The role of plasmid stability and the associated resistant gene in the antimicrobial resistance of fusobacterium spp. isolates from chronic periodontitis

الملخص EN

Background : The microbial composition of dental plaque is highly diverse.

Fusobacterium spp.

is gram negative, nonmotile, anaerobic rods that are consider as part of the normal flora of oral cavity playing a major role in initiation & progression of periodontal diseases.

The purpose of the present study is to evaluate the plasmid stability & the association of the resistance gene with the plasmid in oral Fusobacterium spp.

Isolated from subjects with chronic periodontitis Materials and Method : A total of 11 Fusobacterium isolates were taken from 32 subjects with chronic periodontitis with average pocket depth range between 6- 8mm.

Antibiotic susceptibility to 12 antimicrobials, DNA extraction, plasmid profile analysis, curing, & conjugation & transformation were carried out on these isolates.

Results : The isolates showed variable degree of resistance to different antimicrobials but all were susceptible to Doxycycline.

Plasmid analysis of isolates, three major plasmid patterns were observed 3.1, 4.9 and 6.2-kb.

In curing experiments, resistance to Erythromycin, Penicillin, and Clarithromycin were lost together and their loss was accompanied by the loss of a plasmid of 3.1-kb.

Similarly, resistance was accompanied by the loss of a 6.2 –kb plasmid.

In transfer experiments, no resistance determinants were transferred by conjugation, indicating that they did not harbor conjugative plasmid.

Conclusion : The antimicrobial resistance among isolates is either plasmid- related for certain antibiotics or chromosomally- mediated for the others.