Environmental investigations and molecular typing of Aspergillus flavus during an outbreak of postoperative infections

A single-source nosocomial outbreak of Aspergillus flavus uncovered by genotyping

During construction work (2017-2019), an increase in Aspergillus flavus infections was noted among pediatric patients, the majority of whom were receiving amphotericin B prophylaxis. Microsatellite genotyping was used to characterize the outbreak. A total of 153 A. flavus isolates of clinical and environmental origin were included. Clinical isolates included 140 from 119 patients. Eight patients were outbreak-related patients, whereas 111 were outbreak-unrelated patients from Danish hospitals (1994-2023). We further included four control strains. Nine A. flavus isolates were from subsequent air sampling in the outbreak ward (2022-2023). Typing followed Rudramurthy et al.(S. M. Rudramurthy, H. A. de Valk, A. Chakrabarti, J. Meis, and C. H. W. Klaassen, PLoS One 6:e16086, 2011, https://doi.org/10.1371/journal.pone.0016086). Minimum spanning tree (MST) and discriminant analysis of principal components (DAPC) were used for cluster analysis. DAPC analysis placed all 153 isolates in five clusters. Microsatellite marker pattern was clearly distinct for one cluster compared to the others. The same cluster was observed in an MST. This cluster included all outbreak isolates, air-sample isolates, and additional patient isolates from the outbreak hospital, previously undisclosed as outbreak related. The highest air prevalence of A. flavus was found in two technical risers of the outbreak ward, which were then sealed. Follow-up air samples were negative for A. flavus. Microsatellite typing defined the outbreak as nosocomial and facilitated the identification of an in-hospital source. Six months of follow-up air sampling was without A. flavus. Outbreak-related/non-related isolates were easily distinguished with DAPC and MST, as the outbreak clone's distinct marker pattern was delineated in both statistical analyses. Thus, it could be a variant of A. flavus, with a niche ability to thrive in the outbreak-hospital environment.

IMPORTANCE

Aspergillus flavus can cause severe infections and hospital outbreaks in immunocompromised individuals. Although lack of isogeneity does not preclude an outbreak, our study underlines the value of microsatellite genotyping in the setting of potential A. flavus outbreaks. Microsatellite genotyping documented an isogenic hospital outbreak with an internal source. This provided the "smoking gun" that prompted the rapid allocation of resources for thorough environmental sampling, the results of which guided immediate and relevant cleaning and source control measures. Consequently, we advise that vulnerable patients should be protected from exposure and that genotyping be included early in potential A. flavus outbreak investigations. Inspection and sampling are recommended at any site where airborne spores might disperse from. This includes rarely accessed areas where air communication to the hospital ward cannot be disregarded.

Aspergillus fumigatus Epidural Abscess and Postsurgical Wound Infection in an Immunocompetent Host

In this case, we present an immunocompetent patient who had a wound infection secondary to Aspergillus fumigatus after undergoing a neurosurgical procedure that was complicated by an epidural abscess. The patient was treated with voriconazole and responded favorably. We highlight the need for awareness of the possibility of an Aspergillus infection in people without any obvious immunocompromise and advocate for the inclusion of this opportunistic fungus in the workup of postneurosurgical infections and dura-based collections. A brief review of relevant literature is also included.

Biosynthesized silver nanoparticles-capped chondroitin sulfate nanogel targeting microbial infections and biofilms for biomedical applications

Medical devices are essential for patient care, but they can also serve as havens for dangerous microbes and the development of biofilm, which can lead to serious infections and higher death rates. To meet these issues, it is crucial to develop novel and effective antimicrobial coatings for medical devices. In this context, we have developed a new biofunctionalized nanosilver (ICS-Ag), employing itaconyl-chondroitin sulfate nanogel (ICSNG) as a synergistic reducing and stabilizing agent, to effectively eradicate microbial infections and biofilm formation. The antibacterial investigations showed that ICS-Ag nanocomposite is an intriguing antibiotic with excellent antibacterial indices (MIC/MBC (μg/mL): 2.29/4.58, 1.25/2.50, and 1.36/1.36 against S. aureus, E. coli, and P. aeruginosa, respectively), as well as antifungal capacity. Furthermore, ICS-Ag demonstrated efficacy superior to that of the antibiotic (ciprofloxacin, Cipro) against both Gram-positive and Gram-negative bacterial biofilms. TEM images of untreated and treated bacterial strains demonstrate synergistic actions that harm the bacterial cytomembrane, leading to the release of intracellular contents and bacterial death. Interestingly, ICS-Ag shows excellent biocompatibility, with an IC50 value (71.25 μg/mL) higher than MICs against tested microbes. Overall, the ICS-Ag film may provide multifunctional antimicrobial coatings for medical equipment to reduce microbial contamination and biofilm development.

