scholarly journals Iron Assimilation during Emerging Infections Caused by Opportunistic Fungi with emphasis on Mucorales and the Development of Antifungal Resistance

Genes ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1296
Author(s):  
Felicia Adelina Stanford ◽  
Kerstin Voigt
Keyword(s):  
Fungal Pathogens ◽  
Current Knowledge ◽  
Iron Acquisition ◽  
Immunocompromised Host ◽  
Antifungal Resistance ◽  
Limiting Factor ◽  
Emerging Infections ◽  
Opportunistic Fungi ◽  
Development Of Resistance ◽  
Iron Assimilation

Iron is a key transition metal required by most microorganisms and is prominently utilised in the transfer of electrons during metabolic reactions. The acquisition of iron is essential and becomes a crucial pathogenic event for opportunistic fungi. Iron is not readily available in the natural environment as it exists in its insoluble ferric form, i.e., in oxides and hydroxides. During infection, the host iron is bound to proteins such as transferrin, ferritin, and haemoglobin. As such, access to iron is one of the major hurdles that fungal pathogens must overcome in an immunocompromised host. Thus, these opportunistic fungi utilise three major iron acquisition systems to overcome this limiting factor for growth and proliferation. To date, numerous iron acquisition pathways have been fully characterised, with key components of these systems having major roles in virulence. Most recently, proteins involved in these pathways have been linked to the development of antifungal resistance. Here, we provide a detailed review of our current knowledge of iron acquisition in opportunistic fungi, and the role iron may have on the development of resistance to antifungals with emphasis on species of the fungal basal lineage order Mucorales, the causative agents of mucormycosis.

scholarly journals Hidden Host Plant Associations of Soilborne Fungal Pathogens: An Ecological Perspective

2013 ◽  
Vol 103 (6) ◽  
pp. 538-544 ◽  
Author(s):  
Glenna M. Malcolm ◽  
Gretchen A. Kuldau ◽  
Beth K. Gugino ◽  
María del Mar Jiménez-Gasco
Keyword(s):  
Host Plant ◽  
Population Biology ◽  
Fungal Pathogens ◽  
Current Knowledge ◽  
Vascular Plant ◽  
Disease Symptoms ◽  
Nonhost Plant ◽  
Plant Associations ◽  
Definition Of ◽  
Forest Plants

Much of the current knowledge on population biology and ecology of soilborne fungal pathogens has been derived from research based on populations recovered from plants displaying disease symptoms or soil associated with symptomatic plants. Many soilborne fungal pathogens are known to cause disease on a large number of crop plants, including a variety of important agronomical, horticultural, ornamental, and forest plants species. For instance, the fungus Verticillium dahliae causes disease on >400 host plants. From a phytopathological perspective, plants on which disease symptoms have not been yet observed are considered to be nonhosts for V. dahliae. This term may be misleading because it does not provide information regarding the nature of the plant–fungus association; that is, a nonhost plant may harbor the fungus as an endophyte. Yet, there are numerous instances in the literature where V. dahliae has been isolated from asymptomatic plants; thus, these plants should be considered hosts. In this article, we synthesize scattered research that indicates that V. dahliae, aside from being a successful and significant vascular plant pathogen, may have a cryptic biology on numerous asymptomatic plants as an endophyte. Thus, we suggest here that these endophytic associations among V. dahliae and asymptomatic plants are not unusual relationships in nature. We propose to embrace the broader ecology of many fungi by differentiating between “symptomatic hosts” as those plants in which the infection and colonization by a fungus results in disease, and “asymptomatic hosts” as those plants that harbor the fungus endophytically and are different than true nonhosts that should be used for plant species that do not interact with the given fungus. In fact, if we broaden our definition of “host plant” to include asymptomatic plants that harbor the fungus as an endophyte, it is likely that the host ranges for some soilborne fungal pathogens are much larger than previously envisioned. By ignoring the potential for soilborne fungal pathogens to display endophytic relationships, we leave gaps in our knowledge about the population biology and ecology, persistence, and spread of these fungi in agroecosystems.

