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1.
J Appl Oral Sci ; 27: e20180593, 2019 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-31508792

RESUMO

There is growing evidence that C. albicans is associated with dental caries, but its role on caries development needs to be better clarified. Label="OBJECTIVE">To evaluate at the hard tissue level the effect of C. albicans on the cariogenic potential of S. mutans biofilms focusing on the mineral profile of induced carious lesions. This study also aimed to evaluate the effect of C. albicans on the acidogenic potential of S. mutans biofilms. METHODOLOGY Dual-species (CA+SM) and single-species biofilms (CA or SM) were grown on the surface of enamel slabs in the presence of glucose/sucrose supplemented culture medium for 24, 48 and 72 hours. Demineralization was evaluated through percentage of surface microhardness change (%SMC) and transversal microradiography analysis (ILM and LD) and pH of the spent medium was recorded daily. Data were analyzed by two-way ANOVA followed by Bonferroni correction. RESULTS%SMC was statistically different among the biofilms at each time point being the highest for SM biofilms and the lowest for CA biofilms which also differed from CA+SM biofilms [SM (24 h: 47.0±7.3; 48 h: 66.3±8.3; 72 h: 75.4±3.9); CA (24 h: 7.3±3.3; 48 h: 7.1±6.4; 72 h: 6.6±3.6); CA+SM (24 h: 35.9±7.39.1; 48 h: 47.2±9.5; 72 h: 47.6±9.5)]. pH of spent medium was statistically lower for SM biofilms compared to the other biofilms at each time point and remained constant over time while pH values increased from 24 to 72 h for both CA and CA+SM biofilms [SM (24 h: 4.4±0.1; 48 h: 4.4±0.1; 72 h: 4.5±0.1); CA (24 h: 6.9±0.3; 48 h: 7.2±0.2; 72 h: 7.5±0.2); CA+MS (24 h: 4.7±0.2; 48 h: 5.1±0.1; 72 h: 6.1±0.6)]. IML and LD for SM biofilms increased over time while no difference was observed from 24 to 72 h for the other biofilms. CONCLUSIONS The present data suggest that C. albicans has low enamel demineralization potential and the presence of C. albicans can reduce both the cariogenic and acidogenic potentials of S. mutans biofilms.


Assuntos
Biofilmes/crescimento & desenvolvimento , Candida albicans/fisiologia , Esmalte Dentário/microbiologia , Streptococcus mutans/metabolismo , Desmineralização do Dente/microbiologia , Ácidos/metabolismo , Animais , Bovinos , Contagem de Colônia Microbiana , Esmalte Dentário/química , Testes de Dureza , Concentração de Íons de Hidrogênio , Microrradiografia/métodos , Valores de Referência , Propriedades de Superfície , Fatores de Tempo
2.
J Assoc Physicians India ; 67(9): 42-45, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31561688

RESUMO

Introduction: The incidence of the urinary tract infections caused by Candida species, are becoming more common. Recently, an increase in the incidence of infection caused by fungi especially non albicans candida species (NAC) has been reported. Several virulence factors like biofilm formation, toxin production and presence of adhesins contribute to its pathogenesis. Objectives: This study was undertaken to determine species distribution, biofilm formation and in-vitro antifungal susceptibility of candida isolated in our tertiary care hospital. Method: Eighty seven clinical isolates obtained from urine specimens were subjected to wet mount, Gram's stain and cultured on Sabouraud's Dextrose agar (SDA) medium. Conventional method for yeast identification was done. Biofilm forming ability of each isolate was detected using microtitre plate method. Antifungal susceptibility against posaconazole, amphotericin-B, fluconazole, itraconazole, ketoconazole, 5-flucytosine, voriconazole, and caspofungin was tested using Sensititre® Yeastone® (Trek diagnostic systems). Results and Discussion: Out of 87 candida isolates, 31.03% (n=27) were C. albicans and 68.97% (n=60) were non albicans candida species (NAC). Among 60 NAC, C. kruseii 29.89% (n=26), C. glabrata 24.14% (n=21), C. tropicalis 14.94% (n=13). Among all isolates, 36.78% (n=32) were biofilm producers and biofilm positivity more among C. albicans 55.56% (n=15) as compared to NAC 28.33% (n=17) (Pvalue<0.002). The maximum positivity was observed with isolates from plastic devices (61.8%). The minimum inhibitory concentrations of all antifungal drugs against all isolates were within susceptible range except for fluconazole which was resistant to C. kruseii. Conclusion: C. albicans remains the major isolate from urine samples and also biofilm formation as a virulence factor might have a higher significance for C. albicans than for NAC and its ability to form biofilm is intricately linked with ability of organisms to adhere, colonize and subsequently cause infection.


