Comparative study of the therapeutic effect of the glycopeptide antibiotics eremomycin, vancomycin and ristomycin in a model of antibiotic-associated colitis in golden hamsters]

Experiments with a model of intraperitoneal or intragastric lincomycin-induced fatal colitis indicated that eremomycin, vancomycin and ristomycin administered orally in daily doses of 100, 100 and 200 mg/kg, respectively, for 5 days protected the animals from development of antibiotic-associated colitis (AAC), which was evident from prolongation of their life-span to 10-23 days against 3-9 days in the controls. Eremomycin administered intraperitoneally according to an analogous scheme protected the animals from development of AAC, prevented 45 per cent of the animals from death and prolonged the life-span of the other animals to 15-28 days against 3-9 days in the controls. Vancomycin administered intraperitoneally was somewhat more efficient. Still, unlike eremomycin it had a local irritating effect. The protective effect of ristomycin administered intraperitoneally was much lower than that of vancomycin and eremomycin.     

Action of lincomycin, chymotrypsin and their combinations on the course of experimental staphylococcal infection

The culture of Staphylococcus aureus was administered intraperitoneally in a dose of LD30 to albino mice. The animals of the 1st, 2nd and 3rd groups were treated with lincomycin, chymotripsin and combination of lincomycin with chymotripsin respectively. The animals of the 4th group were used as control and were not subjected to the treatment with the drugs. A part of the animals from every group was killed on the 3rd, 7th, 14th, 21st and subsequent days and their organs were investigated microscopically and bacteriologically. It was found that staphylococci was isolated from the control mice during a 50-day period after inoculation. Complete liberation of the organs from the causative agent within 25 days from the beginning of the experiment was registered in the animals treated with lincomycin. Isolation of the staphylococci was over by the 27th day in the animals treated with chymotrypsin. Liberation of the organs from the causative agent by the 17th day was observed in the albino mice treated with the combination of lincomycin with chymotrypsin. The combined use of lincomycin with chymotrypsin proved to be most effective: no death was registered among the albino mice, the levels of the pathogenicity and antibiotic resistance in the pathogenic staphylococci decreased.     

Preclinical toxicological study of the new antibiotic eremomycin. Chronic toxicity and effect on intrauterine development of rats

Toxicity of eremomycin was studied after its multiple parenteral administration to albino rats, guinea pigs and dogs in doses equivalent by the body surface to the daily doses for humans i. e. 1 and 3 g. The antibiotic was administered for 1 to 6 months. Tolerance of the antibiotic by the dogs after intravenous and intramuscular administration was satisfactory. In some animals there were observed an insignificant increase in the activity of alanine aminotransferase and a rise in the level of urea in blood serum. Pathomorphological examination of the internal organs of the albino rats and dogs showed that in high doses the antibiotic could have a damaging effect on the kidneys and epithelium of the gastrointestinal tract. The level of the damages depended on the dose of the antibiotic and duration of its use. The damages induced by eremomycin were reversible. It had no marked effect on the peripheral blood count, coagulation system and erythrocyte resistance. In the tested doses the antibiotic had no unfavourable effect on the hearing function in the experiments with guinea pigs. Studies with rats revealed that eremomycin had no teratogenic effect. A slightly pronounced embryotoxic action was observed only after using the antibiotic in doses exceeding more than 12 times the approximate therapeutic dose.     

The structure and antimicrobial activity of the partial degradation products of the antibiotic eremomycin

Antimicrobial activity of partial degradation products of eremomycin, a new glycopeptide antibiotic, was studied. The products formed by eremomycin deglycosylation (deseremosaminyl eremomycin, eremosaminyl aglycone and aglycone) and elimination of the chlorine atom from the molecule aglycone moiety (dechloroeremomycin). The spectral data in favour of the compounds structure are presented. It was found that partial degradation led to a decrease in the antimicrobial activity of the antibiotic. Dechloreremomycin had the highest activity among the products. Its MIC for the methicillin-resistant strains of Staphylococcus aureus was only twice as low as that of the initial antibiotic.     

