CASE REPORT

Case of a cerebral abscess causedby Porphyromonas gingivalis in a subjectwith periodontitisFrederic Van der Cruyssen, Koenraad Grisar, Honorine Maes, Constantinus Politis

OMFS-IMPATH ResearchGroup, Department of Imagingand Pathology, Faculty ofMedicine, Catholic UniversityLeuven, Leuven, Belgium

Correspondence toDr Frederic Van der Cruyssen,frederic.vandercruyssen@uzleuven.be

Accepted 10 February 2017

To cite: Van der Cruyssen F,Grisar K, Maes H, et al. BMJCase Rep Published online:[please include Day MonthYear] doi:10.1136/bcr-2016-218845

SUMMARYWe report the case of a 65-year-old man presentingwith generalised seizures after developing a right frontalbrain abscess. Stereotactic aspiration and subsequentmatrix assisted laser desorption/ionisation time-of-flightanalyzer (MALDI-TOF) spectrometry revealedPorphyromonas gingivalis as the only causative anaerobemicroorganism. Secondary incision and drainage wasrequired due to neurological deterioration with increaseddimensions of the abscess, intracranial pressure andformation of a subdural occipitoparietal empyema. Oralimaging was positive for apical periodontitis of multipleelements; therefore, the remaining dentition wasremoved. Targeted antibiotic treatment includedintravenous ceftriaxone and ornidazole. The patient wasdischarged to our revalidation unit 59 days afteradmission to make a full recovery. To the best of ourknowledge, this is the sixth reported case of P. gingivaliscausing an intracranial abscess and the third case of atrue intracerebral parenchymal abscess caused by thisbacterium.

BACKGROUNDBrain abscesses of odontogenic origin are rarelyseen and account for only a small fraction of allreported cerebral abscesses. The incidence of cere-bral abscesses ranges from 0.4 to 0.9 cases per100 000 people and is more frequent in im-munocompromised patients. Oral pathogens cause3–10% of abscesses,1 while other causative patho-gens are non-oral bacteria, mycobacteria, fungi orparasites. The underlying pathogenic mechanisms arepoorly understood. Contiguous spread of a pathogen isthe most frequent route of infection. Haematogenousor lymphatic dissemination is seen in a limitednumber of cases.2 The initial presentation, symp-toms and results from clinical and radiological inves-tigations vary widely and are non-specific for thecausative pathogen.3–4 Morbidity and mortalityhave improved in recent years due to better imagingtechniques and therapeutic options. Mortalityranges from 0 to 24% for odontogenic brainabscesses.5 Porphyromonas gingivalis, a gram-negative oral pathogen, has rarely been reported insubjects with cerebral abscess formation, but hasbeen widely associated with periodontitis. Its patho-genesis is still being investigated, but includes a widevariety of immunological escape mechanisms.We searched databases (Medline, Scopus, Web of

Science, EMBASE, Cochrane library) and manuallysearched reference lists for relevant articles and

related cases. Well-accepted reviews served as thefoundation for this article. Additional original arti-cles were selected by reading the abstract andobtaining the full text when needed. Search termsincluded: brain abscess, cerebral abscess, P. gingiva-lis, odontogenic, periodontitis, parodontitis, toothinfection and oral pathogen. Five articles wereselected that discussed intracranial abscess forma-tion by P. gingivalis.

CASE PRESENTATIONWe report the case of a 65-year-old man with amedical history of prostate carcinoma, for which heunderwent radical prostatectomy with adjuvantradiotherapy. The patient also had type 2 diabetes,hypertension, hypercholesterolaemia and epilepsyof unknown origin during his childhood. Homemedications included acetylsalicylic acid, olmesar-tan medoxomil, rosuvastatin, lixisenatide, metfor-min and gliclazide. The patient was previouslytreated with valproate, which was reduced and thenstopped 6 months earlier as the patient was seizurefree for over 20 years. Previous imaging reportsnever mentioned intracranial anomalies. Detailedfindings and events are illustrated in the patient’stimeline (figure 1).In August 2016, he was admitted after a general-

ised epileptic seizure at home. The patient’s wifereported that he was increasingly confused in thepreceding days. The clinical neurological examin-ation was normal with a Glasgow Coma scale(GCS) of 15/15. Blood tests were unremarkableexcept for a slightly increased C reactive protein(CRP) of 5.9 mg/L (reference

Figure 1 Timeline of patient showingimportant clinical events, imaging andintervention dates, and antibiotic andantiepileptic treatments. T°,temperature; CRP, C reactive protein.

Figure 2 Initial contrast-enhanced CT imaging at the day ofadmission showing a hypodense nodular lesion in the right frontal lobewith peripheral ring-like contrast uptake as well as perilesionaloedema. The conclusion was possible malignancy, preferablymetastasis.

