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1.
Phys Rev Lett ; 123(17): 178001, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31702266

RESUMO

The transition from monolayers to multilayered structures in bacterial colonies is a fundamental step in biofilm development. Observed across different morphotypes and species, this transition is triggered within freely growing bacterial microcolonies comprising a few hundred cells. Using a combination of numerical simulations and analytical modeling, here we demonstrate that this transition originates from the competition between growth-induced in-plane active stresses and vertical restoring forces, due to the cell-substrate interactions. Using a simple chainlike colony of laterally confined cells, we show that the transition sets when individual cells become unstable to rotations; thus it is localized and mechanically deterministic. Asynchronous cell division renders the process stochastic, so that all the critical parameters that control the onset of the transition are continuously distributed random variables. Here we demonstrate that the occurrence of the first division in the colony can be approximated as a Poisson process in the limit of large cell numbers. This allows us to approximately calculate the probability distribution function of the position and time associated with the first extrusion. The rate of such a Poisson process can be identified as the order parameter of the transition, thus highlighting its mixed deterministic-stochastic nature.


Assuntos
Bactérias/crescimento & desenvolvimento , Modelos Biológicos , Técnicas Bacteriológicas
2.
Am Surg ; 85(10): 1175-1178, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31657319

RESUMO

Early surgical intervention decreases mortality in necrotizing soft tissue infections (NSTIs). Yet, a subset of patients will not have NSTIs (non-NSTIs) at the time of exploration. We hypothesized that NSTI and non-NSTI patients had similar causative organisms and that intraoperative wound cultures could help guide management. Culture results and outcomes were compared for all patients undergoing surgery for suspected NSTIs over a seven-year-period. Of 295 patients, 240 (81.4%) had NSTIs. Of the 55 non-NSTI patients (18.6%), 50 had cellulitis and 5 had abscesses. NSTI and non-NSTI patients had similar rates of bacteremia (20.4% vs 17.6%, P = 0.66), septic shock (15.9% vs 12.7%, P = 0.68), and mortality (10.4% vs 7.2%, P = 0.62). Wound cultures were collected more often in NSTI patients (229/240, 95.4%) than in non-NSTI patients (42/55, 76.4%, P < 0.01). Non-NSTI patients had positive deep wound cultures more than half of the time (23/42, 54.8%). The microbiologic profile was similar between groups, with Methicillin Resistant Staphylococcus aureus and Group A Streptococcus occurring with the same frequency. We advocate for deep wound cultures in all patients being evaluated operatively for NSTIs even if the exploration is considered negative because these patients have similar clinical characteristics and virulent microbiology, and culture results can help guide antimicrobial therapy.


Assuntos
Infecções dos Tecidos Moles/microbiologia , Infecções dos Tecidos Moles/cirurgia , Abscesso/epidemiologia , Abscesso/microbiologia , Adulto , Bacteriemia/epidemiologia , Técnicas Bacteriológicas , Celulite (Flegmão)/epidemiologia , Celulite (Flegmão)/microbiologia , Feminino , Mortalidade Hospitalar , Humanos , Masculino , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Pessoa de Meia-Idade , Necrose/microbiologia , Estudos Retrospectivos , Choque Séptico/epidemiologia , Infecções dos Tecidos Moles/epidemiologia , Infecções dos Tecidos Moles/patologia , Streptococcus pyogenes/isolamento & purificação
4.
Braz Oral Res ; 33: e039, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31508729

RESUMO

This clinical study compared the effectiveness of two rotary systems: HyFlex CM (Coltene-Whaledent, Altstetten, Switzerland) and ProTaper Next (Dentsply Sirona, Ballaigues, Switzerland) on the removal of cultivable bacteria and endotoxins from primarily infected root canals. This study was designed as a randomized single-blinded, 2-arm, clinical trial. Twenty-four primarily infected root canals were selected and randomly divided into 2 groups: HyFlex CM (n = 12); and ProTaper Next (n = 12). Samples were collected before and after the biomechanical preparation and inoculated in specific flasks. Irrigation was performed using 2.5% sodium hypochlorite. A kinetic turbidimetric lysate assay of limulus amoebocytes was used to quantify endotoxins. Microbiological culture technique was used to determine the count of bacterial colony forming units (CFU/mL). Data collected were statistically analyzed using SigmaPlot 12.0 for Windows. The Two-Way ANOVA statistical test was performed and the level of significance was 5%. In the samples before the biomechanical preparation, cultivable bacteria and endotoxins were evidenced in 100% of the cases. The culture analysis revealed that there was no statistically significant difference in the bacterial reduction between the two instrumentation systems. Endotoxins were present in 100% of the canals after instrumentation and there was no statistical difference between the two systems in endotoxin reduction. Thus, it was concluded that both instrumentation systems were effective in reducing root canal bacteria and endotoxins with primary endodontic infection and that there was no statistical difference between them. However, no system was able to eliminate 100% of the bacteria and their by-products.