Assuntos
Antifúngicos/uso terapêutico , Biofilmes/crescimento & desenvolvimento , Candida/efeitos dos fármacos , Infecções Urinárias/tratamento farmacológico , Antifúngicos/farmacologia , Candida/isolamento & purificação , Humanos , Testes de Sensibilidade Microbiana , Centros de Atenção Terciária , Infecções Urinárias/microbiologia
3.
World J Microbiol Biotechnol ; 35(8): 130, 2019 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-31385043

RESUMO

Bacterial biofilms (BFs) are membrane-like structures formed by the secretion of extracellular polymeric substances (EPS) by bacteria. The formation of BFs contributes to bacterial survival and drug resistance. When bacteria proliferate, they produce secondary metabolites that act as signaling molecules in bacterial communities that regulate intracellular and cell-to-cell communication. This communication can directly affect the physiological behavior of bacteria, including the production and emission of light (bioluminescence), the expression of virulence factors, the resistance to antibiotics, and the shift between planktonic and biofilm lifestyles. We review the major signaling molecules that regulate BF formation, with a focus on quorum-sensing systems (QS), cyclic diguanylate (c-di-GMP), two-component systems (TCS), and small RNA (sRNA). Understanding these processes will lead to new approaches for treating chronic diseases and preventing bacterial resistance.


Assuntos
Bactérias/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica , Transdução de Sinais , Bactérias/metabolismo , GMP Cíclico/análogos & derivados , GMP Cíclico/metabolismo , Percepção de Quorum , RNA Bacteriano/metabolismo , Pequeno RNA não Traduzido/metabolismo
4.
J Appl Oral Sci ; 27: e20180699, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411265

RESUMO

OBJECTIVE: This study investigated the role of extracellular deoxyribonucleic acid (eDNA) on Enterococcus faecalis ( E. faecalis ) biofilm and the susceptibility of E. faecalis to sodium hypochlorite (NaOCl). METHODOLOGY: E. faecalis biofilm was formed in bovine tooth specimens and the biofilm was cultured with or without deoxyribonuclease (DNase), an inhibitor of eDNA. Then, the role of eDNA in E. faecalis growth and biofilm formation was investigated using colony forming unit (CFUs) counting, eDNA level assay, crystal violet staining, confocal laser scanning microscopy, and scanning electron microscopy. The susceptibility of E. faecalis biofilm to low (0.5%) or high (5%) NaOCl concentrations was also analyzed by CFU counting. RESULTS: CFUs and biofilm formation decreased significantly with DNase treatment (p<0.05). The microstructure of DNase-treated biofilms exhibited less structured features when compared to the control. The volume of exopolysaccharides in the DNase-treated biofilm was significantly lower than that of control (p<0.05). Moreover, the CFUs, eDNA level, biofilm formation, and exopolysaccharides volume were lower when the biofilm was treated with DNase de novo when compared to when DNase was applied to matured biofilm (p<0.05). E. faecalis in the biofilm was more susceptible to NaOCl when it was cultured with DNase (p<0.05). Furthermore, 0.5% NaOCl combined with DNase treatment was as efficient as 5% NaOCl alone regarding susceptibility (p>0.05). CONCLUSIONS: Inhibition of eDNA leads to decrease of E. faecalis biofilm formation and increase of susceptibility of E. faecalis to NaOCl even at low concentrations. Therefore, our results suggest that inhibition of eDNA would be beneficial in facilitating the efficacy of NaOCl and reducing its concentration.


Assuntos
Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , DNA Bacteriano/farmacologia , Desoxirribonucleases/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Hipoclorito de Sódio/farmacologia , Animais , Bovinos , Contagem de Colônia Microbiana , Cavidade Pulpar/microbiologia , Testes de Sensibilidade Microbiana , Microscopia Confocal , Microscopia Eletrônica de Varredura , Polissacarídeos Bacterianos/isolamento & purificação , Reprodutibilidade dos Testes , Fatores de Tempo
5.
World J Microbiol Biotechnol ; 35(9): 133, 2019 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-31432254

RESUMO

There is a significant increase in the discovery of new antimicrobial compounds in recent past to combat drug resistant pathogens. Members of the genus Bacillus and related genera have been screened extensively due to their ability to produce wide range of antimicrobial compounds. In this study, we have isolated and characterized a new antimicrobial peptide from a marine bacterium identified as Virgibacillus species. The low molecular mass and stability of the antimicrobial substance pointed towards the bacteriocinogenic nature of the compound. The RAST analysis of genome sequence showed presence of a putative bacteriocin biosynthetic cluster containing genes necessary for synthesis of a lanthipeptide. Translated amino acid sequence of mature C-terminal propeptide showed identity with salivaricin A (52.2%) and lacticin A (33.3%). Accordingly, the mass (2417 Da) obtained by MALDI analysis was in agreement with posttranslational modifications of the leader peptide to yield three methyl lanthionine rings and a disulfide bond between two free cysteine residues. The lanthipeptide was named as virgicin, which selectively inhibited the growth of Gram-positive bacteria and biofilm formation by Enterococcus faecalis. Inhibition of biofilm formation by E. faecalis was also observed in in vitro model experiments using hydroxyapatite discs. Thus, virgicin appears to be a promising new bacteriocin to control oral biofilm formation by selective pathogens.


