Infectious diseases in the 21st century: old challenges and new opportunities

It Takes Two to Tangle: Microneedle Patches Co-delivering Monoclonal Antibodies and Engineered Antimicrobial Peptides Effectively Eradicate Wound Biofilms

Wound biofilms pose a great clinical challenge. Herein, this work reports a dissolvable microneedle patch for dual delivery of monoclonal antibodies anti-PBP2a and engineers antimicrobial peptides W379. In vitro antibacterial efficacy testing with microneedle patches containing a combination of 250 ng mL-1 W379 and 250 ng mL-1 anti-BPB2a decreases the bacterial count from ≈3.31 × 107 CFU mL-1 to 1.28 × 102 CFU mL-1 within 2 h without eliciting evident cytotoxicity. Ex vivo testing indicates W379 and anti-PBP2a co-loaded microneedle patch displayed a remarkable reduction of bacterial load by ≈7.18 log CFU after administered only once within 48 h. The bacterial count is significantly diminished compared to the treatment by either W379 or anti-PBP2a-loaded alone microneedle patches. When administered twice within 48 h, no bacteria are identified. Further in vivo study also reveals that after two treatments of W379 and anti-PBP2a co-loaded PVP microneedle patches within 48 h, the bacterial colonies are undetectable in a type II diabetic mouse wound biofilm model. Taken together, W379 and anti-PBP2a co-loaded PVP microneedle patches hold great promise in treating wound biofilms.

Astaxanthin as a King of Ketocarotenoids: Structure, Synthesis, Accumulation, Bioavailability and Antioxidant Properties

Astaxanthin (3,3-dihydroxy-β, β-carotene-4,4-dione) is a ketocarotenoid synthesized by Haematococcus pluvialis/lacustris, Chromochloris zofingiensis, Chlorococcum, Bracteacoccus aggregatus, Coelastrella rubescence, Phaffia rhodozyma, some bacteria (Paracoccus carotinifaciens), yeasts, and lobsters, among others However, it is majorly synthesized by Haematococcus lacustris alone (about 4%). The richness of natural astaxanthin over synthetic astaxanthin has drawn the attention of industrialists to cultivate and extract it via two stage cultivation process. However, the cultivation in photobioreactors is expensive, and converting it in soluble form so that it can be easily assimilated by our digestive system requires downstream processing techniques which are not cost-effective. This has made the cost of astaxanthin expensive, prompting pharmaceutical and nutraceutical companies to switch over to synthetic astaxanthin. This review discusses the chemical character of astaxanthin, more inexpensive cultivating techniques, and its bioavailability. Additionally, the antioxidant character of this microalgal product against many diseases is discussed, which can make this natural compound an excellent drug to minimize inflammation and its consequences.

Functional characterization of α-Gal producing lactic acid bacteria with potential probiotic properties

The possibility of exploiting the human immune response to glycan α-Gal for the control of multiple infectious diseases has been the objective of recent investigations. In this field of research, the strain of Escherichia coli O86:B7 has been at the forefront, but this Gram-negative microorganism presents a safety concern and therefore cannot be considered as a probiotic. To address this challenge, this study explored the identification of novel lactic acid bacteria with a safe history of use, producing α-Gal and having probiotic potential. The lactic acid bacteria were isolated from different traditionally fermented foods (kununn-zaki, kindirmo, and pulque) and were screened for the production of α-Gal and some specific probiotic potential indicators. The results showed that Ten (10) out of forty (40) [25%] of the tested lactic acid bacteria (LAB) produced α-Gal and were identified as Limosilactobacillus fermentum, Levilactobacillus brevis, Agrilactobacillus composti, Lacticaseibacillus paracasei, Leuconostoc mesenteroides and Weissella confusa. Four (4) LAB strains with highest levels of α-Gal were further selected for in vivo study using a mouse model (α1,3GT KO mice) to elucidate the immunological response to α-Gal. The level of anti-α-Gal IgG observed were not significant while the level of anti-α-Gal IgM was lower in comparison to the level elicited by E. coli O86:B7. We concluded that the lactic acid bacteria in this study producing α-Gal have potential probiotic capacity and can be further explored in α-Gal-focused research for both the prevention and treatment of various infectious diseases and probiotic development.