scholarly journals Impact of the Resistance Responses to Stress Conditions Encountered in Food and Food Processing Environments on the Virulence and Growth Fitness of Non-Typhoidal Salmonellae

Foods ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 617
Author(s):  
Silvia Guillén ◽  
Laura Nadal ◽  
Ignacio Álvarez ◽  
Pilar Mañas ◽  
Guillermo Cebrián
Keyword(s):  
Stress Resistance ◽  
Food Processing ◽  
Current Knowledge ◽  
Foodborne Pathogen ◽  
Stress Conditions ◽  
Bacterial Cells ◽  
Modified Atmospheres ◽  
Development Of Resistance ◽  
Salmonella Virulence ◽  
Short Time

The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness.

scholarly journals Succinate dehydrogenase inhibitor (SDHI) fungicide resistance prevention strategy

2011 ◽  
Vol 64 ◽  
pp. 119-124 ◽  
Author(s):  
A.H. McKay ◽  
G.C. Hagerty ◽  
G.B. Follas ◽  
M.S. Moore ◽  
M.S. Christie ◽  
...  
Keyword(s):  
New Zealand ◽  
High Risk ◽  
Succinate Dehydrogenase ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Resistance Management ◽  
Resistance Development ◽  
Development Of Resistance ◽  
Action Committee ◽  
Succinate Dehydrogenase Inhibitor

Succinate dehydrogenase inhibitor (SDHI) fungicides are currently represented in New Zealand by eight active ingredients bixafen boscalid carboxin fluaxapyroxad fluopyram isopyrazam penthiopyrad and sedaxane They are either currently registered or undergoing development in New Zealand for use against a range of ascomycete and basiodiomycete pathogens in crops including cereals ryegrass seed apples pears grapes stonefruit cucurbits and kiwifruit These fungicides are considered to have medium to high risk of resistance development and resistance management is recommended by the Fungicide Resistance Action Committee (FRAC) in Europe Guidelines are presented for use of SDHI fungicides in New Zealand to help avoid or delay the development of resistance in the fungal pathogens that they target

scholarly journals Can High-Risk Fungicides be Used in Mixtures Without Selecting for Fungicide Resistance?

2014 ◽  
Vol 104 (4) ◽  
pp. 324-331 ◽  
Author(s):  
Alexey Mikaberidze ◽  
Bruce A. McDonald ◽  
Sebastian Bonhoeffer
Keyword(s):  
High Risk ◽  
Disease Control ◽  
Fungicide Resistance ◽  
Fungal Pathogens ◽  
Development Of Resistance ◽  
Population Dynamics Model ◽  
Fungicide Mixtures ◽  
Cost Of Resistance ◽  
Selection For ◽  
Crucial Parameter

Fungicide mixtures produced by the agrochemical industry often contain low-risk fungicides, to which fungal pathogens are fully sensitive, together with high-risk fungicides known to be prone to fungicide resistance. Can these mixtures provide adequate disease control while minimizing the risk for the development of resistance? We present a population dynamics model to address this question. We found that the fitness cost of resistance is a crucial parameter to determine the outcome of competition between the sensitive and resistant pathogen strains and to assess the usefulness of a mixture. If fitness costs are absent, then the use of the high-risk fungicide in a mixture selects for resistance and the fungicide eventually becomes nonfunctional. If there is a cost of resistance, then an optimal ratio of fungicides in the mixture can be found, at which selection for resistance is expected to vanish and the level of disease control can be optimized.

scholarly journals Invasive fungal infections in the immunocompromised host: Mechanistic insights in an era of changing immunotherapeutics

