The macrolide revival: Thirty five years after erythromycin

Efficacy of erythromycin compared to clarithromycin and azithromycin in adults or adolescents with community-acquired pneumonia: A Systematic Review and meta-analysis of randomized controlled trials

BACKGROUND

It is debatable whether erythromycin has similar efficacy to other macrolides in treating community-acquired pneumonia (CAP). The aim of this meta-analysis is to compare the efficacy of erythromycin with clarithromycin and azithromycin.

METHODS

We performed this meta-analysis of randomized controlled trials (RCTs) of adults or adolescents with CAP which compared the efficacy of erythromycin monotherapy to either azithromycin or clarithromycin. We searched PubMed and EMBASE and Cochrane Library databases and three clinical trial registries up to November 02, 2021. We evaluated heterogeneity and used random-effects models to perform risk ratios with 95% confidence intervals.

RESULTS

We included four RCTs (total of 472 patients), which compared the clinical efficacy of erythromycin versus clarithromycin. No studies comparing monotherapy of erythromycin versus azithromycin were found. Erythromycin use was associated with significantly lower rates of clinical success (RR, 0.79; 95% CI, 0.64 to 0.98; P-value = 0.033; I² = 20.27%), clinical cure (RR,0.67; 95% CI, 0.48 to 0.92; P-value = 0.014; I² = 8.75%), and radiological success (RR, 0.84; 95% CI, 0.71 to 0.996; P-value = 0.045; I² = 20.12%) than clarithromycin.

CONCLUSION

Erythromycin is less effective than clarithromycin as empiric treatment of CAP in adults and adolescents. Because of this and the higher rate of adverse reactions, erythromycin should not be used in the majority of CAP patients when azithromycin and clarithromycin are available.

The STEP method (statistical test of equivalent pathways): application to pharmaceuticals

The STEP method (Statistical Test of Equivalent Pathways), recently developed to determine primary and secondary fragmentation in the MS/MS of peptides and carbohydrates, is applied in the current study to common pharmaceutical antibiotics. The classification of product ions as primary or secondary is then utilized to construct genealogy diagrams that aid in the structural characterization of the product ions. Four compounds were subjected to the MS/MS conditions used for the STEP method, and the method was used to correctly identify primary and secondary ions in three of the four pharmaceuticals. Calculated STEP values for erythromycin did not match previously characterized fragmentation assignments. This provided an opportunity to explore potential limitations of STEP analysis. It was determined that inaccurate STEP assignments could result, if the starting compound is classified as "fragile", because fragile ions, such as erythromycin can produce abnormally low STEP ratios. While this finding represents a limitation of using the STEP method to determine whether product ions are due to primary or secondary fragmentation for fragile ions, it suggests the possibility of identifying the presence of "fragile ions" by STEP analysis.

Synthesis of two and antibacterial activity of one novel oxime ether derivatives of erythromycin A

The synthesis of novel erythromycin A 9-O-(2-ethenesulfony-ethyl)-oxime and erythromycin A 9-O-(3-oxo-butyl)-oxime from erythromycin A (EA) by the Michael reaction is described and to describe the effects of transformation of ketone in position 9 of EA to an oxime ether. This transformation occurred in a single step without protecting of any functional moiety of erythromycin oxime and zero waste manner in good yield. The antibacterial screen of EA 9-O-(2-ethenesulfony-ethyl)-oxime is also reported.

Cellular accumulation of the new ketolide RU 64004 by human neutrophils: comparison with that of azithromycin and roxithromycin

