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Pharmacokinetics of single-dose erythromycin in normal and alcoholic liver disease subjects.

Six normal males and eight male subjects with alcoholic liver disease (ALD) and ascites were given a single 500-mg dose of erythromycin base. Twelve serum samples were collected at 0, 1, 2, 3, 4, 6, 8, 10, 12, 14, 16, and 24 h after dosing and assayed microbiologically for erythromycin concentration. Absorption was characterized by a zero-order model for both groups. ALD subjects demonstrated a shorter lag time (2.0 versus 3.0 h), an earlier peak (4.6 versus 6.3 h, P less than 0.05), and higher peak concentrations (2.04 versus 1.50 micrograms/ml) than normal subjects. Previously unreported biphasic elimination kinetics after oral dosing were observed in five and four ALD subjects. In the ALD group, the mean half lives for the first (alpha) and terminal (beta) phases were 1.6 and 4.5 h, respectively, and in normal subjects, were 1.3 and 6.6 h. The difference in alpha between groups was significant, P less than 0.05. The clinical significance of this finding for ALD patients receiving prolonged courses of erythromycin is discussed.

Absorption↗

Susceptibility of Shigella species to erythromycin.

Two of the most common causes of inflammatory enteritis are Campylobacter fetus subsp. jejuni and Shigella species. No single antimicrobial agent is recommended for treatment of both diseases. Erythromycin is used to treat C. fetus subsp. jejuni infections but has not been studied in shigellosis. For this reason, we determined the susceptibility of 22 strains of Shigella to erythromycin and found that Shigella species are susceptible to concentrations of erythromycin which are obtainable in stool.

Dose-Response Relationship, Drug↗

Source of methylmalonyl-coenzyme A for erythromycin synthesis: methylmalonyl-coenzyme A mutase from Streptomyces erythreus.

Streptomyces erythreus produces erythromycin, presumably from methylmalonyl-coenzyme A (CoA), which could be generated by the isomerization of succinyl-CoA. In S. erythreus cultures, [1,4-14C,2,3-3H]succinate was incorporated into erythromycin with a doubling of the 3H/14C ratio. This result is consistent with the hypothesis that succinyl-CoA is isomerized to methylmalonyl-CoA before incorporation into the macrocyclic lactone of erythromycin. The presence of methylmalonyl-CoA mutase, which catalyzes this isomerization, was demonstrated in cell-free extracts prepared from this organism. Consistent with the suggested role for this enzyme, methylmalonyl-CoA mutase activity increased over 12-fold at the time of the most rapid antibiotic production, and the activity level drastically declined when the antibiotic production ceased. The mutase was partially purified from this organism with DEAE-cellulose, ammonium sulfate precipitation, and affinity chromatography on a B12-coenzyme Sepharose column. The enzyme was stimulated 2.5-fold by the addition of B12-coenzyme. The enzyme showed a typical Michaelis-Menten type substrate saturation patterns, with KmS of 0.31 mM and 0.09 microM for methylmalonyl-CoA and B12-coenzyme, respectively, and a V of 0.5 mumol/min per mg. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme showed a major band with a molecular weight of 63,000. The properties of this enzyme appear to be fairly similar to those of the mutase previously obtained from other sources.

Acyl Coenzyme A↗

Isolation and preliminary characterization of erythromycin-resistant variants of Legionella micdadei and Legionella pneumophila.

Erythromycin-resistant Legionella spp. variants were obtained by a single passage of the naturally occurring bacteria on medium containing various concentrations of erythromycin. By disk diffusion susceptibility testing, at least three different phenotypic patterns of cross-resistance to macrolide, lincosamide, and streptogramin B antibiotics were observed among the 26 erythromycin-resistant strains examined.

Culture Media↗

Uptake, accumulation, and egress of erythromycin by tissue culture cells of human origin.

