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Microbiology Spectrum

Archana Shrestha, Francisco A Uzal, Bruce A McClane
In humans and livestock, Clostridium perfringens is an important cause of intestinal infections that manifest as enteritis, enterocolitis, or enterotoxemia. This virulence is largely related to the toxin-producing ability of C. perfringens . This article primarily focuses on the C. perfringens type F strains that cause a very common type of human food poisoning and many cases of nonfoodborne human gastrointestinal diseases. The enteric virulence of type F strains is dependent on their ability to produce C. perfringens enterotoxin (CPE)...
September 2018: Microbiology Spectrum
Blanca M Perez-Sepulveda, Jay C D Hinton
Developments in transcriptomic technology and the availability of whole-genome-level expression profiles for many bacterial model organisms have accelerated the assignment of gene function. However, the deluge of transcriptomic data is making the analysis of gene expression a challenging task for biologists. Online resources for global bacterial gene expression analysis are not available for the majority of published data sets, impeding access and hindering data exploration. Here, we show the value of preexisting transcriptomic data sets for hypothesis generation...
September 2018: Microbiology Spectrum
Medha Raina, Alisa King, Colleen Bianco, Carin K Vanderpool
Bacteria are known to use RNA, either as mRNAs encoding proteins or as noncoding small RNAs (sRNAs), to regulate numerous biological processes. However, a few sRNAs have two functions: they act as base-pairing RNAs and encode a small protein with additional regulatory functions. Thus, these so called "dual-function" sRNAs can serve as both a riboregulator and an mRNA. In some cases, these two functions can act independently within the same pathway, while in other cases, the base-pairing function and protein function act in different pathways...
September 2018: Microbiology Spectrum
Fernando Baquero
Transmission is a basic process in biology that can be analyzed in accordance with information theory. A sender or transmitter located in a particular patch of space is the source of the transmitted object, the message. A receiver patch interacts to receive the message. The "messages" that are transmitted between patches (eventually located in different hierarchical biological levels) are "meaningful" biological entities (biosemiotics). cis -acting transmission occurs when unenclosed patches acting as emitter and receiver entities of the same hierarchical level are linked (frequently by a vehicle) across an unfit space; trans -acting transmission occurs between biological individuals of different hierarchical levels, embedded within a close external common limit...
September 2018: Microbiology Spectrum
Johann D D Pitout
Surveillance of antibiotic resistance involves the collection of antibiotic susceptibility patterns undertaken by clinical microbiology laboratories on bacteria isolated from clinical specimens. Global surveillance programs have shown that antibiotic resistance is a major threat to the public at large and play a crucial role in the development of enhanced diagnostics as well as potential vaccines and novel antibiotics with activity against antimicrobial-resistant organisms. This review focuses primarily on examples of global surveillance systems...
September 2018: Microbiology Spectrum
Jingyi Fei, Cynthia M Sharma
Diverse mechanisms and functions of posttranscriptional regulation by small regulatory RNAs and RNA-binding proteins have been described in bacteria. In contrast, little is known about the spatial organization of RNAs in bacterial cells. In eukaryotes, subcellular localization and transport of RNAs play important roles in diverse physiological processes, such as embryonic patterning, asymmetric cell division, epithelial polarity, and neuronal plasticity. It is now clear that bacterial RNAs also can accumulate at distinct sites in the cell...
September 2018: Microbiology Spectrum
Jonathan R Goodson, Wade C Winkler
Transcription is a discontinuous process, where each nucleotide incorporation cycle offers a decision between elongation, pausing, halting, or termination. Many cis -acting regulatory RNAs, such as riboswitches, exert their influence over transcription elongation. Through such mechanisms, certain RNA elements can couple physiological or environmental signals to transcription attenuation, a process where cis -acting regulatory RNAs directly influence formation of transcription termination signals. However, through another regulatory mechanism called processive antitermination (PA), RNA polymerase can bypass termination sites over much greater distances than transcription attenuation...
