Over the past 20 years, exposure to mycotoxin producing mold has been recognized as a significant health risk. Scientific literature has demonstrated mycotoxins as possible causes of human disease in water-damaged buildings (WDB). This study was conducted to determine if selected mycotoxins could be identified in human urine from patients suffering from chronic fatigue syndrome (CFS). Patients (n = 112) with a prior diagnosis of CFS were evaluated for mold exposure and the presence of mycotoxins in their urine. Urine was tested for aflatoxins (AT), ochratoxin A (OTA) and macrocyclic trichothecenes (MT) using Enzyme Linked Immunosorbent Assays (ELISA). Urine specimens from 104 of 112 patients (93%) were positive for at least one mycotoxin (one in the equivocal range). Almost 30% of the cases had more than one mycotoxin present. OTA was the most prevalent mycotoxin detected (83%) with MT as the next most common (44%). Exposure histories indicated current and/or past exposure to WDB in over 90% of cases. Environmental testing was performed in the WDB from a subset of these patients. This testing revealed the presence of potentially mycotoxin producing mold species and mycotoxins in the environment of the WDB. Prior testing in a healthy control population with no history of exposure to a WDB or moldy environment (n = 55) by the same laboratory, utilizing the same methods, revealed no positive cases at the limits of detection.
Aflatoxins (AFs) are highly carcinogenic compounds produced by Aspergillus species in seeds with high lipid and protein contents. It has been known for over 30 years that peptone is not conducive for AF productions, although reasons for this remain unknown.
Ruminant diets include cereals, protein feeds, their by-products as well as hay and grass, grass/legume, whole-crop maize, small grain or sorghum silages. Furthermore, ruminants are annually or seasonally fed with grazed forage in many parts of the World. All these forages could be contaminated by several exometabolites of mycotoxigenic fungi that increase and diversify the risk of mycotoxin exposure in ruminants compared to swine and poultry that have less varied diets. Evidence suggests the greatest exposure for ruminants to some regulated mycotoxins (aflatoxins, trichothecenes, ochratoxin A, fumonisins and zearalenone) and to many other secondary metabolites produced by different species of Alternaria spp. (e.g., AAL toxins, alternariols, tenuazonic acid or 4Z-infectopyrone), Aspergillus flavus (e.g., kojic acid, cyclopiazonic acid or β-nitropropionic acid), Aspergillus fuminatus (e.g., gliotoxin, agroclavine, festuclavines or fumagillin), Penicillium roqueforti and P. paneum (e.g., mycophenolic acid, roquefortines, PR toxin or marcfortines) or Monascus ruber (citrinin and monacolins) could be mainly related to forage contamination. This review includes the knowledge of mycotoxin occurrence reported in the last 15 years, with special emphasis on mycotoxins detected in forages, and animal toxicological issues due to their ingestion. Strategies for preventing the problem of mycotoxin feed contamination under farm conditions are discussed.
Azole resistance in Aspergillus fumigatus: can we retain the clinical use of mold-active antifungal azoles?
- Clinical infectious diseases : an official publication of the Infectious Diseases Society of America
- Published about 5 years ago
Azole resistance in Aspergillus fumigatus has emerged into a global health problem. Although the number of cases of azole-resistant aspergillosis is still limited, resistance mechanisms continue to emerge thereby threatening the role of the azole class in the management of Aspergillus diseases. The majority of cases of azole-resistant disease are due to resistant A. fumigatus originating from the environment. Patient management is difficult due to the absence of patient risk factors, delayed diagnosis and limited treatment options, resulting in poor treatment outcome. International and collaborative efforts are required to understand how resistance develops in the environment in order to allow effective measures to be implemented aimed at retaining the use of azoles both for food production and human medicine.
