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ABSTRACT: Aggregatibacter actinomycetemcomitans is strongly implicated in the pathogenesis of periodontitis. In this study, the phenotypic and genotypic features of A. actinomycetemcomitans and the presence of genes involved in toxicity were determined. Sixty-five patients with periodontal pocket and 48 healthy subjects were evaluated. Biotyping, adherence and invasion, neuraminidase and biofilm production, presence of capsule and fimbria, as well as the presence of flp-1, apaH, ltx, and cdt genes were determined. Biotype II was the most prevalent. Sixty-six strains were adherent and 33 of them were able to invade KB cells. Sixty strains produced neuraminidase, and 55 strains biofilms. Strains showed capsule but not fimbriae. Forty-six strains were cytotoxic, and most strains harbored the apaH and flp-1 genes. LTX promoter and the ltxA gene were observed in all strains from periodontal patients. The cdtA gene was observed in 50 (71.4%) strains, cdtB in 48 (68.6%) strains, cdtC in 60 (85.7%), and cdtABC in 40 (57.1%) strains. The presence of A. actinomycetemcomitans harboring the cdtC gene from healthy subjects may represent a transitory microorganism in the oral microbiota. More studies are necessary to understand the real role of this microorganism in the pathogenesis of periodontal disease.
Diagnostic microbiology and infectious disease 02/2013; · 2.45 Impact Factor
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ABSTRACT: The occurrence of Porphyromonas gulae, Porphyromonas macacae, Fusobacterium nucleatum and Fusobacterium canifelinum in subgingival plaque from dogs with and without periodontitis as well as their antimicrobial susceptibility were evaluated. From 50 dogs with periodontitis were identified 38 P. gulae, 8 P. macacae, 26 F. nucleatum and 15 F. canifelinum, and from 50 dogs without periodontitis were identified 15 P. gulae, 12 F. nucleatum and 11 F. canifelinum. All strains were susceptible to most of the antibiotics tested, however, different resistance rates to clarithromycin, erythromycin and metronidazole among strains were observed. The role of P. gulae, P. macacae, F. nucleatum and F. canifelinum in periodontal disease of household pets needs to be defined to a better prevention and treatment of the canine periodontitis.
Anaerobe 05/2012; 18(4):381-5. · 2.41 Impact Factor
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ABSTRACT: A rapid PCR approach was developed to detect Porphyromonas gulae strains from subgingival samples of dogs with and with periodontitis. The presence of P. gulae was observed in 92% and 56%, respectively, in dogs with and without periodontitis. The new primer pair was specific to detect this microorganism, and this technique could be used to evaluate a correlation between periodontitis and P. gulae in companion animals.
Anaerobe 06/2011; 17(5):257-8. · 2.41 Impact Factor
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ABSTRACT: This study examined the antimicrobial resistance profile and the prevalence of resistance genes in Bacteroides spp. and Parabacteroides distasonis strains isolated from children's intestinal microbiota.
The susceptibility of these bacteria to 10 antimicrobials was determined using an agar dilution method. β-lactamase activity was assessed by hydrolysis of the chromogenic cephalosporin of 114 Bacteriodales strains isolated from the fecal samples of 39 children, and the presence of resistance genes was tested using a PCR assay.
All strains were susceptible to imipenem and metronidazole. The following resistance rates were observed: amoxicillin (93%), amoxicillin/clavulanic acid (47.3%), ampicillin (96.4%), cephalexin (99%), cefoxitin (23%), penicillin (99%), clindamycin (34.2%) and tetracycline (53.5%). P-lactamase production was verified in 92% of the evaluated strains. The presence of the cfiA, cepA, ermF, tetQ and nim genes was observed in 62.3%, 76.3%, 27%, 79.8% and 7.8% of the strains, respectively.
Our results indicate an increase in the resistance to several antibiotics in intestinal Bacteroides spp. and Parabacteroides distasonis and demonstrate that these microorganisms harbor antimicrobial resistance genes that may be transferred to other susceptible intestinal strains.
