PubMed · 4131440
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1974-03-16. Editorial: Chronic sinusitis.. https://pubmed.ncbi.nlm.nih.gov/4131440/
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The purpose of the present study was to investigate the complement activation by lipopolysaccharides purified from Porphyromonas (Bacteroides) endodontalis, Veillonella parvula, and Fusobacterium nucleatum isolated from infected root canals. The rate of consumption of the C3T component of the complement increased remarkably when lipopolysaccharides of more than 10 micrograms were added.
This report describes a genetic and molecular analysis of two transferable Bacteroides plasmids, pIP417 and pIP419, which carry genetic determinants conferring low-level resistance to 5-nitroimidazoles. The restriction endonuclease cleavage sites for each plasmid were localized. The NiR genetic determinants of pIP417 and pIP419 plasmids have been cloned into the Bacteroides cloning vector pBI191 (C.J. Smith, J. Bacteriol. 164, 294-301, 1985) as PvuII and Sau3A fragments, respectively. Both inserts had different restriction sites and did not cross-hybridize by Southern blot analysis. Genetic data obtained by cloning into pBI191 clearly show that the PvuII-generated fragments A (Rep) and B (Mob) of pIP417 are involved in plasmid replication and transfer, respectively. Although encoding resistance to the same antibiotic, both plasmids appeared different with regard to the 5-nitroimidazole resistance and replication genetic determinants. However, they share a homology in a region involved, at least in one case, in plasmid transfer. Considering the spontaneous high level of resistance to 5-nitroimidazole in Escherichia coli, this work, based on direct gene cloning into Bacteroides, demonstrates the value of such an approach.
The in vitro activity of cefotaxime (CTX) alone and in combination with its metabolite desacetylcefotaxime (dCTX) was evaluated against 106 isolates of Bacteroides species. and 32 strains of Staphylococcus aureus. All strains were recovered from infected tissues of diabetic patients. Addition of dCTX to the parent compound markedly increased the inhibitory activity against Bacteroides species in general and Bacteroides fragilis and Bacteroides vulgatus in particular. No effect of the combination of both agents on Bacteroides thetaiotaomicron or Bacteroides ovatus was observed; 50% of B. fragilis infections were susceptible to CTX alone and 81% became susceptible to CTX plus dCTX. In addition, a partial synergistic interaction against 20 strains of B. fragilis resulted in a four- to nine-fold reduction in the minimal inhibitory concentration (MIC) after dCTX was added to CTX. Interestingly, 10 of 20 strains that exhibited an MIC of 64-128 micrograms/mL with CTX alone became very susceptible after the combination of parent and metabolite. This favorable positive interaction of both agents was also observed with S. aureus; a two- to four-fold reduction in MIC values was observed when dCTX was added.