Assuntos
Bacteriocinas/isolamento & purificação , Bacteriocinas/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/crescimento & desenvolvimento , Peptídeos/isolamento & purificação , Peptídeos/farmacologia , Virgibacillus/metabolismo , Bacteriocinas/química , Bacteriocinas/genética , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Vias Biossintéticas/genética , Genoma Bacteriano , Peso Molecular , Família Multigênica , Peptídeos/química , Peptídeos/genética , Água do Mar/microbiologia , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Virgibacillus/classificação , Virgibacillus/isolamento & purificação
6.
Dokl Biochem Biophys ; 486(1): 206-208, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31367822

RESUMO

The aim of this work was to study the fine structure of bacterial films grown on the inner tube surface of a flow reactor. Using the scanning electron microscopy (SEM) approaches, the detailed biofilm relief was visualized. The action of electrochemically reduced water (ERW) on the biofilm ultrastructure generated by the plankton form of E. coli and/or lacto bacteria was investigated. The treatment with an ERW solution destroyed the biofilm organic polymer matrix and bacterial cells embedded in the matrix.


Assuntos
Biofilmes/efeitos dos fármacos , Água/química , Água/farmacologia , Biofilmes/crescimento & desenvolvimento , Eletroquímica , Escherichia coli/efeitos dos fármacos , Escherichia coli/fisiologia
7.
Microbiol Res ; 227: 126292, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31421719

RESUMO

Azotobacter chroococcum (Az) and Trichoderma viride (Tv) represent agriculturally important and beneficial plant growth promoting options which contribute towards nutrient management and biocontrol, respectively. When Az and Tv are co-cultured, they form a biofilm, which has proved promising as an inoculant in several crops; however, the basic aspects related to regulation of biofilm formation were not investigated. Therefore, whole transcriptome sequencing (Illumina NextSeq500) and gene expression analyses were undertaken, related to biofilm formation vis a vis Tv and Az growing individually. Significant changes in the transcriptome profiles of biofilm were recorded and validated through qPCR analyses. In-depth evaluation also identified several genes (phoA, phoB, glgP, alg8, sipW, purB, pssA, fadD) specifically involved in biofilm formation in Az, Tv and Tv-Az. Genes coding for RNA-dependent RNA polymerase, ABC transporters, translation elongation factor EF-1, molecular chaperones and double homeobox 4 were either up-regulated or down-regulated during biofilm formation. To our knowledge, this is the first report on the modulation of gene expression in an agriculturally beneficial association, as a biofilm. Our results provide insights into the regulatory factors involved during biofilm formation, which can help to improve the beneficial effects and develop more effective and promising plant- microbe associations.


Assuntos
Azotobacter/genética , Biofilmes/crescimento & desenvolvimento , Perfilação da Expressão Gênica , Interações Microbianas/genética , Transcriptoma , Trichoderma/genética , Técnicas de Cocultura , Regulação para Baixo , Regulação Bacteriana da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Genes Bacterianos/genética , Genes Fúngicos/genética , Interações Microbianas/fisiologia , Desenvolvimento Vegetal , Plantas/microbiologia , Regulação para Cima
8.
J Med Microbiol ; 68(9): 1330-1340, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31347999

RESUMO

Purpose. This study aimed to characterize 27 Escherichia coli isolates obtained from peritoneal dialysis (PD)-related peritonitis that occurred at the University Hospital of Botucatu Medical School, Brazil, between 1997 and 2015.Methodology. These isolates were characterized regarding the occurrence of 22 virulence factor-encoding genes, antimicrobial resistance and biofilm production. We then evaluated whether these factors influenced the clinical outcome.Results. Over an 18-year period, 726 episodes of PD-related peritonitis were diagnosed, with 27 of them (3.7 %) being due to E. coli. The majority of the isolates were classified in phylogroups B1 (33.3 %), B2 (30.0 %) or F (18.0 %). fimH (100.0 %), ompT (66.7 %) and irp2 (51.9 %) were the most prevalent genes, while papA, papC, iha, sat, irp2, iucD, ireA, ibe10, ompT and kpsMTII were significantly more prevalent among isolates belonging to phylogroups B2 and F (P<0.05). Non-susceptibility to quinolones was detected in six isolates, which harboured chromosomal and/or plasmid-mediated quinolone resistance determinants, while two CTX-M extended-spectrum ß-lactamase-producing E. coli were identified. Virulence factor-encoding genes (alone or in combination) and antimicrobial resistance were not associated with non-resolution outcomes. However, there was a trend for the ability to produce biofilm to be associated with treatment failure, although this association was not statistically significant.Conclusion. The E. coli isolates were heterogeneous in terms of the features investigated, and were susceptible to most of the antimicrobial drugs tested, despite the unsuccessful treatment observed in more than 50.0 % of the patients. Studies including more cases could help to clarify if biofilm production can influence the outcome in patients with PD-related peritonitis.


