Macrolide Drugs Research Articles

In-vitro antimycoplasmal activity of flurithromycin

The in vitro activity of flurithromycin, a 14-membered macrolide drug, was found to be similar to that of erythromycin against 41 strains of Mycoplasma spp. and 100 strains of Ureaplasma urealyticum. All 28 strains of Mycoplasma hominis were uniformly resistant to both macrolides with MICs > 256 mg/L, U. urealyticum showed intermediate resistance with MIC50s of 0.5 and 1 mg/L for erythromycin and flurithromycin, respectively, whereas the ten strains of Mycoplasma pneumonia were susceptible to < or = 0.03 mg/L of both macrolides.

Efficacy of Clarithromycin vs. Amoxicillin/Clavulanate in the Treatment of Acute Maxillary Sinusitis

A new macrolide drug, clarithromycin (Biaxin) was compared with amoxicillin/clavulanate (Augmentin) in a single-blind (investigator-blind), randomized, multicenter study of 497 outpatients with acute maxillary sinusitis; treatment was 500 mg clarithromycin bid (n = 246) or 500 mg amoxicillin/clavulanate tid (n = 251). Pathogens included Streptococcus pneumoniae in 22% of patients, Staphylococcus aureus in 16%, Haemophilus influenzae in 10%, and Moraxella catarrhalis in 7%. For evaluable patients, clinical success (cure or improvement) was noted for 97% (128/132) of clarithromycin recipients and 93% (119/128) amoxicillin/clavulanate recipients. Clinically significant improvement in signs and symptoms was comparable between groups. Bacteriologic cure rates were 87% (115/132) and 90% (115/128), respectively. Respective pathogen eradication rates were 87% (125/143) and 90% (125/139). Adverse events not due to concurrent conditions occurred in 41% of the former and 46% of the latter group; most were mild to moderate gastrointestinal upsets (21% and 38%, respectively; P < 0.001). We conclude that clarithromycin appears to be as effective as amoxicillin/clavulanate in acute maxillary sinusitis and may cause fewer gastrointestinal upsets.

Activities of fluoroquinolone, macrolide, and aminoglycoside drugs combined with inhibitors of glycosylation and fatty acid and peptide biosynthesis against Mycobacterium avium

Smooth- and rough-colony variants of Mycobacterium avium serovar 4 were treated with three classes of drugs. The drugs were chosen for their potential inhibitory effects on the biosynthesis of the cell envelope-associated serovar-specific glycopeptidolipid antigens. Growth was monitored radiometrically with a BACTEC 460-TB instrument, and MICs were determined for each drug. Both variants were then treated with inhibitory drugs in combination with antimicrobial agents that have demonstrated effectiveness against M. avium. No growth inhibition was observed with 6-fluoro-6-deoxy-D-glucose or avidin. Inhibitors of glycosylation, i.e., 2-deoxy-D-glucose, bacitracin, and ethambutol, were inhibitory to smooth- and rough-colony variants, whereas drugs that inhibit peptide synthesis, i.e., N-carbamyl-L-isoleucine and m-fluoro-phenylalanine, were more inhibitory for the rough-colony variant. Cerulenin, which affects fatty acid synthesis, was inhibitory for both variants, but it appeared to be more effective at inhibiting the growth of the smooth-colony variant at equivalent concentrations. Generally, when inhibitors of glycosylation were used with sparfloxacin and amikacin, a synergistic effect was observed for only the smooth variant. When drugs that affect peptide synthesis were used in combination with amikacin, a synergistic effect was observed for the rough variant, and when cerulenin was used in combination with sparfloxacin or amikacin, a synergistic effect was observed for both variants. Lipid analysis revealed that although the rough variant lacks the serovar-specific glycopeptidolipid antigens, it does possess a group of phenylalanine-isoleucine-containing lipopeptides that may explain its different susceptibility patterns to m-fluoro-phenylalanine and N-carbamyl-L-isoleucine. The significance of these results is discussed with reference to various components in the cell envelope and their importance in cell wall permeability.

Antimicrobial activity of ten macrolide, linsosamine and streptogramin drugs tested againstLegionella species

RP59500, a semisynthetic pristinamycin combination, and 14 other antimicrobial agents were tested against 108 Legionella strains. Of the ten macrolide, lincosamine and streptogramin agents tested, the new streptogramin RP59500 ranked seventh in order of activity against Legionella pneumophila on the basis of MIC90 results as follows: clarithromycin = 14-OH clarithromycin (MIC90 0.12 mg/l) > roxithromycin > erythromycin = tylosin = virginiamycin > RP59500 (MIC90 1 mg/l) = azithromycin > dirithromycin > clindamycin (MIC90 8 mg/l). Of all 14 drugs tested in this study, rifampicin was the most potent with an MIC90 of 0.008 mg/l. In this retrospective study of Legionella strains (1981-1990 isolates), we observed no trend toward resistance to the agents investigated.

Induction of neurofibrillary degeneration following treatment with maytansine in vivo

The effects of maytansine (MYT), a naturally occurring ansa macrolide and potent antimitotic drug that binds to tubulin, were studied by light and electron microscopy in the central nervous system of rabbits. Respectively, 17 and 5 animals were sacrificed at various time intervals following a single intrathecal or intraocular injection of the agent. The rabbits responded to the intrathecal injection with progressively severe weakness. By 19 h following injection the neurons of the cervical spinal cord, medulla and pons showed, by light microscopy, a marked clumping of the Nissl substance, while on the third day and later the nerve cell perikarya and dendrites displayed severe neurofibrillary changes. By electron microscopy several cytological alterations were observed as early as 19 h; among them were the clumping of the rough endoplasmic reticulum, the reduction in number of microtubules, and the presence of a fine, floccular and amorphous material. The perikaryonal and dendritic neurofibrillary changes appeared as tangles and/or bundles of 10 nm neurofilaments. In the intraocularly injected rabbits the earliest changes observed in retinal ganglion cells were the severe reduction in microtubule number and the presence of an amorphous material. The neurofibrillary changes seen at later times were comparable with those observed in the cervical cord and brain stem. Although the molecular events occurring between the formation of the intracytoplasmic MYT-tubulin complexes and the accumulation of filaments are not known, the present results indicate that the proliferation of neurofilaments is chronologically preceded by the reduction in number of the microtubules and by the appearance of an amorphous floccular material in the cytoplasm. It is emphasized that despite differences in binding characteristics and physico-chemical properties, maytansine, colchicine and the Vinca alkaloids have, as a common denominator, the property of interfering with the process of utilization of tubulin and in that way they seem to differ from other chemical agents known to induce neurofibrillary degeneration.

Treatment of Pneumococcal Pneumonia

The emergence of Streptococcus pneumoniae strains with resistance to penicillin, macrolide, and other drugs has made the treatment of pneumococcal infections more complicated. Although resistance to penicillin has had a profound impact on the outcome of meningitis, it has had little impact on the mortality from pneumococcal pneumonia because the serum and pulmonary levels achieved with penicillin (or related drugs) are several times higher than the minimal inhibitory concentration of the strains. Thus, based on current levels of resistance to penicillin and cephalosporin, most patients with mild/moderate pneumococcal pneumonia may respond to oral amoxicillin, and most with severe pneumonia may be successfully treated with intravenous ceftriaxone, cefotaxime, or amoxicillin-clavulanic acid. It is of concern that patients infected with erythromycin-resistant pneumococci may not respond to therapy with a macrolide. In our opinion, except for well-selected patients, imipenem and vancomycin should not be widely used for the treatment of pneumococcal pneumonia. Some new drugs such as the new quinolones may play an important role in the management of pneumonia in the near future.