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Brazilian Journal of Microbiology :... Jun 2015The occurrence of psychrotrophic bacteria in raw milk is studied worldwide due to the difficulties associated with controlling their growth during cold storage and the... (Review)
Review
The occurrence of psychrotrophic bacteria in raw milk is studied worldwide due to the difficulties associated with controlling their growth during cold storage and the consequent negative effects upon fluid milk or dairy products. Among the psychrotrophic bacteria, the genus Pseudomonas (represented primarily by P. fluorescens) has been highlighted as the cause of numerous defects in dairy products. In light of its perceived predominance, this species has frequently been chosen as a model organism to assess the effects of psychrotrophic bacteria on milk or to evaluate the efficacy of control measures. However, recent findings derived from the application of molecular biological techniques have exposed a number of deficiencies in our knowledge of the biology of milk-associated psychrotrophs. Furthermore, it has been revealed that microbe to microbe communication plays a significant role in determining both the identities and the extent to which different groups of microbes develop during cold storage. The application of molecular identification methods has exposed errors in the classification of members of the genus Pseudomonas isolated from cold stored milk and has stimulated a reevaluation of the presumed status of P. fluorescens as the predominant milk-associated psychrotrophic species. This article presents a succinct review of data from studies on psychrotrophic bacteria in milk, some of which contest established theories in relation to the microbiology of cold stored raw milk, and poses the question: how much do we really know?
Topics: Animals; Bacteria; Biodiversity; Cold Temperature; Milk
PubMed: 26273245
DOI: 10.1590/S1517-838246220130963 -
Gut Microbes 2021Cardiovascular diseases (CVDs) still remain the leading concern of global health, accounting for approximately 17.9 million deaths in 2016. The pathogenetic mechanisms... (Review)
Review
Cardiovascular diseases (CVDs) still remain the leading concern of global health, accounting for approximately 17.9 million deaths in 2016. The pathogenetic mechanisms of CVDs are multifactorial and incompletely understood. Recent evidence has shown that alterations in the gut microbiome and its associated metabolites may influence the pathogenesis and progression of CVDs such as atherosclerosis, heart failure, hypertension, and arrhythmia, yet the underlying links are not fully elucidated. Owing to the progress in next-generation sequencing techniques and computational strategies, researchers now are available to explore the emerging links to the genomes, transcriptomes, proteomes, and metabolomes in parallel meta-omics approaches, presenting a panoramic vista of culture-independent microbial investigation. This review aims to outline the characteristics of meta-omics pipelines and provide a brief overview of current applications in CVDs studies which can be practical for addressing crucial knowledge gaps in this field, as well as to shed its light on cardiovascular risk biomarkers and therapeutic intervention in the near future.
Topics: Animals; Bacteria; Cardiovascular Diseases; Diet; Gastrointestinal Microbiome; Genomics; Humans; Metabolomics; Proteomics
PubMed: 34170211
DOI: 10.1080/19490976.2021.1936379 -
Microbiology Spectrum Dec 2021In the beer brewing industry, microbial spoilage presents a consistent threat that must be monitored and controlled to ensure the palatability of a finished product....
In the beer brewing industry, microbial spoilage presents a consistent threat that must be monitored and controlled to ensure the palatability of a finished product. Many of the predominant beer spoilage microbes have been identified and characterized, but the mechanisms of contamination and persistence remain an open area of study. Postproduction, many beers are distributed as kegs that are attached to draft delivery systems in retail settings where ample opportunities for microbial spoilage are present. As such, restaurants and bars can experience substantial costs and downtime for cleaning when beer draft lines become heavily contaminated. Spoilage monitoring on the retail side of the beer industry is often overlooked, yet this arena may represent one of the largest threats to the profitability of a beer if its flavor profile becomes substantially distorted by contaminating microbes. In this study, we sampled and cultured microbial communities found in beers dispensed from a retail draft system to identify the contaminating bacteria and yeasts. We also evaluated their capability to establish new biofilms in a controlled setting. Among four tested beer types, we identified over a hundred different contaminant bacteria and nearly 20 wild yeasts. The culturing experiments demonstrated that most of these microbes were viable and capable of joining new biofilm communities. These data provide an important reference for monitoring specific beer spoilage microbes in draft systems and we provide suggestions for cleaning protocol improvements. Beer production, packaging, and service are each vulnerable to contamination by microbes that metabolize beer chemicals and impart undesirable flavors, which can result in the disposal of entire batches. Therefore, great effort is taken by brewmasters to reduce and monitor contamination during production and packaging. A commonly overlooked quality control stage of a beer supply chain is at the retail service end, where beer kegs supply draft lines in bars and restaurants under nonsterile conditions. We found that retail draft line contamination is rampant and that routine line cleaning methods are insufficient to efficiently suppress beer spoilage. Thus, many customers unknowingly consume spoiled versions of the beers they consume. This study identified the bacteria and yeast that were resident in retail draft beer samples and also investigated their abilities to colonize tubing material as members of biofilm communities.
