Miocamycin-containing triple therapy for H. pylori infection.

INTRODUCTION: In Northern Sardinia, one-week triple standard therapies containing a proton-pump inhibitor and two antibiotics for H. pylori infection have an average cure rate of 57% largely due to a high prevalence of antimicrobial resistance. The efficacy of miocamycin-containing treatment for 10 days was evaluated. MATERIALS AND METHODS: Patients referred to the endoscopy service for dyspeptic symptoms were enrolled. H. pylori infection was defined as a positive rapid urease test, presence of the bacteria on gastric biopsies, and a positive 13C-UBT. Treatment consisted of 10 days with omeprazole 20 mg, miocamycin water-soluble 900 mg, and tinidazole 500 mg all bid. Success was evaluated 40-50 days after the end of therapy and defined by a negative 13C-UBT. Compliance was considered good if at least 90% of the total number of the pills were taken. Fluorescent in situ hybridization (FISH) technique was applied on paraffin-embedded gastric tissue sections to test susceptibility to clarithromycin of the bacteria. RESULTS: 50 patients were enrolled (mean age; 52, 36% men). Miocamycin-containing therapy cured 86% (42/49; 95% CI = 72-94%) of infected patients by PP analysis. Susceptibility data (FISH) was available for 38 patients. Cure rates for the 28 with clarithromycin-susceptible infection was 96% vs 50% for those with resistant or mixed infection, (p = .003). Good compliance was recorded in 48 patients. None of the patients discontinued therapy. CONCLUSIONS: Miocamycin appears to be a valid alternative for clarithromycin for H. pylori eradication. Head-to-head studies will be needed to ascertain whether it is superior.

Aberrant gene methylation is a biomarker for the detection of cancer cells in peritoneal wash samples from advanced gastric cancer patients.

PURPOSE: To assess whether gene methylation in peritoneal fluid (PF) is clinically feasible for determining micrometastasis to the peritoneum in gastric cancer. METHODS: The gene methylation of BNIP3, CHFR, CYP1B1, MINT25, SFRP2, and RASSF2 were analyzed in 107 specimens of PF by quantitative methylation-specific polymerase chain reaction. All patients were placed into one of 3 groups: group A (n = 42), patients with depth of cancer invasion at muscularis propria (MP) or less than MP; group B (n = 45), depth of cancer invasion beyond the MP; and group C (n = 20), histologically diagnosed peritoneal metastasis or cancer cells cytologically defined in the peritoneal cavity. Patients in both groups A and B were diagnosed as having no cancer cells by peritoneal cytology and histology. RESULTS: The methylation status of the 6 genes was found to be significantly different among the 3 groups (group A, 0-5%; group B, 0-15%; group C, 15-45%; P < 0.01). Furthermore, the rate of positive methylation in any of the 6 genes was significantly different in each group (group A, 7%; group B, 20%; group C, 75%; P < 0.001). Three of 9 patients in group B with positive methylation in any of 6 genes experienced peritoneal recurrence. On the other hand, only 1 of 36 patients without gene methylation experienced peritoneal recurrence (P < 0.05). CONCLUSIONS: DNA methylation in PFs is a possible marker detecting occult neoplastic cells on the peritoneum. Methylation analysis along with a cytological examination might therefore improve the positive detection of cancer cells in PF of gastric cancer.

Solithromycin Can Specifically Induce Macrolide-Lincosamide-Streptogramin B Resistance.

