Update on minocycline in vitro activity against odontogenic bacteria

Periodontitis, which is a chronic inflammation caused by biofilm from numerous gram-negative and -positive oral bacterial species between gingiva and tooth, is known to have a poor prognosis. Susceptibility of standard strains (19 strains) and clinical isolates (90 strains) of aerobic and anaerobic oral bacteria, including a recently recovered as novel pathogens for periodontitis called Filifactor alocis, was tested to minocycline (MINO) by using the agar dilution method according to the Clinical and Laboratory Standards Institute. MINO is a well-used therapeutic antibiotic for periodontits. In this study, minimum inhibitory concentrations (MICs) of MINO against Aggregatibacter actinomycetemcomitans (n = 1), Porphyromonas gingivalis (n = 5), Prevotella intermedia (n = 1), Tannerella forsythia (n = 1) and F. alocis (n = 1), were 0.12, ≤0.016–0.03, ≤0.016, 0.03, and 2 μg/mL, respectively. MICs range of MINO against clinical isolates (10 isolates each) Streptococcus intermedius, P. gingivalis, P. intermedia, Fusobacterum nucleatum, Parvimonas micra were 0.06–16, ≤0.016–0.03, ≤0.016–1, ≤0.016–0.12, and ≤0.016–0.25 μg/mL, respectively. These results showed that MINO has superior in vitro activities against to known and recent recovered oral bacteria. Moreover, low prevalence in non-susceptible bacteria was observed to MINO.