Outbreaks of Fungal Infections in Hospitals: Epidemiology, Detection, and Management

Nosocomial clusters of fungal infections, whilst uncommon, cannot be predicted and are associated with significant morbidity and mortality. Here, we review reports of nosocomial outbreaks of invasive fungal disease to glean insight into their epidemiology, risks for infection, methods employed in outbreak detection including genomic testing to confirm the outbreak, and approaches to clinical and infection control management. Both yeasts and filamentous fungi cause outbreaks, with each having general and specific risks. The early detection and confirmation of the outbreak are essential for diagnosis, treatment of affected patients, and termination of the outbreak. Environmental sampling, including the air in mould outbreaks, for the pathogen may be indicated. The genetic analysis of epidemiologically linked isolates is strongly recommended through a sufficiently discriminatory approach such as whole genome sequencing or a method that is acceptably discriminatory for that pathogen. An analysis of both linked isolates and epidemiologically unrelated strains is required to enable genetic similarity comparisons. The management of the outbreak encompasses input from a multi-disciplinary team with epidemiological investigation and infection control measures, including screening for additional cases, patient cohorting, and strict hygiene and cleaning procedures. Automated methods for fungal infection surveillance would greatly aid earlier outbreak detection and should be a focus of research.

Cervico-Dorsal Intramedullary Spinal Cord Abscess with Aspergillus fumigates following Pulmonary Infection in an Immunocompetent Patient

Invasive forms of aspergillosis of the nervous system are relatively rare and are usually diagnosed in immunocompromised patients. We present the case of a young female patient, treated in the last two months with corticosteroids and antifungal drug for pulmonary aspergillosis, who developed progressive paraparesis. An intramedullary abscess at the C7-D1 level was identified and the lesion was treated with a combination of surgery and antifungal therapy. Histopathologic findings of surgical specimens showed myelomalacia with Aspergillus hyphae and a peripheral rim of neutrophils. We consider that the use of multiple drugs and corticosteroids for our patient's initial community pneumonia could be the factor that transformed her into a mildly immunocompromised individual and permitted the Aspergillus spp. to disseminate through the blood and into the spinal cord. Moreover, we highlight the fact that more attention should be paid to living and working conditions of the patients, as a simple colonization of the lung with Aspergillus spp. could develop, in a short time, into an invasive disease with a high risk of mortality.

Mycetoma due to Aspergillus flavus in a diabetic patient: Case report and literature review

Diabetes mellitus patients are prone to cutaneous and subcutaneous fungal infections due to pathogenic fungi, including dermatophytes, Mucorales, Candida, Aspergillus, and Fusarium species. Here, we report a case of A. flavus mycetoma confirmed by isolation and molecular identification. The case was a 38-year-old male farmer with a seven-year history of type 2 diabetes mellitus, living in Khuzestan, southwest of Iran. The patient presented with a right foot swelling associated with a nodule and multiple discharging sinuses following trauma sustained on the foot while working barefoot on the rice farm, a year ago. The nodule appeared at the site of the trauma two months after the injury. The initial diagnosis was based on direct microscopic examination of lesions scraping using 20% potassium hydroxide and radiology. Molecular analysis confirmed the isolates to be A. flavus. In vitro susceptibility of the isolate to voriconazole, posaconazole, caspofungin, itraconazole, and amphotericin B was determined. Treatment with voriconazole (200 mg twice daily) stopped the purulent discharge, reduced the swelling, and improved the clinical condition within two months. The study emphasizes the importance of wearing footwear to prevent skin trauma as the main risk factor of patient involvement.

Peroxin FgPEX22-Like Is Involved in FgPEX4 Tethering and Fusarium graminearum Pathogenicity

Peroxisomes are essential organelles that play important roles in a variety of biological processes in eukaryotic cells. To understand the synthesis of peroxisomes comprehensively, we identified the gene FgPEX22-like, encoding FgPEX22-like, a peroxin, in Fusarium graminearum. Our results showed that although FgPEX22-like was notably different from other peroxins (PEX) in Saccharomyces cerevisiae, it contained a predicted PEX4-binding site and interacted with FgPEX4 as a rivet protein of FgPEX4. To functionally characterize the roles of FgPEX22-like in F. graminearum, we performed homologous recombination to construct a deletion mutant (ΔPEX22-like). Analysis of the mutant showed that FgPEX22-like was essential for sexual and asexual reproduction, fatty acid utilization, pathogenicity, and production of the mycotoxin deoxynivalenol. Deletion of FgPEX22-like also led to increased production of lipid droplets and decreased elimination of reactive oxygen species. In addition, FgPEX22-like was required for the biogenesis of Woronin bodies. Taken together, our data demonstrate that FgPEX22-like is a peroxin in F. graminearum that interacts with PEX4 by anchoring PEX4 at the peroxisomal membrane and contributes to the peroxisome function in F. graminearum.

CWI pathway participated in vegetative growth and pathogenicity through a downstream effector AflRlm1 in Aspergillus flavus

The cell wall is an essential dynamic structure for shielding fungus from environmental stress, and its synthesizing and remodeling are regulated by the cell wall integrity (CWI) pathway. Here, we explored the roles of a putative downstream effector AflRlm1 of CWI pathway in Aspergillus flavus. The results showed that AflRlm1 played a positive role in conidia production, sclerotium formation, aflatoxin biosynthesis, and pathogenicity. Furthermore, we provided evidence for the physical connection between AflRlm1 and AflSlt2 and determined the role of AflSlt2 in the phosphorylation of AflRlm1. Then, we discovered the importance of WSCs (cell wall integrity and stress response component) to the CWI signal and the process of AflRlm1 transferring to the nucleus after receiving the signal. Overall, this study clarified the transmission process of CWI signals and proves that the CWI pathway plays a key role in the development of A. flavus and the production of aflatoxin combined with transcriptome data analysis.

