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Liquid chromatography-UV diode-array detection method for multi-residue determination of macrolide antibiotics in sheep's milk.

A rapid, simple and sensitive liquid chromatography-UV diode-array detection method was developed for the simultaneous determination of seven macrolides (erythromycin, oleandomycin, roxithromycin, josamycin, spiramycin, tylosin and ivermectin) in sheep's milk. The column, mobile phase, temperature and flow rate were optimised to provide the best resolution of these analytes. The extraction of the antibiotic residues involves the treatment of protein-free samples with a combination of concentrated sodium hydroxide and ethyl acetate. Necessary defatting is achieved by alkaline hydrolysis. The recovery of each antibiotic was between 55% and 77%, with relative standard deviations ranging from 1% to 6.5%. The limit of quantification was 72.4 microg/kg for ivermectin, 48.3 microg/kg for roxithromycin, and 24.1 microg/kg for erythromycin, oleandomycin, spiramycin, josamycin and tylosin. The procedure was successfully used in the multi-residue determination of these macrolides at levels below the maximum concentrations legally allowed in milk samples.

Animals↗

Determination of five macrolide antibiotic residues in eggs using liquid chromatography/electrospray ionization tandem mass spectrometry.

A method using liquid chromatography electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) for the determination of trace levels of five macrolide antibiotics (spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin) in eggs is presented. Data acquisition under MS/MS was achieved by applying multiple reaction monitoring (MRM) of two or three fragment ion transitions to provide a high degree of sensitivity and specificity for both quantification and confirmation. Matrix-matched standard calibration curves were used to achieve the best accuracy of the method. A fully nested experimental design was used to study the measurement uncertainty arising from intermediate precision and trueness or proportional bias. The overall recoveries, that is, those determined by the nested experiments, of spiramycin, tilmicosin, oleandomycin, erythromycin, and tylosin at fortified levels of 60, 100, 200, and 300 microg/kg were 96.8, 98.2, 98.3, 98.8, and 95.4%, respectively. The LC/ESI-MS/MS method detection limits (S/N > or = 3:1) of five macrolides were <1.0 microg/kg.

Anti-Bacterial Agents↗

Binding of antibiotics to glycoproteins of the vitelline and fertilization envelopes of cherry salmon eggs.

The binding of antibiotics (gentamicin, oleandomycin and chloramphenicol) to vitelline and fertilization envelopes and their extracts was investigated by immunohistochemical and immunocytochemical techniques and immunoblot analysis using mature and artificially activated eggs of the fish Oncorhynchus masou. Binding of antibiotics was detected in the vitelline and fertilization envelope outermost layers, the fertilization envelope inner surface and cortical alveolus exudates, with differences in immunoreactive intensity and deposition. The fertilization envelope outermost layer had the capacity to bind much greater amounts of the antibiotics than the vitelline envelope outermost layer. The greater capacity was caused by the deposition of cortical alveolus exudates, which were known to be responsible for functional roles of protection against bacteria, fungi and noxious materials. Treatment of the vitelline and fertilization envelopes with neuraminidase markedly reduced the binding of gentamicin and chloramphenicol but slightly increased that of oleandomycin; binding of the latter to the vitelline and fertilization envelope outermost layers was considerably reduced after treatment with alpha-fucosidase. Treatment of the two envelopes with alpha-mannosidase, beta-galactosidase or beta-D-glucosaminidase did not cause any alteration in immunoreactive intensity or number of immunoreactive deposits. Immunoblot analysis of the vitelline or fertilization envelope extracts indicated that many of the antibiotic-binding substances were glycoproteins, and several major bands were bound by all three antibiotics. These results suggest that the vitelline or fertilization envelopes may have the ability to protect the egg itself, or the embryo, respectively, by trapping antibiotics, and the trapping may be related to the presence of carbohydrate moieties, such as sialyl or fucosyl residues.