Assuntos
Infecções por Escherichia coli/microbiologia , Escherichia coli/isolamento & purificação , Diálise Peritoneal/efeitos adversos , Peritonite/microbiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Biofilmes/crescimento & desenvolvimento , Variação Biológica da População , Brasil/epidemiologia , Criança , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/patogenicidade , Infecções por Escherichia coli/epidemiologia , Variação Genética , Técnicas de Genotipagem , Hospitais Universitários , Humanos , Masculino , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Peritonite/epidemiologia , Filogenia , Plasmídeos/análise , Fatores de Virulência/genética , Adulto Jovem
9.
Bol. latinoam. Caribe plantas med. aromát ; 18(4): 411-424, jul. 2019. tab, ilus
Artigo em Inglês | LILACS | ID: biblio-1008180

RESUMO

Thymol (2-isopropyl-5-methylphenol) is an aromatic monoterpene found in essential oils extracted from plants belonging to the Lamiaceae family, such as Thymus, Ocimum, Origanum, Satureja, Thymbra and Monarda genera. Growth and biofilm formation by Listeria monocytogenes CLIP 74902 were evaluate using three carbon sources in the presence of thymol. Specific growth rate (h-1) values at 37o with glucose, trehalose and cellobiose with the addition of thymol (µg/mL) 0 (control) and 750, were respectively: 0.22, 0.07; 0.14, 0.04; 0.11, 0.04. Lag periods obtained under the same conditions were (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. A marked antibiofilm activity was observed against the exposure with 750 µg/mL of thymol, showing a high percentage of inhibition: glucose (99 %), trehalose (97 %) and cellobiose (98%), compared to the control. The results suggest that thymol could be used to inhibit the growth and production of biofilms by L. monocytogenes in the food industry.


Timol (2-isopropil-5-metilfenol) es un monoterpeno aromático presente en los aceites esenciales extraídos de plantas pertenecientes a la familia Lamiaceae, como los géneros Thymus, Ocimum, Origanum, Satureja, Thymbra y Monarda. El crecimiento y formación de biopelícula por Listeria monocytogenes CLIP 74902 fueron evaluados utilizando tres fuentes de carbono en presencia de timol. La velocidad específica de crecimiento (h-1) a 37o con glucosa, trehalosa y celobiosa con la adición de timol (µg/mL) 0 (control) y 750, fueron respectivamente: 0.22, 0.07; 0.14, 0.04, 0.11, 0,04. Los períodos lag obtenidos en las mismas condiciones fueron (h): 8.19, 13.2; 22.5, 27.5; 23.1, 28.1. Una marcada actividad antibiofilm fue obtenida con 750 µg/mL de timol, mostrando un alto porcentaje de inhibición con glucosa (99%), trehalosa (97%) y celobiosa (98%), respecto al control. Los resultados sugieren que timol podría ser usado para inhibir el crecimiento y producción de biopelículas por L. monocytogenes en la industria alimentaria.


Assuntos
Timol/farmacologia , Biofilmes/efeitos dos fármacos , Listeria monocytogenes/efeitos dos fármacos , Terpenos/farmacologia , Cinética , Biofilmes/crescimento & desenvolvimento , Meio Ambiente , Fermentação , Microbiologia de Alimentos , Listeria monocytogenes/crescimento & desenvolvimento
10.
Chemosphere ; 233: 472-481, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31181494

RESUMO

Ammonia-rich lagoon supernatant was treated using anammox process in an integrated fixed-film activated sludge (IFAS) laboratory reactor. Effective anammox activities were demonstrated over 259 days of operation. The ammonium removal efficiency reached 94% in Phase I with influent concentrations of NH4+, NO2- and chemical oxygen demand (COD) at 250 mg-N/L, 325 mg-N/L, and 145 mg-COD/L, and reached 88% in Phase II at 420 mg-N/L, 525 mg-N/L, and 305 mg-COD/L. When supplemented with nitritation effluent for nitrite sources in Phase III, the influent COD concentration increased to 583 mg-COD/L without loss of ammonia removal efficiency (87%). The specific anammox activity was higher in biofilm than in the suspended flocs (P < 0.05), increased from Phase I to II (P < 0.05), and decreased in Phase III. Ammonia removal related genes were quantified using qPCR. Results showed higher anammox gene (AMX nirS) prevalence in biofilm, while denitrification genes (nosZ and narG) were higher in flocs (P < 0.05). Microbial community analysis showed that the seeded anammox bacteria Candidatus Brocadia was maintained at 19% in the biofilm and only 0.3% in the flocs. The major taxa in the flocs were related to denitrifiers. The floc community was affected largely under high COD conditions, but the biofilm community was not. These results suggest that the anammox activity in biofilm is resilient to high COD loadings, due to the existence of flocs with denitrification activity. The segregation of bacterial communities between biofilm and flocs in the anammox IFAS system resulted in high ammonia removal efficiency and resistance to high organic loadings.


