Paula Prazeres Magalhães

Federal University of Minas Gerais, Belo Horizonte, Estado de Minas Gerais, Brazil

Are you Paula Prazeres Magalhães?

Claim your profile

Publications (25)69.98 Total impact

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacteriocins are antibacterial, proteinaceous substances that mediate microbial dynamics. Bacteriocin production is a highly disseminated property among all major lineages of bacteria, including Shigella. In this paper, we addressed the purification and characterisation of a bacteriocin produced by a Shigella sonnei strain (SS9) isolated from a child with acute diarrhoea. The substance was purified through ammonium-sulphate precipitation and sequential steps of chromatography. The intracellular fraction obtained at 75% ammonium sulphate maintained activity following exposure to pH values from 1-11 and storage at -80ºC for more than two years and was inactivated by high temperatures and proteases. The molecular mass of the purified bacteriocin was determined by mass spectrometry to be 18.56 kDa. The N-terminal sequence of the bacteriocin did not match any other antibacterial proteins described. A putative new bacteriocin produced by S. sonnei has been detected. This bacteriocin may represent a newly described protein or a previously described protein with a newly detected function. Considering that SS9 expresses antagonism against other diarrhoeagenic bacteria, the bacteriocin may contribute to S. sonnei virulence and is potentially applicable to either preventing or controlling diarrhoeal disease.
    Memórias do Instituto Oswaldo Cruz 09/2013; 108(6):724-9. · 1.36 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Rotavirus has been considered the main agent of infectious diarrhea especially among younger children. We addressed the prevalence of rotavirus-associated diarrhea and the diversity of circulating electropherotypes by immunochromatography and RNA electrophoresis. Stool samples were taken from 391 children (267 with diarrhea) from the lower socioeconomic stratum who sought treatment in the Hospital Infantil João Paulo II/Belo Horizonte, during 2005 and 2006. Rotavirus was detected in 79/20.2% of subjects, 64/24.0% with diarrhea and 15/12.1% with no diarrhea. The virus was strongly associated with diarrhea (p = 0.003). A total of 76/19.4% and 69/17.6% rotavirus-positive children were identified by immunochromatography and electrophoresis, respectively. Rotavirus-associated diarrhea was more frequently detected in dry months (p < 0.001) and almost exclusively in children aged up to three years. Long profile strains prevailed (54/78.3%) but a shift toward short electropherotype was identified. Despite the decrease seen in 2006, rotavirus infection is still very common in our area. Although viral RNA electrophoresis is useful as a typing method, it should not be used exclusively in the diagnosis of rotavirus infection. We confirmed a shift from long to short profile strains, as already described for other South American countries.
    Revista do Instituto de Medicina Tropical de São Paulo 04/2013; 55(2):137-40. · 0.96 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Diarrhoeal disease is still considered a major cause of morbidity and mortality among children. Among diarrhoeagenic agents, Shigella should be highlighted due to its prevalence and the severity of the associated disease. Here, we assessed Shigella prevalence, drug susceptibility and virulence factors. Faeces from 157 children with diarrhoea who sought treatment at the Children's Hospital João Paulo II, a reference children´s hospital in Belo Horizonte, state of Minas Gerais, Brazil, were cultured and drug susceptibility of the Shigella isolates was determined by the disk diffusion technique. Shigella virulence markers were identified by polymerase chain reaction. The bacterium was recovered from 10.8% of the children (88.2% Shigella sonnei). The ipaH, iuc, sen and ial genes were detected in strains isolated from all shigellosis patients; set1A was only detected in Shigella flexneri. Additionally, patients were infected by Shigella strains of different ial, sat, sen and set1A genotypes. Compared to previous studies, we observed a marked shift in the distribution of species from S. flexneri to S. sonnei and high rates of trimethoprim/sulfamethoxazole resistance.
