Periodontitis-associated bacteria

The bacteria chiefly responsible for periodontitis differ markedly in terms of their properties and pathogenicity.

Periodontitis is caused by various bacteria that differ markedly in terms of their properties and characteristics. The individual species also differ in terms of their sensitivity to particular antibiotics. It is therefore particularly important to know which bacteria are present in a patient and what the best option is for treating them. The main characteristics of periodontitis-associated bacteria are summarized in this list.

Aggregatibacter actinomycetemcomitans (Aa)

Complex affiliation: Green complex. Because of its extraordinary pathogenicity, it is presented separately in the result report as an “Aa-complex”.

Pathogenicity: very highly pathogenic

Pathogenicity factors: produces potent virulence factors such as phosphatases, leukotoxin and immunosuppressive factor

Properties: facultatively anaerobic; exogenous transmission (particularly parent-to-child and between partners); tissue invasive (hence risk of recurrence); resistant to metronidazole and clindamycin

Occurrence: high correlation with severe clinical forms; considered as the predominant pathogen in juvenile and aggressive forms of periodontitis

Therapy: SRP incl. adjunctive antibiotic therapy, because SRP is usually not sufficient on account of the invasiveness.

First-line antibiotic: Amoxicillin

Porphyromonas gingivalis (Pg)

Complex affiliation: Red complex

Pathogenicity: very highly pathogenic

Pathogenicity factors: Proteases and hemagglutinins. Hemagglutinins enable bacteria to accumulate on surfaces/ and to form clumps. Proteases enable them to actively penetrate surrounding tissue and to destroy it.

Properties: obligate anaerobic; exogenous transmission (particularly between partners); tissue invasive (hence risk of recurrence)

Occurrence: Predominant pathogen in aggressive and chronic forms of periodontitis, peri-implantitis and recurrent disease; high correlation with pocket depth and bleeding score

Therapy: SRP incl. adjunctive antibiotic therapy, because SRP is usually not sufficient on account of the invasiveness.

First-line antibiotic: Metronidazole

Tannerella forsythia (Tf)

Complex affiliation: Red complex

Pathogenicity: very highly pathogenic

Properties: obligate anaerobic; exogenous transmission possible; tissue invasive (hence risk of recurrence)

Occurrence: in periodontitis, chronic periodontitis and peri-implantitis; high correlation with pocket depth and bleeding on probing

Therapy: SRP incl. adjunctive antibiotic therapy, because SRP is usually not sufficient on account of the invasiveness.

First-line antibiotic: Metronidazole

Treponema denticola (Td)

Complex affiliation: Red complex

Pathogenicity: highly pathogenic

Properties: obligate anaerobic; tissue invasive (hence risk of recurrence); can be identified and quantified only by means of DNA techniques

Occurrence: Predominant pathogen in ANUG; high correlation with pocket depth and bleeding on probing

Therapy: SRP incl. adjunctive antibiotic therapy, because SRP is usually not sufficient on account of the invasiveness.

First-line antibiotic: Metronidazole

Prevotella intermedia (Pi)

Complex affiliation: Orange complex

Pathogenicity: highly pathogenic

Pathogenicity factors: Exotoxins and various enzymes (e.g. proteases) drive the destruction of periodontal tissue.

Properties: obligate anaerobic; exogenous transmission possible; risk of recurrence, correlation with poor oral hygiene; “bridge species”: they supply the bacteria of the red complex with metabolites that the latter need for survival.

Occurrence: Risk factor for aggressive periodontitis, gingivitis and ANUG

Therapy: SRP incl. adjunctive antibiotic therapy, because SRP is usually not sufficient in the presence of higher microbial counts.

First-line antibiotic: Metronidazole

Parvimonas micra (Pm)

Complex affiliation: Orange complex

Pathogenicity: moderately pathogenic

Properties: obligate anaerobic; “bridge species”: they supply the bacteria of the red complex with metabolites that the latter need to survive.

Occurrence: frequent component of destructive periodontal consortia and in advanced periodontitis

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy is required where the microbial count is very high.

First-line antibiotic: Clindamycin

Fusobacterium nucleatum (Fn)

Complex affiliation: Orange complex

Pathogenicity: moderately pathogenic

Properties: anaerobic; “bridge species”: they supply the bacteria of the red complex with metabolites that the latter need to survive.

Occurrence: Indicator of oral hygiene quality and SRP effectiveness. For ANUG and chronic periodontitis.

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy may be necessary.

First-line antibiotic: Metronidazole

Campylobacter rectus (Cr)

Complex affiliation: Orange-associated complex

Pathogenicity: moderately pathogenic

Properties: microaerophilic; forms leukotoxin-like protein; early colonizer of periodontal pockets

Occurrence: frequent in adult and rapidly progressive periodontitis

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy is indicated only in the presence of very high bacterial counts and severe clinical findings.

First-line antibiotic: Where the orange-associated complex occurs isolated: Clarithromycin. In combination with other complexes of bacteria: Metronidazole.

Eubacterium nodatum (En)

Complex affiliation: Orange-associated complex

Pathogenicity: highly pathogenic

Properties: obligate anaerobic; through its colonization and metabolism, facilitates colonization with more demanding bacteria

Occurrence: significant association with periodontitis

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy is indicated only in the presence of very high bacterial counts and severe clinical findings.

First-line antibiotic: Where the orange-associated complex occurs in isolation: Clarithromycin. In combination with other complexes of bacteria: Metronidazole.

Eikenella corrodens (Ec)

Complex affiliation: Green complex

Pathogenicity: moderately pathogenic

Properties: facultatively anaerobic; early colonizer; plaque bacteria; risk of recurrence; resistant to metronidazole and clindamycin

Occurrence: Correlation with pocket depth; increase in concentration of bacteria with increasing probing depth

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy is indicated only in the presence of high microbial counts and severe clinical findings.

First-line antibiotic: Amoxicillin

Capnocythophaga spec. (Cs)

Because of their similar properties, the species C. sputigena, C. gingivalis and C. ochracea  are included as a group.

Complex affiliation: Green complex

Pathogenicity: moderately pathogenic

Properties: facultatively anaerobic; early colonizer; resistant to metronidazole and clindamycin

Occurrence: Correlation with pocket depth; increase in concentration of bacteria with increasing probing depth

Therapy: SRP is usually sufficient. Adjunctive antibiotic therapy is indicated only in the presence of high microbial counts and severe clinical findings.

First-line antibiotic: Amoxicillin