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Linked the CWI pathway from membrane receptors to transcription factors in A. flavus

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Found the phosphorylate activation and subcellular metastasis of AflRlm1 in stress

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Discovered the important role of AflRlm1 in aflatoxin biosynthesis

Aspergillus mediastinitis in a post-operative immunocompetent child

Post-operative Aspergillus mediastinitis is regarded to be a devastating infection, usually affecting patients undergoing cardiothoracic surgery with specific predisposing factors characterised by a high mortality and chronic morbidity. Patient outcome after such a complication is extremely poor despite antifungal therapy and surgery. We describe the case of an immunocompetent 2-month-old child with obstructed supracardiac total anomalous pulmonary venous circulation (TAPVC) and severe pulmonary artery hypertension, who underwent TAPVC repair through median sternotomy and developed post-operative mediastinitis due to Aspergillus flavus.

Invasive Aspergillosis by Aspergillus flavus: Epidemiology, Diagnosis, Antifungal Resistance, and Management

Aspergillus flavus is the second most common etiological agent of invasive aspergillosis (IA) after A. fumigatus. However, most literature describes IA in relation to A. fumigatus or together with other Aspergillus species. Certain differences exist in IA caused by A. flavus and A. fumigatus and studies on A. flavus infections are increasing. Hence, we performed a comprehensive updated review on IA due to A. flavus. A. flavus is the cause of a broad spectrum of human diseases predominantly in Asia, the Middle East, and Africa possibly due to its ability to survive better in hot and arid climatic conditions compared to other Aspergillus spp. Worldwide, ~10% of cases of bronchopulmonary aspergillosis are caused by A. flavus. Outbreaks have usually been associated with construction activities as invasive pulmonary aspergillosis in immunocompromised patients and cutaneous, subcutaneous, and mucosal forms in immunocompetent individuals. Multilocus microsatellite typing is well standardized to differentiate A. flavus isolates into different clades. A. flavus is intrinsically resistant to polyenes. In contrast to A. fumigatus, triazole resistance infrequently occurs in A. flavus and is associated with mutations in the cyp51C gene. Overexpression of efflux pumps in non-wildtype strains lacking mutations in the cyp51 gene can also lead to high voriconazole minimum inhibitory concentrations. Voriconazole remains the drug of choice for treatment, and amphotericin B should be avoided. Primary therapy with echinocandins is not the first choice but the combination with voriconazole or as monotherapy may be used when the azoles and amphotericin B are contraindicated.

Molecular and structural basis of nucleoside diphosphate kinase-mediated regulation of spore and sclerotia development in the fungus Aspergillus flavus

The fundamental biological function of nucleoside diphosphate kinase (NDK) is to catalyze the reversible exchange of the γ-phosphate between nucleoside triphosphate (NTP) and nucleoside diphosphate (NDP). This kinase also has functions that extend beyond its canonically defined enzymatic role as a phosphotransferase. However, the role of NDK in filamentous fungi, especially in Aspergillus flavus (A. flavus), is not yet known. Here we report that A. flavus has two NDK-encoding gene copies as assessed by qPCR. Using gene-knockout and complementation experiments, we found that AfNDK regulates spore and sclerotia development and is involved in plant virulence as assessed in corn and peanut seed-based assays. An antifungal test with the inhibitor azidothymidine suppressed AfNDK activity in vitro and prevented spore production and sclerotia formation in A. flavus, confirming AfNDK's regulatory functions. Crystallographic analysis of AfNDK, coupled with site-directed mutagenesis experiments, revealed three residues (Arg-104, His-117, and Asp-120) as key sites that contribute to spore and sclerotia development. These results not only enrich our knowledge of the regulatory role of this important protein in A. flavus, but also provide insights into the prevention of A. flavus infection in plants and seeds, as well as into the structural features relevant for future antifungal drug development.

Central Nervous System Aspergillosis: An Unexpected Complication following Neurosurgery

Post-surgical aspergillosis is an uncommon complication that carries a high mortality rate in affected patients. The diagnosis is challenging given the lack of highly sensitive methods to isolate Aspergillus from surgical sites. Here, we present a case of post-surgical aspergillosis that occurred after the resection of acoustic neuroma in an immunocompetent patient. Imaging revealed leptomeningeal enhancement and a cerebellar extra-axial fluid collection adjacent to the right retrosigmoid craniotomy. The patient was taken to the operating room for debridement, where purulent fluid was obtained from subdural space. The diagnosis was achieved by histopathology and polymerase chain reaction (PCR) in brain tissue. Appropriate investigations failed to detect contamination in the operating room. The patient was successfully treated with 3 months of voriconazole. We highlight the importance of recognizing this uncommon complication and advocate for the use of molecular techniques to improve the diagnostic yield in central nervous system aspergillosis.

Surface contamination in operating rooms: a risk for transmission of pathogens?