Animals↗

Parallel pathways for oxidation of 14-membered polyketide macrolactones in Saccharopolyspora erythraea.

The glycosyltransferases OleG1 and OleG2 and the cytochrome P450 oxidase OleP from the oleandomycin biosynthetic gene cluster of Streptomyces antibioticus have been expressed, either separately or from artificial gene cassettes, in strains of Saccharopolyspora erythraea blocked in erythromycin biosynthesis, to investigate their potential for the production of diverse novel macrolides from erythronolide precursors. OleP was found to oxidize 6-deoxyerythronolide B, but not erythronolide B. However, OleP did oxidize derivatives of erythronolide B in which a neutral sugar is attached at C-3. The oxidized products 3-O-mycarosyl-8a-hydroxyerythronolide B, 3-O-mycarosyl-8,8a-epoxyerythronolide B, 6-deoxy-8-hydroxyerythronolide B and the olefin 6-deoxy-8,8a-dehydroerythronolide B were all isolated and their structures determined. When oleP and the mycarosyltransferase eryBV were co-expressed in a gene cassette, 3-O-mycarosyl-6-deoxy-8,8a-dihydroxyerythronolide B was directly obtained. When oleG2 was co-expressed in a gene cassette together with oleP, 6-deoxyerythronolide B was converted into a mixture of 3-O-rhamnosyl-6-deoxy-8,8a-dehydroerythronolide B and 3-O-rhamnosyl-6-deoxy-8,8a-dihydroxyerythronolide B, confirming previous reports that OleG2 can transfer rhamnose, and confirming that oxidation by OleP and attachment of the neutral sugar to the aglycone can occur in either order. Similarly, four different 3-O-mycarosylerythronolides were found to be substrates for the desosaminyltransferase OleG1. These results provide additional insight into the nature of the intermediates in OleP-mediated oxidation, and suggest that oleandomycin biosynthesis might follow parallel pathways in which epoxidation either precedes or follows attachment of the neutral sugar.

Bacterial Proteins↗

Gastrointestinal motor-stimulating activity of macrolide antibiotics and analysis of their side effects on the canine gut.

For clarification of the nature of the side effects of macrolide antibiotics on the gastrointestinal tract, the motor-stimulating activity of these agents was studied in unanesthetized dogs. The results showed that erythromycin and oleandomycin, the 14-membered macrolides with two side chain sugars combined at C3 and C5 in a glycosidic linkage in parallel, strongly stimulate gastrointestinal motor activity, an action accompanied by vomiting at large doses. On the other hand, leucomycin, acetylspiramycin, and tylosin, belonging to a 16-membered macrolide with two side chain sugars in series combined at C5 of the lactone ring, did not induce contractions of the gastrointestinal tract. Motor-stimulating activity by erythromycin and oleandomycin was greatly inhibited by atropine sulfate. These results point to structure-physiological activity relationships.

Aminoglycosides↗

Inducible resistance to a 16-membered macrolide, mycinamicin, in Staphylococcus aureus resistant to 14-membered macrolides and streptogramin B antibiotics.

Staphylococcus aureus 8325(pEP2104), a transductant derived from S. aureus PM2104 isolated clinically in Hungary (L. Janosi, and E. Ban, Acta Microbiol. Acad. Sci. Hung., 29: 187-200, 1982), exhibited an inducible resistance to the 14-membered macrolides [erythromycin (EM) and oleandomycin (OL)] and streptogramin B (MKM-B) antibiotics, but not to the 16-membered macrolides and lincosamides. This resistance was referred to as PMS-resistance phenotype (L. Jánosi, Y. Nakajima, and H. Hashimoto, Microbiol. Immunol., 34: 723-735, 1990). In addition to EM, OL, and MKM-B, however, the strain was recently and first observed to have inducible resistance to mycinamicin, a 16-membered ring macrolide. Thereby, we propose that the reference stated just above as PMS-resistance has to be extended to such 16-membered macrolides as mycinamicin. An optimum concentration of erythromycin or oleandomycin for induction of PMS-resistance was 1.35 mu g/ml in the strain 8325(pEP2104). The concentration was about 30 times as great as that (0.05 mu g/ml) required for induction of well-known co-resistance to macrolide-lincosamide-streptogramin B antibiotics in S. aureus ISP447.

