Screening for subgingival occurrence of gram-negative enteric rods in periodontally diseased and healthy subjects.

Objective: This study aimed to determine whether the variations in the occurrence of gram-negative enteric rods as detected through a longitudinal follow up with three consecutive visits, may be associated with the periodontal clinical status.

Design: Clinical and demographic parameters from 63 untreated chronic periodontitis (CP) subjects and 45 healthy controls (HC) were analyzed. Subgingival plaque samples were obtained from 6 sites in each subject at baseline, 1-week, and 1-month visits and processed using culture and biochemical tests. Culture findings were categorized taking into account the detection frequency of gram-negative enteric rods as persistent presence, transient presence, or absence of enteric rods in any sampling time.

Results: Although transient presence of gram-negative enteric rods was more prevalent in CP subjects (16.7%) than HC subjects (9.3%), the difference was not significant (P>0.05). The majority of subjects showed a transient presence of gram-negative enteric rods at concentrations <2 x 10(2)CFU/mL. Persistent presence of gram-negative enteric rods was not observed in any subject through the entire study period. Moreover, differences in both the detection frequencies of individual species and the total number of gram-negative enteric rods were not statistically significant neither inter- nor intragroups.

Conclusion: The findings of the present study could indicate that gram-negative enteric rods are merely transient microorganisms within the subgingival environment and suggest that the periodontal clinical status appeared not to be influenced by the presence of these species.