Chronic lung infection by Pseudomonas aeruginosa biofilm is cured by L-Methionine in combination with antibiotic therapy

Bacterial biofilms are associated with 80-90% of infections. Within the biofilm, bacteria are refractile to antibiotics, requiring concentrations >1,000 times the minimum inhibitory concentration. Proteins, carbohydrates and DNA are the major components of biofilm matrix. Pseudomonas aeruginosa (PA) biofilms, which are majorly associated with chronic lung infection, contain extracellular DNA (eDNA) as a major component. Herein, we report for the first time that L-Methionine (L-Met) at 0.5 μM inhibits Pseudomonas aeruginosa (PA) biofilm formation and disassembles established PA biofilm by inducing DNase expression. Four DNase genes (sbcB, endA, eddB and recJ) were highly up-regulated upon L-Met treatment along with increased DNase activity in the culture supernatant. Since eDNA plays a major role in establishing and maintaining the PA biofilm, DNase activity is effective in disrupting the biofilm. Upon treatment with L-Met, the otherwise recalcitrant PA biofilm now shows susceptibility to ciprofloxacin. This was reflected in vivo, in the murine chronic PA lung infection model. Mice treated with L-Met responded better to antibiotic treatment, leading to enhanced survival as compared to mice treated with ciprofloxacin alone. These results clearly demonstrate that L-Met can be used along with antibiotic as an effective therapeutic against chronic PA biofilm infection.

[THE CONDITION AND TENDENCIES OF DEVELOPMENT OF CLINICAL AND SANITARY MICROBIOLOGY IN THE RUSSIAN FEDERATION AND PROBLEM OF IMPORT SUBSTITUTION]

The import substitution becomes one of the strategic tasks of national economy as a result of prolongation of economic sanctions concerning the Russian Federation of part of the USA, EU countries, Japan and number of other countries. It is not proper to be limited in import substitution only by goods because in conditions ofsanctions when access toforeign technologies is complicated Russia is needed to substitute foreign technologies by national designs in faster manner One of directions of effective import substitution is localization of production of laboratory equipment and consumables for clinical and sanitary microbiology on the territory ofthe Russian Federation and countries of Customs union. In Russia, in the field ofdiagnostic of dangerous and socially significant infections, all components for import substitution to implement gene diagnostic, immune diagnostic. bio-sensory and biochip approaches, isolation and storage of live microbial cultures, implementation of high-tech methods of diagnostic are available. At the same time, national diagnostic instrument-making industry for microbiology is factually absent. The few devices of national production more than on 50% consist of import components. The microbiological laboratories are to be equipped only with import devices of open type for applying national components. The most perspective national designs to be implemented are multiplex polimerase chain reaction test-systems and biochips on the basis of national plotters and readers. The modern development of diagnostic equipment and diagnostic instruments requires supplement of national collections of bacterial and viral pathogens and working-through of organizational schemes of supplying collections with strains. The presented data concerning justification of nomenclature of laboratory equipment and consumables permits to satisfy in fill scope the needs of clinical and sanitary microbiology in devices, growth mediums, consumables of national production and to refuse import deliveries without decreasing quality of microbiological analysis. This approach will ensure appropriate response to occurring challenges and new biological dangers and maintenance of biosecurity of the Russian Federation at proper level.

Global and local health burden trade-off through the hybridisation of quantitative microbial risk assessment and life cycle assessment to aid water management

