Amoxicillin and metronidazole resistance of bacteria isolated from dental implants with peri-implant diseases: a pilot cross-sectional study

Abstract

Peri-implant mucositis is a reversible inflammatory lesion of the mucosa surrounding a dental implant, caused by the accumulation of bacterial plaque and biofilm formation, without bone loss. If peri-implant mucositis is not addressed, it can progress to peri-implantitis, characterized by significant inflammation and infection of the peri-implant mucosa accompanied by the loss of supporting bone. Clinical evidence suggests that the management of peri-implant infections consists of mechanical debridement of the implant, surgical intervention and the administration of antibiotics. However, limited information is available regarding antibiotic resistance in bacteria causing peri-implant diseases. This study is focused on assessing the antibiotic resistance of bacteria isolated from explanted dental implants with peri-implant infections to amoxicillin, clindamycin and metronidazole. To this end, biofilms were recovered using titanium curettes from dental implants of 10 patients with peri-implant infections: patients with peri-implant mucositis (<i>n</i>=4) exhibited redness, swelling or bleeding and absence of bone loss; patients with peri-implantitis (<i>n</i>=6) were diagnosed based on probing depth ≥6 mm and presence of bone loss. Antibiotic sensitivity was assessed using the Kirby-Bauer disc diffusion method in accordance with the Clinical and Laboratory Standards Institute at 10 µg per disc of amoxicillin, 30 µg per disc of clindamycin and metronidazole at a concentration of 50 µg per disc. The results were expressed as the diameters of inhibition zones for each antibiotic. Two peri-implant bacteria were identified by sequencing of their 16S rRNA. Peri-implant bacteria showed resistance to amoxicillin and metronidazole at 100% (10 out of 10). All isolates from dental implants with peri-implant infections (10 out of 10) were sensitive to clindamycin. Two isolates, M29 and P30 strains, were identified as <i>Streptococcus salivarius</i> by 16S rRNA sequencing. Our findings reveal emerging resistance to amoxicillin and metronidazole in clinical isolates from implants with peri-implant infections, yet bacterial susceptibility to clindamycin remains.