Assuntos
Bactérias/isolamento & purificação , Instrumentos Odontológicos , Cavidade Pulpar/microbiologia , Lipopolissacarídeos/análise , Preparo de Canal Radicular/instrumentação , Adulto , Carga Bacteriana , Técnicas Bacteriológicas , Endotoxinas/análise , Feminino , Humanos , Masculino , Teste de Materiais , Pessoa de Meia-Idade , Resultado do Tratamento
5.
Pan Afr Med J ; 33: 110, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31489088

RESUMO

Introduction: The World Health Organization endorsed (2010) the use of Xpert MTB/RIF and countries are shifting from smear microscopy (smear)-based to Xpert MTB/RIF-based tuberculosis (TB) diagnostic algorithms. As with smear, sputum quality may predict the likelihood of obtaining a bacteriologically-confirmed TB when using Xpert MTB/RIF. Methods: From 08/12-11/2014, all people living with HIV were recruited at 22 clinics. For patients screened positive using the four TB symptoms their sputa were tested by Xpert MTB/RIF and smear. Laboratorians assessed and recorded sputum appearance and volume. The yield of bacteriologically-positive sputum evaluated using Xpert MTB/RIF and smear, likelihood-ratios were calculated. Results: Among 6,041 patients enrolled 2,296 were presumptive TB, 1,305 (56.8%) had > 1 sputa collected and 644/1,305 (49.3%) had both Xpert MTB/RIF and smear results. Since >1 sputa collected from 644 patients 954 sputa were tested by Xpert MTB/RIF and smear. Bacteriologically-positive sputum was two-fold higher with Xpert MTB/RIF 11.4% versus smear 5.3%, p < 0.001. Sputum appearance and quantity were not predictive of bacteriologically-positive results, except volume of 2ml to < 3ml, tested by Xpert MTB/RIF LR+= 1.26 (95% CI, 1.05-1.50). Conclusion: Xpert MTB/RIF test yield to bacteriologically-positive sputum was superior to smear. Sputum quality and quantity, however, were not consistently predictive of bacteriologically-positive results by Xpert MTB/RIF or smear.


Assuntos
Técnicas Bacteriológicas/métodos , Microscopia/métodos , Escarro/microbiologia , Tuberculose/diagnóstico , Adulto , Feminino , Seguimentos , Humanos , Masculino , Técnicas de Diagnóstico Molecular/métodos , Estudos Prospectivos , Tuberculose/epidemiologia
6.
Anal Bioanal Chem ; 411(26): 7027-7038, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31486868

RESUMO

Biotyping using matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectroscopy (MS) has revolutionized microbiology by allowing clinicians and scientists to rapidly identify microbes at genus and species levels. The present study extensively assesses the suitability and reliability of MALDI-ToF biotyping of 14 different aerobic and anaerobic bacterial species as pure and mixed cultures. Reliable identification at species level was possible from biomaterial of older colonies and even frozen biomaterial, although this was species dependent. Using standard instrument settings and direct application of biomaterial onto the MALDI-ToF target plates, it was determined that the cell densities necessary for completely reliable identification of pure cultures varied between 2.40 × 108 and 1.10 × 1010 viable cell counts (VCCs) per mL, depending on the species. Evaluation of the mixed culture algorithm of the Bruker Biotyper® software showed that the performance of the algorithm depends greatly on the targeted species, on their phylogenetic distance, and on their ratio of VCC per mL in the mixed culture. Hence, the use of MALDI-ToF-MS with incorporation of the mixed culture algorithm of the software is a useful pre-screening tool for early identification of contaminants, but due to the great variability in performance between different species and the usually unknown percentage of the possible contaminant in the mixture, it is advisable to combine this method with other microbiology methods.