BACKGROUND

The role of surface contamination in the transmission of nosocomial pathogens is recognized increasingly. For more than 100 years, the inanimate environment in operating rooms (e.g., walls, tables, floors, and equipment surfaces) has been considered a potential source of pathogens that may cause surgical site infections (SSIs). However, the role of contaminated surfaces in pathogen acquisition in this setting generally is considered negligible, as most SSIs are believed to originate from patients' or healthcare workers' flora.

METHODS

A search of relevant medical literature was performed using PubMed to identify studies that investigated surface contamination of operating rooms and its possible role in infection transmission.

RESULTS

Despite a limited number of studies evaluating the role of surface contamination in operating rooms, there is accumulating evidence that the inanimate environment of the operating room can become contaminated with pathogens despite standard environmental cleaning. These pathogens can then be transmitted to the hands of personnel and then to patients and may result in SSIs and infection outbreaks.

CONCLUSION

Contaminated surfaces can be responsible for the transmission of pathogens in the operating room setting. Further studies are necessary to quantify the role of contaminated surfaces in the transmission of pathogens and to inform the most effective environmental interventions. Given the serious consequences of SSIs, special attention should be given to the proper cleaning and disinfection of the inanimate environment in operating rooms in addition to the other established infection control measures to reduce the burden of SSIs.

Could Histoplasma capsulatum Be Related to Healthcare-Associated Infections?

Healthcare-associated infections (HAI) are described in diverse settings. The main etiologic agents of HAI are bacteria (85%) and fungi (13%). Some factors increase the risk for HAI, particularly the use of medical devices; patients with severe cuts, wounds, and burns; stays in the intensive care unit, surgery, and hospital reconstruction works. Several fungal HAI are caused by Candida spp., usually from an endogenous source; however, cross-transmission via the hands of healthcare workers or contaminated devices can occur. Although other medically important fungi, such as Blastomyces dermatitidis, Paracoccidioides brasiliensis, and Histoplasma capsulatum, have never been considered nosocomial pathogens, there are some factors that point out the pros and cons for this possibility. Among these fungi, H. capsulatum infection has been linked to different medical devices and surgery implants. The filamentous form of H. capsulatum may be present in hospital settings, as this fungus adapts to different types of climates and has great dispersion ability. Although conventional pathogen identification techniques have never identified H. capsulatum in the hospital environment, molecular biology procedures could be useful in this setting. More research on H. capsulatum as a HAI etiologic agent is needed, since it causes a severe and often fatal disease in immunocompromised patients.

Environmental investigations and molecular typing of Aspergillus in a Chinese hospital

Invasive fungal infections due to Aspergillus species have become a major cause of morbidity and mortality among immunocompromised patients. In order to determine the possible relationship between environmental contamination by Aspergillus and the occurrence of invasive aspergillosis, a 1-year prospective study was carried out in a tertiary hospital in China. Air, surface, and tap water sampling was performed twice monthly at the bone marrow transplant (BMT) department, intensive care unit (ICU), neurosurgery intensive care unit (NICU), and outdoors. Nose, pharynx, and sputum samples were collected from high-risk patients. Isolates of Aspergillus from the environment and patients were genotyped by random amplification of polymorphic DNA (RAPD) assay to investigate the origin of infection. Mean total Aspergillus count was 7.73, 8.94, 13.19, and 17.32 cfu/m(3) in the BMT department, ICU, NICU, and outdoors, respectively. RAPD analysis by R108 primer demonstrated that strains isolated from patients in NICU were identical to the environmental strain. Strains isolated from patients in ICU differed from the environmental strain. Aspergillus contamination was found in the BTM department, NICU, and ICU. Clinical and environmental strains from NICU had identical genotypes. These findings suggest that Aspergillus is found in the hospital environment including the air, surface, and tap water. The genotypes of Aspergillus were identical from patients and the environment, suggesting that clinical infection may originate from the hospital environment.

Environmental contamination by Aspergillus spp. in laying hen farms and associated health risks for farm workers

Data on the occurrence and epidemiology of Aspergillus spp. in laying hens farms are scant. With the aims of determining levels of airborne contamination in laying hen farms and evaluating the potential risk of infection for workers and animals, 57 air samples from 19 sheds (Group I), 69 from faeces (Group II), 19 from poultry feedstuffs (Group III) and 60 from three anatomical sites (i.e. nostrils, pharynx, ears) of 20 farm workers (Group IV) were cultured. The Aspergillus spp. prevalence in samples ranged from 31.6% (Group III) to 55.5% (Group IV), whereas the highest conidia concentration was retrieved in Group II (1.2 × 10(4) c.f.u. g(-1)) and in Group III (1.9 × 10(3) c.f.u. g(-1)). The mean concentration of airborne Aspergillus spp. conidia was 70 c.f.u. m(-3) with Aspergillus fumigatus (27.3%) being the most frequently detected species, followed by Aspergillus flavus (6.3%). These Aspergillus spp. were also isolated from human nostrils (40%) and ears (35%) (P<0.05) (Group IV). No clinical aspergillosis was diagnosed in hens. The results demonstrate a relationship between the environmental contamination in hen farms and presence of Aspergillus spp. on animals and humans. Even if the concentration of airborne Aspergillus spp. conidia (i.e. 70 c.f.u. m(-3)) herein detected does not trigger clinical disease in hens, it causes human colonization. Correct management of hen farms is necessary to control environmental contamination by Aspergillus spp., and could lead to a significant reduction of animal and human colonization.

