Research Assistant Professor
Pharmacist/Biochemist, State University of Londrina
M.Sc., Federal University of Rio de Janeiro
Ph.D., Federal University of Rio de Janeiro/University of Glasgow, UK
B. fragilis is the most frequent opportunistic anaerobe pathogen isolated from human infections. The success of B. fragilis pathogenicity is still not completely understood. In general, Bacteroides infections occur as a consequence of a disruption in the integrity of the intestinal mucosa wall resulting from conditions such as gastrointestinal surgery, perforated or gangrenous appendicitis, perforated ulcer, diverticulitis, trauma and inflammatory bowel disease.Despite being only 0.5 - 1% of the intestinal microbial flora which typically contains 1011 to 1012 anaerobic bacteria per gram of stool, B. fragilis accounts for 50 to 70% of all anaerobes isolated from human infections such as, intra-abdominal abscesses, infections of the female genital tract, deep wounds, brain abscesses, bacteremia, and midgestation infectious abortion. Because of this extraordinary paradox, understanding the mechanisms by which B. fragilis break away from the colon to cause systemic disease and death in humans is an extremely important scientific objective. We have found that B. fragilis produces nine hemolysins/cytolysins and their role in B. fragilis pathogenicity is poorly understood. Hemolysins/cytolysins are powerful virulence factors in both Gram positive and Gram negative bacteria. Moreover, bacterial cytolysins/hemolysins play an important role in the equilibrium control of the microbial ecosystem population associated with eukaryotic hosts due to their cytolytic/bactericidal properties which are used to inhibit other prokaryotes and eukaryotes in highly competitive ecological systems. In this regard, current research aims to investigate the role and function of this extensive number of hemolysins/cytolysins in Bacteroides species play in the establishment of infectious process and also their contribution to the ability of Bacteroides to dominate and take over the colonization of the human large intestinal tract.
Peixoto, R. J. M., Miranda, K. R., Ferreira, E. O., de Paula, G. R., Rocha, E. R., Lobo, L. A. and Domingues, R. M. C. P. 2013. Production of AI-2 is mediated by the S-ribosylhomocystein lyase gene luxS in Bacteroides fragilis and Bacteroides vulgatus. J. Basic Microbiol. DOI: 10.1002/jobm.201300311 PMID: 24026770
Ferreira, E. D., Teixeira, F. L., Cordeiro, F., Araujo Lobo, L., Rocha, E. R., Smith, C. J. and Domingues, R. M. 2013. The Bfp60 surface adhesin is an extracellular matrix and plasminogen protein interacting in Bacteroides fragilis. Int. J. Med. Microbiol. "In Press" PMID: 23850366
Rocha, E. R. and Smith, C. J. 2013. Ferritin-like family proteins in the anaerobe Bacteroides fragilis: when an oxygen storm is coming, take your iron to the shelter.Biometals 26:577-591. PMID: 23842847
Lobo, L. A, Jenkins, A. L, Jeffrey Smith, C. and Rocha, E. R. 2013. Expression of Bacteroides fragilis hemolysins in vivo and role of HlyBA in an intra-abdominal infection model. MicrobiologyOpen 2:326-337. PMID: 23441096
Gauss, G. H., Reott, M. A., Rocha, E. R., Young, M. J., Dougla, T., Smith, C. J. and Lawrence, C. M. 2012. Characterization of the Bacteroides fragilis bfr gene product identifies a bacterial DPS-like protein and suggests evolutionary links in the ferritin superfamily. J. Bacteriol. 194:15-27. PMID: 22020642
Lobo, L. A., Smith, C. J. and Rocha, E. R. 2011. Flavin mononucleotide (FMN)-based fluorescent protein (FbFP) as reporter for gene expression in the anaerobe Bacteroides fragilis. FEMS Microbiol Lett. 317:67-74. PMID: 21223361
Rocha, E. R. and Smith, C. J. 2010. Heme and iron metabolism in Bacteroides. In: Simon C. Andrews and Pierre Cornelis (Eds), Iron uptake and homeostasis in microorganisms, chapter 9, pp. 155-165, Caister Academic Press, Norwich, UK.
Reott, M. A., Parker, A. C., Rocha, E. R. and Smith, C. J. 2009. Thioredoxins in redox maintenance and survival during oxidative stress of Bacteroides fragilis. J. Bacteriol. 191:3384-3391. PMID: 1928681
Ferreira, E. D., de Carvalho, J. B., Peixoto, R. J., Lobo, L. A., Zingalli, R. B., Smith, C. J., Rocha, E. R. and Domingues, R. M. 2009. The interaction of Bacteroides fragilis with components of the human fibrinolytic system. FEMS Immunol. Med. Microbiol. 56:48-55. PMID: 19260960
Smith, C. J., Rocha, E. R. and B. J. Paster. 2006. The medically important Bacteroides spp. in health and disease. The Prokaryotes, vol. 7 (Dworkin M, Falkow S, Rosenberg E, Schleifer KH & Stackebrandt E, eds), pp. 381–427. Springer-Verlag, New York, NY.