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Cerebral abscess caused by Rhizobium radiobacter: first case report

Rojas, Luis O.; Martínez, Luis F.; Vives, Carlos H.G.; Lopez, Edgar A.G.; Cifuentes, Marcela

doi: 10.1097/QAD.0b013e3283528b3f

Departamento de Neurocirugía, Facultad De Medicina, Hospital Militar Central, Universidad Militar Nueva Granada, Bogotá, Colombia.

Correspondence to Carlos H.G. Vives, Hospital Militar Central, Departamento de Neurocirugía, Facultad de Medicina, Universidad Militar Nueva Granada, Cra 57 # 53-50 interior 1 apto 101, Bogota, Colombia. Tel: + 57 1 3002126316; fax: + 57 1 4776817; e-mail: carlosusf@hotmail

Received 1 February, 2012

Accepted 14 February, 2012

We present a 28-year-old male patient, soldier, originally from Honda (Tolima), Colombia, who consulted in September 2009 complaining of 25 days of right-sided facial palsy of central origin, motor dysphasia, progressive hemiparesis, right-sided. Fever is not documented during the evolution of symptoms. Complete blood count, electrolytes, C-reactive protein, erythrocyte sedimentation rate, renal and liver function and coagulation times were all within normal limits.

The computed tomography scan ordered by the emergency room department showed a round hypodense lesion of 6 × 5 cm in the left parietal region, generating a mass effect over the ventricular system, with an image that suggests vasogenic edema because of its finger-like projections (Fig. 1).

Fig. 1

Fig. 1

The patient was taken into surgery and a stereotactic-guided craniotomy was performed with the preliminary diagnosis of cerebral abscess vs. neoplasic lesion. During surgery, a light brown friable lesion was found. The sample was sent to pathology, and it was reported as: negative for malignancy, negative for microorganisms, cerebral parenchyma with fibrinous necrosis, cellular debris, edema, vascular congestion, lymphoplasmacytic and eosinophilic infiltrates. No granulomas were found, no signs of vasculitis, no tumoral infiltration. It was reported as an acute and chronic inflammation (abscess), possibly an area of gliosis of bacterial origin. The microbiology exam reported: gram with moderate polymorphonuclear cells, negative for microorganism and the culture showed the Rhizobium radiobacter.

Because of the pathology and microbiology findings, the infectious disease department started treatment with third-generation cephalosporins according to the sensitivity of the microorganism. An ELISA for HIV was ordered; it was positive with a CD4 cell count of less than 200, the patient was considered AIDS C3 and antiretroviral therapy was initiated.

At this moment, the patient is on antiretroviral therapy, a complete antibiotic regimen with adequate response and neurological improvement. The patient was discharged and is currently being followed as an outpatient.

The first case of human infection by R. radiobacter was published in 1980 by Plotkin in a patient with a prosthetic aortic valve and endocarditis [1].

In 1993, Edmon et al.[2] reviewed 18 literature cases and added a series of 4 cases for a total of 22 cases of infections by Rhizobacterium radiobacter that presented in the context of four syndromes: peritonitis, urinary tract infections, bacteremia and endocarditis [1–11].

Laffut et al.[4] in 2005 reported the only case of meningitis caused by R. radiobacter in a female patient with chronic lumbar pain that was being managed with an intrathecal catheter for the administration of morphine. The patient received empiric treatment with cefotaxime 2 g i.v. q.i.d. for 7 days with clinical improvement [12].

We describe the case of a patient without any significant past medical history who presented with a subacute mixed motor and sensitive syndrome. In neuroimages, a hypodense lesion with significant perilesional edema was found. Once the contrast agent was administered, the lesion showed an enhancing halo in its periphery (Fig. 1). Clinically, the patient did not present signs of a systemic inflammatory response; in the admitting laboratory studies, there was no evidence of an infectious process. It was considered appropriate to take the patient to surgery based on the suspicion of a cerebral abscess vs. a tumoral lesion.

A stereotactic-guided craniotomy was chosen because the lesion was located in one of the eloquent regions; macroscopically, the consistency of the lesion and its characteristics made us think of a granulomatous vs. tumoral lesion, but the pathology and microbiology reports confirmed the diagnosis of cerebral abscess by R. radiobacter.

In the review of the literature, we did not find report cases of cerebral abscess by R. radiobacter, reason why we find it pertinent to publish the case of this patient who was finally diagnosed with AIDS and neuroinfection by this very infrequent microorganism which is strictly opportunistic, and, in our patient, it presented spontaneously without having the predisposing factor of a foreign body as in the majority of cases reported. The patient was treated with third-generation cephalosporins during 4 weeks with a favorable clinical evolution and improvement in the radiological imaging studies obtained. It is because of this reason that we believe this approach should be considered for future cases of cerebral abscesses by R. radiobacter[3,5,6,12,13].

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L.O.R. (neurosurgeon, functional and stereotactic neurosur); L.F.M., C.H.G. and E.A.G.L. (Department of Neurosurgery, Resident of Neurosu.); M.C. (Medical Universidad Militar Nueva Granada).

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Conflicts of interest

There are no conflicts of interest.

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