Objectives: Solithromycin is a fluoroketolide that is considered to be a noninducing antibiotic for macrolide-lincosamide-streptogramin B resistance mediated by erm genes. The exact activity of solithromycin to induce erm gene expression remains to be determined. Materials and Methods: The potential of solithromycin to induce erm(A), erm(C), and erm(B) gene expression was examined using a lacZ reporter assay, double-disk diffusion test, and determination of the minimal inhibitory concentration after incubation with subinhibitory concentration of different antibiotics. Results: Neither solithromycin nor the ketolides telithromycin and cethromycin induced erm(A) or erm(C) gene expression. However, solithromycin could significantly induce erm(B) gene expression at levels greater than that seen for cethromycin and clindamycin, but less than that for erythromycin, rokitamycin, and telithromycin. Conclusion: Solithromycin does not induce erm(A) and erm(C) gene expression, but does induce erm(B) gene expression, although to a weaker extent than that seen for macrolides.

Therapeutic effect of rokitamycin in vitro and on experimental meningoencephalitis due to Naegleria fowleri.

Inhalation of freshwater containing the free-living amoeba Naegleria fowleri leads to a potentially fatal infection known as primary amoebic meningoencephalitis (PAME). Amphotericin B is the only agent with clinical efficacy in the treatment of PAME in humans, however this drug is often associated with adverse effects on the kidney and other organs. In an attempt to select other useful therapeutic agents for treating PAME, the amoebicidal activities of antibacterial agents including clarithromycin, erythromycin, hygromycin B, neomycin, rokitamycin, roxithromycin and zeocin were examined. Results showed that the growth of amoeba was effectively inhibited by treatment with hygromycin B, rokitamycin and roxithromycin. Notably, when N. fowleri trophozoites were treated with rokitamycin, the minimal inhibitory concentration was 6.25 microg/mL on Day 2. In the treatment of experimental meningoencephalitis due to N. fowleri, survival rates of mice treated with roxithromycin and rokitamycin were 25% and 80%, respectively, over 1 month. The mean time to death for roxithromycin and rokitamycin treatment was 16.2 days and 16.8 days, respectively, compared with 11.2 days for control mice. Finally, rokitamycin showed both in vitro and in vivo therapeutic efficacy against N. fowleri and may be a candidate drug for the treatment of PAME.

Design and synthesis of novel leucomycin analogues modified at the C-3 position. Part II: 3-O-(3-Aryl-2-propenyl)leucomycin analogues.

The design and synthesis of 16-membered macrolides modified at the C-3 position are described. Starting from fully protected intermediate (5), appropriate modifications including Heck reaction were performed to furnish 3-O-(3-aryl-2-propenyl)leucomycin A(7) analogues (9a-9m). These leucomycin A(7) derivatives showed improved in vitro antibacterial activities against clinically important pathogens including erythromycin-resistant Streptococcus pneumoniae (ERSP). SAR analysis of derivatives modified at the C-3 and C-3'' positions suggested that single modification at C-3 or C-3'' was effective for in vitro antibacterial activity.

Novel 16-membered macrolides modified at C-12 and C-13 positions of midecamycin A1 and miokamycin. Part 1: Synthesis and evaluation of 12,13-carbamate and 12-arylalkylamino-13-hydroxy analogues.

Design and synthesis of 16-membered macrolides modified at the C-12 and 13 positions are described. The compounds we report here have an arylalkylamino group attached to the C-12 position of the macrolactone. Both types of derivatives, 12,13-cyclic carbamates and non-carbamate analogues, were synthesized via 12-amino-13-hydroxy intermediates derived from 12,13-epoxide that was prepared by selective epoxidation at the C-12 and C-13 positions. 4'-Hydroxyl analogues were also prepared by acidic hydrolysis of a neutral sugar. These compounds were evaluated for in vitro antibacterial activity against respiratory tract pathogens. Some of these analogues exhibited an improved activity compared with the corresponding parent compound.

[Comparison of antimicrobial and bactericidal activities and postantibiotic effects of macrolides antibiotics against clinical isolates, and examination of shape alteration by scanning electron microscope].

