RESUMO
OBJECTIVES: To determine whether it was feasible to use a haemorrhage assessment tool (HAT) within a trauma trial and whether the data obtained could differentiate patients who had achieved haemostasis. BACKGROUND: Major haemorrhage is one of the leading causes of death worldwide, affecting 40% of trauma patients. Clinical trials evaluating haemostatic interventions often use transfusion outcomes as a primary endpoint. Transfusion is highly dependent on local practice, limiting its reliability as a robust, transferable endpoint. METHODS: A five-point HAT questionnaire was applied to participants enrolled into the EFIT-1 trial. This RCT evaluated the feasibility of administering a 6 g fibrinogen concentrate to patients with severe trauma haemorrhage. RESULTS: Of participants, 98% completed a HAT; 75% participants had 'achieved haemostasis' at the time of tool completion, as determined by clinical acumen alone. HAT scores were able to differentiate which participants required transfusion after 3 h. Of participants, 56% were transfused red blood cells when they scored 0-2, compared to 17% with HAT scores between 3 and 5. CONCLUSION: This study has confirmed the feasibility of using a HAT during the emergency care of patients suffering trauma haemorrhage, and future studies should be conducted to determine its value as an endpoint in haemostasis studies.
Assuntos
Serviços Médicos de Emergência , Transfusão de Eritrócitos , Hemorragia , Hemostasia , Inquéritos e Questionários , Ferimentos e Lesões , Feminino , Hemorragia/diagnóstico , Hemorragia/terapia , Humanos , Masculino , Projetos Piloto , Ferimentos e Lesões/diagnóstico , Ferimentos e Lesões/terapiaRESUMO
BACKGROUND: The aim of this study was to describe the prevalence, patterns of blood use and outcomes of major haemorrhage in trauma. METHODS: This was a prospective observational study from 22 hospitals in the UK, including both major trauma centres and smaller trauma units. Eligible patients received at least 4 units of packed red blood cells (PRBCs) in the first 24 h of admission with activation of the massive haemorrhage protocol. Case notes, transfusion charts, blood bank records and copies of prescription/theatre charts were accessed and reviewed centrally. Study outcomes were: use of blood components, critical care during hospital stay, and mortality at 24 h, 30 days and 1 year. Data were used to estimate the national trauma haemorrhage incidence. RESULTS: A total of 442 patients were identified during a median enrolment interval of 20 (range 7-24) months. Based on this, the national incidence of trauma haemorrhage was estimated to be 83 per million. The median age of patients in the study cohort was 38 years and 73·8 per cent were men. The incidence of major haemorrhage increased markedly in patients aged over 65 years. Thirty-six deaths within 24 h of admission occurred within the first 3 h. At 24 h, 79 patients (17·9 per cent) had died, but mortality continued to rise even after discharge. Patients who received a cumulative ratio of fresh frozen plasma to PRBCs of at least 1 : 2 had lower rates of death than those who received a lower ratio. There were delays in administration of blood. Platelets and cryoprecipitate were either not given, or transfused well after initial resuscitation. CONCLUSION: There is a high burden of trauma haemorrhage that affects all age groups. Research is required to understand the reasons for death after the first 24 h and barriers to timely transfusion support.
