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Spondylodiscitis, also termed ver-tebral osteomyelitis, is uncommonlycaused by anaerobic bacteria. In a studyby McHenry et al. (1), only 2 of 255(0.8%) cases of vertebral osteomyelitiswere due to anaerobic bacteria. In bothpatients, Propionibacterium acnes wasthe causative organism (1), and it isthe most frequent anaerobic bacteriumresponsible for spondylodiscitis (2).Spondylodiscitis is usually caused byfacultative organisms, with Staphylo-coccus aureus being the bacterium

most commonly isolated (1). Wedescribe a 70-year-old patient withspondylodiscitis of the lumbar spinecaused by Fusobacterium nucleatum.Case Report

A 70-year-old man was admitted tothe emergency department of our uni-versity hospital in November 2009. Hismedical history included chronic right-sided brachialgia and numbness in theright C6 and C7 dermatomes. He com-plained of generalized weakness, lossof appetite, chills, and mild sweatingfor a week. On the day of admission,he experienced diffuse abdominal andlumbar back pain. His body temperaturewas 37.7°C. On physical examination,there was generalized tenderness on

palpation of the abdomen and abdominalrigidity, mainly in the right lower quad-rant. There was tenderness on percus-sion over the spine from the second tothe fourth lumbar vertebrae. Lasègue’ssign was positive on the right side. Thepatient had difficulty walking and hadlumbar stiffness. Physical examinationof the heart and lungs was normal.Laboratory tests showed a hemoglobinvalue of 12.6 g/dl, a white blood cellcount of 5.8 x 109/L with 71.3% neu-trophils, and a platelet count of 151 x109/L. The C-reactive protein (CRP)level was 201.8 mg/L (normal value,<5 mg/L). Electrolytes and hepatic andrenal function tests were normal. Chestand abdominal radiographs were unre-markable. An abdominal ultrasound and

Mailing address: Jan Verhaegen, M.D.,Ph.D., Department of Microbiology,University Hospitals Leuven,Herestraat 49, 3000, Leuven, Belgiumjan.verhaegen@uz.kuleuven.ac.be

Case Report

Fusobacterium nucleatum Spondylodiscitis: Case Report andLiterature ReviewAn Joosten, M.D.,1 Jan Verhaegen, M.D., Ph.D.,1 and Eric Van Wijngaerden, M.D., Ph.D.,2 Departments of 1Microbiology and2Internal Medicine, University Hospitals Leuven, Leuven, Belgium

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computed tomography scan of theabdomen showed no abnormalities andno evidence of appendicitis. Magneticresonance imaging of the lumbar spineshowed L3 to L4 edema and an epiduralsoft tissue structure at the right side ofthe L4 vertebral body level. An 18F-fluorodeoxyglucose (FDG) positron-emission tomographic scan showedincreased accumulation of FDG at theright side in the L3 and L4 vertebralbodies. These findings confirmed theclinical diagnosis of spondylodiscitis.

Two anaerobic blood culture bottlesof four sets collected at the time ofadmission became positive after 2 daysof incubation using the BacT/ALERT3D system (bioMérieux, Durham, NC).Three other anaerobic blood culturebottles of 10 sets taken during the 5 daysbefore the start of antibiotic treatmentalso became positive. A needle aspira-tion of the spine was not performed,because the same organism was recov-ered from multiple blood culture bottlescollected on different days. Bacterialgrowth on solid medium was observedafter 3 days on Columbia blood agarmedium incubated anaerobically at37°C. Gram-stained smears showed thepresence of fusiform, gram-negativebacilli. Therapy was begun with 1 g ofamoxicillin-clavulanic acid adminis-tered intravenously (i.v.) three times aday, but this was changed the next dayto 2 g of ceftriaxone i.v. daily and 500mg of metronidazole orally twice daily(b.i.d). The isolate was further identi-fied using the Anaerobe ID Mastring-SSystem MID8 (Mast Laboratories,Bootle, U.K.). Additional identificationtests included a positive test for indoleproduction but negative activities forlipase, catalase, urease, esculin hydroly-sis, nitrate reduction, and beta-galacto-sidase. Negative fermentation reactionsin CTAmedium were observed for fruc-tose, glucose, lactose, and mannose. Byusing these tests, the isolate was identi-fied as F. nucleatum. We also identifiedthe strain as F. nucleatum with the useof matrix-assisted laser desorption ion-ization time-of-flight (MALDI-TOF)mass spectrometry (Bruker Daltonics,Billerica, MA). The MICs of the strainsdetermined by using the Etest (ABBiodisk, Solna, Sweden) on Mueller-Hinton blood agar were as follows:penicillin, <0.016 mg/L; clindamycin,0.016 mg/L; metronidazole, <0.016

