Antimicrobial resistance of aerobes and facultative anaerobes isolated from the oral cavity

Objectives

This study evaluated the resistance to antimicrobials of aerobes and facultativeanaerobes isolated from patients wearing complete dentures, patients withgingivitis and periodontitis, and periodontally health subjects.

Material and methods

Three hundred and four isolates were tested. The minimal inhibitory concentrationsof the drugs were evaluated through the agar dilution method using Mueller-Hintonagar.

Results

The most active antimicrobial drugs were the carbapenems (meropenem and imipenem),and resistance to these drugs was restrict to 1.6-2.3% of the isolates, as well asciprofloxacin and rifampin. Microbial resistance to ampicillin,amoxicillin/clavulanic acid, cefoxitin, cephalothin, amikacin, chloramphenicol andnalidixic acid was particularly high. In most cases, the resistance to β-lactamswas mediated by the production of hydrolytic enzymes, especially in gram-negativeenteric rods, while enterococci did not evidence production ofthese enzymes. The association amoxicillin/clavulanic acid was not effective in28.3% of the tested isolates.

Conclusions

The results of this investigation confirmed that the oral cavity of patients withperiodontitis and gingivitis, and particularly edentulous patients wearingcomplete dentures, could harbor microorganisms with several antimicrobialresistance markers, and these microorganisms are frequently implicated inmultiresistant, systemic, oral or nosocomial infections.