Subgingival bacterial profiles and antimicrobial resistance patterns in periodontitis: a multi-center observational study

Subgingival bacterial profiles and antibiotic resistance patterns in individuals with periodontitis exhibit significant geographical variations. However, data from the Chinese population remain scarce. This study aimed to characterize the subgingival bacterial profiles and antibiotic resistance patterns among individuals with periodontitis in Shanghai, China. A three-center observational study was conducted from 2021 to 2022, enrolling individuals with periodontitis. Subgingival plaque samples were collected for culture, species identification by matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS, VITEK MS), and antimicrobial susceptibility testing using the agar dilution method for anaerobes and the broth dilution method for aerobes. Descriptive statistics were used to summarize the demographic and periodontal characteristics of participants, bacterial prevalence, and antimicrobial susceptibility profiles. Group comparisons were conducted using the Mann-Whitney U test for continuous variables, and the chi-square or Fisher’s exact tests for categorical variables, as appropriate. Minimum inhibitory concentration (MIC50 and MIC90) values and resistance rates were calculated for each antimicrobial agent. A total of 240 individuals with periodontitis were enrolled. Streptococcus spp. (97.5%) and Neisseria spp. (80.8%) were the most prevalent aerobes. Among anaerobes, Prevotella spp. (86.3%), Fusobacterium spp. (53.3%), and Capnocytophaga spp. (42.1%) were predominant. Most bacterial species showed low resistance rates to amoxicillin (< 10%), except for Prevotella spp. (32.1%). Anaerobic isolates exhibited low resistance rates to metronidazole and all isolates remained highly susceptible to amoxicillin-clavulanic acid. However, high resistance rates to clindamycin were observed in Prevotella spp. (45.7%), Porphyromonas gingivalis (37.5%), and Streptococcus spp. (36.5%). The subgingival bacterial profiles in this cohort exhibited low resistance to commonly used antimicrobials, except for clindamycin. All these highly susceptible antimicrobials could be considered in specific cases, such as Stage III or IV, Grade C periodontitis in young individuals. This study is registered with the Chinese Clinical Trial Registry (Identifier: ChiCTR2100048025; 28 June 2021).