mg/L; amoxicillin-clavulanic acid,0.016 mg/L; chloramphenicol, 0.75mg/L; piperacillin/tazobactam, <0.016mg/L; meropenem, 0.003 mg/L; andtigecycline, 0.016 mg/L. Since the strainwas susceptible to metronidazole, ther-apy with ceftriaxone was stopped after3 days and monotherapy with 500 mgof metronidazole orally b.i.d. was initi-ated with an excellent clinical response.Because the patient developed mouthulcers and an itchy skin rash on hischest and back after 3.5 weeks of treat-ment with metronidazole, therapy wasswitched to 600 mg of clindamycinorally three times a day. Therapy withclindamycin was stopped after 18 weeks.The patient improved symptomatically,The CRP level became normal, and anMRI showed decreased edema in the L4vertebral body. He remained asympto-matic with a normal CRP level 6 weeksafter discontinua-tion of all antibiotictherapy.

DiscussionThe genus Fusobacterium, which

currently includes 13 species, is a het-erogeneous group of gram-negative,non-spore-forming, nonmotile, anaero-bic bacilli belonging to the family Bac-teroidaceae, which includes the generaBacteroides, Prevotella, Porphyromonas,Fusbacterium, and Leptotrichia. Fuso-bacteria are differentiated from theother genera by their production ofmajor amounts of N-butyric acid alone;iso-butyric and iso-valeric acids are notproduced (3,4). F. nucleatum is a mem-ber of the genus Fusobacterium. Fivesubspecies of F. nucleatum have beendescribed from human flora: F. nucle-atum subsp. nucleatum, F. nucleatumsubsp. polymorphum, F. nucleatumsubsp. vincentii, F. nucleatum subsp.fusiforme, and F. nucleatum subsp.animalis (3).

Fusobacterium spp. are commonlyfound as normal flora of all mucosalsurfaces, including the mouth, upperrespiratory tract, gastrointestinal tract,and the female genital tract (4). Clinicalinfections with Fusobacterium spp.include infections of the head and neck,brain abscesses, and bacteremia (4-9).The most common Fusobacteriumspecies found in clinical infections areF. nucleatum and F. necrophorum (6-10). F. nucleatum and F. necrophorumare also the most common causative

agents of Lemierre syndrome (11-16).We have described here a case of

spondylodiscitis caused by F. nucleatumin a 70-year-old man. Spondylodiscitiscaused by Fusobacterium spp. is rare.Thirteen cases have been reported inthe literature (17-27). Eleven cases (17-24,26) have been reviewed by Le Moalet al. (26). One case was excluded fromthe analysis because of the absence ofdescription in the published series (25).Of the 13 remaining cases, includingours (17-24,26,27), F. nucleatumaccounted for 7 (54%) of the cases, fol-lowed by F. necrophorum with 3 (23%),F. Varium with 1 (8%), and two species(15%) that were not further identified.The mean age of the patients was 50years (range, 8 to 78 years), and themale/female ratio was 9:4. A previousear, nose, or throat infection or maxillo-facial problem was found in the nine(69%) patients without any other knownportal of entry. Most patients with ver-tebral osteomyelitis have underlyingrisk factors, most commonly diabetesmellitus, intravenous drug abuse,immunosuppression, and malignancy(28). However, among the 13 patientswith Fusobacterium sp. spondylodisci-tis, only two had diabetes mellitus, andone had a history of alcohol abuse. Thevertebral site of involvement was lum-bar in eight (62%) patients, thoracic intwo (15%), thoracolumbar in one (8%),lumbosacral in one (8%), and cervicalin one (8%). Eight (62%) patients hada vertebral biopsy, and five of the eight(63%) were culture positive. A vertebralbiopsy was not performed in the otherfive patients, because blood culturespermitted early identification of thebacterial cause of infection. Althoughthey are infrequently isolated, anaerobicbacteria recovered from blood culturesshould not be disregarded as a possiblecause of spondylodiscitis.

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