Production of infectious RNA and serum-blocking antigen by poliovirus temperature-sensitive mutants.
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Antigens↗
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Report from the European Conference on the Role of Research in Combating Antibiotic Resistance, 2003.
Europe has been at the forefront of efforts to control antibiotic resistance, and this globally important health care problem has prompted numerous recommendations for action at both the national and international levels. Starting in 2002, research on antimicrobial resistance has been considered to be one of the specific objectives of the Sixth Framework Programme (FP6) within the European Union. This report summarises the plenary presentations, as well as the findings of six Working Groups covering specific areas of antibiotic resistance, given at a conference in November 2003 entitled 'The Role of Research in Combating Antibiotic Resistance', co-organised by the European Union and the European Society for Clinical Microbiology and Infectious Diseases, and held in Rome under the patronage of the Italian government.
Anti-Bacterial Agents↗
International multicenter evaluation of latex agglutination tests for identification of Staphylococcus aureus.
A newly marketed rapid agglutination kit for the identification of Staphylococcus aureus, Slidex Staph Plus (bioMérieux), was compared to Staphaurex Plus (Murex Diagnostics) and Pastorex Staph-Plus (Sanofi Diagnostics Pasteur). The study took place in three clinical microbiology laboratories in three different European countries. A total of 892 staphylococcal isolates, including 278 methicillin-sensitive S. aureus (MSSA) isolates, 171 methicillin-resistant S. aureus (MRSA) isolates, and 443 coagulase-negative staphylococcal isolates, were analyzed. The sensitivities (MSSA/MRSA) and specificities, respectively, were 98. 2% (98.9%/97.1%) and 98.9% for Slidex Staph Plus, 98.2% (98.2%/98. 2%) and 96.2% for Staphaurex Plus, and 98.7% (98.6%/98.8%) and 95.7% for Pastorex Staph Plus. The specificity of the Slidex Staph Plus kit was statistically significantly higher than the specificities of Staphaurex Plus and Pastorex Staph-Plus. The Slidex Staph Plus is a very reliable test for the identification of S. aureus.
Coagulase↗
Competition and cooperation: The plasticity of bacterial interactions across environments.
Bacteria live in diverse communities, forming complex networks of interacting species. A central question in bacterial ecology is whether species engage in cooperative or competitive interactions. But this question often neglects the role of the environment. Here, we use genome-scale metabolic networks from two different open-access collections (AGORA and CarveMe) to assess pairwise interactions of different microbes in varying environmental conditions (provision of different environmental compounds). By computationally simulating thousands of environments for 10,000 pairs of bacteria from each collection, we found that most pairs were able to both compete and cooperate depending on the availability of environmental resources. This modeling approach allowed us to determine commonalities between environments that could facilitate the potential for cooperation or competition between a pair of species. Namely, cooperative interactions, especially obligate, were most common in less diverse environments. Further, as compounds were removed from the environment, we found interactions tended to degrade towards obligacy. However, we also found that on average at least one compound could be removed from an environment to switch the interaction from competition to facultative cooperation or vice versa. Together our approach indicates a high degree of plasticity in microbial interactions in response to the availability of environmental resources.
Microbial Interactions↗
Building communication networks: international network for the study and prevention of emerging antimicrobial resistance.
The global nature of antimicrobial resistance and the failure to control the emergence of resistant organisms demand the implementation of a global surveillance program involving both developed and developing countries. Because of the urgent need for infection control interventions and for rapid distribution of information about emerging organisms, we initiated the International Network for the Study and Prevention of Emerging Antimicrobial Resistance (INSPEAR). Its main objectives are to serve as an early warning system for emerging antimicrobial-drug resistant pathogens, to facilitate rapid distribution of information about emerging multidrug-resistant pathogens to hospitals and public health authorities worldwide, and to serve as a model for the development and implementation of infection control interventions.
Communicable Disease Control↗
Letter: Treatment of bacterial meningitis.
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Administration, Oral↗
Antimicrobial resistance: a global response.
Resistance to antimicrobial therapies reduces the effectiveness of these drugs, leading to increased morbidity, mortality, and health care expenditure. Because globalization increases the vulnerability of any country to diseases occurring in other countries, resistance presents a major threat to global public health, and no country acting on its own can adequately protect the health of its population against it. International collective action is therefore essential. Nevertheless, responsibility for health remains predominantly national. Consequently, there is a potentially significant disparity between the problems and solutions related to antimicrobial resistance and the institutions and mechanisms that are available to deal with them. This paper considers the capacity of national and international institutions and mechanisms to generate a collective response to antimicrobial resistance. Strategies for containing resistance are outlined, with particular reference to globally coordinated activities of countries. The adequacy of national and international responses to resistance is assessed, and the actions that international bodies could take to solve difficulties associated with present responses are highlighted. Approaches are suggested for securing international collective action for the containment of antimicrobial resistance.
Anti-Infective Agents↗
Vancomycin-resistant Enterococcus faecium sepsis following persistent colonization.
