycin and tunicamycin (25,28), or indirect inhibitors like amphomycin, bacitracin, and colicin M (29 -31), all of which are known to induce bacteriolysis (9,29,(31)(32)(33). The direct inhibitors all resemble the nucleotide substrate with additional hydrophobic moieties attached.…”

Section: Discussionmentioning

confidence: 99%

The Lysis Protein E of φX174 Is a Specific Inhibitor of the MraY-catalyzed Step in Peptidoglycan Synthesis

Bernhardt

Struck

Young

2001

Journal of Biological Chemistry

108

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Coliphage X174 encodes a single lysis protein, E, a 91-amino acid membrane protein. Dominant mutations have been isolated in the host gene mraY that confer E resistance. mraY encodes translocase I, which catalyzes the formation of the first lipid intermediate in bacterial cell wall synthesis, suggesting a model in which E inhibits MraY and promotes cell lysis in a manner analogous to cell wall synthesis inhibitors like penicillin. To test this model biochemically, we monitored the effect of E on cell wall synthesis in vivo and in vitro. We find that expression of Emyc, encoding an epitope-tagged E protein, from a multicopy plasmid inhibits the incorporation of [ 3 H]diaminopimelic acid into cell wall and leads to a profile of labeled precursors consistent with MraY inhibition. Moreover, we find that membranes isolated after Emyc expression are drastically reduced in MraY activity, whereas the activity of Rfe, an enzyme in the same superfamily, was unaffected. We therefore conclude that E is indeed a cell wall synthesis inhibitor and that this inhibition results from a specific block at the MraY-catalyzed step in the pathway.There are at least two distinct mechanisms by which phage promote destruction of the bacterial cell wall and subsequent cell lysis, the choice of which appears to be determined by the phage genome size. Bacteriophages with large genomes encode a holin-endolysin system. In the prototypic model, the S holin protein accumulates in the cell membrane and the R endolysin accumulates in the cytoplasm. At a genetically programmed time, S forms a membrane lesion to release the R endolysin into the periplasm where it can degrade the cell wall and cause lysis (1). In contrast, bacteriophages with small genomes can only afford to encode a single lysis protein. Three unrelated single protein lysis systems are known: the E protein from X174 (ssDNA, Microviridae), and the L and A 2 proteins from MS2 (ssRNA, group I) and Q␤ (ssRNA, group III) respectively (1-5). The molecular mechanism of lysis caused by any of these proteins has been elusive. No cell wall-degrading activity has been associated with any of these phages, indicating that their lytic mechanism is distinct from the holin-endolysin system of the larger phages.Working from the premise that these phage proteins are targeting a host protein to promote lysis, we took a genetic approach to isolate lysis-resistant host mutants and identify the target genes. We recently isolated dominant mutations in Escherichia coli mraY that result in resistance to the bacteriophage X174 E lysis protein (6). mraY encodes translocase I, which catalyzes the formation of the first lipid intermediate in cell wall synthesis (7) and is a member of the UDP-GlcNAc/ MurNAc 1 :polyisoprenyl-P GlcNAc/MurNAc 1-P transferase family of enzymes, which we will refer to as the GPT enzyme family (8). Inhibition of MraY by the antibiotic mureidomycin results in lysis of Pseudomonas aeruginosa, and depletion of MraY activity from E. coli also results in concomitant cell lysis (9, 10). Th...

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Antibiotic-induced lysis of enterococci.

Cited by 38 publications

References 34 publications

Bactericidal activity of deptomycin (LY146032) compared with those of ciprofloxacin, vancomycin, and ampicillin against enterococci as determined by kill-kinetic studies

Bactericidal activity of deptomycin (LY146032) compared with those of ciprofloxacin, vancomycin, and ampicillin against enterococci as determined by kill-kinetic studies

Identification and Molecular Analysis of PcsB, a Protein Required for Cell Wall Separation of Group B Streptococcus

The Lysis Protein E of φX174 Is a Specific Inhibitor of the MraY-catalyzed Step in Peptidoglycan Synthesis

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