September 2018: Microbiology Spectrum
Debra E Bessen, Pierre R Smeesters, Bernard W Beall
The clinico-epidemiological features of diseases caused by group A streptococci (GAS) is presented through the lens of the ecology, population genetics, and evolution of the organism. The serological targets of three typing schemes (M, T, SOF) are themselves GAS cell surface proteins that have a myriad of virulence functions and a diverse array of structural forms. Horizontal gene transfer expands the GAS antigenic cell surface repertoire by generating numerous combinations of M, T, and SOF antigens. However, horizontal gene transfer of the serotype determinant genes is not unconstrained, and therein lies a genetic organization that may signify adaptations to a narrow ecological niche, such as the primary tissue reservoirs of the human host...
September 2018: Microbiology Spectrum
Michael Otto
Staphylococci, with the leading species Staphylococcus aureus and Staphylococcus epidermidis , are the most frequent causes of infections on indwelling medical devices. The biofilm phenotype that those bacteria adopt during device-associated infection facilitates increased resistance to antibiotics and host immune defenses. This review presents and discusses the molecular mechanisms contributing to staphylococcal biofilm development and their in-vivo importance. Furthermore, it summarizes current strategies for the development of therapeutics against staphylococcal biofilm-associated infection...
August 2018: Microbiology Spectrum
Thea S Lotz, Beatrix Suess
RNA is a versatile biomolecule capable of transferring information, taking on distinct three-dimensional shapes, and reacting to ambient conditions. RNA molecules utilize a wide range of mechanisms to control gene expression. An example of such regulation is riboswitches. Consisting exclusively of RNA, they are able to control important metabolic processes, thus providing an elegant and efficient RNA-only regulation system. Existing across all domains of life, riboswitches appear to represent one of the most highly conserved mechanisms for the regulation of a broad range of biochemical pathways...
August 2018: Microbiology Spectrum
Constança Pomba, Boudewijn Catry, Jordi Torren Edo, Helen Jukes
The importance of antimicrobial resistance and the urgent need to combat it has increased the already existent complexity of licensing and approval of antimicrobial agents for use in animals due to its possible impact on animal and public health. VICH-the International Cooperation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products-is the trilateral (European Union-Japan-United States) program that has the goal of harmonizing technical requirements for veterinary product registration...
August 2018: Microbiology Spectrum
Carmen Torres, Carla Andrea Alonso, Laura Ruiz-Ripa, Ricardo León-Sampedro, Rosa Del Campo, Teresa M Coque
Enterococci are natural inhabitants of the intestinal tract in humans and many animals, including food-producing and companion animals. They can easily contaminate the food and the environment, entering the food chain. Moreover, Enterococcus is an important opportunistic pathogen, especially the species E. faecalis and E. faecium , causing a wide variety of infections. This microorganism not only contains intrinsic resistance mechanisms to several antimicrobial agents, but also has the capacity to acquire new mechanisms of antimicrobial resistance...
July 2018: Microbiology Spectrum
Sara Masachis, Fabien Darfeuille
Toxin-antitoxin (TA) systems are small genetic loci composed of two adjacent genes: a toxin and an antitoxin that prevents toxin action. Despite their wide distribution in bacterial genomes, the reasons for TA systems being on chromosomes remain enigmatic. In this review, we focus on type I TA systems, composed of a small antisense RNA that plays the role of an antitoxin to control the expression of its toxin counterpart. It does so by direct base-pairing to the toxin-encoding mRNA, thereby inhibiting its translation and/or promoting its degradation...