    Memórias do Instituto Oswaldo Cruz 02/2013; 108(1):30-5. · 1.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Objectives: We aimed to evaluate the profile of hospitalized patients presenting with odontogenic infections requiring intensive care and to identify predictive factors of worsening of the disease. Study Design: In this retrospective study, 119 consecutive medical records were assessed for data regarding odontogenic infections. The variables examined were age, gender, etiology, time from onset of infection to hospital admission, hospital stay, complications during hospitalization, and anatomical sites affected. Results: Most patients were female (64.7%) and the mean age of our study group was 28.3 years. Average length of hospital stay was 7.3 ± 6.3 days and the mean time from onset of infection to hospitalization was 6.9 days. Lower teeth corresponded to the initially affected site in the great majority (72.3%) of the cases and the mandibular third molar was the most commonly first infected tooth (31.9%). Post-surgical infection was involved in 21.8% of the cases. Systemic conditions were reported for 18.5% of the patients, mainly hypertension, but they were not determinant for admission. The main reasons for hospitalization were dyslalia, dysphagia, and dyspnea, either as single or associated signs (96.6%). Antimicrobial therapy was administered alone or combined with surgical drainage to 64 (53.8%) and 53 (44.5%) patients, respectively. Conclusions: Overall data generated by this investigation on the profile of severe odontogenic infection patients in our region are similar to those reported by other researchers. Conversely we found a higher prevalence of the disease among women in disagreement with previously published results. Such a kind of study may improve our knowledge relative to the disease and also reveal the regional scenario regarding severe odontogenic infections. Consequently it may contribute to the designing of strategies that may lead to a more efficient oral health care system what ultimately would culminate with the prevention of more severe outcomes from the disease.
    Journal of Clinical and Experimental Dentistry. 11/2012; 4:e271- e274.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: INTRODUCTION: Several microorganisms, among them enteric adenovirus, are widely recognized as etiological agents of acute diarrhea. The association between adenovirus and the disease varies among geographical regions and is poorly known in Brazil. OBJECTIVES: To investigate the presence of adenovirus in stool samples from children with and without diarrhea in Belo Horizonte-MG. To study factors associated with enteric adenovirus infection. MATERIAL AND METHOD: A qualitative immunochromatographic assay (kit VIKIA® Rota-Adeno, bioMérieux) was performed to detect adenovirus antigens in stool samples from 268 children with acute diarrhea and 124 without diarrhea at Hospital Infantil João Paulo II from January/2005 to December/2006. Clinical, laboratory, and epidemiologic data were recorded in SPSS database (SPSS Statistical package, IBM). RESULTS: Adenovirus was detected in 16 samples (4.1%): 12 of them (4.5%) were from children with acute diarrhea and 4 of them (3.2%) from children without diarrhea. The viral infection was more prevalent among girls and the age distribution was homogenous. Among the 16 children infected by adenovirus,11 (68.8%) were younger than 12 months old. However, no significant statistical difference was observed within the analyzed parameters. There was no seasonal distribution of adenovirus infection. CONCLUSION: Our data demonstrate that the prevalence of enteric adenovirus infection is low among children with diarrhea in Belo Horizonte-MG.
    Jornal Brasileiro de Patologia e Medicina Laboratorial 08/2012; 48(4):259-263.
  • Jornal de pediatria 07/2012; 88(4):367-8. · 1.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Intimins of atypical EPEC strains from children with and without diarrhea were genotyped. κ was not found and β was the most common. η- and ζ-alleles prevailed in strains from children without diarrhea and ι-allele among children older than 13 months. ε-allele emerged in 2006 and was the most common in 2007.
    Diagnostic microbiology and infectious disease 06/2012; 74(1):81-3. · 2.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This 3.5-year prospective study was conducted to ascertain the level of attaching and effacing Escherichia coli (AEEC) associated diarrhoea in children from Teresina, a northeastern state of Brazil. Passed faecal specimens from 400 patients (250 with and 150 without diarrhoea) up to 60 months of age attending from 2004 to 2007 at two public hospitals were investigated. Conventional microbiology methods and PCR were employed. Escherichia coli was isolated from 390 children, 240 of them with diarrhoea. A total of 117 AEEC strains were cultivated from specimens from 63 children, 37 with and 26 without diarrhoea. No association between AEEC and diarrhoea was observed. Atypical enteropathogenic E. coli (a-EPEC) (79.4%) was more commonly found than typical EPEC (t-EPEC). Association between EPEC and EPEC subtypes and diarrhoea was not detected. Mixed infection by t-EPEC and a-EPEC and infection by Shiga toxin-producing E. coli (STEC) were rare. Enteropathogenic E. coli was more common in males and in children aged less than 12 months. Correlation between serotyping and PCR results was 0.19. High resistance rates of AEEC to ampicillin, cephalotin, and trimethoprim-sulfamethoxazole were found. In conclusion, EPEC is very common in children with diarrhoea and controls in the population we studied, with a-EPEC predominating. This diarrhoeagenic E. coli (DEC) pathotype is more common in infant males and is resistant to drugs frequently used in clinical practice.