Assuntos
Bactérias/classificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos , Bactérias/química , Bactérias/citologia , Infecções Bacterianas/microbiologia , Carga Bacteriana/métodos , Técnicas Bacteriológicas/métodos , Humanos , Viabilidade Microbiana
7.
Plant Dis ; 103(11): 2893-2902, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31436473

RESUMO

Uniqprimer, a software pipeline developed in Python, was deployed as a user-friendly internet tool in Rice Galaxy for comparative genome analyses to design primer sets for PCRassays capable of detecting target bacterial taxa. The pipeline was trialed with Dickeya dianthicola, a destructive broad-host-range bacterial pathogen found in most potato-growing regions. Dickeya is a highly variable genus, and some primers available to detect this genus and species exhibit common diagnostic failures. Upon uploading a selection of target and nontarget genomes, six primer sets were rapidly identified with Uniqprimer, of which two were specific and sensitive when tested with D. dianthicola. The remaining four amplified a minority of the nontarget strains tested. The two promising candidate primer sets were trialed with DNA isolated from 116 field samples from across the United States that were previously submitted for testing. D. dianthicola was detected in 41 samples, demonstrating the applicability of our detection primers and suggesting widespread occurrence of D. dianthicola in North America.


Assuntos
Agricultura , Técnicas Bacteriológicas , Primers do DNA , Enterobacteriaceae , Solanum tuberosum , Agricultura/métodos , Técnicas Bacteriológicas/métodos , Primers do DNA/genética , Enterobacteriaceae/genética , América do Norte , Doenças das Plantas/microbiologia , Solanum tuberosum/microbiologia
8.
Arch Microbiol ; 201(10): 1427-1433, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31414157

RESUMO

We controlled and observed individual magneto-tactic bacteria (Magnetospirillum gryphiswaldense) inside a [Formula: see text]-high microfluidic channel for over 4 h. After a period of constant velocity, the duration of which varied between bacteria, all observed bacteria showed a gradual decrease in their velocity of about [Formula: see text]. After coming to a full stop, different behaviour was observed, ranging from rotation around the centre of mass synchronous with the direction of the external magnetic field, to being completely immobile. Our results suggest that the influence of the high-intensity illumination and the presence of the channel walls are important parameters to consider when performing observations of such long duration.


Assuntos
Técnicas Bacteriológicas/métodos , Magnetospirillum/fisiologia , Microfluídica , Técnicas Bacteriológicas/normas , Fatores de Tempo
9.
World J Microbiol Biotechnol ; 35(8): 126, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31363938

RESUMO

Isolation and identification of temperature tolerant phosphate solubilizing bacteria (TTPSB) and their use as microbial fertilizers was the main goal of the study. In this study, TTPSB were isolated from soil samples treated for 16 h at 55 °C. Their phosphate solubilizing activity was either evaluated in solid media by forming a clear zone (halo) or in liquid media by quantification of the soluble phosphate in the growth medium. Five colonies (RPS4, RPS6, RPS7, RPS8 and RPS9) were identified to be able to form a halo and two of the isolates (RPS9 and RPS7) tolerated a temperature of 55 °C. With tricalcium phosphate (TCP) as the sole P-source, the phosphate solubilizing capacity of RPS9 and RPS7 was determined to be 563.8 and 324.1 mg P L-1 in liquid Sperber medium, respectively. Both bacterial isolates were identified as Pantoea agglomerans by molecular and biochemical characterization. To be used as a microbial fertilizer a carrier system for the temperature tolerant bacteria consisting of rock phosphate, sulfur and bagasse was used. It could be established that the bacterial cell counts of the microbial fertilizers were acceptable for application after storage for 4 months at 28 °C. In a greenhouse experiment using pot cultures, inoculation of maize (S.C.704) with the microbial fertilizers in an autoclaved soil resulted in a significant effect on total fresh and dry weight of the plant root and shoot as well as on the P content of the root and shoot. The effects observed with RPS9 as a component of the microbial fertilizer on plant growth and P nutrition was comparable with the addition of 50% of recommended triple superphosphate (TSP) dose. Using temperature tolerant bacteria in microbial fertilizers will overcome limitations in production and storage of the microbial fertilizers and contribute to a environmentally-friendly agriculture. The temperature tolerant P. agglomerans strain RPS9 was shown to be effective as part of a microbial fertilizer in supporting the growth and P uptake in maize.