[Genotyping of clinical isolates of Aspergillus flavus and its relationship with environmental isolates of an oncohematological center]

BACKGROUND

During 4 months, and while conducting an environmental sampling of air, 2 cases of aspergillosis by Aspergillus flavus (A. flavus) were diagnosed at an oncohematological center in Buenos Aires, Argentina.

AIMS

The aim of this study was to know the variability and the genetic relationship between the clinical and environmental isolates, obtained in the oncohematological center.

METHODS

Two genotyping techniques of different discriminatory power (RAPD and AFLP) were used. A genetic similarity matrix was calculated using Jaccard method and was the basis for the construction of a dendrogram by UPGMA. The level of genetic variability was assessed by measuring the percentage of polymorphic loci, number of effective allele, expected heterocygozity and association index test (I(A)).

RESULTS

The dendrogram reveals that the A. flavus isolates recovered from the patients were not genetically related to those gotten from the rooms occupied by the patients. The environmental isolates had higher values of genetic diversity than the clinical isolates. The I(A) estimated for all the isolates suggest that recombination events occurred.

CONCLUSIONS

Patients 1 and 2 were not infected with isolates from the nosocomial environment. Clinical and environmental isolates of A. flavus showed high genetic variability among them.

Simple and highly discriminatory VNTR-based multiplex PCR for tracing sources of Aspergillus flavus isolates

Aspergillus flavus is second only to A. fumigatus in causing invasive aspergillosis and it is the major agent responsible for fungal sinusitis, keratitis and endophthalmitis in many countries in the Middle East, Africa and Southeast Asia. Despite the growing challenge due to A. flavus, data on the molecular epidemiology of this fungus remain scarce. The objective of the present study was to develop a new typing method based on the detection of VNTR (Variable number tandem repeat) markers. Eight VNTR markers located on 6 different chromosomes (1, 2, 3, 5, 7 and 8) of A. flavus were selected, combined by pairs for multiplex amplifications and tested on 30 unrelated isolates and six reference strains. The Simpson index for individual markers ranged from 0.398 to 0.818. A combined loci index calculated with all the markers yielded an index of 0.998. The MLVA (Multiple Locus VNTR Analysis) technique proved to be specific and reproducible. In a second time, a total of 55 isolates from Chinese avian farms and from a Tunisian hospital have been evaluated. One major cluster of genotypes could be defined by using the graphing algorithm termed Minimum Spanning Tree. This cluster comprised most of the isolates collected in an avian farm in southern China. The MLVA technique should be considered as an excellent and cost-effective typing method that could be used in many laboratories without the need for sophisticated equipment.

Late post-operative Aspergillus flavus endocarditis: Demonstration of a six years incubation period using microsatellite typing

Late post-operative Aspergillus endocarditis is an under recognized life-threatening complication of heart valvular surgery. Optimal prevention and treatment need enhanced awareness. We report three cases of post-operative Aspergillus flavus endocarditis, including one with a 6-year long incubation period. Microsatellite typing incriminated a recurrent contamination of hospital environment.

Microbial air monitoring in operating theatres: experience at the University Hospital of Parma

BACKGROUND

Microbial air monitoring in operating theatres has been a subject of interest and debate. No generally accepted sampling methods and threshold values are available.

AIM

To assess microbial air contamination in empty and working conventionally ventilated operating theatres over a three-year period at the University Hospital of Parma, Italy.

METHODS

Air sampling was performed in 29 operating theatres. Both active and passive sampling methods were used to assess bacterial and fungal contamination.

FINDINGS

In empty theatres, median bacterial values of 12 colony-forming units (cfu)/m(3) [interquartile range (IQR) 4-32] and 1 index of microbial air contamination (IMA) (IQR 0-3) were recorded. In working theatres, these values increased significantly (P < 0.001) to 80 cfu/m(3) (IQR 42-176) and 7 IMA (IQR 4-13). Maximum recorded values were 166 cfu/m(3) and 8 IMA for empty theatres, and 798 cfu/m(3) and 42 IMA for working theatres. Combining active and passive samplings, fungi were isolated in 39.13% of samples collected in empty theatres and 56.95% of samples collected in working theatres. Over the three-year study period, bacterial contamination decreased in both empty and working theatres, and the percentage of samples devoid of fungi increased. In working theatres, a significant correlation was found between the bacterial contamination values assessed using passive and active sampling methods (P < 0.001).

CONCLUSION

Microbiological monitoring is a useful tool for assessment of the contamination of operating theatres in order to improve air quality.

Phylogeography of the cosmopolitan fungus Aspergillus flavus: is everything everywhere?

