Viability of four putative periodontal pathogens and enteric rods in the anaerobic transport medium VMGA III.

The aim of this study was to determine the survival in VMGA III of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinobacillus actinomycetemcomitans and enteric rods in laboratory cultures as well as in subgingival plaque samples. Laboratory strains of the 4 putative periodontal pathogens and Escherichia coli were used in the laboratory part of this study. Also, 31 subgingival plaque samples were obtained from 22 periodontal patients and stored in VMGA III. Each sample, from both the laboratory and the clinical parts, was divided into 3 portions. One portion was cultured within a few hours of collection (baseline), while the second was processed after 24 h (day 2) and the third 48 h later (day 3). The results of the clinical part indicate that the detection frequencies of all 4 periodontal pathogens and their levels in positive samples decreased, to different degrees, by day 2 and decreased further by day 3. Enteric rods were not detected in base line samples. However, they were present in 16.1% and 22.6% of day 2 and day 3 samples, respectively. Similarly, the laboratory results demonstrate a significant decrease in the levels of the 4 periodontal pathogens tested by day 2 and day 3, whereas the opposite occurred for E. coli. P. gingivalis, P. intermedia, and F. nucleatum survived better in the presence of E. coli than alone, whereas A. actinomycetemcomitans survived less well when co-inoculated with E. coli. VMGA III appears to maintain microbial population ratios for periods up to 24 h. After 24 h, the multiplication of enteric organisms may alter the original proportions of the sample.