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Antibiotic Susceptibility of Periodontal Streptococcus constellatus and Streptococcus intermedius Clinical Isolates
Author(s) -
Rams Thomas E.,
Feik Diane,
Mortensen Joel E.,
Degener John E.,
Winkelhoff Arie J.
Publication year - 2014
Publication title -
journal of periodontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.036
H-Index - 156
eISSN - 1943-3670
pISSN - 0022-3492
DOI - 10.1902/jop.2014.130291
Subject(s) - streptococcus intermedius , microbiology and biotechnology , clindamycin , antibiotics , amoxicillin , periodontitis , ciprofloxacin , metronidazole , biology , agar dilution , doxycycline , streptococcus , minimum inhibitory concentration , medicine , dentistry , bacteria , genetics
Background: Streptococcus constellatus and Streptococcus intermedius in subgingival dental plaque biofilms may contribute to forms of periodontitis that resist treatment with conventional mechanical root debridement/surgical procedures and may additionally participate in some extraoral infections. Because systemic antibiotics are often used in these clinical situations, and little is known of the antibiotic susceptibility of subgingival isolates of these two bacterial species, this study determined the in vitro susceptibility to six antibiotics of fresh S. constellatus and S. intermedius clinical isolates from human periodontitis lesions. Methods: A total of 33 S. constellatus and 17 S. intermedius subgingival strains, each recovered from separate patients with severe chronic periodontitis (n = 50) before treatment, were subjected to antibiotic gradient strip susceptibility testing with amoxicillin, azithromycin, clindamycin, ciprofloxacin, and doxycycline on blood‐supplemented Mueller‐Hinton agar and to the inhibitory effects of metronidazole at 16 mg/L in an enriched Brucella blood agar dilution assay. Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing interpretative standards were used to assess the results. Results: Clindamycin was the most active antibiotic against S. constellatus (minimum inhibitory concentration at 90% [MIC 90 ] 0.25 mg/L), and amoxicillin was most active against S. intermedius (MIC 90 0.125 mg/L). A total of 30% of the S. constellatus and S. intermedius clinical isolates were resistant in vitro to doxycycline, 98% were only intermediate in susceptibility to ciprofloxacin, and 90% were resistant to metronidazole at 16 mg/L. Conclusion: Subgingival S. constellatus and S. intermedius exhibited variable antibiotic susceptibility profiles, potentially complicating empirical selection of periodontitis antibiotic therapy in patients who are species positive.