Life cycle assessment (LCA) and quantitative risk assessment (QRA) are commonly used to evaluate potential human health impacts associated with proposed or existing infrastructure and products. Each approach has a distinct objective and, consequently, their conclusions may be inconsistent or contradictory. It is proposed that the integration of elements of QRA and LCA may provide a more holistic approach to health impact assessment. Here we examine the possibility of merging LCA assessed human health impacts with quantitative microbial risk assessment (QMRA) for waterborne pathogen impacts, expressed with the common health metric, disability adjusted life years (DALYs). The example of a recent large-scale water recycling project in Sydney, Australia was used to identify and demonstrate the potential advantages and current limitations of this approach. A comparative analysis of two scenarios - with and without the development of this project - was undertaken for this purpose. LCA and QMRA were carried out independently for the two scenarios to compare human health impacts, as measured by DALYs lost per year. LCA results suggested that construction of the project would lead to an increased number of DALYs lost per year, while estimated disease burden resulting from microbial exposures indicated that it would result in the loss of fewer DALYs per year than the alternative scenario. By merging the results of the LCA and QMRA, we demonstrate the advantages in providing a more comprehensive assessment of human disease burden for the two scenarios, in particular, the importance of considering the results of both LCA and QRA in a comparative assessment of decision alternatives to avoid problem shifting. The application of DALYs as a common measure between the two approaches was found to be useful for this purpose.

The Spectrum of Infectious Diseases in Kidney Transplantation: A Review of the Classification, Pathogens and Clinical Manifestations

Kidney transplantation is the treatment-of-choice for a significant number of patients with end-stage renal disease. Renal transplant recipients (RTRs) benefit from a longer life expectancy, with a better quality of life. Despite, recent accomplishments in the field of kidney transplantation, both short- and long-term, surgical and medical complications still exist. Among these complications, cardiovascular disease, carcinogenesis and infections are the most important. Infectious diseases constitute the most common complications after renal transplantation and the second most common cause of death among RTRs with a functioning graft. Theoretically, all infectious pathogens could cause disease in immunocompromised RTRs, yet among these, one could identify more important ones, such as the Enterobacteriaceae, causing urinary tract infections; pneumonia due to Pneumocystis jirovecii; Candida species which cause invasive fungal infections; herpes viruses; hepatitis viruses and parasites. Early diagnosis and effective treatment are key elements in salvaging both the allograft and the patient. However, clinical manifestations and diagnosis of such infectious diseases are not easily identified due to the altered state of immune response of the RTR. Thus, apart from possessing a deep knowledge of the etiology and the treatment options in each case, transplant physicians should also always remain alert when dealing with RTRs.

Beyond QMRA: Modelling microbial health risk as a complex system using Bayesian networks

BACKGROUND

Quantitative microbial risk assessment (QMRA) is the current method of choice for determining the risk to human health from exposure to microorganisms of concern. However, current approaches are often constrained by the availability of required data, and may not be able to incorporate the many varied factors that influence this risk. Systems models, based on Bayesian networks (BNs), are emerging as an effective complementary approach that overcomes these limitations.

OBJECTIVES

This article aims to provide a comparative evaluation of the capabilities and challenges of current QMRA methods and BN models, and a scoping review of recent published articles that adopt the latter for microbial risk assessment. Pros and cons of systems approaches in this context are distilled and discussed.

METHODS

A search of the peer-reviewed literature revealed 15 articles describing BNs used in the context of QMRAs for foodborne and waterborne pathogens. These studies were analysed in terms of their application, uses and benefits in QMRA.

DISCUSSION

The applications were notable in their diversity. BNs were used to make predictions, for scenario assessment, risk minimisation, to reduce uncertainty and to separate uncertainty and variability. Most studies focused on a segment of the exposure pathway, indicating the broad potential for the method in other QMRA steps. BNs offer a number of useful features to enhance QMRA, including transparency, and the ability to deal with poor quality data and support causal reasoning.

CONCLUSION

The method has significant untapped potential to describe the complex relationships between microbial environmental exposures and health.