Topics: Bacteria; Bacterial Physiological Phenomena; Beer; Biofilms; Food Contamination; Food Microbiology; Microbiota; Yeasts
PubMed: 34935420
DOI: 10.1128/Spectrum.01404-21 -
Frontiers in Cellular and Infection... 2020Chronic infections present a serious economic burden to health-care systems. The severity and prevalence of chronic infections are continuously increasing due to an... (Review)
Review
Chronic infections present a serious economic burden to health-care systems. The severity and prevalence of chronic infections are continuously increasing due to an aging population and an elevated number of lifestyle related diseases such as diabetes. Treatment of chronic infections has proven difficult, mainly due to the presence of biofilms that render bacteria more tolerant toward antimicrobials and the host immune response. Chronic infections have been described to harbor several different bacterial species and it has been hypothesized that microscale interactions and mixed-species consortia are present as described for most natural occurring biofilms i.e., aquatic systems and industrial settings, but also for some commensal human biofilms i.e., the mouth microbiota. However, the presence of mixed-species biofilms in chronic infections is most often an assumption based on culture-based methods and/or by means of molecular approaches, such as PCR and sequencing performed from homogenized bulk tissue samples. These methods disregard the spatial organization of the bacterial community and thus valuable information on biofilm aggregate composition, spatial organization, and possible interactions between different species is lost. Hitherto, only few studies have made visual presentations of mixed-species biofilms in chronic infections, which is pivotal for the description of bacterial composition, spatial distribution, and interspecies interaction on the microscale. In order for bacteria to interact (synergism, commensalism, mutualism, competition, etc.) they need to be in close proximity to each other on the scale where they can affect e.g., solute concentrations. We argue that visual proof of mixed species biofilms in chronic infections is scarce compared to what is seen in e.g., environmental biofilms and call for a debate on the importance of mixed-species biofilm in chronic infections.
Topics: Aged; Anti-Infective Agents; Bacteria; Biofilms; Humans
PubMed: 32850494
DOI: 10.3389/fcimb.2020.00396 -
Frontiers in Immunology 2022Similar to other pathogens, bacteria have developed during their evolution a variety of mechanisms to overcome both innate and acquired immunity, accounting for their... (Review)
Review
Similar to other pathogens, bacteria have developed during their evolution a variety of mechanisms to overcome both innate and acquired immunity, accounting for their ability to cause disease or chronic infections. The mechanisms exploited for this critical function act by targeting conserved structures or pathways that regulate the host immune response. A strategic potential target is the immunological synapse (IS), a highly specialized structure that forms at the interface between antigen presenting cells (APC) and T lymphocytes and is required for the establishment of an effective T cell response to the infectious agent and for the development of long-lasting T cell memory. While a variety of bacterial pathogens are known to impair or subvert cellular processes essential for antigen processing and presentation, on which IS assembly depends, it is only recently that the possibility that IS may be a direct target of bacterial virulence factors has been considered. Emerging evidence strongly supports this notion, highlighting IS targeting as a powerful, novel means of immune evasion by bacterial pathogens. In this review we will present a brief overview of the mechanisms used by bacteria to affect IS assembly by targeting APCs. We will then summarize what has emerged from the current handful of studies that have addressed the direct impact of bacterial virulence factors on IS assembly in T cells and, based on the strategic cellular processes targeted by these factors in other cell types, highlight potential IS-related vulnerabilities that could be exploited by these pathogens to evade T cell mediated immunity.