The ability of erythromycin A base to penetrate and accumulate in tissue culture cells of human origin was investigated. The antibiotic was highly concentrated by early passage cells of normal bronchus, kidney, liver, lung, and skin and by cancer cells derived from breast, liver, and lung. Intracellular levels 4 to 12 times that of the extracellular milieu were obtained in both early-passage and transformed cells. The total quantity of erythromycin accumulated depended on the extracellular concentration of antibiotic, but the cellular/extracellular ratios were, for the most part, independent of the initial extracellular drug concentration. In all cell types tested, the accumulated antibiotic rapidly egressed when cells were incubated in antibiotic-free medium. Bioactivity assays demonstrated that the expelled drug was unmetabolized, fully active antibiotic. The concentration of erythromycin by a variety of human cell types probably accounts, in part, for the effectiveness of the antibiotic against intracellular parasites such as Legionella and Chlamydia spp.

Cells, Cultured↗

Plasmid-mediated high-level resistance to erythromycin in Escherichia coli.

Escherichia coli BM2195 was found to be resistant to high levels of erythromycin. This new resistance phenotype was due to the constitutive synthesis of an erythromycin esterase which inactivates the antibiotic. The gene conferring resistance to erythromycin in this strain is carried on a 61-kilobase self-transferable plasmid, pIP1100, belonging to incompatibility group X.

Drug Resistance, Microbial↗

Epidemiology of intestinal colonization by members of the family Enterobacteriaceae highly resistant to erythromycin in a hematology-oncology unit.

Intestinal colonization by highly erythromycin-resistant members of the family Enterobacteriaceae was surveyed for 4 years in a hematology-oncology unit. Fifty-four of 555 patients (9.7%) were colonized, each with a different strain. The incidence of intestinal carriage was not correlated with erythromycin consumption in the ward but was strongly associated with individual exposure to erythromycin.

Carrier State↗

In vitro activity of A-56268 (TE-031), a new macrolide, compared with that of erythromycin and clindamycin against selected gram-positive and gram-negative organisms.

The in vitro activity of A-56268 was determined and compared with that of erythromycin and clindamycin against a limited spectrum of 401 gram-positive and gram-negative organisms. A-56268 was quite active against erythromycin-susceptible Staphylococcus aureus, Neisseria gonorrhoeae, Listeria monocytogenes, Streptococcus pneumoniae, Streptococcus pyogenes, and group B streptococci and was moderately active against Campylobacter fetus subsp. fetus. A-56268 was consistently bactericidal only for S. pneumoniae. The activity of A-56268 was comparable to that of erythromycin against most organisms tested.

Anti-Bacterial Agents↗

Activity of A-56268 compared with that of erythromycin and other oral agents against aerobic and anaerobic bacteria.

A-56268 was compared with erythromycin, roxithromycin (RU 28965), and perorally administered antimicrobial agents. Its in vitro activity was similar to that of erythromycin and slightly greater than that of roxithromycin, with beta-hemolytic streptococci and Streptococcus pneumoniae inhibited by less than 2 micrograms of A-56268 per ml (50% inhibited by 0.06 microgram/ml). Streptococcus pyogenes, S. agalactiae, S. Pneumoniae, and S. faecalis resistant to erythromycin were resistant to A-56268, and 4 micrograms/ml inhibited 90% of Haemophilus influenzae isolates.

Anti-Bacterial Agents↗

Tetracycline and erythromycin resistance among clinical isolates of Branhamella catarrhalis.

We reviewed tetracycline and erythromycin disk diffusion susceptibility of 457 isolates of Branhamella catarrhalis. Four isolates were resistant to tetracycline, with MICs for two available isolates of 16 micrograms/ml. Sixteen isolates were in the moderately susceptible range for erythromycin, with an MIC for one available isolate being greater than 8 micrograms/ml. These are the first tetracycline- and (by MIC) erythromycin-resistant B. catarrhalis isolates reported from the United States.

Drug Resistance, Microbial↗

Interaction of imipenem with erythromycin and tetracycline assessed by microdilution checkerboard techniques.

Microdilution methodology was used to study the interaction of imipenem with erythromycin and tetracycline, a combination therapy that might be used for the treatment of serious pelvic inflammatory disease. The combination of imipenem and erythromycin showed no antagonism for Escherichia coli and Haemophilus influenzae but was antagonistic for Staphylococcus aureus, Enterococcus faecalis, and group B streptococci; the combination of imipenem and tetracycline was antagonistic for all strains except H. influenzae. Correlation between the results of kill curves and the measurement of fractional bactericidal concentration (FBC) indices was good, although FBC indices showed less antagonism than kill curves. Fractional inhibitory concentration indices showed poor correlation, rarely showing antagonism, and indeed showed synergy in three cases. If erythromycin or tetracycline is considered necessary in addition to imipenem in the treatment of pelvic inflammatory disease, it is probably more effective when given after the course of imipenem has been completed.