    Transactions of the Royal Society of Tropical Medicine and Hygiene 11/2011; 106(1):43-7. · 1.82 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To evaluate the distribution and susceptibility to antimicrobials of Shigella isolated from children with acute diarrhea and without diarrhea in Teresina, state of Piauí, Brazil. Four hundred children aged up to 60 months were studied. Stools were collected from all the patients between January 2004 and August 2007. Shigella was identified by conventional methods and antibiogram and extended-spectrum beta-lactamase (ESBL) were performed by agar diffusion. Shigellosis was only detected in children with acute diarrhea (26/250; 10.4%), especially in those aged from 6 to 24 months and in the rainy months. Shigella was susceptible to ceftriaxone, ciprofloxacin and nalidixic acid. More than half of the strains were resistant to sulphametoxazole-trimethoprim and ampicillin. ESBL was not detected. S. flexneri is common in Teresina. The resistance to ampicillin and sulphametoxazole-trimethoprim gives cause for concern, as these drugs are widely used in practice and sulphametoxazole-trimethoprim is also recommended for treating children suspected of having shigellosis.
    Jornal de pediatria 11/2011; 88(2):125-8. · 1.07 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To investigate the distribution of the genes that encode enterotoxins and the colonization factors (CF) types as well as the antibiotic susceptibility profile of enterotoxigenic Escherichia coli (ETEC) isolated from children from the Brazilian Northeast. We conducted a 3·5-year prospective study that involved 250 children with and 150 without diarrhoea, aged 1-60 months, from low-income families in Teresina/Brazilian Northeast. All samples were assayed for E. coli, enterotoxin and CF genes and antimicrobial susceptibility by microbiological methods and PCR. ETEC strains were isolated from 9·2% children with and 4·0% without diarrhoea. Infection was more common in children aged 6-24 months in rainy months. elt⁺ /CFA/IV⁺ and elt⁺ /CS14⁺ were the most frequent genotypes. Susceptibility to nalidixic acid, ciprofloxacin and gentamicin and resistance to ampicillin, cephalothin and sulfamethoxazole-trimethoprim were common. elt ⁺isolates and ETEC strains harbouring genes encoding CFA/IV and CS/14 were the most common ETEC found in Brazilian Northeast. Our data, the first generated for north-eastern Brazilian children, may be important for the development of an effective vaccine and for facilitation of an empirical choice of antibiotic treatment or prophylaxis for traveller's diarrhoea in the area studied.
    Journal of Applied Microbiology 07/2011; 111(1):224-32. · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The elimination of microorganisms from root canals is a critical step in endodontic treatment. We aimed to evaluate the antimicrobial effectiveness of an alternating irrigation regimen during chemomechanical preparation (CMP). During 21 days, root canals of extracted human teeth were infected with Enterococcus faecalis, and colonization was confirmed by scanning electron microscopy (SEM). Canals were irrigated with saline solution (control group), with 5.25% NaOCl followed by a final rinse with 17% EDTA (conventional irrigation group), or with the alternating use of NaOCl and EDTA (alternating irrigation [AI] group). Samples were taken before treatment (S1), after CMP (S2), and during the following 14 days. Two specimens/group were analyzed by SEM. The AI group yielded negative agar and liquid cultures from immediately after CMP and from the 5th day on, respectively. SEM confirmed several bacterium-free sites in the AI group. The irrigation regimen based on the alternating use of NaOCl and EDTA seems to be a promising endodontic tool because it promoted the elimination of root canal E. faecalis biofilms throughout the experimental period.