Assuntos
Transfusão de Sangue/normas , Transfusão de Sangue/tendências , Cuidados Críticos/métodos , Hemorragia/mortalidade , Traumatismo Múltiplo/mortalidade , Centros de Traumatologia , Adulto , Estudos Transversais , Inglaterra/epidemiologia , Feminino , Seguimentos , Hemorragia/etiologia , Hemorragia/terapia , Mortalidade Hospitalar/tendências , Humanos , Escala de Gravidade do Ferimento , Masculino , Pessoa de Meia-Idade , Traumatismo Múltiplo/complicações , Estudos Prospectivos , Fatores de Tempo , Resultado do Tratamento , Adulto JovemRESUMO
BACKGROUND: Low fibrinogen (Fg) concentrations in trauma haemorrhage are associated with poorer outcomes. Cryoprecipitate is the standard source for Fg administration in the UK and USA and is often given in the later stages of transfusion therapy. It is not known whether early cryoprecipitate therapy improves clinical outcomes. The primary aim of this feasibility study was to determine whether it was possible to administer cryoprecipitate, within 90 min of admission to hospital. Secondary aims were to evaluate laboratory measures of Fg and clinical outcomes including thrombotic events, organ failure, length of hospital stay and mortality. METHODS: This was an unblinded RCT, conducted at two civilian UK major trauma centres of adult trauma patients (age ≥16 yrs), with active bleeding and requiring activation of the major haemorrhage protocol. Participants were randomised to standard major haemorrhage therapy (STANDARD) (n=22), or to standard haemorrhage therapy plus two early pools of cryoprecipitate (CRYO) (n=21). RESULTS: 85% (95% CI: 69-100%) CRYO participants received cryoprecipitate within 90 min, median time 60 min (IQR: 57-76) compared with 108 min (67-147), CRYO and STANDARD arms respectively (P=0.002). Fg concentrations were higher in the CRYO arm and were maintained above 1.8 g litre(-1) at all time-points during active haemorrhage. All-cause mortality at 28 days was not significantly different (P=0.14). CONCLUSIONS: Early Fg supplementation using cryoprecipitate is feasible in trauma patients. This study supports the need for a definitive RCT to determine the effect of early Fg supplementation on mortality and other clinical outcomes. TRIAL REGISTRY NUMBER: ISRCTN55509212.
Assuntos
Transfusão de Sangue/métodos , Fibrinogênio/uso terapêutico , Hemorragia/complicações , Hemorragia/terapia , Ferimentos e Lesões/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Centros de Traumatologia , Reino Unido , Adulto JovemRESUMO
Although there is increasing interest in the use of a viscoelastic test procedure (ROTEM/TEG) for diagnostics and therapy guidance of severely injured and bleeding patients, currently no uniformly accepted guidelines exist for how this technology should be integrated into clinical treatment. In September 2014 an international multidisciplinary group of opinion leaders in the field of trauma-induced coagulopathy and other disciplines involved in the treatment of severely injured patients were assembled for a 2-day consensus conference in Philadelphia (USA). This panel included trauma/accident surgeons, general/abdominal surgeons, vascular surgeons, emergency/intensive care surgeons, hematologists, transfusion specialists, anesthesiologists, laboratory physicians, pathobiologists/pathophysiologists and the lay public. A total of nine questions regarding the impact of viscoelastic testing in the early treatment of trauma patients were developed prior to the conference by a panel consensus. Early use was defined as baseline viscoelastic test result thresholds obtained within the first minutes of hospital arrival, when conventional laboratory results are not yet available. The available data for each question were then reviewed in person using standardized presentations by the expert panel. A consensus summary document was then developed and reviewed by the panel in an open forum. Finally, a 2-round Delphi poll was administered to the panel of experts regarding viscoelastic thresholds for triggering the initiation of specific treatments including fibrinogen (concentrates), platelet concentrates, blood plasma products and prothrombin complex concentrates (PCC). This report summarizes the findings and recommendations of this consensus conference, which correspond to a S2k guideline according to the system of the Association of the Scientific Medical Societies in Germany (AWMF) and taking formal consensus findings including Delphi methods into consideration.