Vancomycin-resistant enterococci have emerged as important nosocomial pathogens and represent a serious threat to patients with impaired host defenses. We describe a patient with leukemia who developed prolonged colonization with vancomycin-resistant Enterococcus faecium and ultimately died of sepsis due to this multidrug-resistant organism. This case report confirms that colonization with vancomycin-resistant enterococci may last indefinitely and that asymptomatic carriage can lead to invasive infection.
Adult↗
The role of international agencies in emerging infections.
Emergent and resurgent infections have no respect for national borders. Surveillance programmes, policies and practices, educational activities and control initiatives all require international leadership, multinational funding, and the ability to transcend national barriers if we are to prevent and control these infections. Society seems to expect us to organise ourselves to do this job well without building "impossible to maintain" barriers to the flow of people or goods. As a result, we must determine how international organisations, including United Nations agencies, international societies, and academic groups in universities, can work together with national organisations to achieve effective surveillance, ongoing education, important research and control initiatives to prevent infections from becoming an ever-increasing global threat to our security.
Drug Resistance, Microbial↗
[Formation of an acetic-acid type microbial metabolism pathway and its stability during the course of sulfate-reduction].
Continuous-flow experiment was conducted in an acidogenic sulfate-reducing reactor supplied with molasses as sole carbon resource and sulfate sodium as electron acceptor. The composition of Volatile fat acid(VFA) in terminal liquid products, the distribution of acetic acid, the existence of microbial populations and the interspecific relationship between sulfate-reducing bacteria (SRB) and acidogenic bacteria (AB) were investigated in different experimental stages when sulfate removal rate and gas production maintained at a relatively stable status. The experimental results showed that an acetic-acid type microbial metabolism pathway was formed based on the fact that the proportion of acetic acid in terminal liquid products was as high as 50% to 82%. It was also explained the formation of acetic-acid type microbial metabolism pathway was resulted from acetic acid accumulation in the terminal liquid products, which was subjected to the bio-chain cooperation relationship between populations of SRB and AB, and the incomplete-oxidation of organic substance in acidogenic-phase reactor of two-phase anaerobic treatment process. It was also presented that the formation of acetic-acid type microbial metabolism pathway depended on the capability of acetic-acid utilized-SRB (ASRB) population competing against other populations and its ability of acetic acid consumption. Furthermore, this kind of metabolism pathway could offer suitable carbon resource for methane producing reactor in the two-phase anaerobic treatment process, and has significant effect on the sulfate removal rate of the whole treatment system and its running stability.
Acetic Acid↗
The European Community strategy against antimicrobial resistance.
In 2001 the European Commission presented a 'Community strategy against Antimicrobial Resistance'. In previous years, the problem was addressed through an increasing number of isolated measures, but in this strategy the Commission outlined a comprehensive European Community approach across all sectors. The strategy consists of fifteen actions in four key areas: surveillance, prevention, research and product development, and international cooperation. An important part of this strategy is the 'Council Recommendation on the prudent use of antimicrobial agents in human medicine'. The Recommendation provides a detailed set of public health actions to contain antimicrobial resistance. This paper presents the eleven points of action of the strategy that are directly related to human medicine, and discusses related European Community activities. Under the new public health programme as well as under the research programme of the European Union, antimicrobial resistance is a key priority.
Drug Resistance, Microbial↗
[Nosocomial infections: new agents, incidence, prevention].
Nosocomial infection is one of the major health problems confronting clinicians in intensive care units. Incidence has been estimated to vary from 5 to 10%, leading to death in one of every 5000 persons hospitalized. This situation is not however static since hospital epidemics and nosocomial infections evolve as a consequence of advances in antibiotic drug therapy and surgical and intensive care techniques. Microbial investigations themselves are of major importance as the collection of epidemiological data and its communication to hospital partners affects their approach to patient management. Nosocomial pneumonia, particularly in ventilated patients, urinary infection in those with indwelling catheters and wound colonization after surgery are still major problems and explain part of the variations between wards and hospitals. The main changes concern the bacteria involved. Classical agents with new mechanisms of resistance (Klebsiella pneumoniae, extended spectrum beta-lactamase producers) have been joined by other "new" agents emerging as pathogens (Xanthomonas maltophilia, Acinetobacter baumannii). The incidence of resistance in Staphylococcus and Enterococcus strains as well as new Gram positive species including Corynebacterium jeikeium and Rhodococcus equi, now recognized as opportunistic agents, has also increased. The multiresistance of these pathogens is often responsible for failure of antibiotic therapy and emphasizes the need both for rigorous prevention through active cooperation between bacteriologists, ward clinicians and intensive care units, and further research in the fields of microbial resistance mechanisms and antibiotics. Preventive measures have become a priority creating an international challenge to health care policy makers.
Cross Infection↗
Inhibition of NO3- and NO2- reduction by microbial Fe(III) reduction: evidence of a reaction between NO2- and cell surface-bound Fe2+.
