Keywords cerebral abscess - dental infection - Streptoccocus intermedius
Palavras-chave abcesso cerebral - infecção odontológica - Streptoccocus intermedius
Introduction
Cerebral abscess is a suppurative infection that affects the cerebral parenchyma.[1 ] It is the second most common purulent infection in the immunocompetent central nervous
system (CNS), followed only by bacterial meningitis.[2 ] Parenchyma involvement can occur due to contiguous infection mechanisms (between
40 and 50% of cases), hematogenous dissemination of distant focus (25% of cases),
secondary to open traumatic brain injuries (10% of cases) or idiopathic (15% of cases).[3 ]
[4 ]
In most cases, the etiologic agent is of bacterial origin; however, it should be noted
that these can also occur via other microorganisms, such as protozoa or fungi.[5 ] The microbiological agent involved in the genesis of the abscess depends on how
it is inoculated into the brain tissue. Furthermore, abscesses that occur due to contiguous
infection are usually caused by infections in nearby regions, such as otitis, mastoiditis,
sinusitis, periodontal disease, among others.[6 ]
[7 ]
[8 ] Among the most common pathogens are: Staphylococcus aureus , Streptococcus sp, Haemophylos influenzae , Bacteroides and Peptostreptococcus .[4 ]
[6 ]
Abscesses related to dental infections typically have polymicrobial derivation, highlighting
the streptococci, staphylococci species, Actinomyces sp, Actinobacillus sp, Fusobacterium
sp .[9 ] Secondary spreads to otitis, mastoiditis or sinusitis are more related to streptococcal
(especially Streptococcus pneumoniae ), Enterobacteriaceae, S. aureus and some anaerobes such as Prevotella sp., Bacteroides sp .[1 ] Abscesses caused by otitis and/or mastoiditis have a greater coefficient of temporal
lobe and cerebellum infection, while the secondary to rhinosinusitis or periodontal
infection most commonly affect the frontal lobe.[2 ]
[4 ]
[10 ] In addition, abscesses originating from hematogenous dissemination are usually multiple
and tend to affect, predominantly, regions irrigated by the middle brain (posterior
frontal lobe and parietal lobe).[2 ]
[3 ]
[10 ]
In relation to the most common focus of hematogenous dissemination, it could be mentioned:
infective endocarditis, cardiac alterations such as tetralogy of Fallot, patent foramen
ovale, cyanotic heart disease; lung abscess or bronchiectasis.[2 ]
[3 ]
[10 ] The foci of the spread of infectious endocarditis are often related to S. Aureus , species of streptococcus and bacteria of the HACEK group (Haemophilus spp, Actinobacillus actinomycetemcomitans, Cardiobacterium hominis, Eikenella
corrodens and Kingella kingae ).[1 ] Infections of pulmonary dissemination focus or heart diseases that involve formation
of arteriovenous shunts are generally polymicrobial, and involve streptococcus, anaerobic
species (Actinomyces sp., Prevotella sp., Bacteroides sp., Fusobacterium sp ), staphylococci and Enterobacteriaceae
[1 ]
[10 ].
Infections linked to neurosurgical procedures due to nosocomial infections have Meticycline-resistant S. Aureus as its main cause, but other species such as propionibacterium and coagulase-negative
staphylococcus may also be involved.[4 ]
[10 ] In trauma-related abscesses, it is known that Cranioencephalic S. Aureus is the main agent.[4 ]
[11 ]
Objective
To report a clinical case to identify the etiology and other cause and effect relationships
involved in the genesis of a rare case of brain abscess.
To analyze the diagnostic approach performed and correlate it with the main current
diagnostic protocols.
Clinical Case Report
Anamnesis
A 63-year-old male patient sought assistance due to complaints of low back pain and
severe headache. He reported that 4 days before he presented with severe headache
in the frontal region, associated with chills and lack of appetite. He sought care
at the local Emergency Unit, where he received symptomatic medication, resulting in
partial improvement of symptoms. He also reported that 24 hours before he noticed
the onset of pain in the lumbar region, of the prick type, associated with paresis
in the lower limbs and partial paresthesia in sporadic moments.
General physical examination did not show any particularity and, at the neurological
examination, he was bedridden, with no signs of meningeal irritation, with muscle
strength and reduced tactile sensitivity in the left lower limb.
Laboratory admission tests were requested, namely: Leukocytes 18,540 without deviation
presence of rods, platelets 517,000, urea 54, creatinine 0.9, sodium 140, potassium
4.5, lactate 17.20, ionic calcium 1.2, magnesium 2, 3, c-reactive protein 2, urine
test unchanged. Simple chest radiographs did not show any significant changes. In
such case, magnetic resonance imaging (MRI) of the skull was performed with contrast
([Fig. 1 ]).
Fig. 1 Shows the magnetic resonance of the skull, performed with the patient under discussion,
showing expansive lesions compatible with multiple brain abscesses. Source : The authors (2020).
After referral to blood cultures and echocardiography, to rule out possible foci of
hematogenous dissemination, no underlying changes were demonstrated. Then, antibiotic
therapy with ceftriaxone and metronidazole was started.
Seven days after admission, the patient showed an evolution with a lower level of
consciousness, requiring orotracheal intubation and urgent surgery. Therefore, craniotomy
was performed to remove cystic lesions, with the collection of material for culture.