Anti-Bacterial Agents↗

[Study of the structure of amplifying sequence of Streptomyces antibioticus].

A low productive laboratory strain of S. antibioticus and a strain with an increased productivity of oleandomycin derived from it were studied comparatively with using restriction analysis and blotting hybridization. Amplification, site specific integration and segregation of the DNA sequence 32.0 kb in size were detected in the strains. The chromosomes of the laboratory strain contained one copy of the amplifying sequence AUD. After uniting of the end sequences AUD appeared to be capable of segregating from the chromosomes and its one copy per five genomes was present in the form of an extrachromosomal genetic element eSA1. The genome of the strain with increased productivity of oleandomycin contained in its chromosomes sequence ADS-Sa1 amplified to 150 copies and the eSA1 extrachromosomal genetic element in the form of mono-, di- and trimeric structures in the quantity of approximately one copy per genome. The BamHIB fragment of the eSA1 DNA 4 kb in size was identified. The fragment was able to participate in segregation or integration of eSA1 from or into the chromosomes since its subfragments were flanking AUD and ADS-SA1 in the chromosomes. The BamHIB fragment was hybridizing with a number of fragments of the chromosomal DNA of S. antibioticus, S. erythraeus. S. lividans and other strains of streptomycetes. It probably contained an IS-like element or a dispersed genetic element of another class. The DNA sequence of the eSA1 genetic element contained regions homologous to the sequence of the Erm E gene in S. erythraeus NRRL 2338.

Blotting, Southern↗

[Nitrogen metabolism of Streptomyces antibioticus on media with various glucose contents].

The dynamics of the glutamine synthetase and glutamate dehydrogenase activity was studied during cultivation of Str. antibioticus on media with different contents of glucose and ammonium sulfate. No correlation between the enzymes activity and the levels of oleandomycin production by the mycelium was observed. It was shown that the levels of oleandomycin biosynthesis repression by glucose did not depend on ammonium sulfate concentration in the medium.

Ammonium Sulfate↗

[Interrelationship of the antibiotic and proteolytic activities of the producer Streptomyces antibioticus when different substances are added to the culture broth].

Interrelation between biosynthesis of oleandomycin and alkaline proteases was studied during cultivation of Str. antibioticus in flasks with the complex soybean-corn medium containing lactose. Increasing of the activity of oleandomycin and that of alkaline proteases in the fermentation broth was simultaneous and reached the maximum within 168-192 hours. After that period the activity levels lowered. ATP and glucose induced inhibition of the antibiotic activity and stimulation of the proteolytic activity, 1.25- or 1.5-fold dilution of the fermentation process resulted in stimulation of both the antibiotic activity and the proteolytic activity. At the same time organic acid salts, leucine or gelatin induced their inhibition. Interrelation between these processes was rather complex since lowering of the levels of autolytic processes in the cells by inhibition of the proteases with physiological regulators and respective prolongation of the culture productive phase did not result in increase of the antibiotic yield.

Culture Media↗

[Comparative activity of sulfamethoxazole-trimethoprim (SMZ-TMP) on bacteria responsible for ORL infections].