A recent study (D. C. Cooper, F. W. Picardal, A. Schimmelmann, and A. J. Coby, Appl. Environ. Microbiol. 69:3517-3525, 2003) has shown that NO(3)(-) and NO(2)(-) (NO(x)(-)) reduction by Shewanella putrefaciens 200 is inhibited in the presence of goethite. The hypothetical mechanism offered to explain this finding involved the formation of a Fe(III) (hydr)oxide coating on the cell via the surface-catalyzed, abiotic reaction between Fe(2+) and NO(2)(-). This coating could then inhibit reduction of NO(x)(-) by physically blocking transport into the cell. Although the data in the previous study were consistent with such an explanation, the hypothesis was largely speculative. In the current work, this hypothesis was tested and its environmental significance explored through a number of experiments. The inhibition of approximately 3 mM NO(3)(-) reduction was observed during reduction of a variety of Fe(III) (hydr)oxides, including goethite, hematite, and an iron-bearing, natural sediment. Inhibition of oxygen and fumarate reduction was observed following treatment of cells with Fe(2+) and NO(2)(-), demonstrating that utilization of other soluble electron acceptors could also be inhibited. Previous adsorption of Fe(2+) onto Paracoccus denitrificans inhibited NO(x)(-) reduction, showing that Fe(II) can reduce rates of soluble electron acceptor utilization by non-iron-reducing bacteria. NO(2)(-) was chemically reduced to N(2)O by goethite or cell-sorbed Fe(2+), but not at appreciable rates by aqueous Fe(2+). Transmission and scanning electron microscopy showed an electron-dense, Fe-enriched coating on cells treated with Fe(2+) and NO(2)(-). The formation and effects of such coatings underscore the complexity of the biogeochemical reactions that occur in the subsurface.
Ferric Compounds↗
Interval observers for biochemical processes with uncertain kinetics and inputs.
This paper concentrates on the state observation in bioprocesses when there is uncertainty on the process parameters and/or the process inputs. An interval observer is designed on the basis of the cooperativity properties of the model for a standard stirred tank bioreactor model with a single microbial growth and a kinetic model depending on the substrate concentration. Further assumptions are the (lower and upper) boundedness of the specific growth rate and the inlet substrate concentration. Mathematical analysis of the stability and convergence of the interval observer is performed both in absence and in presence of uncertainty on the measurements. It is shown in particular that when the process inputs are known, the static observation error on the unknown state is inversely proportional to one of the observer gains. The performance of the interval observer are also illustrated through numerical simulation.
Bacteria↗
Role of the classical pathway of complement activation in experimentally induced polymicrobial peritonitis.
The complement system and the natural antibody repertoire provide a critical first-line defense against infection. The binding of natural antibodies to microbial surfaces opsonizes invading microorganisms and activates complement via the classical pathway. Both defense systems cooperate within the innate immune response. We studied the role of the complement system in the host defense against experimental polymicrobial peritonitis using mice lacking either C1q or factor B and C2. The C1q-deficient mice lacked the classical pathway of complement activation. The factor B- and C2-deficient mice were known to lack the classical and alternative pathways, and we demonstrate here that these mice also lacked the lectin pathway of complement activation. Using inoculum doses adjusted to cause 42% mortality in the wild-type strain, none of the mice deficient in the three activation routes of complement (factor B and C2 deficient) survived (mortality of 100%). Mortality in mice deficient only in the classical pathway of complement activation (C1q deficient) was 83%. Application of further dilutions of the polymicrobial inoculum showed a dose-dependent decrease of mortality in wild-type controls, whereas no changes in mortality were observed in the two gene-targeted strains. These results demonstrate that the classical activation pathway is required for an effective antimicrobial immune defense in polymicrobial peritonitis and that, in the infection model used, the remaining antibody-independent complement activation routes (alternative and lectin pathways) provide a supporting line of defense to gain residual protection in classical pathway deficiency.
Animals↗
Spatial self-organization in a cyclic resource-species model.
Biological communities are remarkable in their ability to form cooperative ensembles that lead to coexistence through various types of niche partitioning, usually intimately tied to spatial structure. This is especially true in microbial settings where differential expression and regulation of genes allows members of a given species to alter their lifestyle so as to fill a functional role within the community. The resulting species interactions can involve feedback, as in the case of some bacterial consortia that participate in the cooperative degradation of a given resource in a succession of steps and in such a way that certain "later" species provide catalytic support for the primary degrader. We seek to capture the essential features of such spatially extended biological systems by introducing a lattice-based stochastic spatial model (interacting particle system) with cyclic local dynamics. Here, a given site progresses through a sequence of resource and species states in a prescribed order. Furthermore, this succession of states (at a site) is assumed to form a cyclic pattern due to a natural feedback mechanism. We explore conditions under which all the species are able to coexist and consider the extent to which this coexistence requires the development of spatio-temporal patterns, including spiral waves. This self-organization, if it occurs, results when synchronization of the dynamics at the microscopic level leads to macroscopic patterns. These patterns result in consumer-driven resource fluctuations that generate a form of spatio-temporal niche partitioning. As with most models of this complexity, we employ a mixture of mathematical analysis and simulations to develop an understanding of the resulting dynamics.
Adaptation, Biological↗
Editorial: microbial ecology.
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Bacteria↗