Residual biomass from surfactin production is a source of arginase and adsorbed surfactin that is useful for environmental remediation

Lipopeptides are important secondary metabolites produced by microbes. They find applications in environmental decontamination and in the chemical, pharmaceutical and food industries. However, their production is expensive. In the present work we propose three strategies to lower the production costs of surfactin. First, the coproduction of surfactin and arginase in a single growth. Second, extract the fraction of surfactin that adsorbs to the biomass and is removed from the growth medium through centrifugation. Third, use microbial biomass for the remediation of organic and inorganic contaminants. The coproduction of surfactin and arginase was evaluated by factorial design experiments using the LB medium supplemented with arginine. The best conditions for surfactin production were 22 h of growth at 37 °C using LB supplemented with arginine 7.3 g/L. Almost similar conditions were found to produce highest levels of arginase, 24 h and 6.45 g/L arginine. Decontamination of phenol and copper from artificial samples was attained by treatment with residues from lipopeptide production. Thus, cell suspensions and wash-waters used to extract surfactin from the biomass. Cell suspensions were used to successfully remove hydroquinone. Cell suspensions and wash-waters containing surfactin were successfully used to recover copper from solution. Specific monitoring methods were used for phenol and metal solutions, respectively a biosensor based on tyrosinase and either atomic absorption flame ionization spectrometry or absorbance coupled to the Arduino™ platform. Therefore, we report three alternative strategies to lower the production costs in lipopeptide production, which include the effective recovery of copper and phenol from contaminated waters using residues from surfactin production. Sustainable and profitable production of surfactin can be achieved by a coproduction strategy of lipopeptides and enzymes. Lipopeptides are collected in the supernatant and enzymes in the biomass. In addition, lipopeptides that coprecipitate with biomass can be recovered by washing. Lipopeptide wash-waters find applications in remediation and cells can also be used for environmental decontamination.

Molecular Binding and Simulation Studies of Staphylococcus aureus Superantigens with Flavonoid Compounds

BACKGROUND

Superantigens of Staphylococcus aureus namely enterotoxin A, exfoliative toxin A, and Toxic shock syndrome toxin-1 cause detrimental effects on the cells of the immune system.

METHODS

In this work, the toxins were downloaded from the Protein DataBank database and energies were minimized using KoBaMIN server. Forty flavonoids compounds were identified by pubchem compound database through extensive literature study and their 3D structures were obtained by submitting SMILES to CORINA tool. Based on Lipinski's rule of five, the molecules were filtered that resulted in 27 compounds. Molecular docking was performed for identifying the binding and interaction sites of flavonoids with the toxins using Autodock 4.

RESULTS AND CONCLUSION

The docked complexes were then subjected to molecular dynamics simulation using Gromacs. The analysis revealed the stability of the complexes as indicated by three hydrogen bonds formed during the simulation time period of 20 ns.

Functional Food for the Stimulation of the Immune System Against Malaria

Drug resistance has become a threat to global health, and new interventions are needed to control major infectious diseases. The composition of gut microbiota has been linked to human health and has been associated with severity of malaria. Fermented foods contribute to the community of healthy gut bacteria. Despite the studies connecting gut microbiota to the prevention of malaria transmission and severity, research on developing functional foods for the purpose of manipulating the gut microbiota for malaria control is limited. This review summarizes recent knowledge on the role of the gut microbiota in malaria prevention and treatment. This information should encourage the search for lactic acid bacteria expressing α-Gal and those that exhibit the desired immune stimulating properties for the development of functional food and probiotics for malaria control.