F901318 is an antifungal agent with a novel mechanism of action and potent activity against Aspergillus spp. An understanding of the pharmacodynamics (PD) of F901318 is required for selection of effective regimens for study in phase II and III clinical trials. Neutropenic murine and rabbit models of invasive pulmonary aspergillosis were used. The primary PD endpoint was serum galactomannan. The relationships between drug exposure and the impacts of dose fractionation on galactomannan, survival, and histopathology were determined. The results were benchmarked against a clinically relevant exposure of posaconazole. In the murine model, administration of a total daily dose of 24 mg/kg of body weight produced consistently better responses with increasingly fractionated regimens. The ratio of the minimum total plasma concentration/MIC (Cmin/MIC) was the PD index that best linked drug exposure with observed effect. An average Cmin (mg/liter) and Cmin/MIC of 0.3 and 9.1, respectively, resulted in antifungal effects equivalent to the effect of posaconazole at the upper boundary of its expected human exposures. This pattern was confirmed in a rabbit model, where Cmin and Cmin/MIC targets of 0.1 and 3.3, respectively, produced effects previously reported for expected human exposures of isavuconazole. These targets were independent of triazole susceptibility. The pattern of maximal effect evident with these drug exposure targets was also apparent when survival and histopathological clearance were used as study endpoints. F901318 exhibits time-dependent antifungal activity. The PD targets can now be used to select regimens for phase II and III clinical trials.IMPORTANCE Invasive fungal infections are common and often lethal. There are relatively few antifungal agents licensed for clinical use. Antifungal drug toxicity and the emergence of drug resistance make the treatment of these infections very challenging. F901318 is the first in a new class of antifungal agents called the orotomides. This class has a novel mechanism of action that involves the inhibition of the fungal enzyme dihydroorotate dehydrogenase. F901318 is being developed for clinical use. A deep understanding of the relationship between dosages, drug concentrations in the body, and the antifungal effect is fundamental to the identification of the regimens to administer to patients with invasive fungal infections. This study provides the necessary information to ensure that the right dose of F901318 is used the first time. Such an approach considerably reduces the risks in drug development programs and ensures that patients with few therapeutic options can receive potentially life-saving antifungal therapy at the earliest opportunity.
Aflatoxin contamination in peanuts poses major challenges for vulnerable populations of sub-Saharan Africa and South Asia. Developing peanut varieties to combat pre-harvest Aspergillus flavus infection and resulting aflatoxin contamination has thus far remained a major challenge, confounded by highly complex peanut-Aspergilli pathosystem. Our study reports achieving high level of resistance in peanut by over expressing (OE) antifungal plant defensins MsDef1 and MtDef4.2, and through host-induced gene silencing (HIGS) of aflM and aflP genes from the aflatoxin biosynthetic pathway. While the former improves genetic resistance to A. flavus infection, the latter inhibits aflatoxin production in the event of infection providing durable resistance against different Aspergillus flavus morphotypes and negligible aflatoxin content in several peanut events/ lines well. A strong positive correlation was observed between aflatoxin accumulation and decline in transcription of the aflatoxin biosynthetic pathway genes in both OE-Def and HIGS lines. Transcriptomic signatures in the resistant lines revealed key mechanisms such as regulation of aflatoxin synthesis, its packaging and export control, besides the role of reactive oxygen species-scavenging enzymes that render enhanced protection in the OE and HIGS lines. This is the first study to demonstrate highly effective biotechnological strategies for successfully generating peanuts that are near-immune to aflatoxin contamination, offering a panacea for serious food safety, health and trade issues in the semi-arid regions. This article is protected by copyright. All rights reserved.
