Stability study of tetracyclines with respect to their use in slow release systems.

In the aim of optimizing implantable slow-release systems for the local delivery of antibiotics, the stability of tetracyclines was studied in water at 37 degrees C or under gamma irradiation. Four tetracyclines in their chlorhydrate form were chosen depending on their hydrophilic/hydrophobic balance. Their chemical stability was established by HPLC, and biological stability by bacteriological tests. It was shown that methacycline and doxycycline are stable in water for three days. Tetracycline and minocycline exhibit limited decomposition (less than 10%) under the same conditions. So, in vitro drug release for at most three days, appears to be possible. Besides, all four tetracyclines either in powdered form or included in a calcium phosphate matrix, kept their bacteriological activity after gamma irradiation at 32.4 kGr. Consequently, the in vivo study of these implantable slow drug release systems, can be carried out.

[The adhesion of Actinobacillus actinomycetemcomitans to oral epithelial cells]. / Etude de l'adhesion d'Actinobacillus actinomycetemcomitans aux cellules epitheliales buccales.

Adherence is a major pathogenicity factor for many bacteria. The aim of this study was to measure the adherence potential of Actinobacillus actinomycetemcomitans (A.a.) for buccal epithelial cells (BEC). In the second part of the study, the inhibitory potential of saliva on adherence between A.a. and BEC was tested. Saliva specimens were obtained from three groups of subjects: a group of normal subjects (NS), a group of subject with localized juvenile periodontitis (LJPS) and a group of subjects with adult periodontitis (APS). Clinical strains of A.a. showed a major adherence potential for BEC (25.5 A.a./BEC). In contrast, reference strains of bacteria appeared to possess a much lower potential for adherence (12.6 A.a./BEC). Saliva samples taken from from the LJPS and APS group had a high inhibitory adherence potential, since in each of these groups a reduction of 60.9% and 66.7% respectively, was observed in the number of bacteria adhering to BEC.

[The distribution and prevalence of Haemophilus actinomycetemcomitans in the oral cavity]. / Distribution et prévalence de Haemophilus actinomycetemcomitans dans la cavité buccale.

The prevalence and distribution of Haemophilus actinomycetemcomitans (H.a.) were studied in 3292 specimens of subgingival plaque on the four subgingival aspects of all teeth of the dental arch, 150 specimens from the mucosal surface (tongue and cheek) and 30 saliva specimens in 30 subjects. The sample population of 30 subjects was subdivided into three groups: 10 normal subjects, 10 subjects with localised juvenile periodontitis (SLJP) and 10 subjects with adult chronic periodontitis (SACP). The prevalences of H.a. in subgingival areas of each group mentioned were 30%, 90% and 60% respectively. Scores for prevalence obtained with other types of specimens proved to be lower except for saliva specimens which appear to be a less representative marker of subgingival prevalence of H.a.. Histograms for the distribution of H.a. revealed a predominance of this microorganism on the proximal surface of molar teeth in the three groups of patients. Only the SLJP also exhibited a high prevalence on the proximal aspect of the incisor teeth. The wide distribution of H.a. in all of the clinical groups studied suggests that this bacterium is not a good marker of periodontal disease and that it is necessary to define the most characteristic phenotypes and genotypes.

[The transmission of Actinobacillus actinomycetemcomitans between spouses]. / Etude de la transmission d'Actinobacillus actinomycetemcomitans entre conjoints.

The aim of this investigation was to study the transmission of Actinobacillus actinomycetemcomitans (A.a) between husband and wife when one of them was affected by acute juvenile periodontitis (P.A.J.). The hypothesis tested was the role played by the reservoir of the non-infected partner in explaining the frequent recurrences of the disease in the affected spouse despite combined antibiotherapeutical and surgical treatments. Twenty subjects with P.A.J. were studied. A.a. was found in the sub-gingival flora of nineteen of them. This micro-organism was also isolated in each of the partners of the nineteen patients. Each couple presented strains of the same biotype. The serotypes were studied in seven of these couples and confirmed the results of the biotypes. All theses results are in favour of the transmission of A.a. between partners.

[A comparison between 4 subgingival bacteriologic sampling technics]. / Comparaison entre quatre techniques de prèlévements bacteriologiques sous-gingivaux.

A comparative study of four classical techniques employed in the sampling of subgingival microflora (paper points, swabbing, curette and washing followed by aspiration) has been carried out. This study was based upon quantitative criteria (number of bacteria sampled) and qualitative criteria (number of morphologically distinct colonies found per sampling technique). Sampling was done on three different groups of patients: a control group, a group of patients with gingivitis and a group of patients with periodontitis. The curette sampling technique was found to be efficient both quantitatively and qualitatively. Difficulties in standardizing this method however were encountered with the failure to achieve reproducible results. For this reason the technique of paper point was preferred. This method was found to be more reliable and reproducible in each of the three groups of patients sampled.