Aspergillus flavus is one of the most common fungal eukaryotes on the planet. It is notorious for production of aflatoxins, for causing aspergillosis in humans and animals, and as an opportunistic pathogen of animals and plants. Its role in marine habitats is unclear. Until now, little phylogeographic structure has been detected for the species, except at very local scales, and it appears to fit the classic dictum of microbial biogeography: Everything is everywhere. Here we use genetic relationships among isolates to determine phylogeographic structure, mating types, and differences in preferences for: marine vs. terrestrial habitats, various substrates, and clinical vs. nonclinical environments. Phylogenetic relationships among isolates were estimated using amplified fragment length polymorphisms (AFLPs) and mating types were determined for a worldwide sample of A. flavus isolates from diverse substrates and geographic locations. All isolates composed a single population, with no significant differentiation of marine vs. terrestrial isolates, clinical vs. environmental isolates, or association with substrate or geographic origin. There was evidence for local dominance of a single clade, probably clonal in origin and short-lived. The proportion of mating types was 1:1, supporting the hypothesis of recombination in natural populations. However, a high proportion of clinical isolates were MAT1-1 (85%), suggesting that a gene linked to the MAT1-1 idiomorph could play a role in pathogenicity. This study suggests that a more appropriate description of the phylogeography of A. flavus is 'everything is everywhere, but not all the time.'

Nosocomial fungal infections: epidemiology, infection control, and prevention

Fungal infections are an increasing cause of morbidity and mortality in hospitalized patients. This article reviews the current epidemiology of nosocomial fungal infections in adult patients, with an emphasis on invasive candidiasis and aspergillosis. Recently published recommendations and guidelines for the control and prevention of these nosocomial fungal infections are summarized.

A review molecular typing methods for Aspergillus flavus isolates

Aspergillus flavus is the second most important Aspergillus species causing human infections. The importance of this fungus increases in regions with a dry and hot climate. Small phylogenetic studies in Aspergillus flavus indicate that the morphological species contains several genetically isolated species. Different genotyping methods have been developed and employed in order to better understand the genetic and epidemiological relationships between environmental and clinical isolates. Understanding pathogen distribution and relatedness is essential for determining the epidemiology of nosocomial infections and aiding in the design of rational pathogen control methods. Typing techniques can also give us a deeper understanding of the colonization pattern in patients. Most of these studies focused on Aspergillus fumigatus because it is medically the most isolated species. To date, there has not been any publication exclusively reviewing the molecular typing techniques for Aspergillus flavus in the literature. This article reviews all these different available methods for this organism.

High resolution genotyping of clinical Aspergillus flavus isolates from India using microsatellites

BACKGROUND

Worldwide, Aspergillus flavus is the second leading cause of allergic, invasive and colonizing fungal diseases in humans. However, it is the most common species causing fungal rhinosinusitis and eye infections in tropical countries. Despite the growing challenges due to A. flavus, the molecular epidemiology of this fungus has not been well studied. We evaluated the use of microsatellites for high resolution genotyping of A. flavus from India and a possible connection between clinical presentation and genotype of the involved isolate.

METHODOLOGY/PRINCIPAL FINDINGS

A panel of nine microsatellite markers were selected from the genome of A. flavus NRRL 3357. These markers were used to type 162 clinical isolates of A. flavus. All nine markers proved to be polymorphic displaying up to 33 alleles per marker. Thirteen isolates proved to be a mixture of different genotypes. Among the 149 pure isolates, 124 different genotypes could be recognized. The discriminatory power (D) for the individual markers ranged from 0.657 to 0.954. The D value of the panel of nine markers combined was 0.997. The multiplex multicolor approach was instrumental in rapid typing of a large number of isolates. There was no correlation between genotype and the clinical presentation of the infection.

CONCLUSIONS/SIGNIFICANCE

There is a large genotypic diversity in clinical A. flavus isolates from India. The presence of more than one genotype in clinical samples illustrates the possibility that persons may be colonized by multiple genotypes and that any isolate from a clinical specimen is not necessarily the one actually causing infection. Microsatellites are excellent typing targets for discriminating between A. flavus isolates from various origins.

Aspergillus flavus

Aspergillus flavus is saprophytic soil fungus that infects and contaminates preharvest and postharvest seed crops with the carcinogenic secondary metabolite aflatoxin. The fungus is also an opportunistic animal and human pathogen causing aspergillosis diseases with incidence increasing in the immunocompromised population. Whole genome sequences of A. flavus have been released and reveal 55 secondary metabolite clusters that are regulated by different environmental regimes and the global secondary metabolite regulators LaeA and VeA. Characteristics of A. flavus associated with pathogenicity and niche specialization include secondary metabolite production, enzyme elaboration, and a sophisticated oxylipin host crosstalk associated with a quorum-like development program. One of the more promising strategies in field control involves the use of atoxic strains of A. flavus in competitive exclusion studies. In this review, we discuss A. flavus as an agricultural and medical threat and summarize recent research advances in genomics, elucidation of parameters of pathogenicity, and control measures.

Post-operative Aspergillus mediastinitis in a man who was immunocompetent: a case report

Introduction

Aspergillus spp. infections mainly affect patients who are immunocompromised, and are extremely rare in immunocompetent individuals.

Case presentation

Aspergillus post-operative mediastinitis is considered to be a devastating infection, usually affecting patients undergoing cardiothoracic surgery with specific predisposing factors. We describe the case of an immunocompetent 68-year-old Caucasian man with severe chronic thromboembolic pulmonary hypertension, who underwent pulmonary thromboendarterectomy and developed post-operative mediastinitis due to Aspergillus flavus. The environmental control did not reveal the source of A. flavus infection and, despite combined antifungal therapy, our patient died as a result of septic shock and multiple organ failure.