We analyzed the uptake of RU 64004 by human neutrophils (polymorphonuclear leukocytes [PMNs]) relative to those of azithromycin and roxithromycin. RU 64004 was strongly and rapidly accumulated by PMNs, with a cellular concentration/extracellular concentration ratio (C/E) of greater than 200 in the first 5 min, and this was followed by a plateau at 120 to 180 min, with a C/E of 461 +/- 14.8 (10 experiments) at 180 min. RU 64004 uptake was moderately sensitive to external pH, and activation energy was also moderate (63 +/- 3.8 kJ/mol). RU 64004 was mainly located in PMN granules (about 70%) and egressed slowly from loaded cells, owing to avid reuptake. The possibility that PMN uptake of RU 64004 and other macrolides occurs through a carrier-mediated system was suggested by three key results. First, there existed a strong interindividual variability in uptake kinetics, suggesting variability in the numbers or activity of a transport protein. Second, macrolide uptake displayed saturation kinetics characteristic of that of a carrier-mediated transport system: RU 64004 had the highest Vmax value (3,846 ng/2.5 x 10(6) PMNs/5 min) and the lowest Km value (about 28 microM), indicating a high affinity for the transporter. Third, as observed previously with other erythromycin A derivatives, Ni2+ (a blocker of the Na+/Ca2+ exchanger which mediates Ca2+ influx in resting neutrophils) impaired RU 64004 uptake by PMNs, with a 50% inhibitory concentration of about 3.5 mM. In addition, we found that an active process is also involved in macrolide efflux, because verapamil significantly potentiated the release of all three macrolides tested. This effect of verapamil does not seem to be related to an inhibition of Ca2+ influx, because neither EGTA [ethylene glycol-bis (beta-aminoethyl ether)-N,N',N'-tetraacetic acid] nor Ni2+ modified macrolide efflux. The nature and characteristics of the entry- and efflux-mediating carrier systems are under investigation.

Multi-centre collaborative study for the in vitro evaluation of new macrolides dirithromycin and erythromycylamine. Australian Group for Antimicrobial Resistance (AGAR)

A national study was conducted to determine the in vitro activity of 2 newer macrolides, dirithromycin and erythromycylamine compared with that of erythromycin, tetracycline and penicillin. Nineteen major teaching hospitals participated in the study. Minimal Inhibitory Concentrations (MICs) were determined by agar dilution, mostly using Iso-Sensitest Agar and an inoculum of 10(4) cells per spot. 2284 clinically significant strains were isolated in late 1991 and early 1992, comprising 1736 Gram-positive cocci, 355 Haemophilus influenzae, 97 Moraxella catarrhalis, 32 Listeria monocytogenes, 25 Neisseria meningitidis and 39 Neisseria gonorrhoeae were tested. The study indicates that dirithromycin and erythromycylamine possess antibacterial activity equivalent to that of erythromycin against most Gram-positive cocci and M. catarrhalis. Strains resistant to erythromycin were also resistant to dirithromycin and to erythromycylamine. Tetracycline was as active as the macrolides against both penicillin-resistant and penicillin-susceptible strains of Staphylococcus aureus. Coagulase-negative penicillin-resistant staphylococci, compared with tetracycline, were relatively resistant to the macrolides. H. influenzae was less susceptible than the Gram-positive cocci.

Validation of NCCLS macrolide (azithromycin, clarithromycin, and erythromycin) interpretive criteria for Haemophilus influenzae tested with the Haemophilus test medium. National Committee for Clinical Laboratory Standards

Some recently marketed macrolide antimicrobial agents possess physiochemical, antimicrobial, and pharmacokinetic advantages that enable their wider clinical use against Haemophilus influenzae infections. A five-laboratory study assessed the validity of existing or proposed azithromycin, clarithromycin, and erythromycin interpretive criteria for tests with H. influenzae isolates. National Committee for Clinical Laboratory Standards (NCCLS) methods, criteria, and quality-control guidelines were used. A total of 350 H. influenzae strains were processed, including fresh clinical isolates (250 strains) and replicate tests of 100 stock cultures sampling strains isolated from 1984 to 91. Azithromycin interpretive criteria (susceptible at < or = 4 micrograms/ml, > or = 12 mm) produced a 99.8% absolute agreement between the minimum inhibitory concentrations and disk diffusion results (0.2% false-susceptible error). Clarithromycin breakpoint criteria (susceptible at < or = 8 micrograms/ml, > or = 13 mm; and resistant at > or = 32 micrograms/ml, < or = 10 mm) produced high minor interpretive error, but < or = 1% combined false-susceptible and false-resistant discrepancies. Erythromycin interpretive guidelines were initially proposed for susceptible at < or = 0.5 microgram/ml, > or = 26 mm. This categorizes nearly all H. influenzae strains as resistant to this older macrolide. The NCCLS should consider the proposed erythromycin criteria for publication in appropriate tables, and a class drug should also be selected (azithromycin) that would best predict macrolide-class susceptibility for those agents indicated by the US Food and Drug Administration for H. influenzae infection chemotherapy (azithromycin and clarithromycin). No serious interpretive problems were observed with the current NCCLS criteria using Haemophilus test medium.