Assuntos
Transtornos da Coagulação Sanguínea/sangue , Transtornos da Coagulação Sanguínea/terapia , Testes de Coagulação Sanguínea , Viscosidade Sanguínea , Hemorragia/sangue , Hemorragia/terapia , Tromboelastografia/métodos , Transtornos da Coagulação Sanguínea/etiologia , Transfusão de Sangue , Técnica Delphi , Guias como Assunto , Hemorragia/mortalidade , Humanos , Sistemas Automatizados de Assistência Junto ao LeitoRESUMO
Microbial abundance is central to most investigations in microbial ecology, and its accurate measurement is a challenging task that has been significantly facilitated by the advent of molecular techniques over the last 20 years. Fluorescence in situ hybridization (FISH) is considered the gold standard of quantification techniques; however, it is expensive and offers low sample throughput, both of which limit its wider application. Quantitative PCR (qPCR) is an alternative that offers significantly higher throughput, and it is used extensively in molecular biology. The accuracy of qPCR can be compromised by biases in the DNA extraction and amplification steps. In this study, we compared the accuracy of these two established quantification techniques to measure the abundance of a key functional group in biological wastewater treatment systems, the ammonia-oxidizing bacteria (AOB), in samples from a time-series experiment monitoring a set of laboratory-scale reactors and a full-scale plant. For the qPCR analysis, we tested two different sets of AOB-specific primers, one targeting the 16SrRNA gene and one targeting the ammonia monooxygenase (amoA) gene. We found that there was a positive linear logarithmic relationship between FISH and the amoA gene-specific qPCR, where the data obtained from both techniques was equivalent at the order of magnitude level. The 16S rRNA gene-specific qPCR assay consistently underestimated AOB numbers.
Assuntos
Bactérias/isolamento & purificação , Hibridização in Situ Fluorescente/métodos , Oxirredutases/genética , Reação em Cadeia da Polimerase/métodos , Esgotos/microbiologia , Amônia/metabolismo , Bactérias/enzimologia , Bactérias/genética , Betaproteobacteria/enzimologia , Betaproteobacteria/genética , Betaproteobacteria/isolamento & purificação , DNA Bacteriano/química , DNA Bacteriano/isolamento & purificação , Modelos Lineares , Oxirredução , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Especificidade da Espécie , Eliminação de Resíduos LíquidosAssuntos
Transtornos da Coagulação Sanguínea/etiologia , Transtornos da Coagulação Sanguínea/terapia , Fator VIII/uso terapêutico , Fibrinogênio/uso terapêutico , Hemorragia/etiologia , Hemorragia/terapia , Ferimentos e Lesões/terapia , Pesquisa Biomédica , Ensaios Clínicos como Assunto , Humanos , Reino Unido , Ferimentos e Lesões/complicações , Ferimentos e Lesões/mortalidadeRESUMO
OBJECTIVE: This meta-analytic review aimed to synthesise evidence on personality and cognitive factors related to depression and anxiety in endometriosis and determine whether sociodemographic and clinical variables moderate factor-symptom relations. Additionally, this review aimed to evaluate the quality of research and formulate recommendations for future research. METHODS: A systematic search was conducted across databases (Medline, Embase, PsycInfo, Web of Science, ProQuest) through to February 2024. Search terms were used for endometriosis, depression, anxiety, cognitive factors and personality traits. Random-effects meta-analyses were conducted to produce pooled weighted effects (r) for factor-symptom relationships. RESULTS: Thirteen studies (11 samples; N = 3287; Mage 33.89 ± 2.48) were included in a narrative synthesis. One study provided evidence for a positive association between neuroticism and depression. Seven studies contributed to meta-analyses on three cognitive factors. Medium-to-large associations were identified between illness perceptions of low control/power (r = 0.35, 95 % CI: 0.01,0.62), rumination (r = 0.52, 95 % CI: 0.09, 0.78), pain-catastrophising (r = 0.37, 95 % CI: 0.28, 0.45) and higher levels of depression. The statistical power to detect significant effects was >80 %. Findings for anxiety were non-significant, although limited data were available. Quality appraisal revealed a high risk of within-study bias (4.69 ± 1.38, range: 3-7), with issues related to sample representativeness and measurement selection. CONCLUSION: Rumination, pain-catastrophising, and illness perceptions of low control/power are important in understanding depression in endometriosis. There is a lack of research on personality traits, necessitating further study. Findings highlight the importance of prioritising modifiable cognitive factors in psychological research and clinical practice in endometriosis.
