Microbiology and treatment of
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Microbiology and treatment of

DisciplinaOdontologia Morfofuncional do Ecossistema Bucal154 materiais1.381 seguidores
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part of the abscess, where bacteria might have lost
their viability or at least are inhibited. Methods em-
ployed to avoid false-negative and false-positive re-
sults are not sufficiently described in many studies,
and the microbiological findings are therefore some-
times difficult to evaluate. Caution should also be
exercised when sampling patients already on anti-
biotic administration, due to the bacteriostatic effect
of antibiotics on parts of the flora. The abscess-pro-
ducing bacterial species may not be detected unless
a specific antibiotic inactivation procedure is en-
acted (153).
Microbial transportation
If microbial samples cannot be processed and cul-
tured promptly, it is possible for routine analysis to
delay culturing for 24 hours by using transport me-
dia such as VMGA III or RTF (34, 153, 189).
Methods for microbiological evaluation
Culture is considered the gold standard in microbio-
logical evaluation of dental abscesses. Correctly em-
ployed with consideration to transportation, media
selection, anaerobiosis and other atmosphere con-
ditions, length of incubation etc., culture remains
the best choice for unbiased searching for the pre-
dominant species in a sample with a polymicrobial
mixture. However, few studies carry the microbial
identification to species level but group them at ge-
nus level or into other groups based on limited
phenotypic characteristics. Furthermore, taxonomic
insufficiency or reclassification may confuse identi-
Microscope evaluation has been used for detec-
tion of noncultivable species, such as Treponema
spp. (205, 206). Recent studies have used immuno-
fluorescence, DNA probe or PCR methods in mi-
crobial identification (10, 66, 191). It is plausible that
molecular detection methods may reveal micro-
organisms that have not yet been identified in dental
abscesses (43).
Microbiology of the dentoalveolar
abscess (Table 2)
Anaerobic streptococci
Anaerobic streptococci (Peptostreptococcus spp.,
Peptococcus spp. and Streptococcus spp.) belong to
one of the most frequently isolated group of or-
ganisms in the dentoalveolar abscess. Among the
Microbiology and treatment of dental abscesses and periodontal-endodontic lesions
strictly anaerobic genera, Peptostreptococcus spp.
predominate. Commonly isolated species are Pep-
tostreptococcus anaerobius, Peptostreptococcus
micros and Peptostreptococcus prevotii. Peptococcus
species are less frequently reported, although Pep-
tococcus magnus and Peptococcus asaccharolyticus
have been identified in several studies. The micro-
aerophilic streptococcal species are frequently re-
covered, but some streptococci are true anaerobes
(Streptococcus intermedius and Streptococcus con-
stellatus), whereas other strains of the \u2018\u2018Streptococ-
cus milleri\u2019\u2019 group (such as Streptococcus ang-
inosus) are commonly placed among facultative
species. Gemella (formerly Streptococcus) morbillo-
rum, belonging to this microaerophilic group, has
also been reported in dental abscesses.
Gram-negative anaerobic cocci
Gram-negative anaerobic cocci, often represented by
Veillonella parvula, are reported in most studies al-
though in a limited number of cases (Table 2).
Gram-postive anaerobic rods
Gram-positive anaerobic rods are commonly recov-
ered from dental abscesses. Since several species are
aero-tolerant and other species are strictly anaer-
obic, the classification of the isolates into anaerobes
or facultative anaerobes can sometimes give rise to
confusion. Actinomyces isolates are often not speci-
ated. However, A. israelii, Actinomyces meyeri, Acti-
nomyces odontolyticus, Actinomyces viscosus and Ac-
tinomyces naeslundii are among the species re-
ported. Actinomyces spp. are important due to their
ability to cause actinomycosis, attributed mostly to
A. israelii, even if other species may also participate.
Actinomyces species have been reported to persist in
the periapical granuloma, especially in treatment-re-
sistant cases (82, 181).
Lactobacillus is often isolated from dental ab-
scesses but, similarly to Actinomyces, it is seldom
speciated. Lactobacillus spp. have been regarded as
having low virulence (48), even if they are frequently
present in endodontic lesions and dental abscesses.
The frequent isolation in endodontic failures indi-
cates a need for reconsidering the pathogenicity of
oral lactobacilli (150). Lactobacillus plantarum,
Lactobacillus casei, Lactobacillus acidophilus and
Lactobacillus fermentum have been identified in oral
infections. Oral Bifidobacterium isolates belong
mainly to the Bifidobacterium brevis species. In the
Eubacterium genus, isolates of Eubacterium alacto-
lyticus, Eubacterium lentum and Eubacterium yuri
are most commonly recovered from the oral cavity
(38). Propionibacterium acnes and Propionibacteri-
um propionica (formerly A. propionica) are also re-
ported by several studies of oral abscesses (Table 2).
Clostridium species are very rare isolates from dental
Gram-negative anaerobic rods
Gram-negative anaerobic rods are the most frequent
isolates in dentoalveolar abscesses. Heimdahl et al.
noted that, the more severe the abscesses, the more
gram-negative anaerobes and S. milleri were recov-
ered (88). However, the taxonomy is confusing, and
literature older than 10 years refers to isolates as
either Bacteroides or Fusobacterium species. The
most commonly reported group according to mod-
ern taxonomy is Prevotella spp. Prevotella intermedia
may best represent this group of organisms. Current
differentiation into P. intermedia and Prevotella nig-
rescens should be considered. It is interesting to note
that, whereas P. intermedia tended to be associated
with severe periodontal infections, Prevotella nigres-
cens was more frequently isolated from endodontic
infections (5). Prevotella melaninogenica is also fre-
quently reported in dentoalveolar abscesses and, to-
gether with P. intermedia and Porphyromonas spe-
cies, have placed the black-pigmented gram-nega-
tive rods (Bacteroides) in focus as major pathogens
in dentoalveolar abscesses (217, 218). The import-
ance of black-pigmented species has been further
stressed by several authors relating these organisms
to the presence of symptoms in acute infections.
Sundqvist (192) suggested a relationship between
black-pigmented Bacteroides and pain and sinus
tract formation in acute endodontic infections, later
supported by Griffee et al. (71) and Baumgartner et
al. (10). These studies also revealed a higher fre-
quency of saccharolytic species (Prevotella) than as-
accharolytic species (Porphyromonas) in acute endo-
dontic infections. On the other hand, Haapasalo et
al. (73) stressed the presence of Porphyromonas spe-
cies in symptomatic cases and isolated both P. gingi-
valis and Porphyromonas endodontalis from acute
endodontic infections. It seems that P. endodontalis
for some reason is selected for in root canal infec-
tions and, together with P. intermedia, is present in
symptomatic teeth (217, 219). Other studies have
also described a relationship between black-pig-
mented gram-negative species and symptoms but
also underscored the importance of other bacterial
species in acute infections. Non-pigmented Prevotel-
la, Peptostreptococcus, Peptococcus, Eubacterium and
Fusobacterium species have been significantly as-
sociated with endodontic symptoms (65, 83, 98, 223).
In dentoalveolar abscesses, non-pigmented Prevotel-
la species (such as Prevotella oralis, Prevotella rumi-
nicola, Prevotella buccae, Prevotella oris, Prevotella
bivius and Prevotella oulorum) are almost as com-
mon as the black-pigmented species (75). However,
some reports on species occurrence are difficult to
interpret due to changed taxonomy. Bacteroides ru-
minicola should probably have been classified as P.