Semi-synthetic derivatives of 16-membered macrolide antibiotics

The fermentation-derived 16-membered and 14-membered macrolides have been equally productive sources of semi-synthetic derivatives which have significantly extended the utility of the macrolide class as important antibiotics. New derivatives, prepared by both chemical and biochemical methods, have exhibited a variety of improved features, such as an expanded antimicrobial spectrum, increased potency, greater efficacy, better oral bioavailability, extended chemical and metabolic stability, higher and more prolonged concentrations in tissues and fluids, lower and less frequent dosing, and/or diminished side-effects [302]. However, even more improvements are both achievable and necessary if problems such as resistance to existing antibiotics continue to rise [303, 304]. Newer semi-synthetic macrolides which satisfy these important needs should be anticipated as the contributions from new fields such as genetic engineering of macrolide-producing organisms and more powerful computational chemistry are combined with the more traditional disciplines of chemical synthesis, bioconversions, and screening fermentation broths.

Clarithromycin: review of a new macrolide antibiotic with improved microbiologic spectrum and favorable pharmacokinetic and adverse effect profiles

OBJECTIVE

To compare the new macrolide antibiotic clarithromycin with erythromycin in terms of in vitro activity, pharmacokinetics, pharmacodynamics, clinical efficacy, and toxicity.

DATA IDENTIFICATION

An English-language literature search employing MEDLINE (1987-91), Index Medicus (1987-91), Program and Abstracts of the 30th Interscience Conference on Antimicrobial Agents and Chemotherapy (1990), Program and Abstracts of the 31st Interscience Conference on Antimicrobial Agents and Chemotherapy (1991), and bibliographic reviews of related textbooks and review articles.

STUDY SELECTION

Eighty-five articles were selected. Clinical trials with clarithromycin have been limited, and emphasis was placed on trials reported in the Program and Abstracts of the 30th Interscience Conference on Antimicrobial Agents and Chemotherapy and Program and Abstracts of the 31st Interscience Conference on Antimicrobial Agents and Chemotherapy.

DATA EXTRACTION

Articles were assessed for study quality and specific information addressing the stated purpose. In articles reporting the results of clinical trials, emphasis was placed on comparative efficacy and toxicity.

RESULTS OF DATA ANALYSIS

A review of 24 human trials suggests that clarithromycin is equally effective as erythromycin, penicillin VK, ampicillin, or amoxicillin for treatment of a variety of upper and lower respiratory tract or skin infections. Clarithromycin also appears to be better tolerated than these agents, with a lower incidence of gastrointestinal adverse effects. Limited clinical studies in patients with Mycobacterium leprae or Mycobacterium avium-intracellulare complex (MAI) suggest that clarithromycin may prove to be efficacious and well tolerated in the treatment of these infections.

CONCLUSIONS

Clarithromycin is as effective in vivo as erythromycin, with less gastrointestinal irritation. Additionally, clarithromycin appears to expand the traditional spectrum of macrolide antibiotics, with promising activity against M. leprae and MAI.

Resistance to erythromycin in group A streptococci

BACKGROUND

The use of erythromycin in Finland nearly tripled from 1979 to 1989. In 1988, we observed an unusually high frequency of resistance to erythromycin in group A streptococci in one geographic region. Because routine testing does not detect the sensitivity of these organisms to antibiotics, we initiated a national study to evaluate the extent of this resistance.

METHODS

We studied 272 isolates of group A streptococci obtained from blood cultures from 1988 through 1990. In 1990 we collected from six regional laboratories 3087 consecutive isolates from throat swabs and 1349 isolates from pus samples. Resistance was indicated by growth on blood agar containing 2 micrograms of erythromycin per milliliter after incubation in 5 percent carbon dioxide. We also evaluated the clinical importance of erythromycin resistance in a retrospective study of consecutive patients with pharyngitis.

RESULTS

The frequency of resistance to erythromycin in group A streptococci from blood cultures increased from 4 percent in 1988 to 24 percent in 1990. From January to December 1990, the frequency of resistance in isolates from throat swabs increased from 7 percent to 20 percent, and resistance in isolates from pus increased from 11 percent to 31 percent. In four communities within 50 km of each other, the frequency of erythromycin resistance ranged from 2 to 5 percent to 26 to 44 percent. Several distinct DNA restriction profiles and serotypes were found among resistant isolates from the same area, suggesting a multiclonal origin. The treatment of pharyngitis with erythromycin failed in 9 of 19 patients infected with erythromycin-resistant group A streptococci, as compared with 1 of 26 patients with erythromycin-susceptible isolates (47 percent vs. 4 percent, P = 0.008).