Conclusion

Aspergillus mediastinitis mainly affects patients after cardiosurgery operations with predisposing factors, and it is unusual in patients who are immunocompetent. The identification of the Aspergillus spp. source is often difficult, and there are no guidelines for the administration of pre-emptive therapy in this population of at-risk patients.

Microsatellite typing to trace Aspergillus flavus infections in a hematology unit

Assessing the relatedness of strains isolated from patients and their environment is instrumental in documenting the source of preventable health care-associated life-threatening Aspergillus flavus human infection clusters. The present study aimed at identifying and selecting suitable microsatellite markers for A. flavus typing. This typing scheme was then applied to investigate the A. flavus epidemiology within a hematology unit in Sfax, Tunisia. Use of a combination of five markers made it possible to discern clusters of isolates and to substantiate the genetic diversity of A. flavus within clusters. Isolates from Tunisia and Marseille, France, displayed distinct haplotypes, indicating a highly significant geographical structuring of A. flavus. The typing of clinical and environmental A. flavus isolates in a hematology unit provided insights into its hospital epidemiology. From a heterogeneous genetic background, a cluster indicative of a clonal propagation episode within the unit could be identified. In two patients with invasive aspergillosis, the same genotype was found in clinical and environmental isolates, indicating hospital-acquired colonization and infection. In further studies, this novel microsatellite typing scheme might be instrumental in illuminating important epidemiological issues about A. flavus population genetics or epidemiology, including tracing the sources and routes of transmission.

The first documented case of Aspergillus cardiac surgical site infection in Sweden: an epidemiology study using arbitrarily primed PCR

Here we report two rare cases of severe thoracic Aspergillus fumigatus infections after lung and heart surgery at the same thoracic intensive care unit at the same time. The main objective was to identify a possible source of transmission. With arbitrarily primed polymerase chain reaction a patient-to-patient transmission could rapidly be ruled out as the cause of the first documented case of aspergillosis after open-heart surgery in Sweden. Although no definitive source was identified, a genetically similar strain was found in a contaminated supply room.

Aspergillus flavus: an emerging non-fumigatus Aspergillus species of significance

Invasive aspergillosis is rare in immunocompetent people but contributes to significant morbidity and mortality in immunosuppressed patients. The majority (approximately 80%) of invasive Aspergillus infections is caused by Aspergillus fumigatus. The second most frequent (approximately 15-20%) pathogenic species is Aspergillus flavus and to a lesser extent, Aspergillus niger and Aspergillus terreus. Aspergillus flavus has emerged as a predominant pathogen in patients with fungal sinusitis and fungal keratitis in several institutions worldwide. To date, there has not been any publication exclusively reviewing the topic of A. flavus in the literature. This article reviews the microbiology, toxigenicity and epidemiology of A. flavus as well as describes the clinical characteristics, diagnosis and management of infections caused by this organism.

An investigation of Aspergillus cardiac surgical site infections in 3 pediatric patients

BACKGROUND

Within a 3-month period, 3 pediatric patients at our hospital developed Aspergillus surgical site infections after undergoing cardiac surgery.

METHODS

A multidisciplinary team conducted an epidemiologic review of the 3 patients and their infections, operative and postoperative patient care delivery, and routine maintenance of hospital equipment and air-filtration systems and investigated potential environmental exposures within the hospital that may have contributed to the development of these infections.

RESULTS

Review of the patients and their infections, operative and postoperative patient care delivery, and routine maintenance did not reveal a source for infection. Inspection of operating room (OR) facilities identified several areas in need of repair. Of the 58 samples of air and equipment exhaust in the ORs and patient care areas, 11 revealed 2 to 4 colony-forming units of various Aspergillus species per cubic meter of air, and the remaining 47 samples were negative for Aspergillus. Eighty-three samples of surfaces and equipment water reservoirs were obtained from the OR and patient care areas. One culture of a soiled liquid nitrogen tank housed between the 2 cardiac ORs revealed 13 colony-forming units of Aspergillus.

CONCLUSION

No definitive source was identified, although a soiled liquid nitrogen tank contaminated with Aspergillus and kept near the OR was found and could have been a possible source.

Clustering of invasiveAspergillus ustuseye infections in a tertiary care hospital: A molecular epidemiologic study of an uncommon species

Aspergillus infections are being increasingly recognized as an important cause of morbidity and blindness. We report here the first cluster of Aspergillus ustus endophthalmitis cases which occurred in a large tertiary care hospital during the period October 2003 to June 2004. In three of the cases, the patients required enucleation following cataract surgery, while the fourth involved a fatal infection in a pediatric patient hospitalized for osteopetrosis. Patient charts from the four cases were reviewed retrospectively and indicated that postoperative signs of fungal endophthalmitis developed in the patients 1-11 weeks after surgery. The molecular characterization of the isolates and their epidemiological relatedness were evaluated by Random Amplification of Polymorphic DNA (RAPD). A source investigation of this mini outbreak was performed by environmental sampling, but no isolates of A. ustus were recovered from these studies. All A. ustus strains isolated from three patients with fungal endophthalmitis had the same RAPD pattern suggesting a common source. The strain from the pediatric patient differed from the ophthalmic isolates in five electrophoretic loci. The latter was included solely as an outbreak, unrelated control to evaluate the discriminatory power of the molecular typing method employed in the analysis of the ophthalmic strains. These cases illustrate the potential for uncommon species like A. ustus to cause high morbidity and mortality in some clinical settings. Aspergillus ustus endophthalmitis is a serious and devastating complication of ocular surgery. It is unknown whether ongoing hospital construction may have contributed to this cluster of cases. Random amplification of polymorphic DNA may give valuable clues about the clonality of A. ustus strains.