RESUMO
There is a concerted effort by a number of public and private groups to identify a large set of human single-nucleotide polymorphisms (SNPs). As of March 2001, 2.84 million SNPs have been deposited in the public database, dbSNP, at the National Center for Biotechnology Information (http://www.ncbi.nlm.nih.gov/SNP/). The 2.84 million SNPs can be grouped into 1.65 million non-redundant SNPs. As part of the International SNP Map Working Group, we recently published a high-density SNP map of the human genome consisting of 1.42 million SNPs (ref. 3). In addition, numerous SNPs are maintained in proprietary databases. Our survey of more than 1,200 SNPs indicates that more than 80% of TSC and Washington University candidate SNPs are polymorphic and that approximately 50% of the candidate SNPs from these two sources are common SNPs (with minor allele frequency of > or =20%) in any given population.
Assuntos
Polimorfismo de Nucleotídeo Único , DNA/genética , Humanos , Reação em Cadeia da PolimeraseRESUMO
BACKGROUND: Secondary cardiac injury has been demonstrated in critical illness and is associated with worse outcomes. The aim of this study was to establish the existence of trauma-induced secondary cardiac injury, and investigate its impact on outcomes in injured patients. METHODS: Injured adult patients eligible for enrolment in the Activation of Coagulation and Inflammation in Trauma 2 study, and admitted to the intensive care unit between January 2008 and January 2010, were selected retrospectively for the study. Markers of cardiac injury (brain natriuretic peptide (BNP), heart-type fatty acid binding protein (H-FABP) and troponin I) were measured on admission, and after 24 and 72 h in blood samples from injured patients. Individual records were reviewed for adverse cardiac events and death. RESULTS: During the study period, 135 patients were enrolled (106 male, 78·5 per cent) with a median age of 40 (range 16-89) years. Eighteen patients (13·3 per cent) had an adverse cardiac event during admission and these events were not associated with direct thoracic injury. The in-hospital mortality rate was higher among the adverse cardiac event cohort: 44 per cent (8 of 18) versus 17·1 per cent (20 of 117) (P = 0·008). Raised levels of H-FABP and BNP at 0, 24 and 72 h, and troponin I at 24 and 72 h, were associated with increased adverse cardiac events. BNP levels were higher in non-survivors on admission (median 550 versus 403 fmol/ml; P = 0·022), after 24 h (794 versus 567 fmol/ml; P = 0·033) and after 72 h (1043 versus 753 fmol/ml; P = 0·036), as were admission troponin I levels. CONCLUSION: Clinical and cardiac biomarker characteristics support the existence of trauma-induced secondary cardiac injury, which is associated with death, and unrelated to direct thoracic injury.
Assuntos
Proteínas de Ligação a Ácido Graxo/metabolismo , Cardiopatias/etiologia , Peptídeo Natriurético Encefálico/sangue , Fragmentos de Peptídeos/sangue , Troponina I/sangue , Ferimentos e Lesões/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Proteína 3 Ligante de Ácido Graxo , Feminino , Cardiopatias/sangue , Mortalidade Hospitalar , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Adulto JovemRESUMO
Interpersonal violence involving knives is a major public health problem. The majority of patients are young people in urban areas, but little is known about age-specific patterns of injury and recent trends in injury characteristics. We performed a retrospective cohort study of all patients presenting to an urban major trauma centre with stab injuries resulting from assault between 2012 and 2018. A total of 3583 patients were included. Young people (age under 25) were more likely to have sustained multiple stab wounds compared to older people (43% vs 35%, p < 0.001) and had significantly higher rates of stab injuries involving the lower limbs, groin and buttocks. The annual number of injuries increased steadily during the study period in patients aged under 25 (r2 = 0.82, p = 0.005) and those over 25 (r2 = 0.95, p < 0.001). Over time, limb and junctional injuries accounted for an increasing proportion of stab wounds in young people, overtaking torso injuries as most common pattern of injury by the end of the study period. These findings illustrate the influence of age on injury patterns resulting from knife violence, and support the expansion of outreach initiatives promoting bystander-delivered haemorrhage control of extremity wounds.