2019 ◽  
Vol 57 (Supplement_3) ◽  
pp. S307-S317 ◽  
Author(s):  
Christopher P Eades ◽  
Darius P H Armstrong-James
Keyword(s):  
Intracellular Signaling ◽  
Fungal Pathogens ◽  
Opportunistic Infections ◽  
Fungal Infections ◽  
Immunocompromised Host ◽  
Adaptive Immune ◽  
Mechanistic Approach ◽  
Molecular Immunology ◽  
Nonspecific Cytotoxicity ◽  
Small Molecular Inhibitors

AbstractThe use of cytotoxic chemotherapy in the treatment of malignant and inflammatory disorders is beset by considerable adverse effects related to nonspecific cytotoxicity. Accordingly, a mechanistic approach to therapeutics has evolved in recent times with small molecular inhibitors of intracellular signaling pathways involved in disease pathogenesis being developed for clinical use, some with unparalleled efficacy and tolerability. Nevertheless, there are emerging concerns regarding an association with certain small molecular inhibitors and opportunistic infections, including invasive fungal diseases. This is perhaps unsurprising, given that the molecular targets of such agents play fundamental and multifaceted roles in orchestrating innate and adaptive immune responses. Nevertheless, some small molecular inhibitors appear to possess intrinsic antifungal activity and may therefore represent novel therapeutic options in future. This is particularly important given that antifungal resistance is a significant, emerging concern. This paper is a comprehensive review of the state-of-the-art in the molecular immunology to fungal pathogens as applied to existing and emerging small molecular inhibitors.

Resistance to antifungal therapies

2017 ◽  
Vol 61 (1) ◽  
pp. 157-166 ◽  
Author(s):  
Rajendra Prasad ◽  
Atanu Banerjee ◽  
Abdul Haseeb Shah
Keyword(s):  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Fungal Infections ◽  
Therapeutic Strategies ◽  
Antifungal Resistance ◽  
Antifungal Drugs ◽  
Therapeutic Interventions ◽  
Medical Professionals ◽  
Comprehensive Understanding ◽  
Novel Targets

The evolution of antifungal resistance among fungal pathogens has rendered the limited arsenal of antifungal drugs futile. Considering the recent rise in the number of nosocomial fungal infections in immunocompromised patients, the emerging clinical multidrug resistance (MDR) has become a matter of grave concern for medical professionals. Despite advances in therapeutic interventions, it has not yet been possible to devise convincing strategies to combat antifungal resistance. Comprehensive understanding of the molecular mechanisms of antifungal resistance is essential for identification of novel targets that do not promote or delay emergence of drug resistance. The present study discusses features and limitations of the currently available antifungals, mechanisms of antifungal resistance and highlights the emerging therapeutic strategies that could be deployed to combat MDR.

scholarly journals Antifungal Resistance Regarding Malassezia pachydermatis: Where Are We Now?

2020 ◽  
Vol 6 (2) ◽  
pp. 93
Author(s):  
Andrea Peano ◽  
Elizabeth Johnson ◽  
Elisa Chiavassa ◽  
Paolo Tizzani ◽  
Jacques Guillot ◽  
...  
Keyword(s):  
Treatment Failure ◽  
Antifungal Agents ◽  
Standard Procedure ◽  
Resistance Mechanisms ◽  
Antifungal Resistance ◽  
Antifungal Drugs ◽  
Malassezia Pachydermatis ◽  
Development Of Resistance ◽  
Ear Canals

Malassezia pachydermatis is a yeast inhabiting the skin and ear canals in healthy dogs. In the presence of various predisposing conditions it can cause otitis and dermatitis, which are treated with multiple antifungal agents, mainly azole derivatives. This manuscript aims to review the available evidence regarding the occurrence of resistance phenomena in this organism. Various findings support the capacity of M. pachydermatis for developing resistance. These include some reports of treatment failure in dogs, the reduced antifungal activity found against yeast isolates sampled from dogs with exposure to antifungal drugs and strains exposed to antifungal agents in vitro, and the description of resistance mechanisms. At the same time, the data reviewed may suggest that the development of resistance is a rare eventuality in canine practice. For example, only three publications describe confirmed cases of treatment failure due to antifungal resistance, and most claims of resistance made by past studies are based on interpretive breakpoints that lack sound support from the clinical perspective. However, it is possible that resistant cases are underreported in literature, perhaps due to the difficulty of obtaining a laboratory confirmation given that a standard procedure for susceptibility testing of M. pachydermatis is still unavailable. These considerations highlight the need for maintaining surveillance for the possible emergence of clinically relevant resistance, hopefully through a shared strategy put in place by the scientific community.