Screening of the Dichloromethane: Methanolic Extract of Centella asiatica for Antibacterial Activities against Salmonella typhi, Escherichia coli, Shigella sonnei, Bacillus subtilis, and Staphylococcus aureus

Bacterial infections are responsible for a large number of deaths every year worldwide. On average, 80% of the African population cannot afford conventional drugs. Moreover, many synthetic antibiotics are associated with side effects and progressive increase in antimicrobial resistance. Currently, there is growing interest in discovering new antibacterial agents from ethnomedicinal plants. About 60% of the population living in developing countries depends on herbal drugs for healthcare needs. This study involved the screening of Centella asiatica commonly used by herbal medicine practitioners in Kisii County to treat symptoms related to bacterial infections. Standard bioassay methods were applied throughout the study. They included preliminary screening of dichloromethane: methanolic extract of Centella asiatica against human pathogenic bacteria including Salmonella typhi ATCC 19430, Escherichia coli ATCC 25922, Shigella sonnei ATCC 25931, Bacillus subtilis ATCC 21332, and Staphylococcus aureus ATCC 25923 using agar disc diffusion, broth microdilution method, and time-kill kinetics with tetracycline as a positive control. Phytochemical screening was carried out to determine the different classes of compounds in the crude extracts. Data were analyzed using one way ANOVA and means separated by Tukey's test. Dichloromethane: methanolic extract of Centella asiatica was screened against the selected bacterial strains. Time-kill kinetic studies of the extracts showed dose- and time-dependent kinetics of antibacterial properties. Phytochemical screening of the DCM-MeOH extract revealed the presence of alkaloids, flavonoids, phenolics, terpenoids, cardiac glycosides, saponins, steroids, and tannins. The present study indicates that the tested plant can be an important source of antibacterial agents and recommends that the active phytoconstituents be isolated, identified, and screened individually for activities and also subjected further for in vivo and toxicological studies.

Contents, Construction Methods, Data Resources, and Functions Comparative Analysis of Bacteria Databases

Many bacterial-related databases are developed to meet the researchers' needs of analysis and search for a number of bacterial information. However, these databases have different data resources, construction methods, data formats, and analysis tools. It's difficult for researchers to select appropriate databases and analysis tools to promote their researches. In the paper, we compared the contents, construction methods, data sources, update frequency, scope and scale of data, analysis tools, and features of nine famous bacterial databases: CARD, EffectiveDB, MBGD, MPD, PATRCI, PHI-base, VFDB, gcMeta and SILVA, and help researchers to better make better use of these databases. In addition, we also hope this review can help researchers develop a more comprehensive database and better tools to meet the needs of researchers.

Analysis of protein targets in pathogen-host interaction in infectious diseases: a case study on Plasmodium falciparum and Homo sapiens interaction network

Infection and disease progression is the outcome of protein interactions between pathogen and host. Pathogen, the role player of Infection, is becoming a severe threat to life as because of its adaptability toward drugs and evolutionary dynamism in nature. Identifying protein targets by analyzing protein interactions between host and pathogen is the key point. Proteins with higher degree and possessing some topologically significant graph theoretical measures are found to be drug targets. On the other hand, exceptional nodes may be involved in infection mechanism because of some pathway process and biologically unknown factors. In this article, we attempt to investigate characteristics of host-pathogen protein interactions by presenting a comprehensive review of computational approaches applied on different infectious diseases. As an illustration, we have analyzed a case study on infectious disease malaria, with its causative agent Plasmodium falciparum acting as 'Bait' and host, Homo sapiens/human acting as 'Prey'. In this pathogen-host interaction network based on some interconnectivity and centrality properties, proteins are viewed as central, peripheral, hub and non-hub nodes and their significance on infection process. Besides, it is observed that because of sparseness of the pathogen and host interaction network, there may be some topologically unimportant but biologically significant proteins, which can also act as Bait/Prey. So, functional similarity or gene ontology mapping can help us in this case to identify these proteins.