Assuntos
Amônia/análise , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Esgotos/microbiologia , Purificação da Água/métodos , Análise da Demanda Biológica de Oxigênio , Desnitrificação/genética , Genes Bacterianos , Modelos Teóricos , Planctomycetales/genética
11.
Biochim Biophys Acta Rev Cancer ; 1872(1): 74-79, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31201828

RESUMO

A prominent mucinous phenotype is observed in 10-15% of all colorectal cancers (CRCs). They are associated with a proximal location, and more commonly observed among tumors with mismatch repair defects and a promoter CpG methylator phenotype. However, none of these features has been clearly linked mechanistically to this mucinous subtype. Here, we propose that bacterial biofilms could represent a currently unappreciated contributor to mucinous CRC formation. The colonic microbiome and biofilms in particular, are emerging as important factors in tumor initiation and progression. Intriguingly, biofilms preferentially accompany proximal tumors, suggesting that there may be a direct mechanistic link with mucinous CRCs.


Assuntos
Adenocarcinoma Mucinoso/microbiologia , Biofilmes/crescimento & desenvolvimento , Biomarcadores Tumorais/genética , Neoplasias Colorretais/microbiologia , Adenocarcinoma Mucinoso/genética , Adenocarcinoma Mucinoso/patologia , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Ilhas de CpG/genética , Metilação de DNA/genética , Humanos , Instabilidade de Microssatélites
12.
Medicine (Baltimore) ; 98(23): e15933, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31169713

RESUMO

BACKGROUND: Invasive candidiasis (IC) is a major cause of morbimortality in children. Previous studies described the clinical characteristics and risk factors for this infection; however, limited data are available on the predictors of mortality in these patients. In this context, we evaluated the risk factors associated with death due to IC in a pediatric tertiary care hospital in South of Brazil. METHODS: This is a retrospective, cross-sectional, observational, and analytical study of a series of pediatric patients with clinical and laboratory diagnosis of IC from March 2014 to September 2017. Univariate and multivariate analysis were performed to estimate the association between the characteristics of the patients and death. RESULTS: A total of 94 cases of IC were included. The incidence was 1.13 cases per 1000 patients/d, with a mortality rate of 14%. There was a predominance of non-albicans Candida (71.3%) in IC cases and, although there is no species difference in mortality rates, biofilm formation was associated with increased mortality. Clinical characteristics such as male sex, stay in the intensive care unit, and thrombocytopenia; comorbidities such as cardiological disease and renal insufficiency; and risks such as mechanical ventilation and dialysis were associated with increased mortality. CONCLUSION: Data from this study suggest that biofilm formation by Candida sp. is associated with increased mortality, and this is the first study to correlate the male sex and cardiological disease as risk factors for death in pediatric IC patients.


Assuntos
Biofilmes/crescimento & desenvolvimento , Candida/fisiologia , Candidíase Invasiva/mortalidade , Adolescente , Brasil/epidemiologia , Candidíase Invasiva/microbiologia , Criança , Pré-Escolar , Estudos Transversais , Feminino , Mortalidade Hospitalar , Humanos , Incidência , Lactente , Recém-Nascido , Masculino , Estudos Retrospectivos , Fatores de Risco , Centros de Atenção Terciária
13.
Vet Microbiol ; 234: 92-100, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31213278

RESUMO

Streptococcus suis (SS) is a major pathogen in the swine industry, and also an important zoonotic agent for humans. The novel SS cell surface protein, AtlASS, comprising the special GW module and N-acetylmuramidases domain, was designated as a putative autolysin. Indeed, the atlASS deletion mutant almost completely lost its activity in Triton X-100 induced bacterial autolysis, while the wild-type and CΔatlASS strains showed significant decrease, to less than 20% of the initial OD600 values. Unexpectedly, both immunofluorescence and immunogold electron microscopy confirmed that AtlASS is mainly located in the cell division septum, suggesting autolytic activity in peptidoglycan hydrolysis may be required for cell separation, thus modulating and truncating bacterial chain length. The biofilm capacity of the AtlASS mutation was reduced ˜ 40%, as compared to the wild-type strain. The ΔatlASS strain also attenuated bacterial adherence in human brain microvessel endothelial cells (HBMECs). Furthermore, we confirmed that AtlASS has fibrinogen/fibronectin binding capacities. In mouse infection model, the AtlASS inactivation also significantly attenuated bacterial virulence and proliferation in vivo. In conclusion, these results indicate that AtlASS autolysin modulates bacterial chain length, and contributes to the full virulence of SS during infection.