Pathogenic Fungi Isolated from Desiccated Mushrooms, Seaweed, Anchovies and Rice Sticks Imported from the Orient1

1987 ◽  
Vol 50 (11) ◽  
pp. 933-939 ◽  
Author(s):  
NURIA KAZANAS
Keyword(s):  
Intraperitoneal Injection ◽  
Fungal Pathogens ◽  
Sporothrix Schenckii ◽  
Pathogenic Fungi ◽  
Opportunistic Fungi ◽  
Toxigenic Fungi ◽  
Yeast Fungi ◽  
Commercial Sources ◽  
Etiological Agents ◽  
The U.S

Desiccated mushrooms, seaweed, rice sticks and anchovies imported from the Orient were obtained from commercial sources or from products detained by the U.S. Food and Drug Administration and examined for pathogenic fungi. The etiological agents isolated were mycelial and yeast fungi known to produce deep sporotrichosis, phaeohyphomycosis, mycetoma, chromoblastomycosis, candidosis and cryptococcosis. Other fungi isolated were opportunistic fungi and/or producers of mycotoxins. Total mold counts in the foods examined varied from 2 × 102 to 5 × 106. The predominant pathogens in the mushrooms were Sporothrix schenckii and Wangiella dermatitidis, and counts in the mushrooms imported from Thailand and Taiwan were as high as 1 × 106; however, these pathogens were not isolated from rice sticks, seaweed or anchovies. All presumed pathogenic strains were pathogenic for mice by intraperitoneal injection of 1 × 106 to 107 conidia in saline suspension. It was concluded that food can harbor “virulent” fungal pathogens and potentially opportunistic invaders as well as potentially toxigenic fungi.

scholarly journals Identification, Typing, Antifungal Resistance Profile, and Biofilm Formation ofCandida albicansIsolates from Lebanese Hospital Patients

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Ibrahim Bitar ◽  
Roy A. Khalaf ◽  
Houda Harastani ◽  
Sima Tokajian
Keyword(s):  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Recurrent Infection ◽  
Multidrug Resistant ◽  
Antifungal Resistance ◽  
Drug Resistant ◽  
Treatment Regimens ◽  
Evolutionary Relatedness ◽  
Resistant Strains ◽  
Drug Resistant Strains

As leading opportunistic fungal pathogens identification and subtyping ofCandidaspecies are crucial in recognizing outbreaks of infection, recognizing particularly virulent strains, and detecting the emergence of drug resistant strains. In this study our objective was to compare identification ofCandida albicansby the hospitals through the use of conventional versus identification based on the ITS (Internal Transcribed Spacer) and to assess biofilm forming capabilities, drug resistance patterns and correlate these with MLST typing. ITS typing revealed a 21.2% hospital misidentification rate. Multidrug resistance to three drugs out of four tested was detected within 25% of the isolates raising concerns about the followed treatment regimens. Drug resistant strains as well as biofilm formers were phylogenetically related, with some isolates with significant biofilm forming capabilities being correlated to those that were multidrug resistant. Such isolates were grouped closely together in a neighbor-joining tree generated by MLST typing indicating phylogenetic relatedness, microevolution, or recurrent infection. In conclusion, this pilot study gives much needed insight concerningC. albicansisolates circulating in Lebanese hospitals and is the first study of its kind correlating biofilm formation, antifungal resistance, and evolutionary relatedness.

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