The bacteriostatic activity in vitro of co-trimoxazole (SMZ-TMP); ampicillin, tetracycline and oleandomycin was evaluated against 225 bacterial strains. All the strains (49 Pneumococci, 49 Haemophilus, 41 Streptococci and 86 Staphylococcus aureus) were isolated from sinusitis (63 strains) and otitis (162 strains) in monomicrobial samples. The minimal inhibitory concentrations (MICs) of the 4 antibiotics were determined by the agar diffusion method on all strains. Moreover MICs of SMZ-TMP were determined by the broth dilution method on Haemophilus strains. Seventy seven p. cent of the strains were found sensitive to SMZ-TMP, 70.7% to ampicillin, 85.4% to tetracycline and 73% to oleandomycin. SMZ-TMP was the most effective on Staphylococcus aureus (80% of the isolates were sensitive), whereas ampicillin was effective on all Streptococcus, and Pneumococcus strains and tetracycline was the most active on Haemophilus strains (88% of the isolates were sensitive).

Ampicillin↗

Persistence of antibiotics such as macrolides, tiamulin and salinomycin in soil.

The extensive use of veterinary drugs in agriculture leads to contamination of manure. If this manure is used as fertiliser, soil may be exposed to the respective drugs. Additionally soil exposure may stem from contaminated sewage sludge that is used on some agricultural land as fertiliser. This study focuses on the fate of antibiotics in soil. We present a 120-day degradation experiment of six commonly used antibiotics: erythromycin, roxithromycin oleandomycin, tylosin, salinomycin and tiamulin in soil as well as calculating the resulting half-lives. The half-lives were 20 days for erythromycin, 27 days for oleandomycin, 8 days for tylosin, 16 days for tiamulin and 5 days for salinomycin; all according to 1st order kinetics. The concentration of roxithromycin remained nearly unchanged during the whole experiment.

Agriculture↗

Widespread activation of antibiotic biosynthesis by S-adenosylmethionine in streptomycetes.

The effect of S-adenosylmethionine (SAM) on the production of various antibiotics was investigated to determine whether SAM-dependent methylation is required in biosynthetic pathways of antibiotics. Pristinamycin II(B) and granaticin do not require SAM-dependent methylation in their biosynthesis pathways, and production of these two antibiotics was increased about 2-fold when a low concentration (50 and 10 microM, respectively) of SAM was treated; in contrast, oleandomycin and avermectin B1a require SAM as a methyl donor in their biosynthesis, and production of these two antibiotics was increased 5-fold and 6-fold, depending on the SAM concentration within a certain range. We also found that the transcription of a pathway-specific regulator, gra-ORF9, was activated by exogenous SAM treatment. Production of oleandomycin and avermectin B1a was decreased by using a methyltransferase inhibitor, sinefungin, but the production levels of these antibiotics were restored to the control level by simultaneously adding SAM and sinefungin. Interestingly, we have found a similar stimulatory effect of S-adenosylhomocysteine (SAH), the methylation product of SAM, on antibiotic production in the four strains. Our results clearly demonstrate the widespread activation of antibiotic production using SAM in streptomycetes.

Anti-Bacterial Agents↗

Gas chromatographic-mass spectrometric determination of macrolide antibiotics in beef and pork using single ion monitoring.

A gas chromatographic-mass spectrometric (GC-MS) method using single ion monitoring (SIM) is described for the determination of residual macrolide antibiotics, oleandomycin, kitasamycin, spiramycin and tylosin, in beef and pork. For GC-MS determination, oleandomycin is acid hydrolysed to desoleandomycin and acetylated, in the same way as erythromycin. However, for elution from a GC column, the carbon-carbon double bonds in the antibiotics must be hydrogenated to single bonds before acid hydrolysis. Kitasamycin and spiramycin are therefore converted into hydroforocidine acetate and tylosin into hydro-O-mycaminosyl tylonolide acetate, which are determined by GC-MS with SIM.

Acetylation↗

The penetration of macrolides into bronchial secretions.