We examined antibacterial activities of 4 kinds of macrolides (MLs), erythromycin (EM), clarithromycin (CAM), azithromycin (AZM) and rokitamycin (RKM), against 4 bacterial species of clinical strains isolated in 2004. Bacterial isolates used were 51 strains of methicillin-susceptible Staphylococcus aureus (MSSA), 20 of Streptococcus pyogenes, 68 of Streptococcus agalactiae, and 120 of Streptococcus pneumoniae. Macrolide resistance genes, ermB and mefE, in macrolide-resistant S. pyogenes and S. agalactiae, and all of pneumococci were analyzed by PCR. Antimicrobial activities against macrolide-susceptible MSSA of EM and CAM, were more potent than those of RKM. By contrast, against S. pneumoniae, RKM was more effective than EM, CAM and AZM. Against S. pyogenes and S. agalactiae, 4 antibiotics showed similar antimicrobial activities. Twelve, 1 and 2 strains of MSSA, S. pyogenes and S. agalactiae, respectively, were resistant to EM, CAM and AZM, whereas RKM was active to almost, but not quite, of them. Among 120 strains of S. pneumoniae, 76 (63.3%) were resistant to EM (MIC; > or = 0.5 microg/mL), and 23, 15 and 28 strains were highly resistant (MIC; > 128 microg/mL) to EM, CAM and AZM, respectively. By contrast, for RKM, there were far fewer resistant strains, and there was no highly resistant strain. PCR analyses of macrolide-resistant genes revealed that 1 resistant strain of S. pyogenes and 2 of S. agalactiae carried mefE and ermB, respectively. In the case of S. pneumoniae, 59, 19 and 5 strains, respectively, carried ermB, mefE and both ermB and mefe. We also studied about bactericidal activities and postantibiotic effects (PAE) of MLs using macrolide-susceptible, and ermB- and mefE-carrying S. pneumoniae, and observed morphological alterations of the strains treated with the drugs by a scanning electron microscope. It was demonstrated that RKM had superior bactericidal activities and PAE than other 3 drugs, and potent destructive effects to all of 3 strains.

Miocamycin. A review of its antimicrobial activity, pharmacokinetic properties and therapeutic potential.

Miocamycin is an orally administered 16-membered macrolide antimicrobial drug. It has a spectrum of in vitro activity similar to that of erythromycin, inhibiting a range of Gram-positive and Gram-negative organisms, atypical microbes and some anaerobes. Importantly, miocamycin demonstrates greater in vitro potency than erythromycin against several pathogens including Legionella pneumophila, Mycoplasma hominis, and Ureaplasma urealyticum. Equally noteworthy is its activity against erythromycin-resistant staphylococcal and streptococcal species expressing inducible-type resistance. Miocamycin possesses poor overall activity against Haemophilus influenzae and is inactive against Enterobacteriaceae. Penetration of miocamycin into body tissues and fluids is both rapid and extensive. The 3 major metabolites of miocamycin possess antimicrobial activity and may contribute to the therapeutic efficacy of the drug. Clinical data indicate that miocamycin is useful in the treatment of upper and lower respiratory tract infections in both adult and paediatric patients. Miocamycin is also effective in the treatment of urogenital tract infections caused by Chlamydia trachomatis or U. urealyticum. Several studies suggest that miocamycin is at least as effective as erythromycin in these indications; however, comparisons with newer macrolide agents have yet to be performed. In other studies, miocamycin proved to be a useful agent in the treatment of periodontal infections and as anti-infective prophylaxis in dental surgery. Miocamycin appears to have a tolerability profile qualitatively similar to that of other macrolides, with gastrointestinal and skin disorders being the most commonly reported adverse events. Current data suggest that the potential for drug interactions with miocamycin is low, with the possible exceptions of carbamazepine and cyclosporin. Thus, although further confirmation and elaboration of various aspects of its efficacy and tolerability profile is needed, at this stage miocamycin offers a useful alternative oral therapy to erythromycin for the treatment of uncomplicated community-acquired respiratory tract infections and nongonococcal urethritis.

Antibacterial activity of rokitamycin compared with that of other macrolides.