Bacteria↗

Comparison of the intracellular activities of clarithromycin and erythromycin against Mycobacterium avium complex strains in J774 cells and in alveolar macrophages from human immunodeficiency virus type 1-infected individuals.

The intracellular activities of clarithromycin and erythromycin, alone and in combination with other antimicrobial agents, were tested against Mycobacterium avium complex (MAC) strains inside mouse J774 cells and inside alveolar macrophages obtained from human immunodeficiency type 1-infected individuals. Clarithromycin alone had greater intracellular activity than erythromycin alone, and drug combinations that included clarithromycin were usually more active than combinations that included erythromycin.

Acquired Immunodeficiency Syndrome↗

Clindamycin, erythromycin, and roxithromycin inhibit the proinflammatory interactions of Pseudomonas aeruginosa pigments with human neutrophils in vitro.

The Pseudomonas aeruginosa-derived phenazine pigments pyocyanin and 1-hydroxyphenazine (1-hp) prime human neutrophils for enhanced, stimulus-activated release of superoxide and myeloperoxidase (MPO), respectively. In the present study, the modulatory potentials of the antimicrobial agents clindamycin, erythromycin, and roxithromycin (10 and 20 micrograms/ml) on the prooxidative interactions of pyocyanin and 1-hp (12.5 microM) with human neutrophils have been investigated. Clindamycin, erythromycin, and especially roxithromycin caused dose-related inhibition of the generation of superoxide by both untreated and pyocyanin-treated neutrophils during activation with either the synthetic chemotactic tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) or the calcium ionophore A23187. The antimicrobial agents also inhibited the generation of reactive oxidants by the MPO-H2O2-halide system during activation of both untreated and 1-hp-treated neutrophils by FMLP. These effects appeared to be due to drug-related interference with membrane-associated oxidative metabolism, since none of the antimicrobial agents inhibited the release of MPO by activated neutrophils, nor did they possess oxidant-scavenging properties. These data demonstrate that clindamycin, erythromycin, and especially roxithromycin antagonize the proinflammatory interactions of pyocyanin and 1-hp with neutrophils and indicate a possible therapeutic role for these antimicrobial agents in the prevention of tissue damage in diseases characterized by P. aeruginosa infection.

Clindamycin↗

High rate of erythromycin and clarithromycin resistance among Streptococcus pneumoniae isolates from blood cultures from Providence, R.I.

Four (5%) of 81 recent isolates of Streptococcus pneumoniae from the blood of adult patients but no isolates from pediatric patients (n = 51) were resistant (MIC, > or = 1 microgram/ml) to erythromycin. The MICs of clarithromycin were slightly lower than those of erythromycin, but there was complete cross-resistance. Routine testing and surveillance are needed to determine whether erythromycin resistance among S. pneumoniae isolates is increasing throughout the United States.

Adult↗

Effect of CO2 on susceptibilities of anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin.

The Oxyrase agar dilution method (Oxyrase, Inc., Mansfield, Ohio), which provides an anaerobic environment without added CO2, was compared with the reference agar dilution method recommended by the National Committee for Clinical Laboratory Standards (anaerobic chamber with 10% CO2) to test the susceptibilities of 302 gram-negative and gram-positive anaerobes to erythromycin, azithromycin, clarithromycin, and roxithromycin. For erythromycin, the overall MIC for 50% of isolates tested (MIC50) was 0.5 micrograms/ml and the MIC90 was 8.0 micrograms/ml by the Oxyrase method, whereas they were 4.0 and 64.0 micrograms/ml, respectively, under standard anaerobic conditions with CO2. At a breakpoint of 4.0 micrograms/ml, 88% of strains were susceptible to erythromycin by the Oxyrase method, whereas 63% were susceptible in the chamber. The corresponding MIC50s and MIC90s of azithromycin, clarithromycin, and roxithromycin by the Oxyrase method were 0.5 and 8.0, 0.25 and 4.0, and 0.5 and 16.0 micrograms/ml, respectively, whereas in the chamber they were 4.0 and > 64.0, 2.0 and 64.0, and 2.0 and 64.0 micrograms/ml, respectively. At a breakpoint of 8.0 micrograms/ml for these three drugs, 89, 92, and 85% of the isolates, respectively, were susceptible by the Oxyrase method, whereas 67%, 72, and 68% of the isolates, respectively, were susceptible in the chamber. Most strains resistant to all four compounds by both methods were Bacteroides distasonis, Fusobacterium mortiferum, Fusobacterium varium and non-Clostridium perfringens Clostridium species. Results of the study may lead to a reappraisal of the role played by macrolides and azalides in the treatment of anaerobic infections.