Assuntos
Divisão Celular , N-Acetil-Muramil-L-Alanina Amidase/metabolismo , Streptococcus suis/química , Streptococcus suis/patogenicidade , Animais , Autólise , Biofilmes/crescimento & desenvolvimento , Feminino , Camundongos , Camundongos Endogâmicos BALB C , Mutação , N-Acetil-Muramil-L-Alanina Amidase/genética , Organismos Livres de Patógenos Específicos , Virulência
14.
Microbiol Immunol ; 63(7): 251-260, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31166029

RESUMO

Streptococcus mutans is a cariogenic bacterium that localizes in the oral cavity. Glycyrrhetinic acid (GRA) is a major component of licorice extract. GRA and several derivatives, including disodium succinoyl glycyrrhetinate (GR-SU), are known to have anti-inflammatory effects in humans. In this study, the antimicrobial effect of GRA and its derivatives against the S. mutans UA159 strain were investigated. Minimum inhibitory concentrations (MICs) of GRA and GR-SU showed antibacterial activity against the S. mutans strain, whereas other tested derivatives did not. Because GR-SU is more soluble than GRA, GR-SU was used for further experiments. The antibacterial activity of GR-SU against 100 S. mutans strains was evaluated and it was found that all strains are susceptible to GR-SU, with MIC values below 256 µg/mL. A cell viability assay showed that GR-SU has a bacteriostatic effect on S. mutans cells. As to growth kinetics, sub-MICs of GR-SU inhibited growth. The effect of GR-SU on S. mutans virulence was then investigated. GR-SU at sub-MICs suppresses biofilm formation. Additionally, GR-SU greatly suppresses the pH drop caused by the addition of glucose and glucose-induced expression of the genes responsible for acid production (ldh and pykF) and tolerance (aguD and atpD). Additionally, expression of enolase, which is responsible for the carbohydrate phosphotransferase system, was not increased in the presence of GR-SU, indicating that GR-SU suppresses incorporation of sugars into S. mutans. In conclusion, GR-SU has antibacterial activity against S. mutans and also decreases S. mutans virulence.


Assuntos
Antibacterianos/farmacologia , Ácido Glicirretínico/farmacologia , Glycyrrhiza/química , Extratos Vegetais/farmacologia , Streptococcus mutans/efeitos dos fármacos , Antibacterianos/química , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Genes Bacterianos/genética , Glucose/metabolismo , Ácido Glicirretínico/química , Concentração de Íons de Hidrogênio , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Extratos Vegetais/química , Streptococcus mutans/genética , Streptococcus mutans/crescimento & desenvolvimento , Virulência , Fatores de Virulência/genética , Fatores de Virulência/metabolismo
15.
Bioelectrochemistry ; 129: 242-250, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31229862

RESUMO

A flavin-based extracellular electron transfer mechanism (EET) has recently been described for the gram-positive Listeria monocytogenes. The gram-positive, solvent producing Clostridium acetobutylicum is a known flavin producer. Since flavin secretion in C. acetobutylicum can be triggered by a low-iron environment, the interaction of iron with an electrochemical system as well as the consequences for flavin production are investigated. It is shown that iron adsorbs onto the electrode's surface in the form of iron phosphorus compounds but that this iron is still bioavailable. Moreover, a shift in the flavin spectrum of the supernatant from high flavin mononucleotide percentages of 59% to high riboflavin (43-45%) and flavin adenine dinucleotide (FAD, 40-48%) content can be seen by limiting or omitting the iron source from the culture medium. When additionally an electric potential of -600 mV vs. Ag/AgCl (saturated KCl) is applied, the same overall trend is obtained but an increase in flavin concentration and especially in the FAD share between 6 and 27% is observed. This study is a first hint that a flavin-based EET might also take place in solventogenic Clostridia and highlights the importance of further investigation of flavin production and their involvement in EET mechanisms in different species.


Assuntos
Clostridium acetobutylicum/fisiologia , Flavinas/metabolismo , Ferro/metabolismo , 1-Butanol/metabolismo , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos , Técnicas Eletroquímicas , Eletrodos , Fermentação
16.
Chemosphere ; 232: 396-402, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31158634

RESUMO

Extracellular electron transfer from the biofilm surface to the electrode is the key step for the microbial fuel cell (MFC). More recently, graphene has attracted tremendous attentions for bioelectrochemical applications due to its good biocompatibility, high electrical conductivity and large surface area. In the current work, we report a facile and green synthesis of graphene-modified carbon paper (CP) as an efficient MFC anode through plant-mediated bioreduction coupled with self-assembly. Three-dimensional CFP uniformly wrapped by curled and wrinkled biosynthesized graphene enables more surface area for microbe adhesion and mass diffusion. Significantly, nontoxic and biodegradable biomolecules extracted from Eucalyptus leaves act as reducing agent and adsorb on the graphene, rendering the graphene surface become hydrophilic and biocompatible. Furthermore, the obtained graphene exhibit excellent bioelectrochemical interactions with the microbes. Equipped with the biosynthesized graphene-modified anode, the E. coli-catalyzed MFC delivered an enhanced maximum power density of 1158 mW/m2, 70% higher than a pristine graphene-modified one. This development provides not only a versatile and scalable synthesis strategy for biocompatible graphene-modified devices, but also indicates that biomolecules facilitate the extracellular electron transfer in bioelectrochemical process.


