The microbiota of periodontal pockets with different depths in therapy-resistant periodontitis

This study presents the composition of the cultivable microbiota colonising periodontal pockets of different depths among 2 patient-groups classified as non-responsive (NR-group; 11 participants) or responsive (R-group; 10 participants) to periodontal treatment. Microbiological samples from three types of pocket (< 4 mm deep A-samples; 4-5 mm B-samples; > 5 mm C-samples) were analysed by cultural methods for putative periodontitis pathogens, microbial groups constituting > or = 5% of the total cultivable flora and opportunistic pathogens. Actinomyces naeslundii, A. israelii, Bacteroides forsythus, Fusobacterium spp, Porphyromonas gingivalis, Prevotella intermedia, Peptostreptococcus micros, anaerobic streptococci and facultative anaerobic streptococci were most prevalent. Actinobacillus actinomycetemcomitans, Staphylococcus aureus, enteric rods and yeasts were less prevalent. The periodontitis pathogens Bacteroides forsythus, Fusobacterium spp, Porphyromonas gingivalis, Prevotella intermedia and Peptostreptococcus micros constituted together (on average) < or = 23% of the viable counts in the A- and B-samples of both patient groups and in the C-samples of the R-group. In the C-samples of the NR-group their mean counts were 45%. Correlations were found between smoking habits and the five pathogens in the C-samples and in pooled pocket depth samples. The results show that groups of periodontopathogens should be considered a causal factor in therapy-resistant periodontitis. Further, smoking and deep pockets can enhance a shift in the balance of the subgingival microflora predisposing a site to disease and a susceptible host may be the pre-requisite to therapy-resistant periodontitis.