The activity of rokitamycin, a 16-membered macrolide, was compared with other macrolides and agents used to treat respiratory infections. Rokitamycin had in vitro activity against streptococci and Streptococcus pneumoniae comparable to the other macrolides, inhibiting most organisms at less than 0.03 to 0.5 microgram/ml. It was the most active macrolide agent against Staphylococcus aureus, inhibiting 90% at 1 microgram/ml. Macrolide-resistant streptococci and staphylococci in which resistance was inducible were inhibited, but constitutively resistant Gram-positive bacteria were resistant. Rokitamycin was less active than erythromycin against Haemophilus influenzae, but had activity comparable to erythromycin against Moraxella catarrhalis and Neisseria gonorrhoeae. It inhibited Clostridium spp. and peptostreptococci, but had poor activity against Bacteroides species. Rokitamycin was bactericidal for streptococci and staphylococci, but not for enterococci. Overall rokitamycin has in vitro activity comparable to currently available 14-membered macrolides. Its clinical utility will be influenced by the degree of metabolism to less active metabolites since 70% is rapidly metabolized.

Adhesive binding of rokitamycin to Staphylococcus aureus ribosomes.

Rokitamycin (RKM), a 3"-O-propionyl derivative of leucomycin A5, is bactericidal against staphylococci near the minimum inhibitory concentrations. RKM bound to ribosomes before-hand is only slightly displaced by erythromycin or josamycin, or even by RKM itself. The adhesive binding of the RKM-ribosome complex might prove to be the lethal event for susceptible staphylococci.

Development of macrolide resistance by ribosomal protein L4 mutation in Streptococcus pyogenes during miocamycin treatment of an eight-year-old Greek child with tonsillopharyngitis.

Streptococcus pyogenes isolates with the same pulsed-field patterns were recovered from the throat cultures of a child with tonsillopharyngitis before and after treatment with miocamycin, a 16-membered macrolide. The initial isolate was macrolide-susceptible, but the isolates after the treatment were resistant to 14 and 15-membered macrolides and had two amino acid (65WR66) deletions in ribosomal protein L4.

The post-antibiotic effects of rokitamycin (a 16-membered ring macrolide) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes.

The post-antibiotic effects (PAEs) on susceptible and erythromycin-resistant strains of Streptococcus pyogenes (M phenotype and inducibly resistant) of rokitamycin and erythromycin were investigated in vitro using microbiological impedance measurement. Exposure of susceptible S. pyogenes strains to 1/4, 1/2, 1 and 2 MIC erythromycin and rokitamycin resulted in PAEs of rokitamycin in the same order of magnitude as those of erythromycin and that were dose dependent. The duration of rokitamycin PAEs in erythromycin-resistant S. pyogenes strains (M phenotype and those with inducible resistance) were comparable with those observed in susceptible strains. This was not the case for erythromycin. The investigation showed that a 16-membered ring macrolide such as rokitamycin has different PAEs from those of a 14-membered ring macrolide such as erythromycin. They also indicated that, as the PAEs of rokitamycin on the M phenotype and inducible resistant strains were comparable with those on susceptible strains, no re-evaluation of therapeutic dosing regimens was required.

Treatment with rokitamycin suppresses the lethality in a murine model of Escherichia coli O157:H7 infection.