Macrolides have shown efficacy in the treatment of a large range of respiratory infections. These antibiotics are well tolerated, have a narrow antibacterial spectrum, and excellent diffusion properties. We have studied the penetration into bronchial secretions of three macrolides, erythromycin, josamycin and oleandomycin. The bronchial concentrations of erythromycin reached an average of 1 mg/l 2 h after oral administration of 1 g; they were lower for josamycin (0.52 mg/l) but the ratio between bronchial and simultaneous serum concentrations was similar for both drugs. Bronchial levels of oleandomycin were rapidly higher than the serum levels, reaching 3 to 4 mg/l, a ratio of more than 100%. Other studies on tissue concentrations of erythromycin and josamycin showed local levels of 4 to 6 mg/l, whereas in bronchial secretions the concentrations were identical to those measured in our study. On the whole, the good diffusion of macrolides into respiratory tissues and secretions as well as in-vitro antibacterial activity against most species responsible for respiratory infections confirm their indication in the treatment of these infections.

Adult↗

Patterns of phenotypic resistance to the macrolide-lincosamide-ketolide-streptogramin group of antibiotics in staphylococci.

Phenotypes of resistance to the macrolide-lincosamide-ketolide-streptogramin (MLKS) group of antibiotics have been determined in 540 clinical isolates of staphylococci (210 Staphylococcus aureus and 330 coagulase-negative species). Results of disc diffusion tests using erythromycin A, oleandomycin, rokitamycin, clindamycin, telithromycin, quinupristin and dalfopristin delineated four main groups corresponding to those defined classically using erythromycin and clindamycin only, but with sub-divisions. Resistance to erythromycin was more common in coagulase-negative strains (56%) than in S. aureus (16%); telithromycin, clindamycin, quinupristin-dalfopristin and rokitamycin were active against >97% of S. aureus strains and >88% of the coagulase-negative strains. The commonest resistance phenotype was 'inducible MLS(B)' (12% in S. aureus, 31% in coagulase-negative strains); this group could be divided in terms of the different inducing abilities of erythromycin and oleandomycin. 'Constitutive MLS(B)' and 'MS' phenotypes were more often found in coagulase-negative strains (11 and 13%, respectively) than in S. aureus (2 and 1%). Novel phenotypes were found during the isolation of constitutively resistant mutants from inducible strains, and of resistant mutants from 'MS' strains. This extended phenotyping scheme has revealed further complexities and evolutionary possibilities in patterns of resistance to this group of antibiotics.

Anti-Bacterial Agents↗

[Antibiotic sensitivity and serotypes of group A hemolytic streptococci isolated from clinical specimens and healthy pupils in Japan, 1986-1988].

As an epidemiological survey for streptococcal infection, antibiotic sensitivity test and T-serotyping were made on 2,735 strains of group A hemolytic streptococci isolated from clinical specimens and healthy pupils between 1986 through 1988 in Japan. Most dominant serotype in clinical isolates was T-4 (26.8%) and it was followed T-12 (25.5%), T-1 (11.2%) and T-3 (8.5%), on the other hand, dominant serotypes of the isolates from healthy pupils were T-12 (30.4%), T-1 (19.3%), T-4 (15.3%) and T-28 (13.4%). All of the isolates tested were sensitive to the beta-lactam antibiotics which was found as same as consequence of the previous surveys. However 36.4% to tetracycline, 2.1% to chloramphenicol and 1.4% to oleandomycin of the clinical isolates were resistant. Similarly, 16.2% to tetracycline, 2.3% to chloramphenicol 1.7% to oleandomycin, of the isolates from healthy pupils were resistant. Multi-resistant strains were found 1.4% in clinical isolates and 1.7% in the isolates from healthy pupils. Relation between distribution of multiresistant strain and T-serotypes was found. In T-12, multiresistant strains were encountered at a relatively high rate compared with other serotypes, representing 3.5% in clinical isolates and 5.6% in the isolates from healthy pupils. However this tendency was decreased than previous surveys, while incidence of tetracycline resistant strains in T-4 remained at high level, representing about 94% as same as in the past.

Adolescent↗

Key structural features of ligands for activation of human pregnane X receptor.