Assuntos
Fontes de Energia Bioelétrica , Biofilmes/crescimento & desenvolvimento , Escherichia coli/crescimento & desenvolvimento , Grafite/química , Adsorção , Condutividade Elétrica , Eletrodos , Transporte de Elétrons , Elétrons , Eucalyptus/química , Química Verde , Folhas de Planta/química , Propriedades de Superfície
17.
J Med Microbiol ; 68(8): 1253-1265, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31215857

RESUMO

INTRODUCTION: Acinetobacter baumannii is one of the most important nosocomial pathogens, mainly due to its ability to accumulate antibiotic-resistances and to persist in the hospital environment - characteristics related to biofilm production. It is well-known that A. baumannii is inhibited by the proline-rich peptide Bac7(1-35), but its putative effects at sub-MICs were never considered. AIMS: We examined the sub-MIC effect of Bac7(1-35) on the growth rate, resistance induction and some A. baumannii features linked to virulence. METHODOLOGY: Growth kinetics in the presence of sub-MICs of Bac7(1-35) were evaluated spectrophotometrically. Peptide uptake was quantified by cytometric analysis. The ability of Bac7(1-35) to interfere with biofilm production was investigated by the crystal violet method and confocal microscopy. Bacterial motility was observed at the interphase between a layer of a semi-solid medium and the polystyrene bottom of a Petri dish. The induction of resistance was evaluated after serial passages with sub-MICs of the peptide. RESULTS: Although the MIC of Bac7(1-35) was between 2-4 µM for all tested strains, its effect on the growth rate at sub-MICs was strain-dependent and correlated with the amount of peptide internalized by each strain. Sub-MICs of Bac7(1-35) induced a strongly strain-dependent effect on biofilm formation and reduced motility in almost all strains, but interestingly the peptide did not induce resistance. CONCLUSION: Bac7(1-35) is internalized into A. baumannii and is able to inhibit biofilm formation and bacterial motility, without inducing resistance. This study stresses the importance of considering possible effects that antimicrobials could have at sub-MICs, mimicking a common condition during antibiotic treatment.


Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Acinetobacter baumannii/isolamento & purificação , Acinetobacter baumannii/patogenicidade , Acinetobacter baumannii/fisiologia , Antibacterianos/química , Antibacterianos/metabolismo , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/metabolismo , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Relação Dose-Resposta a Droga , Farmacorresistência Bacteriana , Humanos , Locomoção/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Especificidade da Espécie , Virulência/efeitos dos fármacos
18.
J Med Microbiol ; 68(8): 1129-1136, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31241446

RESUMO

PURPOSE: Staphylococcus aureus causes a wide range of infections, such as endocarditis, pneumonia, osteomyelitis, skin and soft tissue infections, and implant/in-dwelling device-related infections. S. aureus poses a significant challenge to clinicians because of its ability to rapidly acquire multi-drug resistance and quickly progress into a recurrent, chronic infection by biofilm formation. Levonadifloxacin (WCK 771) is a novel broad-spectrum antibacterial agent (it recently completed a phase 3 trial in India) with a differentiated mechanism of action involving high affinity to staphylococcal DNA gyrase, and is active against multi-drug-resistant (MDR) S. aureus, including those that are resistant to quinolones. The present study investigated the bactericidal activity of levonadifloxacin against biofilm-embedded S. aureus clinical isolates in comparison with other anti-S. aureus drugs. METHODOLOGY: The bactericidal activity of levonadifloxacin and comparator drugs such as vancomycin, linezolid and daptomycin was evaluated against planktonic and biofilm-encapsulated recent methicillin- and quinolone-resistant S. aureus clinical isolates using time-kill, biofilm eradication and scanning electron microscopy analysis. RESULTS: Levonadifloxacin displayed a consistent ≥90 % bacterial kill rate against biofilm-embedded organisms, while vancomycin and linezolid displayed variable activity and daptomycin did not show any activity. Scanning electron microscopy images further confirmed the efficacy of levonadifloxacin against biofilm, showing the disruption of biofilm structure and a corresponding reduction in the viable bacterial count. CONCLUSION: These results show that levonadifloxacin has an improved bactericidal effect on biofilm-embedded quinolone-resistant S. aureus and meticillin-resistant S. aureus, and that it can be a promising treatment option for such infections.