Azithromycin↗

Tight binding of clarithromycin, its 14-(R)-hydroxy metabolite, and erythromycin to Helicobacter pylori ribosomes.

Clarithromycin is a recently approved macrolide with improved pharmacokinetics, antibacterial activity, and efficacy in treating bacterial infections including those caused by Helicobacter pylori, an agent implicated in various forms of gastric disease. We successfully isolated ribosomes from H. pylori and present the results of a study of their interaction with macrolides. Kinetic data were obtained by using 14C-labeled macrolides to probe the ribosomal binding site. Clarithromycin, its parent compound erythromycin, and its 14-(R)-hydroxy metabolite all bound tightly to H. pylori ribosomes. Kd values were in the range of 2 x 10(-10) M, which is the tightest binding interaction observed to date for a macrolide-ribosome complex. This tight binding was due to very slow dissociation rate constants of 7.07 x 10(-4), 6.83 x 10(-4), and 16.6 x 10(-4) min-1 for clarithromycin, erythromycin, and 14-hydroxyclarithromycin, respectively, giving half-times of dissociation ranging from 7 to 16 h, the slowest yet measured for a macrolide-ribosome complex. These dissociation rate constants are 2 orders of magnitude slower than the dissociation rate constants of macrolides from other gram-negative ribosomes. [14C]clarithromycin was bound stoichiometrically to 50S ribosomal subunits following incubation with 70S ribosomes and subsequent separation of the 30S and 50S subunits by sucrose density gradient centrifugation. These data predict that the lower MIC of clarithromycin compared with that of erythromycin for H. pylori is likely due to a faster rate of intracellular accumulation, possibly because of increased hydrophobicity.

Centrifugation, Density Gradient↗

Decreased activity of erythromycin against Streptococcus pyogenes in Taiwan.

A total of 78 clinical isolates of Streptococcus pyogenes were collected from January 1992 through December 1993 from patients in southern Taiwan. The in vitro activities of 10 antimicrobial agents were determined by the agar dilution method. Penicillin, cephalothin, cefotaxime, vancomycin, and ofloxacin were shown to be active against S. pyogenes isolates, with MICs at which 90% of isolates are inhibited (MIC90s) being < or = 0.03, < or = 0.13, < or = 0.13, < or = 0.13, and < or = 0.25 microgram/ml, respectively. Erythromycin and azithromycin both had poor activities (MIC50s, 16 and >128 micrograms/ml, respectively; MIC90s, >128 and >128 micrograms/ml, respectively). The activities of tetracycline, clindamycin, and chloramphenicol against a significant number of these isolates were also limited. As the MICs of clindamycin and chloramphenicol for the isolates increased, the MICs of the two macrolides also increased. Clindamycin, chloramphenicol, and the two macrolides were less potent against isolates recovered form throat swab samples than against those from blood or other sources. Isolates of the T12 and T1 serotypes accounted for 53.8% of all isolates. The majority (87.5%) of the isolates recovered from throat swab samples were of the T12 serotype, whereas 19.2% of the isolates recovered from blood were of the T12 serotype. In contrast, 66.7% of the isolates of the T1 serotype were derived from blood but none were derived from throat swab samples. Of the 33 T12 serotype isolates, erythromycin MICs for 78.8% of the isolates were >128 micrograms/ml. Because of the poor activities of erythromycin and azithromycin against S. pyogenes isolates from patients in southern Taiwan, these drugs should no longer be considered the drugs of choice for the management of group A streptococcal infections among patients who live in this area.

Anti-Bacterial Agents↗