Correspondence
Case 16-2003 — Brain Abscess
N Engl J Med 2003; 349:1004-1006September 4, 2003
- Article
To the Editor:
In Case 16-2003, Friedlander et al. (May 22 issue)1 provide a comprehensive discussion of a patient who has a ring-enhancing, unilateral brain mass. What is disappointing is the absence of any mention of mycobacterium. Though relatively uncommon in the United States, tuberculomas are almost always manifested clinically as progressive paresis, with computed tomographic images that reveal a single ring-enhancing lesion.2,3 A peripheral-lung granuloma may also be present. To their credit, the authors make use of a diffusion magnetic resonance imaging (MRI) study that assists in the differential diagnosis.4,5 Because international travel is so common, it would be wise to include mycobacterial infection on the list of usual suspects in cases such as this one.
5 ReferencesMunib Mundia, M.B., B.S., M.D.
159 Locust St., Garden City, NY 11530
drmunibmundia@yahoo.com 1
Case Records of the Massachusetts General Hospital (Case 16-2003). N Engl J Med 2003;348:2125-2132
Full Text | Web of Science | Medline2
Thonell L ,Pendle S ,Sacks L . Clinical and radiological features of South African patients with tuberculomas of the brain. Clin Infect Dis 2000;31:619-620
CrossRef | Web of Science | Medline3
Brown J ,Worthington MG ,Lathi ES . Learning from our errors. N Engl J Med 1996;335:1049-1053
Full Text | Web of Science | Medline4
Basoglu OK ,Savas R ,Kitis O . Conventional and diffusion-weighted MR imaging of intracranial tuberculomas: a case report. Acta Radiol 2002;43:560-562
CrossRef | Web of Science | Medline5
Gupta RK ,Vatsal DK ,Husain N , et al. Differentiation of tuberculous from pyogenic brain abscesses with in vivo proton MR spectroscopy and magnetization transfer MR imaging. AJNR Am J Neuroradiol 2001;22:1503-1509
Web of Science | Medline
To the Editor:
The participants in the discussion of a case of a polymicrobial brain abscess identify “Streptococcus milleri” as one of the common etiologic agents of brain abscesses and as one of the bacteria isolated from the patient's brain abscess. However, S. milleri is not a recognized species of streptococcus.1-3 The correct term, “S. milleri group,” is used to describe a group of streptococci comprising S. anginosus, S. constellatus, and S. intermedius. Streptococci of this group have a propensity to cause abscesses and other serious infectious diseases. The butterscotch odor of these bacteria is often a clue to their presence on culture plates. The individual species within this group may cause peculiar clinical syndromes or may be associated with specific sites within the body, making species identification of potential clinical use.2
Controversy is a constant feature of the taxonomy of streptococci, including controversy over the proper names and relatedness of members of this group.3,4 However, S. milleri is considered an illegitimate species name by the majority of clinical microbiologists, and when species identification is not possible, the bacteria should be identified as S. milleri group.
4 ReferencesPaul H. Edelstein, M.D.
University of Pennsylvania School of Medicine, Philadelphia, PA 191041
LBSN: list of bacterial names with standing in nomenclature. (Accessed August 14, 2003, at http://www.bacterio.cict.fr/.)
2
Clarridge JE III ,Osting C ,Jalali M ,Osborne J ,Waddington M . Genotypic and phenotypic characterization of “Streptococcus milleri“ group isolates from a Veterans Administration hospital population. J Clin Microbiol 1999;37:3681-3687
Web of Science | Medline3
Whiley RA ,Beighton D . Emended descriptions and recognition of Streptococcus constellatus, Streptococcus intermedius, and Streptococcus anginosus as distinct species. Int J Syst Bacteriol 1991;41:1-5
CrossRef | Medline4
Vandamme P ,Torck U ,Falsen E ,Pot B ,Goossens H ,Kersters K . Whole-cell protein electrophoretic analysis of viridans streptococci: evidence for heterogeneity among Streptococcus mitis biovars. Int J Syst Bacteriol 1998;48:117-125
CrossRef | Medline
Author/Editor Response
We appreciate the feedback about Case 16-2003. Dr. Mundia points out that mycobacterial infection should be added to the list of “usual suspects” in the diagnosis of cases involving paresis and a ring-enhancing lesion on imaging. Mycobacteria should be considered as causative agents of a ring-enhancing brain lesion in certain clinical settings. If a patient is immunocompromised, resides in or has a history of travel to an area where tuberculosis is common, or has a known exposure to tuberculosis, then mycobacterial infection should be considered. In the case under discussion, the patient was not reported to be immunocompromised or to have had an exposure that would indicate the likelihood of a brain lesion caused by mycobacteria. Certainly, in the appropriate clinical setting, one should stain and culture for such organisms without hesitation. Of note, whereas bacterial brain abscesses are almost invariably bright on diffusion-weighted MRI, tuberculomas may be either bright or dark.1,2
Dr. Edelstein writes in regard to the controversial area of streptococcal terminology, having noted that the anatomical diagnosis reported in the case was S. milleri infection. He correctly states that S. milleri is not a species but in fact a group of three species: S. anginosus, S. constellatus, and S. intermedius. He suggests that the term “S. milleri group” be used to refer to these three organisms when specific species identification is impossible.
We now suggest that the group term S. milleri itself is no longer the most current. Reports from the streptococcus laboratory at the Centers for Disease Control and Prevention, from members of the Subcommittee on the Taxonomy of Staphylococci and Streptococci, and from the American Society for Microbiology indicate that the current correct group term for these species is “S. anginosus group.”3-5 The group term S. milleri has been abandoned because “it was never accepted . . . as a confirmed taxonomic entity.”3
When specific species identification is not possible, the term “S. anginosus group,” not S. milleri, should be used.
5 ReferencesRobert M. Friedlander, M.D.
Jonathan R. Slotkin, M.D.
Brigham and Women's Hospital, Boston, MA 02115
rfriedlander@rics.bwh. harvard. edu 1
Kaminogo M ,Ishimaru H ,Morikawa M ,Suzuki Y ,Shibata S . Proton MR spectroscopy and diffusion-weighted MR imaging for the diagnosis of intracranial tuberculomas: report of two cases. Neurol Res 2002;24:537-543
CrossRef | Web of Science | Medline2
Basoglu OK ,Savas R ,Kitis O . Conventional and diffusion-weighted MR imaging of intracranial tuberculomas: a case report. Acta Radiol 2002;43:560-562
CrossRef | Web of Science | Medline3
Facklam R . What happened to the streptococci: overview of taxonomic and nomenclature changes. Clin Microbiol Rev 2002;15:613-630
CrossRef | Web of Science | Medline4
Whiley RA ,Beighton D . Current classification of the oral streptococci. Oral Microbiol Immunol 1998;13:195-216
CrossRef | Web of Science | Medline5
Ruoff KL, Whiley RA, Beighton D. Streptococcus. In: Murray PR, ed. Manual of clinical microbiology. 8th ed. Vol. 1. Washington, D.C.: ASM Press, 2003:405-21.