Resistance to Antibiotics and Antifungal Medicinal Products: Can Complementary and Alternative Medicine Help Solve the Problem in Common Infection Diseases? The Introduction of a Dutch Research Consortium

The increase of antibiotic resistance worldwide, rising numbers of deaths and costs associated with this, and the fact that hardly any new antimicrobial drugs have been developed during the last decade have increased the interest in Complementary and Alternative Medicine (CAM) therapeutic interventions, if proven safe and effective. Observational studies on clinical CAM practices demonstrate positive effects of treatment of infections with CAM therapies (clinical effects, patient satisfaction) in combination with small percentages of antibiotics prescription. However, Cochrane reviews and other studies demonstrate that in most instances the quality of clinical trials on CAM treatment of infections is currently too low to provide sufficient evidence. Therefore a Dutch consortium on (in vitro and clinical) scientific research on CAM and antibiotic resistance has been formed. The aim and objective of the consortium is to establish an enduring partnership and to develop expertise to further develop and investigate safe and effective CAM treatments for infectious diseases of humans (and animals). A first ongoing project on the development of safe and effective biobased CAM antimycotics in women with (recurrent) vaginal candidiasis infection is introduced.

Combating pathogenic microorganisms using plant-derived antimicrobials: a minireview of the mechanistic basis

The emergence of antibiotic resistance in pathogenic bacteria has led to renewed interest in exploring the potential of plant-derived antimicrobials (PDAs) as an alternative therapeutic strategy to combat microbial infections. Historically, plant extracts have been used as a safe, effective, and natural remedy for ailments and diseases in traditional medicine. Extensive research in the last two decades has identified a plethora of PDAs with a wide spectrum of activity against a variety of fungal and bacterial pathogens causing infections in humans and animals. Active components of many plant extracts have been characterized and are commercially available; however, research delineating the mechanistic basis of their antimicrobial action is scanty. This review highlights the potential of various plant-derived compounds to control pathogenic bacteria, especially the diverse effects exerted by plant compounds on various virulence factors that are critical for pathogenicity inside the host. In addition, the potential effect of PDAs on gut microbiota is discussed.

Barriers and bridges to infection prevention and control: results of a qualitative case study of a Netherlands' surgical unit

OBJECTIVES

The objectives of the study are to observe the overall work environment including infection prevention and control (IP&C) practices on the target surgical unit; to analyse the policies and procedures in the hospital and unit environments; to analyse the barriers and bridges to IP&C that practitioners identify in visual narratives of their unit environment and to collect monthly specific IP&C-related anonymised data.

DESIGN

In this qualitative case study analysis, a socio-ecological approach on health systems informed the research design and provided a framework to better understand the complexity of implementing effective IP&C.

SETTING

The study was conducted on a surgical unit at a Netherlands' hospital that reported successful reductions in the prevalence of targeted multidrug-resistant organisms.

METHODS

Research methods included unit observations (n=3), review of relevant policies and procedures, five practitioner-led photo walkabouts of the unit (n=7), three photo elicitation focus groups with practitioners (n=13) and the review of related IP&C data.

RESULTS

The findings indicate some conditions and processes present that may influence the low prevalence of multidrug-resistant organisms, including the 'search and destroy' active surveillance strategy, low occupancy rates, a centralised bed cleaning system and the presence of an active grass roots Hygiene in Practice group, which engages practitioners in several ongoing activities to promote IP&C on the units.

CONCLUSIONS

Further research on the benefits of practitioner-led community of practices on IP&C practices such as the Hygiene in Practice group is also recommended. Additional case studies to compare theses practices with other acute care hospital around the world would be a valuable way to better understand what IP&C programmes are most effective in which contexts and for what reasons. Further data are available by contacting the primary author directly.

An integrative review of infection prevention and control programs for multidrug-resistant organisms in acute care hospitals: a socio-ecological perspective

BACKGROUND

The infection rates of multidrug-resistant organisms (MDRO) are increasing in Canada and the United States. The prevention and control of MDRO infections remain an important issue in acute care hospitals. Although comprehensive infection prevention and control programs have been recommended, there is little evidence to date of their effectiveness or of what aspects are most important.