CONCLUSIONS

In Finland since 1988 there has been a rapid and substantial increase in resistance to erythromycin in group A streptococci. The extent of this resistance is particularly serious since there are only a few alternative antibiotics available for peroral treatment of group A streptococcal infections.

The safety and efficacy of clarithromycin in patients with Legionella pneumonia

Clarithromycin, a new macrolide antibiotic, is at least four times more active in vitro than erythromycin against Legionella pneumophila. In this study the safety and efficacy of orally administered clarithromycin (500 to 1,000 mg bid) in the treatment of Legionella pneumonia were evaluated. Forty-six patients were enrolled in the study, 15 of whom had not responded to previous routine anti-Legionella therapy (erythromycin, ofloxacin, rifampin [rifampicin], or tetracycline). Twelve patients prematurely discontinued the study (nine by the patient's request while feeling well; one because of cancer diagnosis; and two because of adverse events). The response rates after treatment were as follows: clinical cure rate, 98 percent (43/44); clinical success (cure or improved), 100 percent (44/44); radiographic success (cure and improved), 93 percent (28/30); direct antigen fluorescence resolution, 100 percent (40/40); and bacteriologic cure, 100 percent (13/13). Ten patients reported 13 adverse events (seven mild, four moderate, and two severe). Clarithromycin is a safe effective treatment for patients with severe chest infections due to Legionella pneumophila.

The future role and importance of macrolides

The new macrolides, notably clarithromycin and azithromycin, are significant advances over previous agents. With an extended antibacterial spectrum, increased activity, improved absorption and excellent tissue and intracellular penetration, they realize therapeutic aims which have been increasingly sought in the 1980s. They are likely to find an extended role in respiratory tract infections, especially in community-acquired pneumonia, where the activity against beta-lactam-resistant bacteria and intracellular pathogens, e.g. Mycoplasma pneumoniae, Legionella spp. and Chlamydia pneumoniae have a significant role to play. Realistic twice or once daily dosing will prove a powerful argument for their use and the major improvement in gastrointestinal tolerance compared with erythromycin is likely to prove a deciding factor in their favour.

Macrolides and host defences to respiratory tract pathogens

An ever-expanding list of macrolides is being developed for therapeutic use. In addition to their direct antimicrobial action, it is being increasingly recognized that these drugs exhibit some degree of immunomodulatory capacity. Some are able to affect polymorphonuclear (PMN) leukocytes, chemotaxis (josamycin, roxithromycin) or respiratory burst (roxithromycin), accumulate within the phagocytic cell (all drugs to a greater or lesser extent) and exhibit intracellular bioactivity (erythromycin, josamycin, roxithromycin). Some of the newer macrolides (rokitamycin and clarithromycin) have not yet been tested in this respect. Nor have the in-vitro effects of the drugs been demonstrated in vivo although indirectly it is well recognized that many of the macrolides are clinically efficacious in the treatment of respiratory tract infections.

Clinical efficacy and tolerance of two new macrolides, clarithromycin and josamycin, in the treatment of patients with acute exacerbations of chronic bronchitis

The efficacy and safety of oral 500 mg clarithromycin given twice daily and 500 mg josamycin given three times daily were compared for up to 14 days in the treatment of 103 out-patients with acute exacerbations of chronic bronchitis in an open, randomized study. The predominant pathogens isolated were Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus. Clinical cures were experienced by 85% of the clarithromycin-treated patients, with an additional 10% showing improvement. In josamycin-treated patients, 76% of the patients experienced clinical cures and an additional 19% showed improvement. Eradication of the causative pathogen occurred in approximately 95% of the patients in both treatment groups. Adverse events, which all involved the gastro-intestinal tract and were mild, transient and probably related to therapy, were experienced by 5.8% and 7.8%, respectively, of the clarithromycin- and josamycin-treated patients. It is concluded that clarithromycin given twice daily is as effective as josamycin given three times daily.