Assuntos
Agricultura/métodos , Fosfatos de Cálcio/metabolismo , Pantoea/isolamento & purificação , Pantoea/metabolismo , Microbiologia do Solo , Zea mays/crescimento & desenvolvimento , Técnicas Bacteriológicas , Biotransformação , Fosfatos de Cálcio/química , Meios de Cultura/química , Temperatura Alta , Pantoea/classificação , Pantoea/efeitos da radiação , Solubilidade , Zea mays/microbiologia
10.
J Med Microbiol ; 68(9): 1306-1313, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31274401

RESUMO

Introduction. Umbilical catheterization offers unique vascular access that is only possible in the neonatal setting due to unobstructed umbilical vessels from foetal circulation. With the cut of the umbilical cord, two arteries and a vein are dissected, allowing quick and painless catheterization of the neonate. Unfortunately, keeping the umbilical access sterile is challenging due to its mobility and necrosis of the umbilical stump, which makes it a perfect model for vessel catheter colonization analysis.Aim. The aim of this study was to evaluate bacterial colonization of the umbilical catheter, with a focus on the difference between various sections of the catheter, the duration of catheterization, patient status and gestational age.Methodology. We performed bacterial cultures for 44 umbilical catheters, analysing the superficial and deep parts of the catheter separately, and revealed colonization in one-third of cases.Results. One hundred per cent of the colonization occurred in preterm infants, with a shift towards extreme prematurity. The catheters were mainly colonized by coagulase-negative staphylococci. The majority of catheters presented with superficial colonization dominance, and there were no cases of deep colonization. The bacterial strains and their resistance were consistent between the catheter's proximal and distal parts, as well as positive blood cultures. The patients with the most intense bacterial catheter colonization presented with sepsis around removal time or a couple of days later, especially if they were extremely premature and exhibited very low birth weight. Catheterization time did not play a major role.Conclusion. Umbilical catheters are vectors for skin microflora transmission to the bloodstream via biofilm formation, regardless of antibiotic use and the duration of catheterization, especially in preterm neonates.


Assuntos
Antibacterianos/uso terapêutico , Bactérias/isolamento & purificação , Cateterismo/métodos , Cateteres/microbiologia , Uso de Medicamentos , Contaminação de Equipamentos , Recém-Nascido Prematuro , Bacteriemia/epidemiologia , Bacteriemia/microbiologia , Bacteriemia/patologia , Bactérias/classificação , Bactérias/efeitos dos fármacos , Técnicas Bacteriológicas , Infecções Relacionadas a Cateter/epidemiologia , Infecções Relacionadas a Cateter/microbiologia , Infecções Relacionadas a Cateter/patologia , Cateterismo/efeitos adversos , Farmacorresistência Bacteriana , Feminino , Humanos , Lactente , Recém-Nascido , Masculino
11.
APMIS ; 127(10): 660-670, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31344275

RESUMO

Multiple approaches were employed to detect pathogens from bone margins associated with Diabetic Foot Osteomyelitis (DFO). Intra-operative bone specimens of 14 consecutive subjects with suspected DFO were collected over a six-month study period from Liverpool Hospital. Infected bone and a proximal bone margins presumed to be 'clean/non-infected' were collected. Bone material was subjected to conventional culture, DNA sequencing and microscopy. In total, eight of 14 (57%) proximal bone margins had no growth by conventional culture but were identified in all proximal bone specimens by DNA sequencing. Proximal margins had lower median total microbial counts than infected specimens, but these differences were not statistically significant. Pathogens identified by sequencing in infected specimens were identified in proximal margins and the microbiomes were similar (ANOSIM = 0.02, p = 0.59). Using a combination of SEM and/or PNA-FISH, we visualized the presence of microorganisms in infected bone specimens and their corresponding proximal margins of seven patients (50%) with DFO. We identify that bacteria can still reside in what seems to be proximal 'clean' margins. The significance and implications of clinical outcomes requires further analysis from a larger sample size that incorporates differences in surgical and post-operative approaches, correlating any outcomes back to culture-sequence findings.