The effects of rokitamycin (ROK) and levofloxacin (LEVX) were investigated in a murine model of enterohaemorrhagic Escherichia coli (EHEC) infection. After C3H/HeN mice were inoculated intragastrically with E. coli O157:H7, ROK (20mg/kg) or LEVX (1.2 mg/kg) was administered intragastrically. The death rate of the mice was noted and the faeces were collected to determine viable cell counts of EHEC and for Shiga-like toxins (SLTs) assays. After the mice were sacrificed, the kidneys and colons of some of the mice were removed for histopathological examination. The death rate of mice administered ROK (19%) was significantly lower than that of the control and LEVX-treated groups (80, 93%, respectively). Viable cell counts of EHEC in the faeces of the control and ROK-treated groups were 10(7) and 10(6) CFU/g at day 5 after the infection, respectively. LEVX reduced the bacterial count by less than 100 CFU/g at day 5. The level of SLTs in the faeces from the ROK group were lower than the LEVX-treated and control groups at day 5. The histopathological findings in the kidneys treated with LEVX showed necrotic tubular epithelial cells and those in the colon, inflammatory infiltrates. These were not seen in the ROK-treated group. These results suggested that ROK suppressed release of SLTs from the EHEC and could be useful in the treatment of EHEC infection.

Macrolides and clindamycin suppress the release of Shiga-like toxins from Escherichia coli O157:H7 in vitro.

We investigated the effects of antimicrobial agents fosfomycin (FOS), cefdinir (CDIN), levofloxacin (LEVX), rokitamycin (ROK), roxithromycin (ROX), and clindamycin (CLI) on the release of Shiga-like toxins (SLTs) by enterohaemorrhagic Escherichia coli (EHEC). EHEC was cultured for 14 h in the presence of ROX, ROK or CLI at sub-minimum inhibitory concentrations (subMICs) of 1.56-6.25 mg/l, followed by assay of the level of SLTs in the supernatants using cytotoxicity assay and reversed passive latex agglutination method. Exposure to ROX, ROK or CLI reduced the amount of released SLTs compared with untreated control cultures (P<0.05). These agents however, did not decrease the number of viable EHEC, indicating the importance of bactericidal agents. When the bacteria was exposed to CDIN, FOS or LEVX, the level of SLTs in the culture supernatant increased with the destruction of bacterial cells in the order of CDIN, FOS, LEVX. When 0.5 mg/l of LEVX was added to cultures with or without pretreatment using ROX, ROK, or CLI, the release of SLTs was reduced by this pretreatment (P<0.05). These results may have clinical implications for the treatment of EHEC infection.

Effect of ponsinomycin on the pharmacokinetics of dihydroergotamine administered orally.

Ponsinomycin is a new macrolide antibiotic. Its effect on DHE pharmacokinetics was investigated in this study. Twelve young healthy volunteers received a single 9 mg oral dose of DHE before and on the 8th day of treatment (800 mg twice daily) with ponsinomycin. DHE was assayed in plasma by RIA. Because of low plasma levels, only peak concentrations could be accurately compared for a ponsinomycin effect. We observed a 3-40-fold increase in maximum DHE plasma levels in the majority of cases and a much more important effect on one occasion, when DHE was administered in the presence of ponsinomycin. These data are consistent with an increase of DHE bioavailability in the presence of ponsinomycin, probably related to a reduction of its first-pass elimination. This pharmacokinetic interaction is likely to have clinical consequences and administration of ponsinomycin should be avoided in patients treated orally with DHE.

Development and validation of a method for the polymorphic analysis of pharmaceutical preparations using near infrared spectroscopy.

A new method for the characterization and determination of crystalline miokamycin in a pharmaceutical preparation using near infrared spectroscopy is proposed. The procedure involves the identification against a spectral library of samples with contents above the legal limit (viz. 5% of the crystalline form in amorphous miokamycin) using the Mahalanobis distance as the discriminating criterion, and the determination of the total and crystalline contents using partial least squares models that provide errors <1%. The proposed method was validated following the ICH guidelines. Its simplicity and expeditiousness make it highly suitable for quality control analyses of solid dosage forms.

Implication of cohesive binding of a macrolide antibiotic, rokitamycin, to ribosomes from Staphylococcus aureus.

