Notes

Outline

SPIROCHETES © 2001 Richard A. Murphy

INTRODUCTION The spirochetes Long Thin Corkscrewlike Gram-negative Anaerobic bacteria

Slide 3

"Spirochetes - usually seen in..." Spirochetes - usually seen in material removed from diseased periodontal sites

"This has led people to..." This has led people to consider these organisms as periodontopathogens Others have suggested that the spirochetes are secondary, opportunistic organisms thriving on the nutrients that are relatively abundant in a periodontally inflamed site

"The difficulty of trying to..." The difficulty of trying to definitively link an organism with any periodontal disease is true for all of the organisms so far studied

MORPHOLOGY AND TAXONOMY The spirochetes - very difficult to culture This is due to their extreme anaerobic requirements their unique nutritional requirements (require a1-globulin) Over the last decade or so, some have been cultured and their characteristics determined

"But many remain uncultured" But many remain uncultured Because they were so hard to grow in culture, their differentiation was based primarily on size and other morphological characteristics Three sizes were seen, giving rise to the categories: small, intermediate, and large

"Spirochetes are structurally unique among..." Spirochetes are structurally unique among bacteria in that they have internal flagellalike structures called axial filaments The number of these filaments varied and so it was a further morphological characteristic to use for classification

Taxonomic Characteristics of Cultured Oral Spirochetes SPECIES SIZE % G + C Treponema denticola Small 27-38 T. macrodentium Small ? T. medium Small ? T. orale Small ? T. socranskii Small 51 T. maltophilum Small ? T. scoliodontium Small ? T. vincentii Intermediate 44 T. pectinovorum Intermediate 39

"Many others exist that have..." Many others exist that have not been grown in culture, mainly because they have very exacting nutritional requirements but also because they are very fragile and are very quickly killed by the mechanics of trying to isolate them

"There is also an organism..." There is also an organism called the large spirochete that is larger than these It is seen in periodontal disease but has never been cultured and there may actually be more than 1 large spirochete

"The spirochetes have been isolated..." The spirochetes have been isolated from several periodontal disease entities One periodontal disease called acute necrotizing ulcerative gingivitis (ANUG) has tremendous numbers of spirochetes and fusiform bacteria This has been referred to as a fuso-spirochetal infection

"The spirochete has now been..." The spirochete has now been grown and named T. vincentii Vincent was the first person to describe ANUG or NUG, which has had other names such as Vincent's angina and Trench Mouth

"Recent studies have shown that..." Recent studies have shown that T. vincentii is often present in the lesions but does not cause them Another, intermediate sized, unnamed spirochete appears involved The fusiform bacteria are in the genus Fusobacterium and are named Fusobacterium fusiforme

"Elevated spirochete levels have also..." Elevated spirochete levels have also been seen in adult periodontitis and early onset periodontitis They are not seen in significant numbers in localized juvenile periodontitis

VIRULENCE MECHANISMS Spirochetes contain endotoxin At least some of them are capable of suppressing the immune response

"When studied in vitro," When studied in vitro, T. denticola and T. vincentii are phagocytized but the polymorphonuclear leukocytes (PMNs) don't degrade them because the treponemes somehow prevent fusion of the lysosomes to the phagosomes

"Treponemes produce a protease that..." Treponemes produce a protease that hydrolyzes benzoyl-DL-arginine-2-naphthylamide (BANA) This substrate has been used to measure whether there is active disease in a periodontal pocket

"Of the various organisms that..." Of the various organisms that are BANA positive, T. denticola was the one making the greatest contribution in pockets Porphyromonas gingivalis and Bacteroides forsythus are also BANA positive and are believed to play a role in periodontal disease

"So the BANA test may..." So the BANA test may be a good one for assessing periodontal disease activity

OTHER SPIROCHETES T. pallidum is the etiologic agent of syphilis Syphilis is transmitted from person to person usually by sexual intercourse The initial lesion may be on the genitals or on the oral or anal mucosa T. pallidum has never been grown in culture So we don't know much about it, only about the disease it causes

Slide 23

Slide 24

Slide 25

"There are other spirochetal diseases..." There are other spirochetal diseases but they are not generally seen in the dental office so they won't be discussed here Important - any venereal disease could be readily transmitted in the dental operatory via dental procedures if instruments are not sterilized between patients

Peace!