Glycopeptide antibiotics: eremomycin, vancomycin, and teicoplanin. Comparison of several parameters of pharmacokinetics and antimicrobial activity

Pharmacokinetic parameters of eremomycin (Institute of New Antibiotics, the USSR Academy of Medical Sciences), teichoplanin (Lepetit) and vancomycin (Eli Lilly) were compared after their intravenous administration to rats in the same dose of 50 mg/kg. It was shown that the area under the concentration time curve of eremomycin was 2 times smaller than that of teichoplanin and 6 times larger than that of vancomycin. The mean retention time of eremomycin was close to that of teichoplanin and 1.6 times higher than that of vancomycin. Bioavailability of eremomycin and teichoplanin after their extravascular administration was the same and amounted to 94 per cent. Antibacterial activity of eremomycin against methicillin resistant strains of staphylococci was 4 times higher than that of teichoplanin and vancomycin.     

Eremomycin--a new antibiotic of the polycyclic glycopeptide group

Eremomycin is a novel antibacterial antibiotic. It was isolated at the Institute of New Antibiotics, the USSR Academy of Medical Sciences from the culture fluid of actinomycete INA-238. By its physico-chemical and biological properties the antibiotic was classified as belonging to the group of polycyclic glycopeptides. Chemical structure of eremomycin was asserted and it was shown to be a new representative of the group close by its structure to vancomycin and differing from it by the carbohydrate composition and structure of tri-phenoxytriaminotricarboxylic acid. By its anti-bacterial spectrum eremomycin was found to be close to ristomycin and vancomycin. Still, its activity was 2-10 times higher. The antibiotic was several times less toxic than vancomycin. Unlike vancomycin and ristomycin, the novel antibiotic induced no tissue necrosis after its intramuscular administration. The chemotherapeutic indices of eremomycin in treatment of staphylococcal and streptococcal sepsis in albino mice exceeded 10 times those of vancomycin. At present eremomycin is under clinical trials.     

The structure of antibiotic eremomycin B

A new biologically active component, antibiotic eremomycin B, was isolated from the culture liquid of Amycolatopsis orientalis subsp. eremomycini, the producing strain for antibiotic eremomycin. Its structure was established by NMR spectroscopy and mass spectrometry. Eremomycin B was shown to differ from eremomycin by the presence of an N-carboxymethyl substituent in the disaccharide eremosamine fragment.     

Effect of the seeding culture media on the biosynthesis of eremomycin

Relationship of eremomycin biosynthesis to the quantity and quality of the inoculate (age, aeration rate, number of subcultures) was studied. The seed medium composition for cultivating the inoculate was defined. A procedure for cultivation of the seed material for biosynthesis of eremomycin providing an increase in the antibiotic yield by 24 per cent was developed.     

Effect of antibiotic and vaccine therapies on the succinate dehydrogenase and phosphatase activity of liver cells of mice infected with Staphylococcus

Changes in the activity of succinate dehydrogenase (SDH), total and acid phosphatase (TP and AP) were studied in treatment of laboratory animals with rifampicin, lincomycin and with inactivated staphylococcal vaccine used alone or in combinations. It was shown that immunization of the animals with inactivated staphylococcal vaccine under conditions of experimental staphylococcal infection promoted stimulation of the enzyme activity. Rifampicin and lincomycin used for the treatment of such animals lowered the activity of the enzymes. The suppressing effect of the antibiotics increased with an increase in the period of their use. It should be noted that the inhibitory effect of rifampicin on the activity of SDH, TP and AP was less pronounced than that of lincomycin. The combined use of the vaccine and antibiotics for the treatment of the animals promoted an increase in the enzyme activity as compared to the use of the antibiotics alone. Sometimes the activity of SDH, TP and AP reached the control levels in such animals or the levels observed in the animals treated with the vaccine alone. Stimulation of the enzyme activity was more pronounced when the vaccine was used in combination with rifampicin.     

Experimental study of the antibacterial activity and chemotherapeutic efficacy of the novel glycopeptide eremomycin

The study of antibacterial and chemotherapeutic activity of eremomycin, a novel glycopeptide antibiotic showed that it inhibited the growth of gram positive and acid fast microbes. The antibacterial spectrum of the novel glycopeptide was close to that of ristomycin and vancomycin. However, the in vitro antibacterial activity of eremomycin was 2-10 times higher than that of ristomycin and vancomycin. It also inhibited the growth of oxacillin resistant microbes at concentrations 5.20 times lower than those of vancomycin and ristomycin. By the therapeutic efficacy in albino mice with staphylococcal or streptococcal sepsis eremomycin was 2-4 times as superior as vancomycin and ristomycin and by the chemotherapeutic indices it was more than 10 times as superior.     