Multidrug-resistant Trichosporon: an unusual fungal sepsis in preterm neonates

We report a cluster of three extremely-low birth weight (ELBW), preterm neonates who developed late-onset sepsis (LOS) by Trichosporon asahii within a span of 1 week period. Two of these cases had the initial diagnosis of respiratory distress syndrome and the third one was admitted for low birth weight and prematurity. Initial sepsis screen was negative and blood culture was sterile in all. Late-onset sepsis was developed after the first week of life and the presenting features were lethargy, feeding intolerance, bleeding manifestations, positive sepsis screen and severe thrombocytopaenia. The isolates were sensitive to voriconazole but resistant to both amphotericin-B and fluconazole on all occasions. All the infants were treated with liposomal amphotericin-B before the availability of culture reports but the clinical deterioration was rapid and all three neonates succumbed to death before we could procure voriconazole. The source of the outbreak could not be identified from multiple surface cultures from the unit and screening of the health care staffs. We emphasise the need for high index of suspicion for unusual fungal pathogens, resistant to conventional antifungal drugs while treating preterm neonates with LOS.

The role of pathogen genomics in assessing disease transmission

Whole genome sequencing (WGS) of pathogens enables the sources and patterns of transmission to be identified during specific disease outbreaks and promises to transform epidemiological research on communicable diseases. This review discusses new insights into disease spread and transmission that have come from the use of WGS, particularly when combined with genomic scale phylogenetic analyses. These include elucidation of the mechanisms of cross species transmission, the potential modes of pathogen transmission, and which people in the population contribute most to transmission. Particular attention is paid to the ability of WGS to resolve individual patient to patient transmission events. Importantly, WGS data seem to be sufficiently discriminatory to target cases linked to community or hospital contacts and hence prevent further spread, and to investigate genetically related cases without a clear epidemiological link. Approaches to combine evidence from epidemiological with genomic sequencing observations are summarised. Ongoing genomic surveillance can identify determinants of transmission, monitor pathogen evolution and adaptation, ensure the accurate and timely diagnosis of infections with epidemic potential, and refine strategies for their control.

Zoonotic aspects of vector-borne infections

Vector-borne diseases are principally zoonotic diseases transmitted to humans by animals. Pathogens such as bacteria, parasites and viruses are primarily maintained within an enzootic cycle between populations of non-human primates or other mammals and largely non-anthropophilic vectors. This 'wild' cycle sometimes spills over in the form of occasional infections of humans and domestic animals. Lifestyle changes, incursions by humans into natural habitats and changes in agropastoral practices create opportunities that make the borders between wildlife and humans more permeable. Some vector-borne diseases have dispensed with the need for amplification in wild or domestic animals and they can now be directly transmitted to humans. This applies to some viruses (dengue and chikungunya) that have caused major epidemics. Bacteria of the genus Bartonella have reduced their transmission cycle to the minimum, with humans acting as reservoir, amplifier and disseminator. The design of control strategies for vector-borne diseases should be guided by research into emergence mechanisms in order to understand how a wild cycle can produce a pathogen that goes on to cause devastating urban epidemics.

Surveillance for antimicrobial drug resistance in under-resourced countries

TOC summary: New programs can be improved by drawing on lessons from previous successful efforts.

Antimicrobial drug resistance is usually not monitored in under-resourced countries because they lack surveillance networks, laboratory capacity, and appropriate diagnostics. This accelerating problem accounts for substantial number of excess deaths, especially among infants. Infections particularly affected by antimicrobial drug resistance include tuberculosis, malaria, severe acute respiratory infections, and sepsis caused by gram-negative bacteria. Nonetheless, mapping antimicrobial drug resistance is feasible in under-resourced countries, and lessons can be learned from previous successful efforts. Specimen shipping conditions, data standardization, absence of contamination, and adequate diagnostics must be ensured. As a first step toward solving this problem, we propose that a road map be created at the international level to strengthen antimicrobial resistance surveillance in under-resourced countries. This effort should include a research agenda; a map of existing networks and recommendations to unite them; and a communication plan for national, regional, and international organizations and funding agencies.