Clinics (São Paulo, Brazil) 01/2011; 66(4):543-7. · 1.59 Impact Factor
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ABSTRACT: In this study the presence of periodontopathic pathogens in atheromatous plaques removed from coronary arteries of patients with chronic periodontitis and periodontally healthy subjects by PCR was detected. Our results indicate a significant association between the presence of Porphyromonas gingivalis and atheromas, and the periodontal bacteria in oral biofilm may find a way to reach arteries.
Anaerobe 12/2010; 16(6):629-32. · 2.41 Impact Factor
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ABSTRACT: Viral and bacterial associations appear to be implicated in the development of periodontal infections. Little information is available describing the periodontopathic agents in root canals with necrotic pulp. In this study, the occurrence and the combinations among herpes simplex virus type 1 (HSV-1) and Dialister pneumosintes, Tannerella forsythia, and Treponema denticola in patients with chronic periodontitis and necrotic pulp were evaluated. Clinical samples from healthy subjects and patients with periodontal or pulp infections were analyzed using a nested polymerase chain reaction PCR to detect HSV and PCR to detect the 3 periodontal bacteria. The presence of Tannerella forsythia and Treponema denticola was observed in healthy, periodontitis, and necrotic pulp patients. HSV was observed in periodontitis and necrotic pulp patients, and no healthy subject harbored D. pneumosintes or HSV. The occurrence of Tannerella forsythia was not statistically significant in patients with necrotic pulp (P = 0.704). Periodontal bacteria were observed varying from 10.3% to 20.7% in periodontitis and necrotic pulp patients. The presence of Treponema denticola - HSV association was predominant in patients showing necrotic pulp (24.1%); however, HSV alone was observed in one patient with periodontitis and in another patient with necrotic pulp. The presence of double association among bacteria or bacteria - HSV could indicate a role in both periodontitis and necrotic pulp, and Tannerella forsythia - Treponema denticola - HSV and Tannerella forsythia - D. pneumosintes - Treponema denticola - HSV associations might be important in periodontitis.
Canadian Journal of Microbiology 05/2008; 54(4):326-30. · 1.36 Impact Factor
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ABSTRACT: Bacteroides fragilis is considered an important clinical pathogen and the most common anaerobe isolated from human and animal clinical specimens; enterotoxigenic strains produce diarrhea. The presence of enterotoxigenic (ETBF) and nonenterotoxigenic B. fragilis in stool samples from calves with or without acute diarrhea and the antimicrobial susceptibility of the strains were evaluated. The stool samples were plated onto a selective B. fragilis-bile-esculin agar, and incubated anaerobically (10% CO(2)/90% N(2)), at 37 degrees C, for 72 h. Species of the B. fragilis group were identified by using the API 32-A kit. Enterotoxigenic strains were detected by PCR and the cytotoxic assay. From 54 diarrhea and 54 nondiarrhea stools, 124 and 92 members of the B. fragilis group, respectively, were recovered. Only two ETBF strains were isolated from two different diarrhea samples and the bft gene was detected in both. Moreover, the bft gene was detected in DNA from four different diarrheal stools samples but no ETBF strain was recovered. All the bacteria were susceptible to chloramphenicol, imipenem, moxifloxacin, piperacillin/tazobactam, metronidazole and tigecycline. Most of the isolates from both calves with and without diarrhea were resistant to all metals. Our results are of concern, and suggest the need to increase the surveillance of antibiotic and metal resistance of this microbial group isolated from animal production such as calves.
FEMS Microbiology Letters 08/2007; 272(1):15-21. · 2.04 Impact Factor
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ABSTRACT: Enterotoxigenic Bacteroides fragilis (ETBF) strains are associated with diarrhea disease in farm animals and young children. In this study, the bft gene subtyping from ETBF strains recovered from one immunodeficient and two immunocompetent children with diarrhea were determined. Thirteen ETBF strains were isolated and by using a multiplex-PCR their bft subtypes were determined. All 13 ETBF strains harbored the bft-1 subtype and by AP-PCR they were clustered in the same group I. This study shows that ETBF strains can be present in acute diarrhea and that bft-1 subtype is often present in these organisms. However, further studies are needed to evaluate the role of this bft-1 subtype in the pathogenesis of diarrhea.