Assuntos
Ferimentos Perfurantes , Adolescente , Idoso , Humanos , Estudos Retrospectivos , Centros de Traumatologia , População Urbana , Violência , Ferimentos Perfurantes/epidemiologiaRESUMO
PURPOSE: Contemporary trauma resuscitation prioritizes control of bleeding and uses major haemorrhage protocols (MHPs) to prevent and treat coagulopathy. We aimed to determine whether augmenting MHPs with Viscoelastic Haemostatic Assays (VHA) would improve outcomes compared to Conventional Coagulation Tests (CCTs). METHODS: This was a multi-centre, randomized controlled trial comparing outcomes in trauma patients who received empiric MHPs, augmented by either VHA or CCT-guided interventions. Primary outcome was the proportion of subjects who, at 24 h after injury, were alive and free of massive transfusion (10 or more red cell transfusions). Secondary outcomes included 28-day mortality. Pre-specified subgroups included patients with severe traumatic brain injury (TBI). RESULTS: Of 396 patients in the intention to treat analysis, 201 were allocated to VHA and 195 to CCT-guided therapy. At 24 h, there was no difference in the proportion of patients who were alive and free of massive transfusion (VHA: 67%, CCT: 64%, OR 1.15, 95% CI 0.76-1.73). 28-day mortality was not different overall (VHA: 25%, CCT: 28%, OR 0.84, 95% CI 0.54-1.31), nor were there differences in other secondary outcomes or serious adverse events. In pre-specified subgroups, there were no differences in primary outcomes. In the pre-specified subgroup of 74 patients with TBI, 64% were alive and free of massive transfusion at 24 h compared to 46% in the CCT arm (OR 2.12, 95% CI 0.84-5.34). CONCLUSION: There was no difference in overall outcomes between VHA- and CCT-augmented-major haemorrhage protocols.
Assuntos
Transtornos da Coagulação Sanguínea , Hemostáticos , Ferimentos e Lesões , Hemorragia/etiologia , Hemorragia/terapia , Hemostasia , Humanos , Estudos Multicêntricos como Assunto , Tromboelastografia , Ferimentos e Lesões/complicações , Ferimentos e Lesões/terapiaRESUMO
BACKGROUND: High estimates of preventable death rates have renewed the impetus for national regionalization of trauma care. Institution of a specialist multidisciplinary trauma service and performance improvement programme was hypothesized to have resulted in improved outcomes for severely injured patients. METHODS: This was a comparative analysis of data from the Royal London Hospital (RLH) trauma registry and Trauma Audit and Research Network (England and Wales), 2000-2005. Preventable mortality was evaluated by prospective analysis of the RLH performance improvement programme. RESULTS: Mortality from critical injury at the RLH was 48 per cent lower in 2005 than 2000 (17.9 versus 34.2 per cent; P = 0.001). Overall mortality rates were unchanged for acute hospitals (4.3 versus 4.4 per cent) and other multispecialty hospitals (8.7 versus 7.3 per cent). Secondary transfer mortality in critically injured patients was 53 per cent lower in the regional network than the national average (5.2 versus 11.0 per cent; P = 0.001). Preventable death rates fell from 9 to 2 per cent (P = 0.040) and significant gains were made in critical care and ward bed utilization. CONCLUSION: Institution of a specialist trauma service and performance improvement programme was associated with significant improvements in outcomes that exceeded national variations.