Experimental study on chemotherapeutic efficacy, acute toxic action and nephrotoxicity of combinations of eremomycin with tobramycin

Chemotherapeutic efficacy of eremomycin in combination with tobramycin was investigated on a model of experimental sepsis of albino mice caused by Staphylococcus aureus cultures resistant to methicillin. Eremomycin is a novel original antibiotic of the glycopeptide structure isolated in the USSR and tobramycin is an aminoglycoside. Acute toxicity of the combination with a wide range of the dose fixed proportions was studied on mice and the nephrotoxic action of the antibiotics and their combinations administered intravenously for 5 days was studied on albino rats. The experiments showed that the chemotherapeutic effect of eremomycin in combination with tobramycin was of synergistic nature. Acute toxicity of the combined drugs mainly summed up and somewhat increased when the proportion of tobramycin and eremomycin was 1:2.4 or 1:3.6. Eremomycin had a dose-depended nephrotoxicity. Summing up of the nephrotoxic action of the drugs on their combined use was observed.     

Study of dimerization of polysynthetic derivatives of the antibiotic eremomycin by ESI MS and its role in elucidating antibacterial activity

The dimerization constants for glycopeptide antibiotics vancomycin, ristocetin, and eremomycin and nine semisynthetic eremomycin derivatives were determined by the electrospray ionization mass spectrometry; the constants for natural antibiotics turned out to be close to those previously determined by NMR. No correlation between these dimerization constants and antibacterial activities of all the compounds toward the clinical strains of Gram-positive bacteria was found.     

The dimerization of semisynthetic eremomycin derivatives studied by the electrospray ionization mass spectrometry and its effect on their antibacterial activity

The dimerization constants for glycopeptide antibiotics vancomycin, ristocetin, and eremomycin and nine semisynthetic eremomycin derivatives were determined by the electrospray ionization mass spectrometry; the constants for natural antibiotics turned out to be close to those previously determined by NMR. No correlation between these dimerization constants and antibacterial activities of all the compounds toward the clinical strains of Gram-positive bacteria was found.     

Modification of eremomycin by amine groups

Possible modification of eremomycin, a novel glycopeptide antibiotic by the amine groups with acylating agents such as Ac2O/MeOH and CH3(CH2)7COCl/Et3N and alkylating agents such as CH3CHO, NaBH and NaBH3CN was studied. N-Acetyl, N,N'-diacetyl. N-pelargoil, N-ethyl, N,N'-diethyl and N,N',N"-triethyl derivatives of eremomycin were prepared. Their structure was asserted and the order of the substitute introduction was determined. The antimicrobial activity against Bacillus subtilis and Staphylococcus aureus was assayed. It was found that with introduction of the ethyl substitutes to the eremomycin molecule the antibiotic activity lowered insignificantly whereas the acylation resulted in its decreasing by 1-2 orders.     

In vitro activity of a new glycopeptide antibiotic eremomycin in relation to obligate anaerobic Gram-positive bacteria]

Antibacterial activity of eremomycin, a novel glycopeptide antibiotic, against obligate anaerobic Gram-positive++ bacteria was studied. Eremomycin was shown to inhibit the growth of obligate anaerobic Gram-positive++ cocci and bacteria belonging to Clostridium in rather low concentrations and within narrow ranges of the MIC which was indicative of the antibiotic undoubted advantages. The antibacterial activity of eremomycin was 2 times as high as that of vancomycin and 8 times as high as that of ristomycin with respect to Gram-positive++ anaerobic cocci. Pathogenic strains of Clostridium spp. were 2 to 4 times more sensitive to eremomycin than to vancomycin. A significant property of the novel glycopeptide antibiotic was shown to be its capacity for inhibiting the growth of Gram-positive++ aerobic and obligate anaerobic cocci within the same concentration ranges which might be of importance in monotherapy of mixed aerobic and anaerobic infections.     

