[Studies on midecamycin 4"-O-propionyltransferase gene structure]

A BamHI-BamHI 8.0 kb DNA fragment which contains midecamycin propionyltransferase (mpt) gene was digested with different restriction enzymes and the restriction map was made. The mpt gene was localized in a EcoRI-EcoRI-PstI3.0 kb DNA fragment by Southern blot analysis using a 2.4 kb DNA fragment of the CarE gene as a probe. The 3.0 kb DNA fragment of mpt gene was cloned into E. coli/Streptomyces shuttle vector pWHM3 and a recombinant plasmid pWFPE was obtained. S. ambofaciens(pWFPE) and S. lividans(pWFPE) can convert endogenously synthesized or exogenously added spiramycin into 4"-O-propionylspiramycin, respectively. Sequence analysis of mpt gene demonstrated an open reading frame in the EcoRI-EcoRI-PstI3.0 kb DNA fragment, which starts with ATG and ends with TGA. Mpt gene encodes a product of 388 aa. G+C mol% of mpt is 68.0 and G+C mol% of 3rd codon position is 91.5. The putative product of mpt has a identity of 67.6% and a similarity of 86.4% with CarE product. A consensus RBS GAGGT in the 6bp upstream from ATG and a promoter region were found. An inverted repeat sequence in the downstream from TGA acts as transcriptional terminator.

Identification of tylosin in bovine muscle at the maximum residue limit level by liquid chromatography-mass spectrometry, using a particle beam interface

A particle beam liquid chromatography-mass spectrometric method is presented as a confirmatory technique for analysis of tylosin residues in bovine muscle. After chloroform extraction and a diol solid-phase extraction clean-up, on-line liquid chromatography-mass spectrometry (LC-MS) of extracts is carried out on an RP-18 bonded silica column. The analyte is introduced into the ion source by a particle beam interface and identified by negative chemical ionization with selective ion monitoring. The tylosin molecular ion is obtained with this ionization mode. The response of the ion chromatogram peak areas is linear for the three levels of spiked muscle analysed (0.5, 1 and 2 maximum residue limit). Under these LC-MS conditions, other macrolide antibiotics such as spiramycin and erythromycin do not interfere with tylosin.

Urticaria from erythromycin

We report an adverse cutaneous reaction (urticaria) due to erythromycin. A positive skin prick and leukocyte histamine release tests, as well as a positive single-blind, placebo controlled oral challenge to erythromycin, strongly suggest an IgE mediated hypersensitivity mechanism.

The role of adjunctive Rodogyl therapy in the treatment of advanced periodontal disease. A longitudinal clinical and microbiologic study

Several studies have indicated that the combination of metronidazole and spiramycin is synergistic against anaerobic bacteria and may be effective against oral infections. The present study sought to determine the efficacy and safety of a commercial preparation of these two antibiotics (Rodogyl) when used adjunctively in the treatment of advanced periodontal disease. In a double-blind parallel randomized trial, 56 patients (mean age = 44 years) with advanced periodontitis (50 of whom completed the study) were assigned to either the Rodogyl or placebo group. Both groups were thoroughly scaled and root planned for approximately 6 hours, with one group receiving Rodogyl for 2 weeks and the other a placebo. No other therapy was received during the study period. Two sites in each patient with probing depths of at least 7 mm were selected for study. Plaque level (P1I), gingival inflammation (GI), probing depth (PD), and attachment level (AL) were measured at baseline, 14 days, 1 month, and then at monthly intervals up to 6 months. Subgingival bacteria were monitored with dark-field microscopy. The development of resistant bacteria, as well as side effects to the medications, was also monitored. The Rodogyl group exhibited a greater gain in AL (0.67 mm) from the 2-month interval until the end of the study. Although this difference was statistically significant (P less than 0.05), it was not necessarily of biologic significance. There was a significantly greater decline in the proportion of spirochetes in the Rodogyl group at the 14-day interval, and this difference remained significant (P less than 0.05) at all study intervals. No difference in the proportion of motile organisms was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro activity of rodogyl against putative periodontopathic bacteria

The minimal inhibitory concentrations of Rodogyl (composite tablet of metronidazole and spiramycin), metronidazole-spiramycin mixture, spiramycin, metronidazole, and tetracycline were determined for selected putative periodontopathic microorganisms. Rodogyl was active against almost all strains, including Bacteroides species and the anaerobic spirochetes. Synergism of the component drugs in the Rodogyl combination was noted against Propionibacterium species. Spiramycin activity against Actinomyces species was enhanced in the presence of metronidazole.

Drug Resistance of Staphylococci II. Joint Elimination and Joint Transduction of the Determinants of Penicillinase Production and Resistance to Macrolide Antibiotics

Mitsuhashi, Susumu (Gunma University, Maebashi, Japan), Hajime Hashimoto, Megumi Kono, and Masato Morimura . Drug resistance of staphylococci. II. Joint elimination and joint transduction of the determinants of penicillinase production and resistance to macrolide antibiotics. J. Bacteriol. 89: 988–992. 1965.—Strains of Staphylococcus aureus , which show high resistance to macrolide antibiotics (erythromycin, oleandomycin, leucomycin, and spiramycin) and the capacity to produce penicillinase, have been isolated from clinical sources. The determinants of penicillinase production (PCase + ) and resistance to macrolide antibiotics (MAC r ) of these strains were irreversibly eliminated by treatment with acridine or with ultraviolet light. Among the 18 strains tested, PCase + and MAC r were eliminated from all strains except one, which lost only PCase + but not MAC r . The characters PCase + and MAC r were jointly transduced with the aid of phage lysates, obtained from the resistant donors by ultraviolet irradiation, into staphylococcal strains sensitive to PC and MAC. Segregation of PCase + and MAC r was rarely observed after transduction. From these results, it is suggested that the determinants of both PCase + and MAC r of staphylococci are located close together on a single genetic element, i.e., a plasmid (or episome), which exists extrachromosomally.