Six days after the surgery, the secretion culture followed, positive for Streptococcus intermedius . In view of the identified etiologic agent, an oral and maxillofacial surgeon evaluation
was requested, since the existence of signs of gingivitis with severe periodontitis
and dental abscess in two teeth was confirmed, associated with mucositis in the soft
structures. Finally, the region was cleaned, in addition to maintaining the use of
intravenous antibiotics for 21 days.
Discussion
When facing a patient with a headache complaint, the first step is to identify whether
this is a primary or secondary disorder.[12 ] Primary headaches refer to chronic and continuous disorders of a dysfunctional nature,
not involving anatomical or structural changes,[13 ] while secondary headaches are symptoms of an underlying, neurological or systemic
disease (meningitis, brain tumor, among others).[14 ]
The main premonitory for identifying a secondary headache is the presence of alarm
signs: change in the pattern of pre-existing headache, progressive intensity headache,
sudden onset, associated focal neurological deficit, decreased level of consciousness,
seizure, systemic manifestations (fever, toxemia, immunodepression, skin rash), beginning
after 50 years of age.[12 ]
[14 ] It is evident that, in the face of a headache with alarm signs, it is necessary
to use imaging exams for better diagnostic clarification, with computed tomography
(CT) being the exam of choice.[12 ]
The patient presented several alarming signs that indicated it was a secondary headache:
sudden onset, progressive intensity, onset after 50 years of age, focal neurological
deficit (reduced strength in the left lower limb), signs of toxemia with fever and
chills. As for the other clinical manifestations, here we show all three classic manifestations
of brain abscesses: headache, fever and focal neurological deficit.
Initially, a CT scan of the skull was performed. However, it became necessary to perform
an MRI to better assess the lesion. This last examination showed multiple brain abscesses
in the parieto-occipital region. As reviewed, multiple abscesses are more common in
hematogenous foci, and tend to occur in the middle cerebral artery supply region,
predominating in the posterior region of the frontal lobe and in the anterior region
of the parietal lobe. Foci of hematogenous dissemination to the occipital lobe may
occur, but are less common.
Under suspicion of hematogenous dissemination, it is mandatory to find the primary
focus. The most common focus of hematogenous dissemination are endocarditis, cardiovascular
malformations and pyogenic lung infections. The complete absence of pulmonary symptomatology,
associated with an admission-free X-ray of the chest, practically rules out the latter
form of dissemination, resting the hypotheses in the probable cardiac focus. The echocardiogram
is the exam of choice for the assessment of endocarditis or cardiac structural changes.
In this case, the echocardiogram showed no changes, making it necessary to investigate
further to find the primary focus of the infection.
While the specific agent is not identified, the guidelines indicate the beginning
of empirical antibiotic therapy. Third and fourth cephalosporins generation are the
first choice for coverage of gram positive and gram negative germs, while the combination
with metronidazole provides adequate coverage against anaerobic germs. It is a given
fact that the choice of antibiotic therapy in this case, performed with ceftriaxone
and metronidazole, was appropriate.
After surgical removal and material collection, the culture showed the etiologic agent
involved in the infection of the parenchyma: S. intermedius . This agent is a highly positive, facultative anaerobic bacterium that is part of
the commensal flora of the oropharynx and gastrointestinal tract. Their involvement
in polymicrobial and suppurative infections is common.[15 ] Faced with an infection by a common agent in the oral mucosa, the hypotheses now
fall on a probable odontogenic spread.
The evaluation of the oral health team showed multiple foci of oral infection, with
the presence of severe periodontitis and dental abscess. Periodontitis is a chronic
inflammatory process of bacterial etiology, which affects a dental structure (connective
tissue, periodontal fiber and bones).[16 ]
[17 ] The most common etiological agents associated with periodontitis are Aggregatibacter actinomycetamcomitans and Porphyromonas gingivalis species.[16 ]
Streptococcus is the group of bacteria most related to oral diseases.[18 ] Some species such as Streptoccocus mutans are related to the occurrence of dental caries, while S. Intermedius and Streptoccocus constellatus usually colonize dental biofilm in patients with untreated chronic periodontitis.[18 ]
[19 ] The colonization of previous periodontal foci by bacteria of the species S. Intermedius and S. constellatus exacerbate the initial infectious process, which can trigger tooth loss and pyogenic
complications such as brain abscess, liver abscess and bacteremia.[19 ]
[20 ]
[21 ] Despite being part of the normal flora of the oropharyngeal, genitourinary and gastrointestinal
tracts, evidence of reports of involvement of these species in purulent infections
such as brain and liver abscesses, as well as the occurrence of bacteremia caused
by S. Intermedius after dental manipulation, even without the presence of an infectious process active
gingival.[20 ]
[21 ]
[22 ]
The finding of a common bacterium of the oral flora in the culture of the abscess,
associated with several foci of dental infection liable to spread, reinforces the
hypothesis that this abscess was caused by contiguous infection from these multiple
odontogenic foci.
Final Considerations
The reported case was a rare case of cerebral abscess secondary to odontogenic infection.
In agreement with the literature, abscesses caused by the spread of contiguous foci
tend to be single abscesses, keeping a close relationship between the dissemination
focus and the location of the abscess formation. Furthermore, this type of case affects
the frontal lobe, and rarely causes multiple abscesses.
We can conclude from the consultation of the literature and the report of the case
presented that it is not common for odontogenic infections to complicate with the
formation of abscesses in the parieto-occipital region, even more so with multiple
involvement. The immediate treatment of the abscess and its source with multidisciplinary
care allows the full recovery of the patient.