Recently, there has been multi-agency promotion of entomophagy as an environmentally-friendly source of food for the ever increasing human population especially in the developing countries. However, food quality and safety concerns must first be addressed in this context. We addressed these concerns in the present study using the edible stink bug Encosternum delegorguei, which is widely consumed in southern Africa. We analysed for mycotoxins, and health beneficials including antioxidants, amino acids and essential fatty acids using liquid chromatography coupled to quadrupole time of flight mass spectrometry (LC-Qtof-MS) and coupled gas chromatography (GC)-MS. We also performed proximate analysis to determine nutritional components. We identified the human carcinogen mycotoxin (aflatoxin B1) at low levels in edible stink bugs that were stored in traditonally woven wooden dung smeared baskets and gunny bags previously used to store cereals. However, it was absent in insects stored in clean zip lock bags. On the other hand, we identified 10 fatty acids, of which 7 are considered essential fatty acids for human nutrition and health; 4 flavonoids and 12 amino acids of which two are considered the most limiting amino acids in cereal based diets. The edible stink bug also contained high crude protein and fats but was a poor source of minerals, except for phosphorus which was found in relatively high levels. Our results show that the edible stink bug is a nutrient- and antioxidant-rich source of food and health benefits for human consumption. As such, use of better handling and storage methods can help eliminate contamination of the edible stink bug with the carcinogen aflatoxin and ensure its safety as human food.
Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic mycotoxins. Consumption of aflatoxin-contaminated food and commodities poses serious hazards to the health of humans and animals. Turmeric, Curcuma longa L., is a native plant of Southeast Asia and has antimicrobial, antioxidant and antifungal properties. This paper reports the antiaflatoxigenic activities of the essential oil of C. longa and curcumin. The medium tests were prepared with the oil of C. longa, and the curcumin standard at concentrations varied from 0.01% to 5.0%. All doses of the essential oil of the plant and the curcumin standard interfered with mycotoxin production. Both the essential oil and curcumin significantly inhibited the production of aflatoxins; the 0.5% level had a greater than 96% inhibitory effect. The levels of aflatoxin B(1) (AFB(1)) production were 1.0 and 42.7 μg/mL, respectively, for the samples treated with the essential oil of C. longa L. and curcumin at a concentration of 0.5%.
In recent years, Aspergillus species are reported frequently as aetiological agents of fungal keratitis in tropical countries such as India. Our aim was to evaluate the epidemiological features of Aspergillus keratitis cases over a 3-year period in a tertiary eye care hospital and to determine the antifungal susceptibilities of the causative agents. This study included culture proven Aspergillus keratitis cases diagnosed between September 2005 and August 2008. Data including prevalence, predisposing factors and demography were recorded, the isolates were identified by morphological and molecular methods and the minimum inhibitory concentration values of antifungal agents towards the isolates were determined by the microdilution method. Two hundred Aspergillus isolates were identified among 1737 culture proven cases. Most of the aspergilli (75%) proved to be A. flavus, followed by A. fumigatus (11.5%). Sixteen (8%) isolates belonged to species that are recently identified causative agents of mycotic keratitis. Most of the infected patients (88%) were adults ranging from 21 to 70 years of age. Co-existing ocular disease was confirmed in 16.5% of the patients. Econazole, clotrimazole and ketoconazole were notably active against A. flavus. Aspergillus keratitis is a significant problem in patients with ocular lesions in South-Indian States, warranting early diagnosis and initiation of specific antifungal therapy to improve outcome.
Aspergillosis is one of the most common causes of death in captive birds. Aspergillus fumigatus accounts for approximately 95 % of aspergillosis cases and Aspergillus flavus is the second most frequent organism associated with avian infections. In the present study, the fungi were grown from avian clinical samples (post-mortem lung material) and environmental samples (eggs, food and litter). Microsatellite markers were used to type seven clinical avian isolates and 22 environmental isolates of A. flavus. A. flavus was the only species (28 % prevalence) detected in the avian clinical isolates, whereas this species ranked third (19 %) after members of the genera Penicillium (39 %) and Cladosporium (21 %) in the environmental samples. Upon microsatellite analysis, five to eight distinct alleles were detected for each marker. The marker with the highest discriminatory power had eight alleles and a 0.852 D value. The combination of all six markers yielded a 0.991 D value with 25 distinct genotypes. One clinical avian isolate (lung biopsy) and one environmental isolate (egg) shared the same genotype. Microsatellite typing of A. flavus grown from avian and environmental samples displayed an excellent discriminatory power and 100 % reproducibility. This study showed a clustering of clinical and environmental isolates, which were clearly separated. Based upon these results, aspergillosis in birds may be induced by a great diversity of isolates.