Summary
In this paper, a case of brain abscess caused by Enterococcus raffinosus in a patient with history of chronic otitis mediais presented. A male patient applied to the emergency unit with severe headache and ear pain. His examination revealed otitis media and perforation of the left ear tympanic membrane. Brain tomography showed an abscess causing a midline shift to theright side in the left temporoparietal lobe. E. raffinosus, a rare pathogen, was identified in the material removed during surgery.
INTRODUCTION
Brain abscess is a serious neurologic condition with a 13.4% mortality rate[1]. Usually, aerobe and anaerobe microorganisms jointly cause this condition[2]. Brain abscess associated with enterococci is quite a rare condition. Untreated or chronic autogenic infections may result in brain abscesses[2,3,4]. Brain abscess secondary to chronic otitis media may develop due to adjacency. In this papera case of brain abscess, believed to have developed secondary to otitis media and for which Enterococcus raffinosus was isolated as the causal factor, is presented.
Introduction
Brain abscess is a serious neurologic condition with a 13.4% mortality rate[1]. Usually, aerobe and anaerobe microorganisms jointly cause this condition[2]. Brain abscess associated with enterococci is quite a rare condition. Untreated or chronic autogenic infections may result in brain abscesses[2-4]. Brain abscess secondary to chronic otitis media may develop due to adjacency. In this papera case of brain abscess, believed to have developed secondary to otitis media and for which Enterococcus raffinosus was isolated as the causal factor, is presented.
Case Report
Laboratory findings were as follows: Hb 9.9 g/dL; leukocyte 14.600/mm3 (neutrophil rate, 81% and lymphocyte rate, 13%); erythrocyte sedimentation rate 68 mm/hour; and C-reactive protein 40 mg/L. Computerized tomography (CT) and magnetic resonance imaging (MRI) demonstrated a smooth, thin-walled mass lesion sized 54 x 44 x 34 mm, consistent with an abscess at the left temporoparietal region with subcortical localization, which caused a shift and had findings of air (Figures 1,2). He was admitted to the brain surgery clinic and an empirical ceftriaxone 4 g per day and metronidazole 2 g per day were initiated intravenously (IV). A brown, putrid abscess material (25 cc) was drawn out by suction. E. raffinosus was identified from direct microbiological culture of the abscess material. The identification of E. raffinosus was made by VITEK 2 system (bioMérieux, France) with 99% certainty and repeated by Phoenix system (BDP, USA). No proliferation was observed in the anaerobe culture. The strain was susceptible to ampicillin, vancomycin, teicoplanin, linezolid, and high level gentamycin but resistant to penicillin by VITEK 2. Ceftriaxone treatment was switched to ampicillin (12 g per day IV), and the patient was transferred to infectious diseases clinic. Since aerobe and anaerobe pathogens usually coexist in brain abscesses, metronidazole (2 g per day IV) was continued for potential anaerobe factors[1]. The patient was negative for human immunodeficiency virus (HIV).
A second abscess drainage was performed ten days later since expected reduction in the abscess size was not achieved. There was no growth in the culture of second drainage material.
A follow-up brain MRI after six-weeks of iv treatmentshowed a regression in the lesion to 24 x 19 mm, and the shifting effect of the mass disappeared. Examination by the otolaryngology department revealed left ear tympanic membrane perforation and chronic otitis media with mastoiditis. Surgical intervention was scheduled for the patient. Although antibiotic therapy continued, he left the hospital at his own request.
Discussion
Enterococcus spp. mainly inhabit the gastrointestinal system in humans. Less frequently, they occupy the genitourinary tract and the oral cavity. Clinically, they most commonly cause urinary system infections. They may be the casual factor of pelvic abscess, neonatal meningitis and sepsis, empyema, endophthalmitis, sinusitis, and chronic otitis media. The most frequently isolated species is Enterococcus faecalis. The second species most commonly isolated from clinical samples is Enterococcus faecium, followed by rare cases of Enterococcus casseliflavus and E. raffinosus[1, 7, 8]. The causative agent of otitis media could not be isolated in our patient since he had no ear discharge. Bone-tissue culture was scheduled after mastoiditis culture; however, the patient refused to undergo this procedure. We believe that patient’s chronic otitis media predisposed the adjacent temporal zone to brain abscess. Previous studies have reported otitis media to be the most common predisposing factor (38.6%) for brain abscess, and the temporal lobe to be the most commonly affected organ[1, 9].
In contrast to antibiotic resistance, which is common in E. faecalis and E. faecium, other enterococci are more sensitive to beta-lactams and aminoglycosides. Superiority of other beta-lactams to ampicillin has not been demonstrated in enterococci infections, where the infection is not polymicrobial[1, 2]. Therefore, ampicillin was prescribed to the patient.
Enterococci may be observed, though rarely, as the cause of brain abscesses in patients with chronic otitis media. This should be taken into consideration when planning empirical antibiotic treatment.