Anaerobe 03/2007; 13(1):1-5. · 2.41 Impact Factor
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ABSTRACT: Enterotoxigenic Bacteroides fragilis (ETBF) strains produce a metalloprotease toxin (BFT) related to diarrheal disease in animals, young children, and adults. Three different isoforms of the enterotoxin, designated BFT-1, BFT-2, and BFT-3, have been identified and sequenced. In the present study, the pathogenicity of the ETBF strains carrying bft-1 or bft-2 was evaluated. Each toxin gene subtype of ETBF (bft-1 or bft-2) was intragastrically monoassociated to germ-free mice during 10 days and histopathological data from intestines and liver compared with those from mice monoassociated to a non-enterotoxigenic B. fragilis. Histopathological alterations were observed in all groups of animals related to ETBF. These alterations were characterized mainly by ulceration, edema, and inflammatory infiltration in intestine. However, these lesions were slightly more severe in mice monoassociated with bft-2 subtype. No alteration or lesion was observed in animals associated with the non-enterotoxigenic B. fragilis. In conclusion, strains harboring bft-1 or bft-2 gene subtypes were able to induce histopathological alterations in intestine of a gnotobiotic mice model and it could explain the effect produced for the enterotoxin.
Current Microbiology 09/2006; 53(2):113-7. · 1.82 Impact Factor
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ABSTRACT: The effects of subinhibitory concentrations of clindamycin on the morphological, biochemical and genetic characteristics of species of the Bacteroides fragilis group isolated from children with diarrhea were determined. The minimal inhibitory and subinhibitory concentrations for clindamycin were determined. Minimal inhibitory concentration values ranging from 0.25 to 512 microg mL(-1) were observed. Cultures grown with clindamycin were used to determine the macroscopic morphological characteristics, cellular viability, ultrastructural characteristics and DNA integrity. Clindamycin did not alter colonial morphology, but after 6 h elongated cells were observed. Also, extracellular vesicles and electron-lucent areas inside the cytoplasm were observed. Bacteria treated with clindamycin also showed fragmentation of DNA as determined by electrophoresis. The alterations produced by clindamycin might be indicative of a possible modification of the structures involved in bacterial pathogenesis.
FEMS Microbiology Letters 05/2006; 257(2):189-94. · 2.04 Impact Factor
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ABSTRACT: Twenty Bacteroides fragilis group species isolated from children with and without diarrhea were analyzed. Antibiotic susceptibility was performed using an agar dilution method; beta-lactamase production was determined using a nitrocefin method, and plasmids were extracted using a commercial Miniprep System. MIC values ranged from 16 to 256 microg/ml for penicillin, 4-128 microg/ml for amoxicillin/clavulanic acid, 0.25-256 microg/ml for clindamycin, and 16-256 microg/ml for penicillin. beta-Lactamase was detected in all isolates. Only five isolates harbored plasmids varying from 7.8 to 1.8 kb. Loss of 6.4- and 3.8-kb plasmids in B. fragilis C68c was related to antibiotic resistance. Low molecular weight plasmids of 2.8-1.8 kb were stable. PCR amplification of cfiA and cepA genes was observed using total DNA, and the cfiA gene was also amplified from the 6.4-kb plasmid.
Research in Microbiology 01/2005; 155(10):843-6. · 2.76 Impact Factor
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ABSTRACT: Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders such as diarrhea. In this study, 181 stool samples from children with and without acute diarrhea were analysed. Eighteen children with acute diarrhea were positive to C. ramosum, C. difficile, C. limosum, C. clostridioforme, C. septicum, C. butyricum, C. innocuum and Clostridium sp. Nineteen children without diarrhea harbored C. ramosum, C. septicum, C. barattii, C. butyricum, C. innocuum, C. sphenoides, C. bifermentans, C. clostridioforme and C. paraputrificum. No patient with diarrhea harbored C. barattii, C. bifermentans, C. paraputrificum and C. sphenoides. In addition, ten C. difficile strains were detected in 5 (5.5%) of the children with diarrhea. Also, no children from control group harbored C. difficile, C. limosum and Clostridium sp. Most of the tested strains were resistant to all the used antimicrobial. Nine C. difficile were toxigenic on VERO cells and by multiplex PCR, six strains showed both toxin A and B genes and three strains showed only toxin B gene. In this study, the presence of C. difficile was not significant, and it is suggested the need of more studies to evaluate the role of clostridia or C. difficile play in the childhood diarrhea and these organisms must be looked for routinely and a periodic evaluation of antimicrobial susceptibility should be performed.