Video 1 Initial contrast-enhanced CT imaging at the day of admissionshowing a hypodense nodular lesion in the right frontal lobe withperipheral ring-like contrast uptake as well as perilesional oedema. Theconclusion was possible malignancy, preferably metastasis.

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MALDI-TOF spectrometry of the pus (Bruker Daltonik MaldiBiotyper) revealed P. gingivalis as the sole causative bacterium(score 2.231, high-confidence identification). Intraoral inspec-tion showed partial dentition complicated with parodontitis. Onprevious CT imaging, apical periodontitis was seen around theelements 16, 23 and 34 (figure 4), and the sinus cavitiesappeared normal. The antibiotic regimen was reduced to intra-venous ornidazole (1 g/day) and ceftriaxone (2 g/day).

Nineteen days after initial drainage, left hemiparesis and lefthemineglect developed as well as an increase in epileptic sei-zures with one tonic–clonic seizure. The patient further

deteriorated with need for intubation and intravenous sedation.Imaging showed the intracerebral abscess was extending to thesubdural space and subcutis, forming a subdural empyema andspreading to the occipital–parietal regions; therefore, incisionand drainage (figure 5) was necessary. Owing to clinical instabil-ity, total extraction of the remaining dentition was performed ina separate procedure. Antibiotic treatment included intravenousceftriaxone (2 g/day) and ornidazole (1 g/day), which were con-tinued for a total of 43 days until clinical, biochemical andradiological improvement. The patient was discharged from theneurosurgical ward after 59 days with almost complete reso-lution of the neurological deficit. He was referred for inhospitalphysiotherapy to regain full motor function.

DISCUSSIONTo the best of our knowledge, this is the sixth reported case ofintracranial abscess formation by P. gingivalis and the third caseof a true intracerebral parenchymal abscess.6–10 An overview ofreported cases is given in table 1. It is well known that the oralcavity hosts a wide variety of microbiological organisms. Studiesidentified up to 350 different bacterial strains in marginal peri-odontitis and up to 150 strains in endodontic infection.5 Someof these oral commensals cause opportunistic infections, forexample, streptococcal endocarditis after dental procedures hasbeen the rationale for endocarditis prophylaxis in high-riskcardiac patients. Iatrogenic or covert bacteremia arising from theoral cavity rarely causes clinical pathology requiring interven-tion. It is extremely rare for P. gingivalis to cause an intracranialabscess and it has only been reported five times in current litera-ture (table 1). This highly adapted non-motile gram-negativeoral anaerobe is strongly associated with periodontitis and canbe cultured in 85.7% of patients diagnosed with periodontitiscompared with 23.1% of healthy subjects.11 Being an opportun-istic pathogen, it has high virulence as indicated by biofilmformation, dipeptidyl peptidase intravenous activity, strong

Figure 3 MRI with T1 (left) anddiffusion-weighted imaging (right)showing central diffusion restrictionsuggestive of a cerebral abscess. Thedural layer is thickened, indicatingpachymeningitis.

Video 2 MRI with diffusion-weighted imaging showing centraldiffusion restriction, suggestive of a cerebral abscess. The dural layer isthickened, indicating pachymeningitis.

Figure 4 Periodontal apicalradiolucent areas of elements 16 (left),23 (middle) and 34 (right).

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induction of proinflammatory cytokine secretion and the inva-sion potential of epithelial cells to escape immune response acti-vation.12 Other reported extraoral infections, other thanintracranial, caused by P. gingivalis include otitis media, appen-dicitis, gas gangrene, thoracic empyema and lung abscessformation.13

An analysis of the cases (table 1) indicated most subjectspresent over the age of 50; however, one case of subduralempyema was reported in a 34-year-old man. In all previouscase reports, no underlying immunodeficiency was reported.Our patient suffered from type 2 diabetes mellitus, an auto-immune inflammatory condition known to disrupt the blood–brain barrier leading to leakage of small arterioles, possiblyfacilitating haematogenous dissemination.14 Presenting symp-toms were non-specific for the causative organism and dependedon the location and elevated intracranial pressure. Suspicionshould be raised when an oral or dental pathology is present.Comorbidities must be taken into account. A full blood countwith inflammatory markers, electrolytes, kidney and liver func-tion tests, blood glucose levels and blood cultures are advised.Cranial contrast-enhanced CT imaging is the preferred initialradiologic investigation followed by MRI with DWI. Thiscase demonstrates the additional benefit of MRI-DWI in

Figure 5 CT imaging 12 days after initial abscess drainage.Subcutaneous collection (arrow) with gas locules (arrowhead), newmanifestation of the subdural occipitoparietal empyema (small arrow)and increased cerebral oedema.