Oral zinc and common childhood infections--An update

Zinc is an essential micronutrient important for growth and for normal function of the immune system. Many children in developing countries have inadequate zinc nutrition. Routine zinc supplementation reduces the risk of respiratory infections and diarrhea, the two leading causes of morbidity and mortality in young children worldwide. In childhood diarrhea oral zinc also reduces illness duration and risk of persistent episodes. Oral zinc is therefore recommended for the treatment of acute diarrhea in young children. The results from the studies that have measured the therapeutic effect of zinc on acute respiratory infections, however, are conflicting. Moreover, the results of therapeutic zinc for childhood malaria also are so far not promising.This paper gives a brief outline of the current evidence from clinical trials on therapeutic effect of oral zinc on childhood respiratory infections, pneumonia and malaria and also of new evidence of the effect on serious bacterial illness in young infants.

Role of glycosaminoglycans in infectious disease

Glycosaminoglycans (GAGs) have been shown to bind to a wide variety of microbial pathogens, including viruses, bacteria, parasites, and fungi in vitro. GAGs are thought to promote pathogenesis by facilitating pathogen attachment, invasion, or evasion of host defense mechanisms. However, the role of GAGs in infectious disease has not been extensively studied in vivo and therefore their pathophysiological significance and functions are largely unknown. Here we describe methods to directly investigate the role of GAGs in infections in vivo using mouse models of bacterial lung and corneal infection. The overall experimental strategy is to establish the importance and specificity of GAGs, define the essential structural features of GAGs, and identify a biological activity of GAGs that promotes pathogenesis.

[Epidemiological risk of introduction of dangerous and exotic infectious diseases on the territory of the XXII Olympic Winter Games and XI Paralympic Winter Games 2014 in Sochi]

To assess the epidemiological risk of introduction of serious infectious diseases in the pre-Olympic period defined list of dangerous and exotic infections and held assessment of potential danger threatening. Initial external information to assess the potential risk of skidding were reports, forecasts, posted on the official websites. The risk of skidding and epidemiological complications conditionally designated as high, moderate and minimal risk importation of measles virus-Rate was considered as high. In confirmation of the forecast for the period of the Olympic Games in Sochi have been registered about 100 cases of measles. Moderate risk of importation was determined for poliomyelitis due to wild poliovirus, Lassa fever, cholera, plague, and the minimal--for Dengue fever, yellow fever, the Middle East and respiratory syndrome, diseases caused by viruses Marburg and Ebola. Based on of analysis of previous Olympic Games and subsequent co-events related to the activity of the infectious diseases in the world, mate-cluded that even a slight risk of importation of infectious diseases requires maximum alertness and readiness to conduct adequate epidemiological issues incorporated.

[Operation and interaction peculiarities of diagnostic laboratories involved in providing protection from infectious diseases during the XXII Olympic Winter Games and XI Paralympic Winter Games 2014 in Sochi]

The experience of the organization and functioning of the laboratory network during the XXII Olympic Winter Games and XI Paralympic Winter Games of 2014 in Sochi is considered. Efforts to establish an effective system of laboratory support, the order of work and interaction of diagnostic laboratories involved in diseases control of population during the Olympic Games are analyzed.

A unified framework of mutual influence between two pathogens in multiplex networks

There are many evidences to show that different pathogens may interplay each other and cause a variety of mutual influences of epidemics in multiplex networks, but it is still lack of a framework to unify all the different dynamic outcomes of the interactions between the pathogens. We here study this problem and first time present the concept of state-dependent infectious rate, in contrast to the constant infectious rate in previous studies. We consider a model consisting of a two-layered network with one pathogen on the first layer and the other on the second layer, and show that all the different influences between the two pathogens can be given by the different range of parameters in the infectious rates, which includes the cases of mutual enhancement, mutual suppression, and even initial cooperation (suppression) induced final suppression (acceleration). A theoretical analysis is present to explain the numerical results.