July 2018: Microbiology Spectrum
Sarah A Woodson, Subrata Panja, Andrew Santiago-Frangos
RNA-binding proteins chaperone the biological functions of noncoding RNA by reducing RNA misfolding, improving matchmaking between regulatory RNA and targets, and exerting quality control over RNP biogenesis. Recent studies of Escherichia coli CspA, HIV NCp, and E. coli Hfq are beginning to show how RNA-binding proteins remodel RNA structures. These different protein families use common strategies for disrupting or annealing RNA double helices, which can be used to understand the mechanisms by which proteins chaperone RNA-dependent regulation in bacteria...
July 2018: Microbiology Spectrum
Kiel D Kreuzer, Tina M Henkin
The T-box riboswitch is a unique, RNA-based regulatory mechanism that modulates expression of a wide variety of amino acid-related genes, predominantly in Firmicutes . RNAs of this class selectively bind a specific cognate tRNA, utilizing recognition of the tRNA anticodon and other tRNA features. The riboswitch monitors the aminoacylation status of the tRNA to induce expression of the regulated downstream gene(s) at the level of transcription antitermination or derepression of translation initiation in response to reduced tRNA charging via stabilization of an antiterminator or antisequestrator...
July 2018: Microbiology Spectrum
Daniela Prasse, Ruth A Schmitz
Global (metabolic) regulatory networks allow microorganisms to survive periods of nitrogen starvation or general nutrient stress. Uptake and utilization of various nitrogen sources are thus commonly tightly regulated in Prokarya ( Bacteria and Archaea ) in response to available nitrogen sources. Those well-studied regulations occur mainly at the transcriptional and posttranslational level. Surprisingly, and in contrast to their involvement in most other stress responses, small RNAs (sRNAs) involved in the response to environmental nitrogen fluctuations are only rarely reported...
July 2018: Microbiology Spectrum
Patrick F McDermott, Shaohua Zhao, Heather Tate
Non-typhoidal Salmonella is the most common foodborne bacterial pathogen in most countries. It is widely present in food animal species, and therefore blocking its transmission through the food supply is a prominent focus of food safety activities worldwide. Antibiotic resistance in non-typhoidal Salmonella arises in large part because of antibiotic use in animal husbandry. Tracking resistance in Salmonella is required to design targeted interventions to contain or diminish resistance and refine use practices in production...
July 2018: Microbiology Spectrum
Kristina Kadlec, Stefan Schwarz
Bordetella bronchiseptica is involved in respiratory tract infections mainly in dogs and pigs but may also cause infections in humans. Valid and representative data on antimicrobial susceptibility of B. bronchiseptica is rare. Approved antimicrobial susceptibility testing methods have been published, but very few clinical breakpoints are available. The MIC values are low for most agents but high for β-lactam antibiotics and macrolides. Information on the genetic basis of resistance is scarce. For a small number of isolates that are resistant or show elevated MICs, the molecular basis of resistance was identified...
July 2018: Microbiology Spectrum
Darren J Trott, Sam Abraham, Ben Adler
Leptospira , Brucella , and Borrelia are major agents of zoonotic disease, causing high morbidity and, in some cases, significant mortality in humans. For all three genera, prompt diagnosis and appropriate antimicrobial therapy are required to prevent the development of chronic, debilitating illness. Leptospira spp. are intrinsically resistant to several antimicrobial classes; however, there is little evidence in the literature for development of acquired resistance to antimicrobial agents used for clinical treatment of acute leptospirosis...
July 2018: Microbiology Spectrum
Laura Luque-Sastre, Cristina Arroyo, Edward M Fox, Barry J McMahon, Li Bai, Fengqin Li, Séamus Fanning
For nearly a century the use of antibiotics to treat infectious diseases has benefited human and animal health. In recent years there has been an increase in the emergence of antibiotic-resistant bacteria, in part attributed to the overuse of compounds in clinical and farming settings. The genus Listeria currently comprises 17 recognized species found throughout the environment. Listeria monocytogenes is the etiological agent of listeriosis in humans and many vertebrate species, including birds, whereas Listeria ivanovii causes infections mainly in ruminants...
July 2018: Microbiology Spectrum
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