Assuntos
Antibacterianos/farmacologia , Biofilmes/efeitos dos fármacos , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Fluoroquinolonas/farmacologia , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Humanos , Meticilina/farmacologia , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Staphylococcus aureus Resistente à Meticilina/fisiologia , Staphylococcus aureus Resistente à Meticilina/ultraestrutura , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Quinolonas/farmacologia , Infecções Estafilocócicas/microbiologia , Fatores de Tempo
19.
World J Microbiol Biotechnol ; 35(7): 96, 2019 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-31218558

RESUMO

The biofilm-forming ability of Listeria spp. is a concern to the food industry and health sectors. The aim of this study was to verify the inhibitory activity of bacteriocins produced by enterococci (Enterococcus faecium 20, 22 and 24 and Enterococcus faecalis 27) on developing biofilm and preformed biofilm of Listeria species. Bacteriocins were partially purified from cell free supernatant (CFS). L. monocytogenes 2032, L. innocua 2050 and L. ivanovii 2056 were selected to analyse the inhibitory effect of bacteriocins on biofilm biomass (crystal violet staining) and biofilm viability (XTT-reduction). The biomass of the developing and preformed biofilms of Listeria species were reduced (p < 0.05) in the presence of all bacteriocins tested. Overall, the reduction in biofilm biomass of developing biofilms was up to 87.4% for bacteriocin produced by E. faecium 22 (CFS22) against L. ivanovii and up to 87.1% for CFS22 against L. monocytogenes. These findings are in accordance with those observed in confocal microscopy analysis. Most of the CFS-containing bacteriocin (CFS22, CFS24, CFS27) were effective at decreasing the viability of biofilm cells from all Listeria species. The highest reduction in viability was observed for L. monocytogenes preformed biofilm cells (up to 98.7%), evidenced by fluorescence microscopy of propidium iodide-labelled cells. Scanning electron microscopy showed that cells of biofilm-treated bacteriocins displayed degenerative changes that may be indicative of cellular leakages. This study suggests that bacteriocins produced by enterococci have prospective applications to prevent biofilm formation and/or to reduce cell viability of formed biofilms of distinct Listeria species.


Assuntos
Bacteriocinas/farmacologia , Biofilmes/efeitos dos fármacos , Enterococcus/metabolismo , Listeria monocytogenes/efeitos dos fármacos , Listeria/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Biomassa , Enterococcus faecalis/metabolismo , Enterococcus faecium/metabolismo , Indústria de Processamento de Alimentos , Viabilidade Microbiana/efeitos dos fármacos
20.
Lett Appl Microbiol ; 69(2): 110-115, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31087370

RESUMO

This study was undertaken to detect the occurrence of beta-lactamase and biofilm producing Enterobacteriaceae in healthy ducks. A total 202 cloacal swabs were collected from ducks kept in organized (n = 92) and backyard (n = 110) farms in West Bengal (India). The ducks had no history of antibiotic intake. Among the 87 phenotypically beta-lactamase producing Escherichia coli, 19 (17·43%), 6 (5·05%) and 15 (13·76%) isolates possessed blaTEM , blaSHV and blaCTX-M respectively. Whereas, 5 (38·46%) Salmonella isolates were found to harbour blaCTX-M . In K. pneumoniae 10 (33·33%), 3 (13·33%), 4 (13·33%) isolates possessed blaTEM , blaSHV and blaCTX-M respectively. The sequences of selected PCR products were found 98% cognate with blaCTX-M-9, blaSHV-12 and blaTEM-1 . Beta-lactamase producing E. coli isolates belonged to 14 different serogroups such as O1, O2, O3, O5, O7, O8, O35, O83, O84, O88, O119, O128, O145 and O157. Moreover, 87 E. coli (79·82%), six Samonella (46·15%) and 13 K. pneumoniae (43·33%) isolates were detected as AmpC producers possessing blaAmpC . Majority of E. coli (46·79%), Salmonella (46·15%) and K. pneumoniae (70%) isolates were detected as biofilm producers and possessed the associated genes (csgA, sdiA, rcsA, rpoS). Significantly higher occurrence of beta-lactamase and biofilm producing Enterobacteriaceae isolates was detected in backyard ducks than organized farms. SIGNIFICANCE AND IMPACT OF THE STUDY: Consumption of antibiotic through feed or during therapy is considered as potential reason for generation of antimicrobial resistant bacteria in birds. This study provides valuable evidence that exposure to contaminated environment may be an additional source for generation of antimicrobial resistant bacteria in backyard ducks. The backyard ducks are reared by marginal farmers in India who cannot offer antibiotics to them either through feed or during therapy due to high cost. The study also reveals a significant correlation between biofilm formation and possession of antimicrobial resistance genes in the bacterial isolates from the ducks.


Assuntos
Biofilmes/crescimento & desenvolvimento , Patos/microbiologia , Infecções por Enterobacteriaceae/veterinária , Enterobacteriaceae/fisiologia , Doenças das Aves Domésticas/microbiologia , beta-Lactamases/genética , Animais , Proteínas de Bactérias/genética , Farmacorresistência Bacteriana , Enterobacteriaceae/enzimologia , Enterobacteriaceae/genética , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/microbiologia , Fazendas , Feminino , Índia/epidemiologia , Masculino , Fenótipo , Doenças das Aves Domésticas/epidemiologia
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