Assuntos
Bactérias/isolamento & purificação , Técnicas Bacteriológicas/métodos , Osso e Ossos/microbiologia , Pé Diabético/microbiologia , Histocitoquímica/métodos , Metagenômica/métodos , Osteomielite/microbiologia , Bactérias/classificação , Bactérias/genética , Osso e Ossos/cirurgia , Pé Diabético/patologia , Pé Diabético/cirurgia , Humanos , Hibridização in Situ Fluorescente , Microscopia Eletrônica de Varredura , Osteomielite/patologia , Osteomielite/cirurgia , Análise de Sequência de DNA
12.
BMC Infect Dis ; 19(1): 630, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31315581

RESUMO

BACKGROUND: In hospitalised patients with diarrhoea a positive campylobacter stool Polymerase Chain Reaction (PCR) test with negative culture results as well as Enteropathogenic Escherichia coli (EPEC) positive stool PCRs, challenges the clinician and may lead the unexperienced clinician astray. The aim of the study was to elucidate the clinical significance of positive Campylobacter and/or EPEC test results in hospitalised patients with diarrhoea. METHODS: We conducted a retrospective case-case study. Case groups with 1) EPEC only and 2) EPEC in combination with any other pathogen in the PCR multiplex array, 3) PCR positive/culture negative Campylobacter, and 4) PCR positive/culture positive Campylobacter were compared. Medical records were reviewed and cases classified according to pre-specified clinical criteria as infectious gastroenteritis or non-infectious causes for diarrhoea. We analyzed the association between laboratory findings (the 4 subgroups) and the pre-specified clinical classification. We further sequenced culture negative campylobacter samples and tested EPEC for bundle forming pilus A (bfpA) gene, distinguishing typical from atypical EPEC. RESULTS: A total of 291 patients were included, 169 were PCR positive for Campylobacter and 122 for EPEC. For both pathogens, co-infections were more common in culture negative/PCR positive samples than in culture positive samples. Clinical characteristics differed significantly in and between groups. Campylobacter culture positive patients had very high prevalence of characteristics of acute infectious gastroenteritis, whereas patients with PCR positive test results only often had an alternative explanation for their diarrhoea. Culture positives were almost exclusively C. jejuni/coli, whereas in culture negatives, constituting a third of the total PCR positives, C. concisus was the most frequent species. The vast majority of EPEC only positives had documented non-infectious factors that could explain diarrhoea. The EPEC co-infected group mimicked the culture positive campylobacter group, with most patients fulfilling the infectious gastroenteritis criteria. CONCLUSIONS: In hospitalised patients, positive PCR results for campylobacter and EPEC should be interpreted in a clinical context after evaluation of non-infectious diarrhoea associated conditions, and cannot be used as a stand-alone diagnostic tool.


Assuntos
Escherichia coli Enteropatogênica/genética , Infecções por Escherichia coli/microbiologia , Fezes/microbiologia , Reação em Cadeia da Polimerase Multiplex/métodos , Idoso , Técnicas Bacteriológicas , Campylobacter/genética , Campylobacter/patogenicidade , Diarreia/microbiologia , Escherichia coli Enteropatogênica/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Feminino , Gastroenterite/epidemiologia , Gastroenterite/microbiologia , Hospitalização/estatística & dados numéricos , Humanos , Masculino , Pessoa de Meia-Idade , Noruega/epidemiologia , Estudos Retrospectivos
14.
Medicine (Baltimore) ; 98(29): e16501, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31335719

RESUMO

By 2030, the annual number of combined total hip and knee arthroplasty is estimated to reach 3.5 to 4 million in the US alone. In the context of a constant increase of the number of primary and revision total hip and knee arthroplasty, an increased risk of complication is expected. Prosthetic joint infections (PJIs) represent major cause of healthcare expenditure and morbidity. PJI still remain the most common and feared arthroplasty complication. A rapid and correct diagnosis of infection is decisive for a correct therapeutical management. In this setting, the Academic Emergency Hospital Sibiu adopted and implemented, with the beginning of September 2016, a new strategy for the diagnosis of PJIs strategy that uses sonication and beacon-based fluorescent in situ hybridization (bbFISH) technology.Until November 2017, 40 patients (40 retrieved implants) were enrolled in the study. Sonication fluid (SF) was collected after sonication of the implants, and samples were harvested on aerobic and anaerobic culture media. A bbFISH was used as a rapid method of bacteria detection.16 patients were diagnosed with PJIs (all 16 patients presented a positive culture of the SF). Comparing bbFISH with culture, 11 samples tested true-positive. As the kit doesn't contain probes for Pseudomonas fluorescens or Ralstonia pickettii, 4 strains of R pickettii and 1 strain of P fluorescens that was associated with Staphylococcus epidermidis were not detected.Bacteria culture of SF remains the gold standard. bbFISH holds promise to be a diagnostic tool for rapid identifying of PJIs. The bbFISH assay needs to be optimized for the detection of bacterial strains that are relevant for the PJIs field.


