In silico screening for identification of novel β-1,3-glucan synthase inhibitors using pharmacophore and 3D-QSAR methodologies

The enzyme β-1,3-glucan synthase, which catalyzes the synthesis of β-1,3-glucan, an essential and unique structural component of the fungal cell wall, has been considered as a promising target for the development of less toxic anti-fungal agents. In this study, a robust pharmacophore model was developed and structure activity relationship analysis of 42 pyridazinone derivatives as β-1,3-glucan synthase inhibitors were carried out. A five-point pharmacophore model, consisting of two aromatic rings (R) and three hydrogen bond acceptors (A) was generated. Pharmacophore based 3D-QSAR model was developed for the same reported data sets. The generated 3D-QSAR model yielded a significant correlation coefficient value (R² = 0.954) along with good predictive power confirmed by the high value of cross-validated correlation coefficient (Q² = 0.827). Further, the pharmacophore model was employed as a 3D search query to screen small molecules database retrieved from ZINC to select new scaffolds. Finally, ADME studies revealed the pharmacokinetic efficiency of these compounds.

Emerging infections due to filamentous fungi in humans and animals: only the tip of the iceberg?

Over the last few decades, the number of patients susceptible to invasive filamentous fungal infections has steadily increased, especially in populations suffering from hematological diseases. The pathogens responsible for such mycoses are now quite well characterized, such as Aspergillus spp. - the most commonly isolated mold -, Mucorales, Fusarium spp., Scedosporium spp. or melanized fungi. An increase in the incidence of this category of 'emerging' fungi has been recently highlighted, evoking a shift in fungal ecology. Starting from these medical findings, taking a step back and adopt a wider perspective offers possible explanations of this phenomenon on an even larger scale than previously reported. In this review, we illustrate the link between emerging fungi in medicine and changes in ecology or human behaviours, and we encourage integrative approaches to apprehend the adverse effects of progress and develop preventive measures in vast domains, such as agriculture or medicine.

Notes from the Field: Probable Mucormycosis Among Adult Solid Organ Transplant Recipients at an Acute Care Hospital - Pennsylvania, 2014-2015

On September 17, 2015, the Pennsylvania Department of Health (PADOH) notified CDC of a cluster of three potentially health care-associated mucormycete infections that occurred among solid organ transplant recipients during a 12-month period at hospital A. On September 18, hospital B reported that it had identified an additional transplant recipient with mucormycosis. Hospitals A and B are part of the same health care system and are connected by a pedestrian bridge. PADOH requested CDC's assistance with an on-site investigation, which started on September 22, to identify possible sources of infection and prevent additional infections.

Infection in cystic fibrosis: impact of the environment and climate

In many countries numbers of adults with cystic fibrosis (CF) exceed that of children, with median survival predicted to surpass 50 years. Increasing longevity is, in part, due to intensive therapies including eradication of early infection and suppressive therapies and pulmonary exacerbations. Initial infections with common CF pathogens are thought to arise from the natural environment. We review the impact of climate and environment on infection in CF. Specifically, several studies indicate that higher ambient temperatures, proximity to the equator and the summer season may be linked to the increased prevalence of Pseudomonas aeruginosa in people with CF. The environment may also play an important role in the acquisition of Gram negative organisms other than P. aeruginosa. There is emerging data suggesting that climatic and environmental factors are likely to impact on the risk of infection with NTM and fungi in people which are found extensively throughout the natural environment.

Infection Prevention in Transplantation

The number of patients undergoing hematopoietic cell and solid organ transplantation are increasing every year, as are the number of centers both transplanting and caring for these patients. Improvements in transplant procedures, immunosuppressive regimens, and prevention of transplant-associated complications have led to marked improvements in survival in both populations. Infections remain one of the most important sources of excess morbidity and mortality in transplant, and therefore, infection prevention strategies are a critical element for avoiding these complications in centers caring for high-risk patients. This manuscript aims to provide an update of recent data on prevention of major healthcare-associated infections unique to transplantation, reviews the emergence of antimicrobial resistant infections, and discusses updated strategies to both identify and prevent transmission of these pathogens in transplant recipients.

Infection Prevention and Control Issues After Solid Organ Transplantation

Infections are an important cause of morbidity and mortality in solid organ transplant recipients. Consequently, infection prevention is an essential component of any organ transplant program. Given their frequent and often prolonged contact with the healthcare system, solid organ transplant recipients are at high risk for healthcare-associated infections, including those caused by antibiotic-resistant organisms. In this chapter we review several different healthcare-associated infections of importance to transplant recipients, including those caused by bacterial, viral, and fungal organisms. We also describe infection prevention and control strategies applicable to this patient population. These practices focus on clinical interventions and environmental controls designed to prevent the spread of potentially pathogenic organisms in the healthcare setting. We also describe post-exposure interventions applicable to solid organ transplant recipients exposed to potential pathogens in order to reduce their risk of subsequent infection.