Assuntos
Centros de Traumatologia/organização & administração , Ferimentos e Lesões/mortalidade , Adulto , Idoso , Atenção à Saúde , Inglaterra/epidemiologia , Feminino , Humanos , Tempo de Internação/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , Admissão do Paciente/estatística & dados numéricos , País de Gales/epidemiologia , Ferimentos e Lesões/terapiaRESUMO
A pilot-scale primary maturation pond was spiked with (15)N-labelled ammonia ((15)NH(4)Cl) and (15)N-labelled nitrite (Na(15)NO(2)), in order to improve current understanding of the dynamics of inorganic nitrogen transformations and removal in WSP systems. Stable isotope analysis of delta(15)N showed that nitrification could be considered as an intermediate step in WSP, which is masked by simultaneous denitrification, under conditions of low algal activity. Molecular microbiology analysis showed that denitrification can be considered a feasible mechanism for permanent nitrogen removal in WSP, which may be supported either by ammonia-oxidising bacteria (AOB) or by methanotrophs, in addition to nitrite-oxidising bacteria (NOB). However, the relative supremacy of the denitrification process over other nitrogen removal mechanisms (e.g., biological uptake) depends upon phytoplanktonic activity.
Assuntos
Nitrogênio/metabolismo , Fitoplâncton/metabolismo , Esgotos/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Amônia/química , Bactérias/metabolismo , Biomassa , Eucariotos/metabolismo , Nitritos/química , Nitrogênio/química , Isótopos de Nitrogênio/química , Estações do Ano , Temperatura , Microbiologia da ÁguaRESUMO
Orang-utans and chimpanzees can discriminate between two objects on the basis of tactile cues and select the one that matches a visually presented sample.
Assuntos
Aprendizagem por Discriminação , Hominidae , Tato , Animais , Sinais (Psicologia)RESUMO
Using an optical-trap/flow-control video microscopy technique, we followed transcription by single molecules of Escherichia coli RNA polymerase in real time over long template distances. These studies reveal that RNA polymerase molecules possess different intrinsic transcription rates and different propensities to pause and stop. The data also show that reversible pausing is a kinetic intermediate between normal elongation and the arrested state. The conformational metastability of RNA polymerase revealed by this single-molecule study of transcription has direct implications for the mechanisms of gene regulation in both bacteria and eukaryotes.
Assuntos
DNA Bacteriano/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Escherichia coli/genética , RNA Mensageiro/genética , Transcrição Gênica , DNA Bacteriano/genética , Escherichia coli/enzimologia , Cinética , Microscopia de Vídeo , Modelos Genéticos , Óptica e Fotônica , RNA Bacteriano/genética , Moldes GenéticosRESUMO
Chemokines are a set of structurally related peptides that were first characterized as chemoattractants and have subsequently been shown to have many functions in homeostasis and pathophysiology. Diversity and redundancy of chemokine function is imparted by both selectivity and overlap in the specificity of chemokine receptors for their ligands. Chemokines have roles impacting transfusion medicine in haematopoiesis, haematologic malignancies, transfusion reactions, graft-versus-host disease, and viral infections. In haematopoietic cell transplantation, chemokines are active in mobilization and homing of progenitor cells, as well as mediating T-cell recruitment in graft-versus-host disease. Platelets are rich source of chemokines that recruit and activate leucocytes during thrombosis. Important transfusion-transmissible viruses such as cytomegalovirus and human immunodeficiency virus exploit chemokine receptors to evade host immunity. Chemokines may also have roles in the pathophysiology of haemolytic and non-haemolytic transfusion reactions.