Assuntos
Artroplastia de Quadril/efeitos adversos , Artroplastia do Joelho/efeitos adversos , Infecções Bacterianas/diagnóstico , Técnicas Bacteriológicas/métodos , Hibridização in Situ Fluorescente/métodos , Infecções Relacionadas à Prótese/diagnóstico , Sonicação , Idoso , Idoso de 80 Anos ou mais , Tecido Conjuntivo/microbiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , RNA Bacteriano/análise , RNA Ribossômico 16S/análise , Líquido Sinovial/microbiologia
15.
BMC Infect Dis ; 19(1): 571, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31266450

RESUMO

BACKGROUND: Carbapenemase-producing organisms (CPOs) have emerged as antibiotic-resistant bacteria of global concern. Here we assessed the performance of the Carba (beta) assay, a multiplex real-time PCR assay developed by SpeeDx for the detection of key carbapenemase-encoding genes: KPC, NDM, OXA-48-like, IMP-4-like, and VIM. METHODS: DNA extracts of 180 isolates were tested with the Carba (beta) assay, using previously validated in-house TaqMan probe assays for the relevant carbapenemase genes as the reference standard. The Carba (beta) assay was then directly used to screen 460 DNA extracts of faecal specimens, with positive results subjected to the aforementioned in-house assays plus Sanger sequencing. RESULTS: The Carba (beta) assay correctly identified the presence of the respective carbapenemase genes in 154 of 156 isolates and provided negative results for all 24 non-CPO isolates. Two isolates provided positive results for OXA-48-like carbapenemase by the Carba (beta) assay only. The Carba (beta) assay had sensitivities of 100% for all targets, and specificities of 100% for KPC, NDM, IMP-4-like, and VIM targets, and 98.5% for OXA-48-like targets. When applied directly to faecal specimens, eight samples were positive by the Carba (beta) assay, two of which were confirmed by in-house TaqMan probe PCR or DNA sequencing. CONCLUSIONS: The Carba (beta) assay is highly sensitive and specific for detecting key carbapenemase genes in isolates. Further testing is required to assess this assay's suitability for direct screening of clinical specimens.


Assuntos
Bactérias/genética , Proteínas de Bactérias/genética , Reação em Cadeia da Polimerase Multiplex/métodos , Reação em Cadeia da Polimerase em Tempo Real/métodos , beta-Lactamases/genética , Antibacterianos , Bactérias/efeitos dos fármacos , Técnicas Bacteriológicas/métodos , Proteínas de Escherichia coli/genética , Fezes/microbiologia , Humanos , Sensibilidade e Especificidade
16.
Zhonghua Jie He He Hu Xi Za Zhi ; 42(6): 432-437, 2019 Jun 12.
Artigo em Chinês | MEDLINE | ID: mdl-31189229