Topics: Antigen Presentation; Bacteria; Immune Evasion; Immunological Synapses; Receptors, Antigen, T-Cell; Virulence Factors
PubMed: 35911720
DOI: 10.3389/fimmu.2022.943344 -
FEMS Microbiology Reviews Dec 2000Flooded rice paddies are one of the major biogenic sources of atmospheric methane. Apart from this contribution to the 'greenhouse' effect, rice paddy soil represents a... (Review)
Review
Flooded rice paddies are one of the major biogenic sources of atmospheric methane. Apart from this contribution to the 'greenhouse' effect, rice paddy soil represents a suitable model system to study fundamental aspects of microbial ecology, such as diversity, structure, and dynamics of microbial communities as well as structure-function relationships between microbial groups. Flooded rice paddy soil can be considered as a system with three compartments (oxic surface soil, anoxic bulk soil, and rhizosphere) characterized by different physio-chemical conditions. After flooding, oxygen is rapidly depleted in the bulk soil. Anaerobic microorganisms, such as fermentative bacteria and methanogenic archaea, predominate within the microbial community, and thus methane is the final product of anaerobic degradation of organic matter. In the surface soil and the rhizosphere well-defined microscale chemical gradients can be measured. The oxygen profile seems to govern gradients of other electron acceptors (e.g., nitrate, iron(III), and sulfate) and reduced compounds (e.g., ammonium, iron(II), and sulfide). These gradients provide information about the activity and spatial distribution of functional groups of microorganisms. This review presents the current knowledge about the highly complex microbiology of flooded rice paddies. In Section 2 we describe the predominant microbial groups and their function with particular regard to bacterial populations utilizing polysaccharides and simple sugars, and to the methanogenic archaea. Section 3 describes the spatial and temporal development of microscale chemical gradients measured in experimentally defined model systems, including gradients of oxygen and dissolved and solid-phase iron(III) and iron(II). In Section 4, the results of measurements of microscale gradients of oxygen, pH, nitrate-nitrite, and methane in natural rice fields and natural rice soil cores taken to the laboratory will be presented. Finally, perspectives of future research are discussed (Section 5).
Topics: Archaea; Bacteria; Ecosystem; Oryza; Oxidation-Reduction; Soil Microbiology
PubMed: 11077155
DOI: 10.1111/j.1574-6976.2000.tb00563.x -
Romanian Journal of Morphology and... 2017Lower respiratory tract infections (LRTIs) is an umbrella term that covers a wide spectrum of diseases, comprising mild and severe, acute and chronic conditions. A wide... (Review)
Review
UNLABELLED
Lower respiratory tract infections (LRTIs) is an umbrella term that covers a wide spectrum of diseases, comprising mild and severe, acute and chronic conditions. A wide spectrum of pathogens can be implicated, from viruses to pyogenic and atypical bacteria. A special place should be reserved for slow growing bacteria (Mycobacteria spp., Nocardia spp.) and parasites (i.e., hydatic cysts caused by Echinococcus granulosus).
OBJECTIVE
The objective of this study is to observe, analyze and establish the drug susceptibility patterns for Enterococcus spp., Staphylococcus aureus, Klebsiella spp., Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter spp. (the ESKAPE pathogens) in the "Marius Nasta" Institute for Pulmonary Medicine (MNIPM), Bucharest, Romania.
MATERIALS AND METHODS
A retrospective healthcare record based study was undertaken to establish the drug susceptibility patterns. We assessed all antibiograms of the ESKAPE pathogens isolated from respiratory samples from adult inpatients hospitalized between 2010-2015 at the MNIPM.
RESULTS
We analyzed 2859 isolates (61% of the 4683 ESKAPE isolates). P. aeruginosa was the most frequent pathogen, while Enterococcus spp. and Enterobacter spp. were practically non-present. The antibiotic profile of P. aeruginosa isolates presented more resistance in the Intensive Care Unit (ICU)÷Surgery wards, probably resulting from antibiotic pressure. The other non-fermenter, A. baumannii, while less frequent (and the only pathogen more frequent in the surgery department) had an even more resistant profile, to almost all antibiotics, with the exception of Colistin. Methicillin-resistant S. aureus (MRSA) accounted for about 60% of all isolates, more in the ICU÷Surgery ward. K. pneumoniae presents a less resistance and shows more stability when analyzing the antibiogram pattern in the Medical wards.