Table 1 Reported cases of intracranial abscesses caused by Porphyromonas gingivalis

Reference SexAge(years)

Predisposingfactors Pathogen Oral pathology

Presentingsymptoms Localisation Treatment Outcome

8 F 64 Eisenmenger’ssyndrome,ventricularseptal defect

LactobacilluscatenaformisP. gingivalisFusobacteriumnucleatum

Periodontitis 15 Seizures Right temporallobe

Initial AB: Ceftriaxone,metronidazole, vancomycinSwitched AB (D2):sulbactam/ampicillinSurgical: drainage (D2),craniotomy (D26)

Dischargeafter 27 days,referred toother hospital

6 F 57 ? P. gingivalisdetected inCSF

Single toothinfection, notfurther specified

Fever HeadacheGait disturbance

Site not specified.Additionalventriculitis

Initial AB: fosfomycin,panipenem, cephalothin(intraspinal)Switched AB (D10):piperacillin, cefozopran,cephalothin (ventricularinjection)Surgical: tooth extraction

Dischargeafter 21 days.Full recovery

10 M 67 None reported P. gingivalis None reported Throbbingright-sidedheadache

Right cavernoussinusInfraorbital cavitySphenoid sinus

Initial AB: carbapenemSwitched AB (D15):ampicillin, sulbactamSurgical: drainage,endoscopic sphenoidotomy

Full recovery

7 M 54 None reported P. gingivalis Periodontitis Right-sidedhomonymoushemianopsiaRighthemiparesis

Leftparieto-occipitallobe

Initial AB: vancomycin, 3rdgeneration cephalosporin,metronidazoleSwitched AB (D10):ampicillin, sulbactamSwitched AB (D14):amoxicillin, clavulanateSurgical (D0): craniotomy

Full recovery

9 M 34 None reported P. gingivalis Sinusitis(bilateralfrontal,ethmoid, andleft maxillary)

FeverHeadachePhotophobiaLeft hemiparesisRepeatedvomiting

Right frontalsubduralempyema

Initial AB: ceftriaxone,metronidazoleSurgical: frontoparietalcraniectomy (D2),ethmoidectomy (D2),bilateral anteriorethmoidectomy (D2),bilateral frontal sinectomy(D2), second drainage (D15)

Full recovery

AB, antibiotic treatment; CSF, cerebrospinal fluid; D, day; F, female; M, male.

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differentiating benign abscesses from primary or metastaticmalignancies; moreover, MRI-DWI can screen for ventriculitis.If present, hydrocephalus can develop with the need for ven-tricular drainage. After a diagnosis is made, possible sites oforigin should be further clinically or radiologically investigated.Transthoracic ultrasound to visualise possible endocarditis orvalvulitis with bacterial vegetations and oral inspection is ofparamount importance to treat underlying infective sources.

Treatment should always include neurosurgical expertise toassess the feasibility of diagnostic and therapeutic stereotacticaspiration. Empiric antibiotic treatment should begin as soon asa brain abscess is suspected. Usually a third-generation broadspectrum antibiotic such as cephalosporin, metronidazole andvancomycin is administered intravenously until positive culturegrowth or identification through mass spectrometry directs theantibiotic treatment. In most previously reported cases, thisapproach was followed (4/5). Treatment duration varies but isusually 4–6 weeks. The need for additional interventions shouldbe based on clinical, laboratory and radiological findings.Drainage was performed in all reported cases. Tooth extractionwas only reported in one previous case. The mortality and mor-bidity rates after intracranial P. gingivalis abscess formation arehopeful. All patients (6/6) made a full recovery; however,reported mortality rates vary from 0 to 24% in cerebralabscesses due to odontogenic infection.5 Small sample size doesnot allow to draw statistically significant conclusions however,we caution not to minimize the possible pathological severity ofthis organism.

Learning points

▸ Porphyromonas gingivalis is a rare but potentiallylife-threatening anaerobe that can cause intracerebralabscesses.

▸ CT imaging cannot always diagnose a cerebral abscess; thus,MRI with diffusion-weighted imaging should be added tothe diagnostic workup.

▸ Quick initiation of broad-spectrum antibiotics, preferablyafter taking cultures, is paramount.

▸ Neurosurgical intervention and timing depends on clinical,laboratory and radiological findings but can be usefuldiagnostically to elucidate the causative pathogen.

▸ The source of infection should be investigated and treatedaccordingly.

Contributors FVdC was responsible for the study concept and design. FVdCcarried out the literature search. KG and HM were responsible for initial proofreading. KG, HM and CP critically reviewed the manuscript for important intellectualcontent. CP was the study supervisor. All authors read and approved the finalversion of the manuscript.

Competing interests None declared.

Patient consent Obtained.

Provenance and peer review Not commissioned; externally peer reviewed.

Open Access This is an Open Access article distributed in accordance with theCreative Commons Attribution Non Commercial (CC BY-NC 4.0) license, whichpermits others to distribute, remix, adapt, build upon this work non-commercially,and license their derivative works on different terms, provided the original work isproperly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

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Case of a cerebral abscess caused by Porphyromonas gingivalis in a subject with periodontitisAbstractBackgroundCase presentationDiscussionReferences