RESUMO

Objective: To study the incremental cost-effectiveness of the second Xpert assay in detection of Mycobacterium tuberculosis (Mtb) and rifampicin (RIF) resistance. Methods: We continuously collected 2 896 specimens from suspected tuberculosis patients who had undergone 2 Xpert tests in a week from March 2015 to March 2018, including 2 402 suspected tuberculosis patients with 1 523 males and 879 females, with an average age of 50 years. Among them, 2 144 specimens of sputum and 258 cases of bronchoalveolar lavage fluid were collected. We also enrolled 494 patients with suspected extrapulmonary tuberculosis, 318 males and 176 females, with an average age of 42 years. Among them, 157 pleural effusion specimens, 106 cerebrospinal fluid specimens, 34 urine specimens and 197 pus specimens were collected. All specimens were subjected to two Xpert tests, smear microscopy, liquid rapid culture (BACTEC MGIT 960), and positively cultured bacteria were tested for drug susceptibility. Results: Among the 2 896 specimens from suspected tuberculosis patients, either one of the two Xpert test results was positive (including both tests were positive, the same below) in 1 639 patients, and 1 502 (91.6%) were positive in the first Xpert tests. The additional 137 (8.4%) test results were positive in the second tests. According to the smear test results, all specimens were divided into the smear negative group and the smear positive group. The second Xpert test was significantly higher than the smear-positive group (14.86%, 3.2%, P<0.001), and the extrapulmonary tuberculosis group was higher than the tuberculosis group (11.2%, 8.0%, P=0.12).Of the susceptibility test results, a total of 371 were rifampicin-resistant specimens. The first Xpert detected 91.4% (339/371), and the second Xpert detected the additional 8.1% (30/371).The cost increase of the second test was very significant. Tests were calculated at 650 yuan per time, the tuberculosis group was 1 184 yuan and 13 696 yuan(P<0.001); the extrapulmonary tuberculosis group was 1 755 yuan and 13 961 yuan(P<0.001). In the test of specimens of tuberculosis and extrapulmonary tuberculosis, the smear-negative specimen cost increase of the second Xpert test was lower than that of the smear-positive specimen. Conclusion: The second xpert test showed significant value-added cost-effectiveness in the diagnosis of tuberculosis.


Assuntos
Antibióticos Antituberculose/farmacologia , Técnicas Bacteriológicas/economia , Farmacorresistência Bacteriana , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/isolamento & purificação , Rifampina/farmacologia , Tuberculose Pulmonar/diagnóstico , Adulto , Técnicas Bacteriológicas/métodos , Análise Custo-Benefício , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Rifampina/uso terapêutico , Sensibilidade e Especificidade , Escarro/microbiologia , Tuberculose Pulmonar/economia
17.
J Med Microbiol ; 68(9): 1269-1278, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31237536

RESUMO

Purpose. Increasing consumption of colistin as treatment for infections with multidrug-resistant (MDR) Gram-negative bacilli (GNB) has been accompanied by increasingly frequent reports of colistin-resistant (ColR) MDR GNB. Higher selective pressure creates a favourable environment that can facilitate the spread of ColR isolates. Monitoring of asymptomatic ColR GNB carriage can give us a better understanding of this emerging healthcare problem, particularly in wards with higher polymyxin selective pressure and prevalence of carbapenem-resistant GNB. Our aim was to assess the ColR GNB colonization rate in intensive care unit (ICU) patients and evaluate the performance of two surveillance protocols using a selective medium.Methodology. A prospective study included 739 surveillance samples (rectal swabs and tracheal aspirates) from 330 patients that were screened for ColR GNB carriage using SuperPolymyxin medium. Two approaches were used: direct sample plating and overnight pre-enrichment of samples followed by plating. Colistin resistance was confirmed with broth microdilution. ColR isolates were molecularly screened for plasmid-mediated mcr genes.Results. A total of 44/739 samples (45 ColR GNB isolates) were positive for ColR GNB, which included 31/330 (9.4 %) colonized patients; mcr genes were not detected. The direct plating method only identified 17/45 (37.8 %) isolates correctly, whereas the pre-enrichment protocol identified all 45 ColR GNB.Conclusion. The colonization rate among our ICU patients was 9.4  %. Based on our findings, the pre-enrichment step is necessary for the determination of ColR GNB carriage - even though the time to result takes an additional day, fewer than half of ColR GNB carriers were detected using the direct plating protocol.


Assuntos
Antibacterianos/farmacologia , Técnicas Bacteriológicas/métodos , Portador Sadio/diagnóstico , Colistina/farmacologia , Farmacorresistência Bacteriana , Bactérias Gram-Negativas/isolamento & purificação , Infecções por Bactérias Gram-Negativas/diagnóstico , Portador Sadio/epidemiologia , Portador Sadio/microbiologia , Meios de Cultura/química , Monitoramento Epidemiológico , Genes Bacterianos , Técnicas de Genotipagem , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/crescimento & desenvolvimento , Infecções por Bactérias Gram-Negativas/epidemiologia , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Unidades de Terapia Intensiva , Plasmídeos/análise , Prevalência , Estudos Prospectivos , Reto/microbiologia , Traqueia/microbiologia
18.
Soft Matter ; 15(27): 5400-5411, 2019 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-31172158