Antimicrobial Susceptibility of Clostridium difficile from Different Sources

A total of 79 Clostridium difficile strains from healthy young and elderly adults, elderly patients without gastrointestinal disease, elderly patients receiving antibiotics without gastrointestinal complications, and elderly patients with antibiotic-associated diarrhea or pseudomembranous colitis were tested for their susceptibilities to 24 antimicrobial agents. All of the 79 strains were inhibited by low concentrations of rifampicin, metronidazole, fusidic acid, vancomycin, ampicillin, and penicillin G. The strains were highly resistant to aminoglycosides, trimethoprim, sulfamethoxazole, nalidixic acid, and cycloserine and often resistant to neomycin, cefoxitin, and cefalexin. Wide variations in the susceptibility of C. difficile strains to erythromycin, clindamycin, lincomycin, chloramphenicol, and tetracycline were found. Strains resistant to erythromycin, clindamycin, and lincomycin were more frequently found among strains isolated from elderly adults than those isolated from young adults, with particularly high frequency among strains isolated from elderly patients receiving antibiotics. None of the 23 strains isolated from healthy young adults was resistant to chloramphenicol. All of the 14 strains resistant to erythromycin, clindamycin, lincomycin, and chloramphenicol were sensitive to tetracycline and all of the 15 strains resistant to erythromycin, clindamycin, lincomycin, and tetracycline were sensitive to chloramphenicol. Only one out of 19 tetracycline-resistant strains was highly toxigenic, whereas 42 (70%) of 60 sensitive strains were highly toxigenic.     

Study of C1. perfringens resistance to lincomycin]

A possibility of developing resistant forms of C1. perfringens during treatment of experimental anaerobic (gaseous) infection with lincomycin was studied. It was shown that treatment of the animals for 7 days resulted in an increase in the resistance by 33-41 times. It was noted that strains with decreased sensitivity to lincomycins had changed morphology and biochemical activity (decreased lecitinase activity, changed biochemical properties), decreased virulence and pathogenicity for animals. So as to obtain the protective effect of the antibiotics in experimental anaerobic (gaseous) infection caused by resistant variants of C1. perfringens it was necessary to increase 1.5-3 times the doses of lincomycin or chlolincocin as compared to the processes induced by sensitive strains.     

Effect of antibiotic therapy and vaccine therapy on the phagocytic reaction in mice infected with Staphylococcus

The time course of changes in the activity, intensity and completeness of phagocytosis with leukocytes of the peritoneal exudate was studied on mice with experimental staphylococcal infection treated with rifampicin, lincomycin and inactivated staphylococcal vaccine used alone or in combination. It was shown that immunization of the animals with inactivated staphylococcal vaccine promoted stimulation of the phagocytic defense. Rifampicin and lincomycin applied therapeutically induced a decrease in the activity, intensity and completeness of phagocytosis. It should be noted that rifampicin had a less pronounced inhibitory effect than lincomycin. The combined use of vaccine and antibiotics with therapeutic purposes promoted an increase in phagocytosis as compared to the use of the antibiotics alone. The combined therapy sometimes resulted in completeness of phagocytosis making it reach the control values (the 10th and 15th days, rifampicin and vaccine). It should be noted that a more pronounced stimulation of the activity, intensity and completeness of the phagocytosis was observed with the use of the combination of rifampicin and the vaccine.     

Study of the activity of a new glycopeptide antibiotic eremomycin combined with tobramycin against Staphylococci in vitro

Eremomycin is an original natural antibiotic with glycopeptide structure isolated at the Institute of New Antibiotics, the USSR Academy of Medical Sciences. Activity of eremomycin alone or in combination with tobramycin was studied with using 25 clinical strains of staphylococci. 56 and 88 per cent of the strains were respectively resistant to gentamicin and kanamycin, two aminoglycoside antibiotics. All the staphylococcal strains were sensitive to eremomycin in concentrations of 0.12 to 1 microgram/ml. The MIC of tobramycin for 10 (40 per cent) sensitive strains ranged within 0.25-2 micrograms/ml. For 60 per cent of the strains the MIC was equal to or higher than 16 micrograms/ml. When eremomycin was used in combination with tobramycin the antibacterial effect with respect to 17 strains (68 per cent) increased. In 32 per cent of the strains the effect was synergistic and in 36 per cent of the strains it was additive. Indifference and antagonism were detected with respect to 7 (28 per cent) and 1 (4% per cent) strains respectively. No significant difference was shown in manifestation of the synergistic-additive nature of eremomycin and tobramycin interaction with respect to the tobramycin sensitive and resistant strains.     

Pharmacokinetics of lincomycin in experimental animals]

When administered parentally, lincomycin satisfactorily penetrated into the organs and tissues of experimental animals. Pronounced tropism of the antibiotic in the bone tissue was observed which provided its recommendation for the treatment of osteomyelitis. The antibiotic was excreted with urine and bile.