OBJECTIVES

Our objectives were to review and critique the literature on the relationship between an MDRO infection and control program and MDRO rates in acute care hospitals.

METHODS

Studies including original research published between January 1, 1998, and May 14, 2009, were identified through MEDLINE, CINAHL, EMBASE, PUBMED, The Cochrane Library, and expert consultation. A comprehensive search strategy was developed with a librarian to find studies that covered the main subject areas of this integrative review.

RESULTS

Of the 1,382 papers retrieved, 47 were reviewed, and 32 studies met the inclusion criteria. The interventions in the included studies were assessed using the tier 1/tier 2 framework. A total of 18 (56.25%) studies had an administrative measure as an intervention; 20 (62.5%) studies had education and training of health care personnel; 8 (25.0%) studies had judicious use of antimicrobial agents; 17 (53.1%) studies used surveillance; 24 (75.0%) studies had infection control precautions to prevent transmission; 7 studies (21.9%) introduced environmental measures; and 9 (28.1%) studies used patient decolonization. Although all the 32 studies were quasiexperimental studies, only 2 (5.9%) studies provided sample size calculations, and only 5 studies reported confounding factors. Whereas 27 used an interrupted time series design and 2 were controlled pre- and post-intervention designs, 3 were pre- and post-intervention without control groups.

CONCLUSION

This integrative review demonstrated that the evidence of the relationship between MDRO infection prevention and control programs and the rates of MDRO is weak. Although major methodologic weaknesses exist in the published literature making it not possible to exclude other plausible explanations for the reduction of the acquisition of MDRO, the overall evidence does support the use of multiple interventions to reduce the rates of MDRO in acute care hospitals. Whereas it is unclear which bundles of interventions are effective, there is a clear suggestion that multiple simultaneous interventions can be effective in reducing MDRO infections. In addition, despite the limitations of interrupted time series, multiple studies employing active surveillance cultures were associated with reduced MDRO infections. Future individual reports of outbreaks and intervention studies should be written in a standardized manner using the recommended Outbreak Reports and Intervention Studies of Nosocomial Infection (ORION) guidelines. Further research is needed on the proposed tier 1/tier 2 framework clearly indicating all the interventions implemented.

An integrative review of the current evidence on the relationship between hand hygiene interventions and the incidence of health care-associated infections

BACKGROUND

The objectives of this integrative review were to critically examine the overall state of the current evidence on the relationship between hand hygiene interventions and the incidence of health care-associated infections (HCAIs) in acute care and long-term care settings, and offer recommendations for future directions in the field based on our findings.

METHODS

We searched for original research and reviews of research published between January 1, 1996, and July 31, 2006. Studies were identified through the electronic databases Medline, CINAHL, EMBASE, PUBMED, the Cochrane Library, and through expert consultation. Our comprehensive search strategy included all English articles for which hand hygiene or handwashing-related terms were combined with HCAIs. All studies that investigated a relationship between hand hygiene practices and HCAIs in acute care facilities were considered. These hand hygiene practices included the initiation of multimodal hand hygiene initiatives, the introduction of alcohol sanitizers, the implementation or changes of the infection control practices or infection control policies, and other organizational interventions. Studies only examining hand hygiene compliance, efficacy of alcohol hand gels, plain soap, and antimicrobial soap in reducing bacteria count recovered from hands were excluded.

RESULTS

Of the 1120 articles retrieved, 35 publications, including 4 reviews of research discussed at the outset of this article, met our inclusion criteria. The remaining 31 eligible original studies included 18 (58.07%) before and after studies without control groups, 4 (12.90%) before and after studies with a control group, 3 (9.68%) cohort studies with no control group, 4 (12.90%) cohort studies with a control group, and 2 (6.45%) randomized trials. Over 50% (16 or 31) of the studies were conducted in the U.S. Two independent reviewers conducted independent evaluations of all eligible studies, critiquing and scoring each study using a rating scale for examining the fatal flaws of quasi-experimental and before and after studies.