Diagnostic of Fungal Infections Related to Biofilms

Fungal biofilm-related infections, most notably those caused by the Candida and Aspergillus genera, need to be diagnosed accurately and rapidly to avoid often unfavorable outcomes. Despite diagnosis of these infections is still based on the traditional histopathology and culture, the use of newer, rapid methods has enormously enhanced the diagnostic capability of a modern clinical mycology laboratory. Thus, while accurate species-level identification of fungal isolates can be achieved with turnaround times considerably shortened, nucleic acid-based or antigen-based detection methods can be considered useful adjuncts for the diagnosis of invasive forms of candidiasis and aspergillosis. Furthermore, simple, reproducible, and fast methods have been developed to quantify biofilm production by fungal isolates in vitro. In this end, isolates can be categorized as low, moderate, or high biofilm-forming, and this categorization may reflect their differential response to the conventional antifungal therapy. By means of drug susceptibility testing performed on fungal biofilm-growing isolates, it is now possible to evaluate not only the activity of conventional antifungal agents, but also of novel anti-biofilm agents. Despite this, future diagnostic methods need to target specific biofilm components/molecules, in order to provide a direct proof of the presence of this growth phenotype on the site of infection. In the meantime, our knowledge of the processes underlying the adaptive drug resistance within the biofilm has put into evidence biofilm-specific molecules that could be potentially helpful as therapeutic targets. Surely, the successful management of clinically relevant fungal biofilms will rely upon the advancement and/or refinement of these approaches.

Seasonal Distribution of Fungi in Soil Found in Two Hospitals in Bandar Abbas, Iran

INTRODUCTION

Fungal contamination in hospitals has been a major health concern, especially in immunosuppressed patients. Construction programs increase the risk of fungal contaminations in hospitals. This study aimed to monitor and compare fungal contamination in two hospitals in Bandar Abbas, Iran, one of which was undergoing construction. Furthermore, the study determined the seasonal variations in the prevalence of fungi identified in the two hospitals.

METHODS

This study was conducted during April-December 2014 on 146 soil samples collected from the Shahid Mohammadi Hospital that was under construction and the Shariati Hospital that was not involved in any construction program. The soil samples were collected in the morning from the dust on the ground. Statistical analysis was performed using the chi-squared test.

RESULTS

Among the fungal cultures, 83.56% were found to be positive. We identified 122 fungal isolates, representing 16 genera, 13 of the genera were isolated from Shahid Mohammadi Hospital and 14 were isolated from Shariati Hospital. Aspergillus was the dominant fungus in both hospitals. In Shariati Hospital, 100% of Aspergiluss niger were isolated in the summer. In the spring, Mocur was dominant in both hospitals, and, in the winter, Rhizopus spp. was the dominant fungus in Shahid Mohammadi Hospital (55.5%); however, this fungus was dominant in spring in Shariati Hospital (66.7%). In Shariati Hospital, Scopulariopsis, Drechslera, Penicillium spp., and Yeasts were present only in the fall, whereas yeast was the dominant fungus in summer (100%) in Shahid Mohammadi Hospital. There were not significant differences between two hospitals, with the exception of Fusarium spp., which was more frequent in Shariati Hospital, where no renovation was taking place (p = 0.008).

CONCLUSION

Our results indicated that specific ecological niches existed in the two general hospitals in Bandar Abbas. Special attention should be paid to environmental control programs. It is recommended that soil exposure be considered in patients' histories in addition to the current focus on infections related to food and water.

Non-Seasonal Variation of Airborne Aspergillus Spore Concentration in a Hospital Building

Nosocomial fungal infections are gaining increased attention from infectiologists. An adequate investigation into the levels of airborne Aspergillus and other fungal spores in hospital settings, under normal conditions, is largely unknown. We monitored airborne spore contamination in a Swiss hospital building in order to establish a seasonally-dependent base-line level. Air was sampled using an impaction technique, twice weekly, at six different locations over one year. Specimens were seeded in duplicate on Sabouraud agar plates. Grown colonies were identified to genus levels. The airborne Aspergillus spore concentration was constantly low throughout the whole year, at a median level of 2 spores/m³ (inter-quartile range = IQR 1-4), and displayed no seasonal dependency. The median concentration of other fungal spores was higher and showed a distinct seasonal variability with the ambient temperature change during the different seasons: 82 spores/m³ (IQR 26-126) in summer and 9 spores/m³ (IQR 6-15) in winter. The spore concentration varied considerably between the six sampling sites in the building (10 to 26 spores/m³). This variability may explain the variability of study results in the literature.