Efficacy and safety of clarithromycin versus josamycin in the treatment of hospitalized patients with bacterial pneumonia

The efficacy and safety of 500 mg clarithromycin and 1000 mg josamycin both given twice daily for a maximum of 14 days were compared in the treatment of 72 hospitalized patients with bacterial pneumonia. The predominant pathogens isolated were Streptococcus pneumoniae and Staphylococcus aureus. Clinical success was reported for 91.5% of patients treated with clarithromycin and for 87.0% of those treated with josamycin. Eradication of the causative pathogen was noted in 85.7% of patients receiving clarithromycin and in 90% of those receiving josamycin. Adverse events considered probably to relate to therapy were experienced by 2% of patients treated with clarithromycin and by 12.5% of those treated with josamycin; one patient treated with josamycin was withdrawn because of severe nausea and moderate vomiting. Treatment with clarithromycin at half the dosage of josamycin was found to have comparable efficacy and to be associated with a lower incidence of adverse events.

Comparative efficacy and tolerability of clarithromycin and amoxycillin in the treatment of out-patients with acute maxillary sinusitis

The efficacy and tolerability of clarithromycin and amoxycillin in the treatment of acute maxillary sinusitis were compared in an open, Phase III multi-centre study. Sixty-one out-patients (40 males, 21 females) received clarithromycin (two 250 mg tablets twice daily) and 59 (34 males, 25 females) out-patients received amoxycillin (two 500 mg capsules twice daily). Fifty-seven and 47 patients in the clarithromycin group were evaluable for clinical efficacy and bacteriological effectiveness, respectively. In the amoxycillin group, 57 and 40 patients were evaluated for clinical efficacy and bacteriological effectiveness, respectively. Body temperature, bacteriological culture results, blood and urine chemistries, and clinical signs and symptoms were evaluated prior to drug administration, between Days 4 to 6 and between Days 9 to 11 of treatment, and within 48 hours and, if required, 6 weeks after the end of treatment. Clinical signs and symptoms improved significantly (p less than 0.001) in both treatment groups. When evaluated within 48 hours after the end of treatment, there was no significant difference between the clinical success rate for clarithromycin (91%) and amoxycillin (84%) nor in the number of patients whose original pathogen was eradicated (89% clarithromycin, 93% amoxycillin). Six patients reported adverse events, 2 with clarithromycin (urticaria, gastro-intestinal) and 4 with amoxycillin (2 urticaria, 2 gastro-intestinal). Clarithromycin was comparable to amoxycillin with respect to clinical efficacy and tolerability and offers a useful addition to the available therapies for the treatment of acute maxillary sinusitis.

Comparison of the clinical and bacteriological efficacy of clarithromycin and erythromycin in the treatment of streptococcal pharyngitis

The efficacy and tolerability of clarithromycin and erythromycin stearate in the treatment of documented Group A beta-haemolytic streptococcal pharyngitis were compared in a single-centre, open, out-patient study. One hundred and twenty patients were randomly assigned to each treatment group. Dosage of clarithromycin and erythromycin was 250 mg twice daily and 500 mg twice daily, respectively; each patient was given a 10-day supply of medication. Clinical success (cured or improved) was observed in 111 (96.5%) of 115 and in 108 (93.9%) of 115 clinically-evaluable patients treated with clarithromycin and erythromycin, respectively. Eradication of the pathogen occurred in 108 (97.3%) of 111 and in 98 (92.5%) of 106 bacteriologically-evaluable clarithromycin and erythromycin patients, respectively. Adverse events reported by 7 (5.8%) of the clarithromycin-treated and by 12 (10%) of the erythromycin-treated patients included epigastritis and nausea and vomiting. In general, the severity of adverse events was greater for the patients treated with erythromycin, necessitating the discontinuation of therapy in 8 (6.7%) patients treated with erythromycin as opposed to 1 (0.8%) patient treated with clarithromycin. Although clarithromycin and erythromycin were comparable in terms of efficacy, clarithromycin was better tolerated.

Bioassay for A-56268 (TE-031) and identification of its major metabolite, 14-hydroxy-6-O-methyl erythromycin

A-56268 is a new macrolide which is generally two-fold more potent than erythromycin. A new bioassay is described in which plasma samples are extracted with acetonitrile prior to bioassay. The concentration range for the assay is between 0.05-4.0 micrograms/ml, and the concentrations measured are within 6% of those measured by high-power liquid chromatography. An active metabolite which is as active as erythromycin was identified in the plasma. The plasma half-life and area under the plasma curve values of A-56268, as determined by bioassay, were significantly greater than those of erythromycin.