Anaerobe 07/2004; 10(3):171-7. · 2.41 Impact Factor
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ABSTRACT: Bacteroides fragilis has been isolated from several human and non-human monomicrobial and mixed infections. In this study, some virulence markers and the antimicrobial susceptibility of bacteria of the B. fragilis group isolated from children's stools were evaluated. All the 64 isolates showed the following characteristics: capsulated, beta-hemolytic, hydrophilic, and serum-resistant. Only, 24 (37.5%) strains were resistant at 60 masculine C, for 30 min, and among them, 12 (18.75%) were resistant at 60 masculine C, for 60 min. Also, none strain was resistant at 100 masculine C. Four strains were able to hemagglutinate erythrocytes and D-mannose, D-galactose, D-arabinose, and D-xylose inhibited hemagglutination in 2 B. fragilis strains (p76a, p76b). The hemagglutination in the strain B. uniformis p3-2 was inhibited by D-xylose and D-galactose. The bft gene detection and the enterotoxin production were observed only in 13 EF-enterotoxigenic species. Fragilysin activity was confirmed on HT-29 cells. The antimicrobial determination confirmed that both imipenem and metronidazole were efficient against B. fragilis species; all the strains were resistant to lead and nickel. Plasmids of 2.9, 4.4, 4.8, and 8.9 kb were observed in 6 tested strains. These results show the values of the species identification from clinical infections, as well as of the periodic evaluation of the resistance patterns of the B. fragilis group at Brazilian medical institutions.
Memórias do Instituto Oswaldo Cruz 06/2004; 99(3):307-12. · 2.15 Impact Factor
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ABSTRACT: The bacteria of the Bacteroides fragilis group are considered important clinical pathogens and they are the most common anaerobes isolated from human endogenous infections. In this study, the susceptibility patterns to antibiotics and metals of 114 species of the B. fragilis group isolated from children with and without diarrhea were determined. Susceptibility was assayed by using an agar dilution method with Wilkins-Chalgren agar. All B. fragilis strains were resistant to lead and nickel, but susceptible to metronidazole and imipenem. beta-lactamase production was detected by using biological and nitrocefin methods, respectively, in 50% and 90.6% of the isolates of children with diarrhea and in 60% and 90% of the isolates of children without diarrhea. Our results show an increase of antibiotics and metals resistance in this microbial group, and a periodic evaluation of the antimicrobial susceptibility is needed. In Brazil, the contamination for antibiotics or metal ions is often observed, and it is suggested an increase the antimicrobial resistance surveillance of this microbial group, mainly those isolated from children's diarrhea.
Memórias do Instituto Oswaldo Cruz 06/2004; 99(3):319-24. · 2.15 Impact Factor
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ABSTRACT: Species of Clostridium are widely distributed in the environment, inhabiting both human and animal gastrointestinal tracts. Clostridium difficile is an important pathogen associated with outbreaks of pseudomembranous colitis and other intestinal disorders, such as diarrhea. In this study, the prevalence of Clostridium spp. and C. difficile, from hospitalized children with acute diarrhea, was examined. These children were admitted to 3 different hospitals for over 12 months. Eighteen (20%) and 19 (21%) stool specimens from children with (90) and without (91) diarrhea respectively, were positive to clostridia. Only 10 C. difficile strains were detected in 5.5% of the stool samples of children with diarrhea. None healthy children (without diarrhea) harbored C. difficile. From these 10 C. difficile, 9 were considered as toxigenic and genotyped as tcdA+/tcdB+ or tcdA-/tcdB+, and 1 strain as nontoxigenic (tcdA-/tdcB-). They were detected by the citotoxicity on VERO cells and by the multiplex-polymerase chain reaction. Thirty clinical fecal extracts produced minor alterations on VERO cells. The presence of C. difficile as a probable agent of acute diarrhea is suggested in several countries, but in this study, the presence of these organisms was not significant. More studies will be necessary to evaluate the role of clostridia or C. difficile in diarrhoeal processes in children.