    Journal of endodontics 05/2010; 36(5):894-8. · 2.95 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Shigella is a common agent of diarrhoea, a worldwide major health problem. The bacterium produces bacteriocins; however, the role of these substances as a virulence factor is completely unknown. With the aim to search for colicin production by Shigella sonnei, to evaluate the influence of culture conditions on bacteriocin expression, and to characterize the substance partially, 16 S. sonnei strains isolated from children with diarrhoea were tested for antagonism against members of the intestinal microbiota or agents of diarrhoea. Nine strains exhibited isoantagonism and heteroantagonism against S. flexneri and diarrhoeagenic Escherichia coli. Autoantagonism and antagonism against the intestinal microbiota were not detected. Culture medium and incubation conditions influenced antagonism expression. Antagonism resulting from bacteriophages, low pH, fatty acids, hydrogen peroxide, and chloroform was excluded. The activity of the intracellular fraction obtained with 75% ammonium sulphate was preserved at pH 1.0-11.0, and was found to be reduced by organic solvents and affected by high temperatures and proteases. The antagonistic spectrum and the in vitro conditions for better antagonism expression suggest that the role of colicin in S. sonnei virulence, if any, would be expressed prior to infection, and may regulate population density of enteropathogens by helping in organism transmission.
    Apmis 02/2010; 118(2):125-35. · 2.07 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic periodontitis is a highly prevalent endogenous polymicrobial disease. To better understand the etiology of the disease a quantitative approach is mandatory and real-time PCR is the molecular technique currently preferred to achieve this purpose. Taking into account that such a kind of study is still scarce, we aimed to evaluate the association between periodontal microbiota and chronic periodontitis. A total of 60 low-income age-matched female adults, 30 with chronic periodontitis and 30 without periodontal disease, were enrolled. DNA obtained from subgingival specimens was used for quantification of Aggregatibacter actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Porphyromonas gingivalis, and Prevotella intermedia by real-time PCR. A. actinomycetemcomitans, E. corrodens, and F. nucleatum were detected in all subjects, P. gingivalis was observed in 70.0% and 46.6% and P. intermedia in 90.0% and 80.0% of chronic periodontitis patients and periodontally healthy subjects, respectively. P. gingivalis mean count was significantly higher in patients with chronic periodontitis than in periodontally healthy individuals. Accurate detection and quantification of five putative periodontal pathogens was feasible using a simple and fast real-time PCR protocol. Although P. gingivalis and P. intermedia have been found more commonly in chronic periodontitis patients, no statistical difference was observed between periodontally diseased and healthy groups. Quantitative data indicated association between P. gingivalis and chronic periodontitis. However, because of its uneven distribution, it should not be solely taken as a marker of periodontal status.
    Anaerobe 02/2010; 16(3):234-9. · 2.02 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To purify and partially characterize a bacteriocin produced by a Fusobacterium nucleatum strain. Following protein precipitation the effect of different treatments on a bacteriocin produced by a F. nucleatum strain named P12.2 isolated from a patient with periodontitis was evaluated. The antagonistic activity of the intracellular fraction obtained at 80% ammonium sulphate was preserved at pH values from 6.0 to 9.0 and showed to be sensitive to high temperatures and to treatment with proteases. The fraction was submitted to sequential steps of gel filtration, ion exchange, and reverse phase chromatography, and SDS-PAGE. Data obtained by mass spectrometry revealed that the molecular mass of the protein was 27,296 Da. For the first time a bacteriocin produced by a F. nucleatum strain was purified and characterized. This is the first description on characterization of a bacteriocin produced by F. nucleatum. It is possible that the bacteriocin plays a role in the regulation of population levels of periodontopathic organisms.
