About the Bacillus Cereus Group We Feel That Uchino’S Paper Is Extremely Relevant, As It Strongly Emphasizes the Role of B
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□ LETTERS TO THE EDITOR □ About the Bacillus cereus Group We feel that Uchino’s paper is extremely relevant, as it strongly emphasizes the role of B. cereus as a human patho- Key words: Bacillus cereus group, Bacillus cereus gen and the importance of comorbidities related to the dis- eases it causes. Nonetheless, the bacteremias described (Intern Med 52: 649, 2013) should be considered related to the B. cereus group in gen- (DOI: 10.2169/internalmedicine.52.9154) eral, rather than B. cereus (sensu strictu), as the molecular characterization in this study is lacking. To the Editor Bacillus cereus is usually depicted as a It is crucial that clinicians report individual species-related Gram-positive rod, which is ubiquitous in the environment pathologies with the scope to shed more light on these or- and responsible for serious human infections (1, 2). ganisms’ pathogenicity and epidemiology. In this context, In a recent Internal Medicine article (2), an interesting Gram staining and colony morphology may provide prelimi- case series of B. cereus septicemias involving hematologic nary information; however, performing genome-based identi- hosts was described. We read this work with interest, as it fication is necessary in order to classify organisms as truly emphasizes this microorganism’s pathogenicity and raises belonging to the B. cereus (sensu strictu) species (4, 5) and further concerns regarding antibiotic resistance it may ex- to more deeply understand the clinical impact of each mem- press, particularly to carbapenem compounds (1). ber of the group. Nonetheless, we would like to highlight the fact that, in this study, the characterization of the strains is debatable, as The authors state that they have no Conflict of Interest (COI). it was based on Gram staining and colony morphology only (2). Indeed, it is known that B. cereus (sensu lato)isa Vincenzo Savini, Ennio Polilli, Roberta Marrollo, group of microorganisms (known as B. cereus group) that Daniela Astolfi, Paolo Fazii and Domenico D’Antonio includes six species (Bacillus anthracis, Bacillus cereus References [sensu strictu], Bacillus mycoides, Bacillus pseudomycoides, Bacillus thuringiensis and Bacillus weihenstephanensis), 1. Savini V, Favaro M, Fontana C, et al. Bacillus cereus heteroresis- sharing phenotypical features (there is however evidence that tance to carbapenems in a cancer patient. J Hosp Infect 71: 288- B. anthracis, B. cereus [sensu strictu], and B. thuringiensis 290, 2009. 2. Uchino Y, Iriyama N, Matsumoto K, et al. A case series of Bacil- may represent one only organism). As a result, identification lus cereus septicemia in patients with hematological disease. In- can only be successfully achieved using molecular, genome- tern Med 51: 2733-2738, 2012. based methodologies (3-5). 3. McIntyre L, Bernard K, Beniac D, Isaac-Renton JL, Naseby DC. Instead, colony observation and Gram staining alone may Identification of Bacillus cereus group species associated with lead to misidentification, with knowledge of species-specific food poisoning outbreaks in British Columbia, Canada. Appl Envi- ron Microbiol 74: 7451-7453, 2008. clinical pictures and virulence determinants remaining frag- 4. Schmidt TR, Scott EJ 2nd, Dyer DW. Whole-genome phylogenies mentary and confused (3). In fact, B. cereus (sensu strictu) of the family Bacillaceae and expansion of the sigma factor gene is not the only microorganism responsible for human disease family in the Bacillus cereus species-group. BMC Genomics 12: within this microbial group (6), and phenotypical investiga- 430, 2011. tions may provide only a preliminary classification of strains 5. Kuwana R, Imamura D, Takamatsu H, Watabe K. Discrimination of the Bacillus cereus group members by pattern analysis of ran- as presumptively belonging to the B. cereus group. dom amplified polymorphic DNA-PCR. Biocontrol Sci 7: 83-86, To conclude, reliable bacterial typing can no longer be 2012. considered a problem for microbiologists only. Indeed, clini- 6. Ghelardi E, Celandroni F, Salvetti S, Fiscarelli E, Senesi S. Bacil- cians too should be aware of the changing classification of lus thuringiensis pulmonary infection: critical role for bacterial clinically relevant bacteria and ask laboratories to provide membrane-damaging toxins and host neutrophils. Microbes Infect them with correct identifications. 9: 591-598, 2007. Microbiology and Virology, Spirito Santo Hospital, Italy Received for publication October 17, 2012; Accepted for publication November 5, 2012 Correspondence to Dr. Vincenzo Savini, [email protected] Ⓒ 2013 The Japanese Society of Internal Medicine Journal Website: http://www.naika.or.jp/imonline/index.html 649.