Memórias do Instituto Oswaldo Cruz 07/2003; 98(4):451-4. · 2.15 Impact Factor
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ABSTRACT: Bacteroides fragilis is the most common anaerobic bacterium isolated from human intestinal tract infections. Before B. fragilis interacts with the intestinal epithelial cells, it is exposed to bile salts at physiological concentrations of 0.1-1.3%. The aim of this study was to determine how pre-treatment with bile salts affected B. fragilis cells and their interaction with intestinal epithelial cells. B. fragilis NCTC9343 was treated with conjugated bile salts (BSC) or non-conjugated bile salts (BSM). Cellular ultrastructure was assessed by electron microscopy, gene expression was quantified by comparative quantitative real-time RT-PCR. Adhesion to the HT-29 human intestinal cell line and to PVC microtitre plates (biofilm formation) was determined. Exposure to 0.15% BSC or BSM resulted in overproduction of fimbria-like appendages and outer membrane vesicles, and increased expression of genes encoding RND-type efflux pumps and the major outer membrane protein, OmpA. Bile salt-treated bacteria had increased resistance to structurally unrelated antimicrobial agents and showed a significant increase in bacterial co-aggregation, adhesion to intestinal epithelial cells and biofilm formation. These data suggest that bile salts could enhance intestinal colonization by B. fragilis via several mechanisms, and could therefore be significant to host-pathogen interactions.
Microbial Pathogenesis 43(2-3):78-87. · 1.94 Impact Factor
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ABSTRACT: The genetic diversity of 23 oral Fusobacterium nucleatum isolated from 15 periodontal patients, eight from seven healthy subjects, nine from nine AIDS patients and two from two Cebus apella monkeys were analyzed. EcoRI restricted the bacterial DNA and 28 ribotypes grouped from A to J groups were obtained. Isolates formed 24 ribotypes which were contained into A, B, C, D, E and F groups, and three reference strains and two clinical isolates of A. actinomycetemcomitans, and E. coli CDC formed four different ribotypes into the G, H, I and J groups. Moreover, from nine F. nucleatum from AIDS patients, six were ribotyped as group C and three as group D. By using ribotyping we distinguished F. nucleatum recovered from different sources. It is possible that isolates from AIDS patients may contain some phenotypic or genotypic factor did not observed in this study.
Revista do Instituto de Medicina Tropical de São Paulo 48(2):59-63. · 1.00 Impact Factor
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ABSTRACT: In this study, a novel, simple and rapid hemagglutination assay by using a peanut lectin to detect a neuraminidase activity in strains of the Bacteroides fragilis group was developed. One hundred and fourteen species of the B. fragilis group isolated from children with and without diarrhea and 15 reference strains were evaluated. Neuraminidase production was determined by using the method above described and its inhibition was observed by using galactose. The neuraminidase production was observed in 54 (84.37%) diarrhea and in 43 (86%) non-diarrhea strains. HA titers were ranged from 2 to 32. This neuraminidase assays based on PNA hemagglutination is highly sensitive, reproducible and could be used as a tool to detect the sialidase activity in anaerobic bacteria, particularly, in species of the B. fragilis group.
Anaerobe 12(5-6):238-41. · 2.41 Impact Factor
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ABSTRACT: Enterotoxigenic Bacteroides fragilis (ETBF) strains are associated with diarrhea disease in farm animals and young children. In this study, the bft gene subtyping from ETBF strains recovered from one immunodeficient and two immunocompetent children with diarrhea were determined. Thirteen ETBF strains were isolated and by using a multiplex-PCR their bft subtypes were determined. All 13 ETBF strains harbored the bft-1 subtype and by AP-PCR they were clustered in the same group I. This study shows that ETBF strains can be present in acute diarrhea and that bft-1 subtype is often present in these organisms. However, further studies are needed to evaluate the role of this bft-1 subtype in the pathogenesis of diarrhea.
Anaerobe.
