Accumulation in Gram-positive and Gram-negative Bacteria as a Mechanism of Resistance to Erythromycin

Abstract

Erythromycin was recovered in high yield after incucation with gram-negative bacteria. The cell-free protein-synthesizing preparation from gram-negative bacteria is equally as susceptible to the antibiotic as is that from gram-positive bacteria. Thus, neither destruction of erythromycin nor the absence of the step susceptible to the antibiotic plays an important role in the resistance mechanism of gram-negative bacteria. A 100-fold d fference in accumulation of erythromycin between gram-positive and gram-negative bacteria was observed. This alone explains the resistance of gram-negative bacteria to erythromycin. Furthe-more, data showed that the inhibition of growth is closely related to the accumulation of erythromycin. The concentration of intracellular erythromycin in gram-positive bacteria was found to be 44to 90-fold greater than that of the extracellular medium. However, the antibiotic did not accumulate on the cell walls, nor was the accumulation energy-dependent. It is proposed that it takes place by the binding of erythromycin to the bacterial ribosomes, forming a very stable complex. The dissociation constants of erythromycin-Staphylococcus aureus complex and erythromycin-Bacillus subtilis complex were determined to be 1.1

Decrease in Accumulation of Macrolide Antibiotics as a Mechanism of Resistance in Staphylococcus aureus

“…According to Teraoka [22], some conformational structure of ribosomes from E. coli Q13 must be necessary for the expression of EM-binding, and Mao and Putterman [10] stated that 50S ribosomes of S. aureus 209P were found to bind EM but neither 42S nucleoprotein nor 50S protein bound the antibiotic. These facts also may support the above speculation of some altered structure of the heat-treated ribosomes, and it is suspected that viability might not directly affect the accumulation of macrolides in cells because of the experimental results of accumulation proceeding with UV-irradiated cells, although Mao and Putterman [9] described that only viable cells accumulated EM from the observation with heat-or toluene-treated cells of S. aureus.…”

“…However, Saito et al [17] found that the lower binding ability of ribosomes obtained from Mac-resistant strains to EM could be a phenotype of Mac-resistance for them, and this fact agreed well with that in previous reports where the lower EM-affinity of ribosomes from either EM-resistant Escherichia coli [20] or Bacillus subtilis [1,21,25] was described. In addition, Mao and Putterman [9] stated that the concentration of intracellular EM in gram-positive bacteria was 44-90-fold greater than that of the extracellular medium, and they proposed that it takes place by the formation of very stable complexes between EM and bacterial ribosomes. The levels of both the EM-accumulation in cells of S. aureus (see Tables 2, 3, 6, Fig.…”

Purification and characterization of an erythromycin esterase from an erythromycin-resistant Pseudomonas sp.

“…Under the assumptions that the density of ribosomes in Pseudomonas sp. GD100 is approximately equal to that in E. coli which contains 90 000 ribosomes at the early exponential phase [20], and that the intracellular concentration of macrolides accumulated in the cell is equal to the concentration of ribosomes [16], one cell could degrade 90 000 molecules of oleandomycin, erythromycin A and erythromycin A enol ether in 5.7U10 34 , 4.5U10 33 and 1.4U10 32 s, respectively. However, the enzymatic degradation of the macrolides may interfere with the competitive binding of ribosomes.…”

“…The outer membrane of Gram-negative bacteria acts as a primary barrier to the passive transport of macrolides into the cell [16]. Macrolides inhibit the protein-synthesizing apparatus by forming a stable complex with bacterial 50S ribosomal subunit in a stoichiometric manner of 1:1 [17^19].…”

Quantifying Attachment and Antibiotic Resistance of Escherichia coli from Conventional and Organic Swine Manure

“…Chloramphenicol is functionally similar to a macrolide in that it affects the 50S ribosomal subunit (Thompson et al, 2002). With the exception of TYL, CMP, and ERY, the antibiotics used in this study are important in the treatment of infections caused by Gram-negative bacteria such as E. coli; however, CMP is often carried on a plasmid that also codes for resistance to multiple antibiotics (Jorgensen, 1978) that are effective on Gram-negative bacteria, and ERY is effective against some Gram-negative bacteria (Mao and Putterman, 1968). Guidelines from the CLSI (formerly the National Committee for Clinical Laboratory Standards) were used to prepare and dilute all antimicrobial agents except TYL, which was dissolved in methanol and adjusted to pH 7.9 using 0.1 mol L -1 phosphate buffer (Kaukas et al, 1988).…”