In a previous paper we reported that rokitamycin (RKM) which killed some types of RKM-susceptible staphylococci bound cohesively to ribosomes obtained from such bacteria whereas other macrolides such as erythromycin and josamycin, which are generally known to be bacteriostatic, bound to these ribosomes only reversibly. From this observation, we speculated that such cohesive binding of RKM to certain ribosomes probably resulted in cell killing (Endou, K. et al., FEMS Microbiology Letters, 72: 93-96, 1990). However, this speculation was based only on circumstantial evidence and we did not show directly that reversible binding of RKM to ribosomes from other strains would bring about bacteriostasis only. A clinically isolated strain. Staphylococcus aureus S704, was found to be susceptible to RKM, mycinamicin and tylosin as well as lincosamide and streptogramin type B antibiotics but not to other macrolides (erythromycin, josamycin, rosamicin, etc.). RKM showed bacteriostatic, but not bactericidal activity, on the strain. Determinant(s) responsible for the bacteriostatic phenotype was transferred into strain NCTC8325 using bacteriophage 80L2; the obtained transductant was referred to as strain 8325MMT7. The drug bound reversibly, not cohesively, to the ribosomes from both strains S704 and 8325MMT7, confirming our earlier hypothesis that rokitamycin can cause bacteriostasis or cell death depending upon whether it binds reversibly or cohesively to the ribosomes of a given strain.

Evaluation of the mutagenicity of miokamycin (MOM), a new macrolide antibiotic in the Ames Salmonella test and the dominant lethal assay.

Miokamycin (MOM), a new macrolide antibiotic, was tested for mutagenicity in the Ames Salmonella test and the dominant lethal assay. MOM was not mutagenic against S. typhimurium strains TA1535-1538, TA100 and TA98 both with and without activation by S-9 mix. No increases in the frequencies of induced dominant lethal effects were found in MOM treated mice. MOM did not have mutagenic activities on either system.

In vitro and in vivo antibacterial activity of 9,3"-Di-o-acetyl midecamycin (Mom), a new macrolide antibiotic.

9,3"-Di-O-acetyl midecamycin (Mom) showed in vitro antibacterial activity against clinical isolates of Staphylococcus aureus and was effective against some of the strans resistant to erythromycin (Em) and josamycin (Jm). The distribution pattern of the level of drug-sensitivity of the isolates to Mom was similar to that of Jm but different from that of Em. Mom- or Jm-resistant strains gradually or rapidly developed among S. aureus strains, that were sensitive or resistant to other macrolide antibiotics. There was no significant difference between Mom and Jm as regards the rate of development of resistant strains. These mutants were always resistant to both Mom and Jm. Mom, like Jm, was effective against Em-inducible strains of S. aureus. The in vivo study demonstrated that Mom was more potent than Jm, similar in its potency to Em against systemic staphylococcal infections, and that it was effective against the infection due to an Em-resistant clinical isolate of S. aureus. Mom was more effective than either Jm or Em against a staphylococcal kidney infection in mice.

Acyl derivatives of 16-membered macrolides. I. Synthesis and biological properties of 3"-O-propionylleucomycin A5 (TMS-19-Q).

Using leucomycin A5 (1), 3"-O-propionylleucomycin A5 (7) was synthesized by the following synthetic route: 2"-O-acetylation, 3,9-di-O-trimethylsilylation, 3"-O-propionylation, 3,9-di-O-detrimethylsilylation and 2'-O-deacetylation. Acylation of the 3"-tertiary hydroxyl group of 2'-O-acetyl-3,9-di-O-trimethylsilylleucomycin A5 with propionyl chloride in the presence of tribenzylamine at 70 degrees C gave a 3"-O-propionyl derivative in 96% yield. The structure of the final compound, 3"-O-propionylleucomycin A5 (7) was confirmed by means of mass, 1H-NMR and 13C-NMR spectrometry and chemical degradations. 3"-O-Propionylleucomycin A5 (7) showed higher antibacterial activity in vitro and higher serum levels than its mother antibiotic. The biological properties of 7 also were compared with those of josamycin and midecamycin.