RESUMO

Two colonies of Bacillus subtilis of identical strains growing adjacent to each other on an agar plate exhibit two distinct types of interactions: they either merge as they grow or demarcation occurs leading to formation of a line of demarcation at the colony fronts. The nature of this interaction depends on the agar concentration in the growth medium and the initial separation between the colonies. When the agar concentration was 0.67% or lower, the two sibling colonies were found to always merge. At 1% or higher concentrations, the colonies formed a demarcation line only when their initial separation was 20 mm or higher. Interactions of a colony with solid structures and liquid drops have indicated that biochemical factors rather than the presence of physical obstacles are responsible for the demarcation line formation. A reaction diffusion model has been formulated to predict if two sibling colonies will form a demarcation line under given agar concentration and initial separation. The model prediction agrees well with experimental findings and generates a dimensionless phase diagram containing merging and demarcation regimes. The phase diagram is in terms of a dimensionless initial separation, d[combining macron], and a dimensionless diffusion coefficient, D[combining macron], of the colonies. The phase boundary between the two interaction regimes can be described by a power law relation between d[combining macron] and D[combining macron].


Assuntos
Ágar/química , Bacillus subtilis/fisiologia , Bacillus subtilis/classificação , Técnicas Bacteriológicas , Meios de Cultura , Difusão , Modelos Biológicos , Movimento
19.
Res Vet Sci ; 125: 185-188, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31252368

RESUMO

Fast and accurate identification of Mycoplasma bovis in cattle samples is of great importance for rational treatment and control of pneumonia, arthritis and mastitis. However, which growth conditions will allow the fastest identification of M. bovis with MALDI-TOF MS remains unclear. Therefore, growth conditions and incubation time were investigated to optimize identification of M. bovis with MALDI-TOF MS and an in-house library was constructed. Nine different M. bovis strains were inoculated in triplicate in three liquid media (B1-3). Basic broth (B1) consisted of pleuropneumonia-like organism broth, enriched with 25% horse serum and 0.7% yeast extract. B2 and B3 were additionally supplemented with 0.5% pyruvate or 520 µg/mL ampicillin, respectively. Protein extraction was performed after 24, 48, 72, 96 and 120 h of incubation (37 °C, 5% CO2) and processed with Autoflex III smartbeam. Identification scores ≥1.7 were interpreted as reliable. The present study showed reliable identification of M. bovis with MALDI-TOF MS as early as 24 h after inoculation, and in broth supplemented with pyruvate, up to 120 h after inoculation. Serial dilutions showed improved survival of M. bovis in broth with pyruvate. The addition of ampicillin to prevent contamination, did not impair identification of M. bovis and state-of-the-art in-house libraries contributed to higher identification scores for M. bovis with MALDI-TOF MS.


Assuntos
Técnicas Bacteriológicas/veterinária , Mycoplasma bovis/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/veterinária , Animais , Bovinos/microbiologia , Feminino , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
20.
J Basic Microbiol ; 59(8): 853-857, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31250936

RESUMO

The identification of the ubiquitous spore-forming bacterium Brevibacillus laterosporus, whose interest in pharma, agriculture, and other industrial sectors is raising, mostly relies on 16S ribosomal RNA gene sequence analysis. However, due to bacterial gene homology, this method appears insufficient for a proper discrimination of this species, so that the availability of other target genes is necessary. Leveraging the morphological and genetic feature uniqueness of B. laterosporus, a sensitive and reliable detection and quantification method based on polymerase chain reaction (PCR) and quantitative PCR assays, respectively, was developed. Targeting a highly conserved spore surface protein-related gene, B. laterosporus could be easily found in different matrices including soil, food, and insect body. Primer set selectivity was confirmed to be very specific and no false positives or negatives were observed using DNA of different bacterial species as a template. The method developed is also suitable for the rapid identification of newly isolated B. laterosporus strains.


Assuntos
Técnicas Bacteriológicas/métodos , Brevibacillus/isolamento & purificação , Reação em Cadeia da Polimerase , Animais , Brevibacillus/genética , Brevibacillus/crescimento & desenvolvimento , Contagem de Colônia Microbiana , DNA Bacteriano/genética , Microbiologia Ambiental , Genes Bacterianos/genética , Insetos/microbiologia , Sensibilidade e Especificidade , Análise de Sequência de DNA
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