DISCUSSION
For methodological or procedural reasons, Enterococcus spp. and Enterobacter spp. were underrepresented in the study. Interventional programs comprising antibiotic stewardship and active surveillance need to be implemented to alleviate the antibiotic profile. Further research needs to focus on more detailed characterization of the molecular mechanisms leading to the high resistance detailed herein.
CONCLUSIONS
This study adds to the body of literature reporting the antibiotic resistance landscape in Romania, for these highly resistant pathogens.
Topics: Acinetobacter baumannii; Enterobacter; Enterococcus; History, 21st Century; Humans; Klebsiella; Pseudomonas aeruginosa; Respiratory Center; Retrospective Studies; Romania; Staphylococcus aureus; Tertiary Care Centers
PubMed: 29250670
DOI: No ID Found -
Journal of Bacteriology Oct 2016The 7th ASM Conference on Biofilms was held in Chicago, Illinois, from 24 to 29 October 2015. The conference provided an international forum for biofilm researchers... (Review)
Review
The 7th ASM Conference on Biofilms was held in Chicago, Illinois, from 24 to 29 October 2015. The conference provided an international forum for biofilm researchers across academic and industry platforms, and from different scientific disciplines, to present and discuss new findings and ideas. The meeting covered a wide range of topics, spanning environmental sciences, applied biology, evolution, ecology, physiology, and molecular biology of the biofilm lifestyle. This report summarizes the presentations with regard to emerging biofilm-related themes.
Topics: Bacteria; Bacterial Physiological Phenomena; Biofilms; Chicago; Congresses as Topic
PubMed: 26977109
DOI: 10.1128/JB.00156-16 -
MBio Dec 2022Chemists have studied marine animals for the better part of a century because they contain a diverse array of bioactive compounds. Tens of thousands of compounds have...
Chemists have studied marine animals for the better part of a century because they contain a diverse array of bioactive compounds. Tens of thousands of compounds have been reported, many with elaborate structural motifs and biological mechanisms of action found nowhere else. The challenge holding back the field has long been that of supply. Compounds are sometimes obtained by cultivating marine animals or by wild harvest, but this often presents logistical and environmental challenges. Some of the most medically important marine animal compounds are supplied by synthesis, often through multistep procedures that delay drug development. A relatively small number of such agents have been approved by the U.S. Food and Drug Administration, often after a heroic effort. In a recent paper, Uppal and coworkers (https://doi.org/10.1128/mBio.01524-22) address key hurdles underlying the supply issue, discovering an uncultivated new bacterial genus from a marine sponge and reconstituting the biosynthetic pathway for expression.
Topics: Animals; Porifera; Bacteria; Drug Development; Drug Discovery; Biological Products
PubMed: 36314838
DOI: 10.1128/mbio.02499-22 -
Microbiology Spectrum Aug 2015Sialic acids, or the more broad term nonulosonic acids, comprise a family of nine-carbon keto-sugars ubiquitous on mammalian mucous membranes as terminal modifications... (Review)
Review
Sialic acids, or the more broad term nonulosonic acids, comprise a family of nine-carbon keto-sugars ubiquitous on mammalian mucous membranes as terminal modifications of mucin glycoproteins. Sialic acids have a limited distribution among bacteria, and the ability to catabolize sialic acids is mainly confined to pathogenic and commensal species. This ability to utilize sialic acid as a carbon source is correlated with bacterial virulence, especially, in the sialic acid rich environment of the oral cavity, respiratory, intestinal, and urogenital tracts. This chapter discusses the distribution of sialic acid catabolizers among the sequenced bacterial genomes and examines the studies that have linked sialic acid catabolism with increased in vivo fitness in a number of species using several animal models. This chapter presents the most recent findings in sialobiology with a focus on sialic acid catabolism, which demonstrates an important relationship between the catabolism of sialic acid and bacterial pathogenesis.
Topics: Animals; Bacteria; Bacterial Infections; Host-Pathogen Interactions; Humans; Sialic Acids; Virulence
PubMed: 26350327
DOI: 10.1128/microbiolspec.MBP-0005-2014