Assuntos
Transfusão de Sangue , Quimiocinas/sangue , Animais , Plaquetas/metabolismo , Citomegalovirus/metabolismo , Doença Enxerto-Hospedeiro/sangue , HIV/metabolismo , Neoplasias Hematológicas/sangue , Neoplasias Hematológicas/terapia , Hematopoese , Transplante de Células-Tronco Hematopoéticas , Hemólise , Homeostase , Humanos , Leucócitos/metabolismo , Receptores de Quimiocinas/metabolismo , Trombose/metabolismoAssuntos
Transtornos Cognitivos/etiologia , Doenças do Sistema Nervoso Periférico/complicações , Idoso , Córtex Cerebral/fisiopatologia , Progressão da Doença , Humanos , Imageamento por Ressonância Magnética , Masculino , Militares , Doenças do Sistema Nervoso Periférico/patologia , Tomografia Computadorizada por Raios XRESUMO
The removal of ß-estradiol (E2) and α-ethinylestradiol (EE2) in biological wastewater treatment plants (WWTP) would need to be improved in order to comply with prospective Environmental Quality Standards (EQS) of 0.4 and 0.035â¯ng.L-1 respectively. The effluent concentration of a micropollutant in an activated sludge process is a function of the removal rate, the hydraulic retention time (HRT) and the flow pattern, which is usually overlooked. In order to better understand this aspect, we carried out tracer studies in eight WWTPs in the UK and found that relatively modest changes in aeration tanks would translate into tangible improvements in their flow pattern. We further evaluated the degradation rates for E1 (estrone), E2, E3 (estriol) and EE2 in each WWTP and we estimated that the modification of the flow pattern would be sufficient to place effluent concentrations of E2 (23.2â¯LâgVSS-1âd-1Assuntos
Esgotos
, Poluentes Químicos da Água
, Estradiol
, Estrogênios
, Estrona
, Estudos Prospectivos
, Eliminação de Resíduos Líquidos
RESUMO
Viruses are thought to control bacterial abundance, affect community composition and influence ecosystem function in natural environments. Yet their dynamics have seldom been studied in engineered systems, or indeed in any system, for long periods of time. We measured virus abundance in a full-scale activated sludge plant every week for two years. Total bacteria and ammonia oxidising bacteria (AOB) abundances, bacterial community profiles, and a suite of environmental and operational parameters were also monitored. Mixed liquor virus abundance fluctuated over an order of magnitude (3.18â¯×â¯108-3.41â¯×â¯109 virus's mL-1) and that variation was statistically significantly associated with total bacterial and AOB abundance, community composition, and effluent concentrations of COD and NH4+- N and thus system function. This suggests viruses play a far more important role in the dynamics of activated sludge systems than previously realised and could be one of the key factors controlling bacterial abundance, community structure and functional stability and may cause reactors to fail. These findings are based on statistical associations, not mechanistic models. Nevertheless, viral associations with abiotic factors, such as pH, make physical sense, giving credence to these findings and highlighting the role that physical factors play in virus ecology. Further work is needed to identify and quantify specific bacteriophage and their hosts to enable us to develop mechanistic models of the ecology of viruses in wastewater treatment systems. However, since we have shown that viruses can be related to effluent quality and virus quantification is simple and cheap, practitioners would probably benefit from quantifying viruses now.
Assuntos
Ecossistema , Vírus , Amônia , Bactérias , Esgotos , Águas ResiduáriasRESUMO
Absolute bacterial quantification receives little serious attention in the literature compared to sequencing, conceivably because it is considered unimportant and facile, or because existing methods are tedious, laborious and/or biased in nature. This is particularly true in engineered systems, including activated sludge, where such information underpins their design and operation. To overcome these limitations we built upon existing work and optimised and comprehensively validated, through comparison with epifluorescence microscopy (EFM), a rapid and precise flow cytometric protocol to enumerate total bacterial numbers in activated sludge. Insights into potential biases were evaluated using appropriate statistical analyses on this comparison, which spanned four orders of magnitude, as well as comparing volatile suspended solid (VSS) concentrations. The results suggest flow cytometry (FCM) is a rapid, reproducible and economical technique for quantifying total bacterial numbers and biomass concentrations in activated sludge, despite within order of magnitude discrepancies with EFM counts, which had inherent and evidently greater errors and biases than FCM. The use of FCM for routine monitoring over both EFM and VSS should help further understanding of the microbial ecology in, and the operation of, engineered systems.