Simplified models for exhaled airflow from a cough with the mouth covered

Covering a cough can be useful in reducing the transmission of airborne infectious diseases. However, no simple method is available in the literature for predicting the exhaled airflow from a cough with the mouth covered. This investigation used smoke to visualize the airflow exhaled by 16 human subjects. Their mouths were covered by a tissue, a cupped hand, a fist, and an elbow with and without a sleeve. This study then developed simplified models for predicting the airflow on the basis of the smoke visualization data. In addition, this investigation performed numerical simulations to assess the influence of mouth coverings on the receptor's exposure to exhaled particles. It was found that covering a cough with a tissue, a cupped hand, or an elbow can significantly reduce the horizontal velocity and cause the particles to move upward with the thermal plumes generated by a human body. In contrast with an uncovered cough, a covered cough or a cough with the head turned away may prevent direct exposure.

PRACTICAL IMPLICATIONS

This study developed simplified models for predicting the exhaled airflow from a cough with the mouth covered. The proposed models can easily be used to investigate the risk of transmission of airborne infectious diseases in enclosed environments.

Human infectious diseases in the genomics era: where do we go from here?

Ripudaman K Bains is the editor of the Genome Biology special issue content on the 'genomics of infectious diseases', and introduces the collection in this editorial.

From the bench to modeling--R0 at the interface between empirical and theoretical approaches in epidemiology of environmentally transmitted infectious diseases

For environmentally transmitted infectious diseases (ETIDs), which spread through the contaminated environment (such as foods, surfaces and fomites), there is a lack of consensus about the mathematical approach to derive R0, leading to inconsistent predictions about the spread and control of these infections in their host populations. The objective of this study was to explain three current, though conflicting, approaches to derive a theoretical expression for R0 for ETIDs and assess their validity through comparison with available empirical data. Salmonella Typhimurium in laboratory mice was used as a theoretical and empirical model system. The three conflicting theoretical expressions for R0 were derived using the next generation matrix approach according to three unverified hypotheses about the role of the environmental phase in the transmission of ETIDs. The hypotheses assume that the environment contaminated with a pathogen is: (H1) an extension of the host's infectious period, (H2) a reservoir for the infectious agent, or (H3) has both of these characteristics. For the parameter values describing the empirical model system, the theoretical values of R0 corresponding to the hypotheses H2 and H3 were very similar (1.38 and 1.62, respectively) and their values were approximately half of the value of R0 for hypothesis H1 (2.94). The theoretical R0 values were compared with an empirical R0 (1.58, 95% confidence interval: 1.14, 2.02) estimated using a Martingale method from published experimental data on Salmonella Typhimurium transmission in mice. The results of the comparison suggested that hypothesis H1 is unlikely to hold true but it could not be rejected with confidence because of uncertainty in the value of the pathogen growth rate in the environment. The hypotheses H2 and H3 were both equally strongly supported with the empirical data suggesting that either of them could be valid. A sensitivity analysis identified critical information gaps about the indirect transmission rate of infection and the pathogen growth rate in the environment. Moreover, we identified experimental conditions for which the theoretical R0 predictions based on the hypotheses H2 and H3 differ greatly, which would assist their discrimination and conclusive validation against future empirical studies. Once a valid theoretical R0 is identified for Salmonella Typhimurium in mice, its generalizability to other host-pathogen-environment systems should be tested. The present study may serve as a template for integrated empirical and theoretical research of R0 in the epidemiology of ETIDs.

Engineering the control of mosquito-borne infectious diseases

Recent advances in genetic engineering are bringing new promise for controlling mosquito populations that transmit deadly pathogens. Here we discuss past and current efforts to engineer mosquito strains that are refractory to disease transmission or are suitable for suppressing wild disease-transmitting populations.

[The role of technogenic and biological factors in spread of foodborne bacterial infections]

Epidemiologic aspects of ecology of foodborne infection causative agents that have taken root in contemporary technogenic loci created by humans in urbocenoses which include agrocomplexes of animal breeding, vegetable growing in open and closed ground are discussed. Soil and water sources with a wide transport network where microorganisms dwell in the environment under favorable for vital functions and growth conditions (humus deposits, temperature regimen, optimal pH, associations with hydrobionts, biofilm formation) are potent secondary reservoirs of infection causative agents. Some molecular-genetic mechanisms of polyhostality of Gram negative bacteria and listeria are examined.