CONCLUSIONS

There is a lack of rigorous evidence linking specific hand hygiene interventions with the prevention of HCAIs. The varied nature of the interventions used and the diverse factors affecting the acquisition of HCAIs make it difficult to show the specific effect of hand hygiene alone. The most frequent methodologies currently used in this research area are before and after observational studies without a control comparison group. Based on these findings, we recommend that researchers used a modified version of Larson's 2005 criteria to guide the design and conduct of future before and after observational studies in this area. We also argue that as we accumulate stronger evidence of which interventions are most effective, we need to develop additional research approaches to study how organizations succeed and fail in fostering the uptake of evidence-based hand hygiene interventions.

The co-evolution of host cationic antimicrobial peptides and microbial resistance

Endogenous cationic antimicrobial peptides (CAMPs) are among the most ancient and efficient components of host defence. It is somewhat of an enigma that bacteria have not developed highly effective CAMP-resistance mechanisms, such as those that inhibit many therapeutic antibiotics. Here, we propose that CAMPs and CAMP-resistance mechanisms have co-evolved, leading to a transient host-pathogen balance that has shaped the existing CAMP repertoire. Elucidating the underlying principles of this process could help in the development of more sustainable antibiotics.

A novel approach to characterise pathogen candidate genetic polymorphisms involved in clinical outcome

Understanding the key factors influencing the clinical outcome of an infection is crucial for early diagnosis and optimised treatment. Despite widespread recognition of the importance of the genetics composition of pathogens, most efforts so far have focused on characterising disease and susceptibility genes in humans. Here, we propose a new flexible and powerful methodological framework to detect candidate genetic polymorphisms influencing clinical outcome from pathogen genomes. The rationale is to use well-supported clades in a phylogeny as statistical predictors for clinical outcomes rather than the individual polymorphisms themselves. This greatly increases the statistical power to detect candidate polymorphisms when analysing a large number of variable sites. In a second step, the candidate polymorphisms are recovered by characterising the polymorphisms that most strongly support the clades predicting the clinical outcome. The modelling approach further allows including host factors and testing for possible interactions between factors. We illustrate the approach by an application on a dataset of hepatitis B polymerase genes. The statistical model retains age at infection as well as six candidate polymorphisms as predictors for clinical outcome (acute, chronic and fulminant). The method is straightforward to apply and computationally effective. While the approach is focused on detecting candidate polymorphisms from pathogen genomes, the method might be more broadly applied for characterising the link between genotype and phenotype while statistically controlling for environmental factors.

Antimicrobial resistance determinants and future control

At the beginning of the 21st century, antimicrobial resistance is common, has developed against every class of antimicrobial drug, and appears to be spreading into new clinical niches. We describe determinants likely to influence the future epidemiology and health impact of antimicrobial-resistant infections. Understanding these factors will ultimately optimize preventive strategies for an unpredictable future.

VFDB: a reference database for bacterial virulence factors

Bacterial pathogens continue to impose a major threat to public health worldwide in the 21st century. Intensified studies on bacterial pathogenesis have greatly expanded our knowledge about the mechanisms of the disease processes at the molecular level over the last decades. To facilitate future research, it becomes necessary to form a database collectively presenting the virulence factors (VFs) of various medical significant bacterial pathogens. The aim of virulence factor database (VFDB) (http://www.mgc.ac.cn/VFs/) is to provide such a source for scientists to rapidly access to current knowledge about VFs from various bacterial pathogens. VFDB is comprehensive and user-friendly. One can search VFDB by browsing each genus or by typing keywords. Furthermore, a BLAST search tool against all known VF-related genes is also available. VFDB provides a unified gateway to store, search, retrieve and update information about VFs from various bacterial pathogens.