Differences in pathogenicity and clinical syndromes due to Aspergillus fumigatus and Aspergillus flavus

Infection Control Department at Santa Casa Complexo Hospitalar, Porto Alegre, and Post-Graduation Program in Pulmonary Sciences, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Brazil.
Medical mycology: official publication of the International Society for Human and Animal Mycology (Impact Factor: 2.34). 01/2009; 47 Suppl 1(Suppl 1):S261-70. DOI: 10.1080/13693780802247702
Source: PubMed


Most of the information available about Aspergillus infections has originated from the study of A. fumigatus, the most frequent species in the genus. This review aims to compare the pathogenicity and clinical aspects of Aspergillosis caused by A. fumigatus an A. flavus. Experimental data suggests that A. flavus is more virulent than A. fumigatus. However, these were mostly models of disseminated Aspergillus infection which do not properly mimic the physiopathology of invasive aspergillosis, a condition that is usually acquired by inhalation. In addition, no conclusive virulence factor has been identified for Aspergillus species. A. flavus is a common cause of fungal sinusitis and cutaneous infections. Chronic conditions such as chronic cavitary pulmonary aspergillosis and sinuses fungal balls have rarely been associated with A. flavus. The bigger size of A. flavus spores, in comparison to those of A. fumigatus spores, may favour their deposit in the upper respiratory tract. Differences between these species justify the need for a better understanding of A. flavus infections.

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Available from: Alessandro Comarú Pasqualotto
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    • "Exactly why Iran and other countries in the Middle East have a much higher incidence of disease due to A. flavus than is seen in other regions is not fully understood. Generally it is assumed that the hot and dry local climate favours growth of desiccation- and thermo-tolerant species including A. flavus, and their higher environmental presence translates into a higher likelihood of infection [35]. However, parts of Australia have similar climatic conditions, and a recent survey found Australian peanut growing soils to be exceptionally high in A. flavus propagules, with a mean of >5,000 (SD > 20,000) CFU/g [33], yet A. flavus is a rare cause of infection in Australia. "
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    ABSTRACT: Background Aspergillus flavus is intensively studied for its role in infecting crop plants and contaminating produce with aflatoxin, but its role as a human pathogen is less well understood. In parts of the Middle East and India, A. flavus surpasses A. fumigatus as a cause of invasive aspergillosis and is a significant cause of cutaneous, sinus, nasal and nail infections. Methods A collection of 45 clinical and 10 environmental A. flavus isolates from Iran were analysed using Variable-Number Tandem-Repeat (VNTR) markers with MICROSAT and goeBURST to determine their genetic diversity and their relatedness to clinical and environmental A. flavus isolates from Australia. Phylogeny was assessed using partial β-tubulin and calmodulin gene sequencing, and mating type was determined by PCR. Antifungal susceptibility testing was performed on selected isolates using a reference microbroth dilution method. Results There was considerable diversity in the A. flavus collection, with no segregation on goeBURST networks according to source or geographic location. Three Iranian isolates, two from sinus infections and one from a paranasal infection grouped with Aspergillus minisclerotigenes, and all produced B and G aflatoxin. Phylogenic analysis using partial β-tubulin and calmodulin sequencing confirmed two of these as A. minisclerotigenes, while the third could not be differentiated from A. flavus and related species within Aspergillus section flavi. Based on epidemiological cut-off values, the A. minisclerotigens and A. flavus isolates tested were susceptible to commonly used antifungal drugs. Conclusions This is the first report of human infection due to A. minisclerotigenes, and it raises the possiblity that other species within Aspergillus section flavi may also cause clinical disease. Clinical isolates of A. flavus from Iran are not distinct from Australian isolates, indicating local environmental, climatic or host features, rather than fungal features, govern the high incidence of A. flavus infection in this region. The results of this study have important implications for biological control strategies that aim to reduce aflatoxin by the introduction of non-toxigenic strains, as potentially any strain of A. flavus, and closely related species like A. minisclerotigenes, might be capable of human infection.
    Full-text · Article · Jul 2014 · BMC Infectious Diseases
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    • "CMRS is clinically characterised by a variable association of symptoms including anterior or posterior, unilateral or sometimes bilateral discharge (purulent, watery, or mucoid), sinus or dental pain, nasal obstruction, hypo-or anosmia facial headaches that intensify in the evening while bending, halitosis, and occasionally coughing [17]. Even if there is no significant difference between classic and odontogenic CMR, anterior discharge, sinus pain, nagging pain of the upper teeth of the damaged side that increases during occlusion and tooth mobilisation, and halitosis seem to be more frequent in the latter [21] [25]. Percussion of the causal tooth may reveal an abnormal sensitivity, unless endodontic filling has been performed. "
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    ABSTRACT: Objectives. The aim of this systematic review is to study the causes of odontogenic chronic maxillary rhinosinusitis (CMRS), the average age of the patients, the distribution by sex, and the teeth involved. Materials and Methods. We performed an EMBASE-, Cochrane-, and PubMed-based review of all of the described cases of odontogenic CMRS from January 1980 to January 2013. Issues of clinical relevance, such as the primary aetiology and the teeth involved, were evaluated for each case. Results. From the 190 identified publications, 23 were selected for a total of 674 patients following inclusion criteria. According to these data, the main cause of odontogenic CMRS is iatrogenic, accounting for 65.7% of the cases. Apical periodontal pathologies (apical granulomas, odontogenic cysts, and apical periodontitis) follow them and account for 25.1% of the cases. The most commonly involved teeth are the first and second molars. Conclusion. Odontogenic CMRS is a common disease that must be suspected whenever a patient undergoing dental treatment presents unilateral maxillary chronic rhinosinusitis.
    Full-text · Article · Apr 2014 · International Journal of Otolaryngology
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    • "A low conidia count may not produce infection. According to Pasqualotto et al25, Aspergillus species caused death when as few as 102 spores were inoculated. Other pathogenic factors detected in patients with invasive aspergillosis are sensory deprivation (environmental pH), mutational restriction of nutrient acquisition, siderophore and amino acid biosynthesis, extracellular elastolytic proteases, gliotoxin and hyaronic acid. "
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    ABSTRACT: Invasive fungal infections are a significant health problem in immunocompromised patients. The clinical manifestations vary and can range from colonization in allergic bronchopulmonary disease to active infection in local aetiologic agents. Many factors influence the virulence and pathogenic capacity of the microorganisms, such as enzymes including extracellular phospholipases, lipases and proteinases, dimorphic growth in some Candida species, melanin production, mannitol secretion, superoxide dismutase, rapid growth and affinity to the blood stream, heat tolerance and toxin production. Infection is confirmed when histopathologic examination with special stains demonstrates fungal tissue involvement or when the aetiologic agent is isolated from sterile clinical specimens by culture. Both acquired and congenital immunodeficiency may be associated with increased susceptibility to systemic infections. Fungal infection is difficult to treat because antifungal therapy for Candida infections is still controversial and based on clinical grounds, and for molds, the clinician must assume that the species isolated from the culture medium is the pathogen. Timely initiation of antifungal treatment is a critical component affecting the outcome. Disseminated infection requires the use of systemic agents with or without surgical debridement, and in some cases immunotherapy is also advisable. Preclinical and clinical studies have shown an association between drug dose and treatment outcome. Drug dose monitoring is necessary to ensure that therapeutic levels are achieved for optimal clinical efficacy. The objectives of this review are to discuss opportunistic fungal infections, diagnostic methods and the management of these infections.
    Full-text · Article · Feb 2014 · The Indian Journal of Medical Research
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