Post-operative aspergillosis

While invasive aspergillosis occurs typically in severely immunocompromised patients, cases of surgical site infection have been reported in immunocompetent individuals. The Medline, LILACS and EMBASE databases were searched for descriptions of cases of post-operative aspergillosis, and references from relevant articles and conference abstracts were reviewed. More than 500 cases of post-operative aspergillosis were found. Cardiac surgery (n = 188), ophthalmological surgery (n > 90) and dental surgery (n > 100) were associated with the majority of cases. Other cases involved wound infections (n = 22), bronchial infections (n = 30), mediastinitis (n = 11), pleural aspergillosis (n = 1), infections following orthopaedic surgery (n = 42), vascular prosthetic surgery (n = 22), breast surgery (n = 5), abdominal surgery (n = 10) and neurosurgery (n = 25). In most patients, the source was presumed to be airborne infection during the surgical procedure. Prevention of these infections requires special care of the ventilation system in the operating room. Successful treatment requires rapid diagnosis, surgical debridement and antifungal therapy, often with voriconazole. In order to improve the outcome, better diagnostic methods are needed, particularly for cases of endocarditis and aortitis.

Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises

The epidemics of severe acute respiratory syndrome (SARS) in 2003 highlighted both short- and long-range transmission routes, i.e. between infected patients and healthcare workers, and between distant locations. With other infections such as tuberculosis, measles and chickenpox, the concept of aerosol transmission is so well accepted that isolation of such patients is the norm. With current concerns about a possible approaching influenza pandemic, the control of transmission via infectious air has become more important. Therefore, the aim of this review is to describe the factors involved in: (1) the generation of an infectious aerosol, (2) the transmission of infectious droplets or droplet nuclei from this aerosol, and (3) the potential for inhalation of such droplets or droplet nuclei by a susceptible host. On this basis, recommendations are made to improve the control of aerosol-transmitted infections in hospitals as well as in the design and construction of future isolation facilities.

Nosocomial aspergillosis in outbreak settings

Nosocomial aspergillosis represents a serious threat for severely immunocompromised patients and numerous outbreaks of invasive aspergillosis have been described. This systematic review summarizes characteristics and mortality rates of infected patients, distribution of Aspergillus spp. in clinical specimens, concentrations of aspergillus spores in volumetric air samples, and outbreak sources. A web-based register of nosocomial epidemics (outbreak database), PubMed and reference lists of relevant articles were searched systematically for descriptions of aspergillus outbreaks in hospital settings. Fifty-three studies with a total of 458 patients were included. In 356 patients, the lower respiratory tract was the primary site of aspergillus infection. Species identified most often were Aspergillus fumigatus (154 patients) and Aspergillus flavus (101 patients). Haematological malignancies were the predominant underlying diseases (299 individuals). The overall fatality rate in these 299 patients (57.6%) was significantly greater than that in patients without severe immunodeficiency (39.4% of 38 individuals). Construction or demolition work was often (49.1%) considered to be the probable or possible source of the outbreak. Even concentrations of Aspergillus spp. below 1 colony-forming unit/m(3) were sufficient to cause infection in high-risk patients. Virtually all outbreaks of nosocomial aspergillosis are attributed to airborne sources, usually construction. Even small concentrations of spores have been associated with outbreaks, mainly due to A. fumigatus or A. flavus. Patients at risk should not be exposed to aspergilli.

Molecular typing of aspergilli: Recent developments and outcomes

Aspergillus spp. have been the subject of numerous epidemiological studies. The most useful typing techniques are DNA based methods including the random amplified polymorphic DNA technique, microsatellite length polymorphisms, restriction fragment length polymorphism (RFLP) analysis using retrotransposon-like sequences as probes, and multilocus sequence typing. The results of typing clinical isolates indicate that most of the invasive aspergillosis (IA) patients were infected by a single strain. Genetic analysis could not discriminate between clinical and environmental isolates of Aspergillus. fumigatus, indicating that every strain present in the environment is a potential pathogen if it encounters the appropriate host. The source of infection can also be monitored by typing. Typing studies led to the discovery of a new pathogenic species, A. lentulus, and to the identification of several species not known previously to be pathogenic. Typing studies revealed the existence of two genetically isolated groups within a global A. fumigatus population. Aspergillus fumigatus was found to be the first example of a true cosmopolitan fungus. Additionally, the results obtained in several studies support the premise that recombination played an important role in A. fumigatus populations. The discovery of functional mating type genes in A. fumigatus indicates that past or recent sexual processes could be responsible for the observed recombining population structure.