    Journal of Applied Microbiology 05/2009; 107(2):699-705. · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to investigate the effect of oxidative stress on physiological and genetic characteristics of Fusobacterium nucleatum and its interference on this microbial identification methods. Fus. nucleatum ssp. nucleatum ATCC 25586 (wt-strain) and an oxidative-stress-adapted strain derived from the wt-strain (aero-strain) were employed in the study. Cell-free crude protein extracts were obtained from both strains and differentially expressed proteins were identified by two-dimensional electrophoresis. Bacterium identification was performed by conventional biochemical tests, automated Rapid ID 32A system and specific PCR analysis. Genetic diversity between wt- and aero-strain was assessed by arbitrarily-primed (AP)-PCR. There were significant changes in the protein profile of aero-strain. The identification of the wt-strain was confirmed by all methods employed. Similar results were obtained for aero-strain when conventional biochemical tests and PCR were used. However, aero-strain was identified as Fusobacterium varium when submitted to Rapid ID 32A system. According to AP-PCR analysis, no significant genetic alteration was detected in aero-strain. The adaptive response of Fus. nucleatum to oxidative stress is associated with changes on its biology, which may lead to misidentification of the organism, according to the conventional identification methods. Oxidative stress may act as a cause of adaptive response in Fus. nucleatum with consequences to its biology, such as alterations on biochemical and physiological profile.
    Journal of Applied Microbiology 08/2007; 103(1):20-6. · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Periodontitis is associated with members of the oral microbiota, such as Actinobacillus actinomycetemcomitans. To our knowledge, this is the first study to evaluate, by PCR, the occurrence of the six known bacterium serotypes that included subjects with and without periodontitis. Our group comprised 49 Brazilian subjects. We studied 146 bacterial isolates from 23 patients with aggressive or chronic periodontitis and 26 subgingival specimens from subjects with or without periodontitis, all originating in our collection. Serotypes b and c were observed in similar frequencies, and no subject harboured d, e, or f serotype strains. Around 78% subjects had single-serotype infection. Mixed infection was seen only in aggressive periodontitis patients. An association between serotype b and healthy periodontium and between serotype c and chronic periodontitis was observed. Our results diverge from those previously reported, which may be explained by specific distribution patterns in distinct populations. The association of different serotypes with the same periodontal status or conversely of a serotype with different periodontal conditions indicates that organism serotyping should not be used as a sole reliable marker for predicting the outcome of the infection. Evaluation of factors involved in human oral cavity colonization by subsets of A. actinomycetemcomitans is essential for elucidating organism-host-environment relationships.
    Canadian Journal of Microbiology 04/2006; 52(3):182-8. · 1.20 Impact Factor
  • Source
    Carcinogenesis 02/2003; 24(1):145; author reply 147. · 5.64 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This PCR-based analysis is the first molecular epidemiological study in Brazil testing Helicobacter pylori cagA and vacA distribution in adults with gastric complaints, that includes a large number of carcinoma patients. Multiple-strain infection was identified in 11/13.4% patients. vacA s1-m1 and cagA(+) genotypes were the most common in patients with a non-mixed infection. All vacA s1 strains were s1b, so subtyping s1 strains was not useful. vacA s1b-m1 and cagA(+) strains were associated with higher prevalence of peptic ulcer and gastric carcinoma than vacA s2-m2 and cagA(-) ones. In conclusion, cagA and vacA genotyping may have clinical relevance in Brazil.
    FEMS Immunology & Medical Microbiology 08/2002; 33(3):173-8. · 2.68 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Helicobacter pylori resistance to metronidazole was detected in 107 (52.97%) of 202 strains. Twenty (9.85%) strains, 18 of them harboring 23S ribosomal DNA mutations, were resistant to clarithromycin. Metronidazole resistance was associated with female gender. Resistance to metronidazole and resistance to clarithromycin were associated. Increasing clarithromycin resistance rates were observed over time.
    Antimicrobial Agents and Chemotherapy 07/2002; 46(6):2021-3. · 4.57 Impact Factor
  • Source
    Jornal Brasileiro de Patologia e Medicina Laboratorial 12/2001; 38(2):79-85.

Publication Stats

238 Citations
69.98 Total Impact Points

Institutions

  • 2003–2013
    • Federal University of Minas Gerais
      • Departamento de Microbiologia
      Belo Horizonte, Estado de Minas Gerais, Brazil
  • 2011
    • Universidade Federal do Piauí
      • Departamento de Parasitologia e Microbiologia
      Teresina, Estado do Piaui, Brazil
  • 2001–2002
    • Federal University of Rio de Janeiro
      • Instituto de Microbiologia Professor Paulo de Góes (IMPPG)
      Rio de Janeiro, Rio de Janeiro, Brazil