The ligand-binding domain of human pregnane X receptor (hPXR) is highly hydrophobic and flexible, allowing promiscuity in accepting structurally diverse ligands. However, little information is available regarding the critical substituents of compounds involved in the activation of hPXR. The aim of this study was to determine the structure-activity relationships for hPXR-mediated transactivation by barbiturates, hydantoins, and macrolide antibiotics. Most of the barbiturates studied (mephobarbital, pentobarbital, phenobarbital, etc.) activated hPXR. However, barbital, which has a low hydrophobic moiety at the 5-position, and primidone, which has no carbonyl moiety at the 2-position, did not activate hPXR. Therefore, a hydrophobic moiety at the 5-position and a hydrogen-bond acceptor being sufficiently separated from the phenyl-ring are responsible for activation of hPXR by barbiturates. In the case of hydantoins, only mephenytoin and ethotoin, which have an alkylchain at the R1-position, strongly activated hPXR at 300 microM. Phenytoin and 5-(4-methylphenyl)-5-phenylhydantoin, which contain a phenyl or methylphenyl group at both R2- and R3-positions, also activated hPXR, whereas 5-(4-hydroxyphenyl)-5-phenylhydantoin did not activate the receptor. These results suggest that the presence of an alkyl-chain at the R1-position and the presence of bulky and hydrophobic moieties at both R2- and R3-positions are important factors for activation of hPXR by hydantoins. In the case of macrolide antibiotics, troleandomycin, but not oleandomycin, showed significant activation of hPXR. Therefore, triacetate esterification of oleandomycin might increase the hydrophobicity and enhance the activation of hPXR. These findings suggest that hydrophobicity of the ligand and adequate distance between the hydrogen-bond acceptor and the hydrophobic group are important for hPXR activation.

Anti-Bacterial Agents↗

Effects of sub-MICs of erythromycin and other macrolide antibiotics on serum sensitivity of Pseudomonas aeruginosa.

We examined the effects of sub-MICs of erythromycin (EM) and other macrolide antibiotics on the serum sensitivity of Pseudomonas aeruginosa. P. aeruginosa S-6 grown for 36 and 48 h on agar with 10 micrograms of EM per ml (1/10th the MIC) showed significantly increased sensitivity to human serum bactericidal activity compared with those of bacteria grown on agar without EM (P < 0.05). No changes in serum sensitivity were observed in bacteria grown for less than 24 h. This increased sensitivity was apparent even at a concentration of 1.5 micrograms of EM per ml (1/67th the MIC) in bacteria grown for 48 h (P < 0.01). Among the other macrolide antibiotics tested, clarithromycin also enhanced sensitivity to serum, but there were no changes in the sensitivities of bacteria grown on agar with kitasamycin, josamycin, rokitamycin, or oleandomycin even at a concentration of 12 micrograms/ml (1/16th, 1/16th, 1/8th, and 1/33rd the MICs, respectively). P. aeruginosa S-6 grown on agar with subinhibitory concentrations of EM showed decreased cell surface hydrophobicity in a dose-dependent manner, whereas oleandomycin and rokitamycin, even at a concentration of 12 micrograms/ml, induced a slight decrease in hydrophobicity which was approximately equivalent to that of 1.5 micrograms of EM per ml. Among six other strains of the nonmucoid phenotype, three strains became more sensitive to serum by exposure to 10 micrograms of EM per ml for 48 h. In contrast, no evident correlation between EM treatment and a change in serum sensitivity was observed in six strains of the mucoid phenotype, as judged by the results of experiments with both 2 and 0.4% serum. These results show that EM at subinhibitory concentrations enhances the serum sensitivity of some P. aeruginosa strains. Since induced serum sensitivity was accompanied by a decrease in bacterial cell surface hydrophobicity, EM may render P. aeruginosa more serum sensitive by changing the cell surface structure(s) of this organism.

Anti-Bacterial Agents↗