Prevalence and mechanism of triazole resistance in Aspergillus fumigatus in a referral chest hospital in Delhi, India and an update of the situation in Asia

Liposomal amphotericin for secondary prophylaxis: A systematic review and meta-analysis

INTRODUCTION

This systematic review and meta-analysis aimed to determine the safety of liposomal amphotericin B (L-AMB) compared to other antifungal agents for secondary prophylaxis.

METHOD

We conducted a comprehensive search across international databases and reference lists of articles to compile all relevant published evidence evaluating the efficacy and safety of L-AMB versus other antifungals (NLAMB) for secondary prophylaxis against invasive fungal infections. Pooled estimates were calculated after data transformation to evaluate mortality, breakthrough infections, and the frequency of adverse effects, including hypokalemia and nephrotoxicity. Comparisons of breakthrough fungal infection and mortality between the L-AMB and NLAMB groups were performed.

RESULT

We identified 10 studies. The cumulative frequency of patients using L-AMB was 148, compared to 341 patients in the NLAMB group. The mortality rates in the L-AMB and NLAMB groups were 10% and 0%, respectively. However, based on the odds ratio, the mortality in the L-AMB group was lower than that in the NLAMB group. No significant difference was observed in breakthrough invasive fungal infections between the L-AMB and NLAMB groups. The frequencies of nephropathy and hypokalemia in the L-AMB group were 36% and 18%, respectively.

CONCLUSION

Our findings indicate a lower incidence of mortality in the L-AMB group compared to the NLAMB group. No statistically significant difference was observed in the incidence of breakthrough infection between the two groups. L-AMB administration is associated with nephropathy and hypokalemia. However, the refusal to continue treatment due to adverse effects is not significantly high.

Evaluation of antifungal activity, mechanisms of action and toxicological profile of the synthetic amide 2-chloro-N-phenylacetamide

Aspergillus niger causes infections such as otitis and pulmonary aspergillosis in immunocompromised individuals. Treatment involves voriconazole or amphotericin B, and due to the increase in fungal resistance, the search for new compounds with antifungal activity has intensified. In the development of new drugs, cytotoxicity and genotoxicity assays are important, as they allow predicting possible damage that a molecule can cause, and in silico studies predict the pharmacokinetic properties. The aim of this study was to verify the antifungal activity and the mechanism of action of the synthetic amide 2-chloro-N-phenylacetamide against Aspergillus niger strains and toxicity. 2-Chloro-N-phenylacetamide showed antifungal activity against different strains of Aspergillus niger with minimum inhibitory concentrations between 32 and 256 μg/mL and minimum fungicides between 64 and 1024 μg/mL. The minimum inhibitory concentration of 2-chloro-N-phenylacetamide also inhibited conidia germination. When associated with amphotericin B or voriconazole, 2-chloro-N-phenylacetamide had antagonistic effects. Interaction with ergosterol in the plasma membrane is the probable mechanism of action.2-Chloro-N-phenylacetamide has favorable physicochemical parameters, good oral bioavailability and absorption in the gastrointestinal tract, crosses the blood-brain barrier and inhibits CYP1A2. At concentrations of 50 to 500 µg/mL, it has little hemolytic effect and a protective effect for type A and O red blood cells, and in the cells of the oral mucosa it promotes little genotoxic change. It is concluded that 2-chloro-N-phenylacetamide has promising antifungal potential, favorable pharmacokinetic profile for oral administration and low cytotoxic and genotoxic potential, being a promising candidate for in vivo toxicity studies.

Clinical epidemiology of pulmonary aspergillosis in hospitalized patients and contribution of Cyp51A, Yap1, and Cdr1B mutations to voriconazole resistance in etiologic Aspergillus species

Pulmonary aspergillosis is a life-threatening fungal infection with worldwide distribution. In the present study, clinical epidemiology of pulmonary aspergillosis and antifungal susceptibility of etiologic Aspergillus species were evaluated in one-hundred fifty patients with special focus on the frequency of voriconazole resistance. All the cases were confirmed by the clinical pictures, laboratory findings, and isolation of etiologic Aspergillus species which belonged to two major species, i.e., A. flavus and A. fumigatus. Seventeen isolates displayed voriconazole MIC greater than or equal to the epidemiological cutoff value. Expression of cyp51A, Cdr1B, and Yap1 genes was analyzed in voriconazole-intermediate/resistant isolates. In A. flavus, Cyp51A protein sequencing showed the substitutions T335A and D282E. In the Yap1 gene, A78C replacement led to Q26H amino acid substitution that was not reported previously in A. flavus resistant to voriconazole. No mutations associated with voriconazole resistance were found in the three genes of A. fumigatus. The expression of Yap1 was higher than that of two other genes in both A. flavus and A. fumigatus. Overall, voriconazole-resistant strains of both A. fumigatus and A. flavus demonstrated overexpression of Cdr1B, Cyp51A, and Yap1 genes compared to voriconazole-susceptible strains. Although there are still ambiguous points about the mechanisms of azole resistance, our results showed that mutations were not present in majority of resistant and intermediate isolates, while all of these isolates showed overexpression in all three genes studied. As a conclusion, it seems that the main reason of the emergence of mutation in voriconazole-resistant isolates of A. flavus and A. fumigatus is previous or prolonged exposure to azoles.

Aspergillosis: an Update on Clinical Spectrum, Diagnostic Schemes, and Management

Purpose of Review

This review gives an overview of the diseases caused by Aspergillus, including a description of the species involved and the infected clinical systems. We provide insight into the various diagnostic methods available for diagnosing aspergillosis, particularly invasive aspergillosis (IA), including the role of radiology, bronchoscopy, culture, and non-culture-based microbiological methods. We also discuss the available diagnostic algorithms for the different disease conditions. This review also summarizes the main aspects of managing infections due to Aspergillus spp., such as antifungal resistance, choice of antifungals, therapeutic drug monitoring, and new antifungal alternatives.

Recent Findings

The risk factors for this infection continue to evolve with the development of many biological agents that target the immune system and the increase of viral illnesses such as coronavirus disease. Due to the limitations of present mycological test methods, establishing a fast diagnosis is frequently difficult, and reports of developing antifungal resistance further complicate the management of aspergillosis. Many commercial assays, like AsperGenius®, MycAssay Aspergillus®, and MycoGENIE®, have the advantage of better species-level identification and concomitant resistance-associated mutations. Fosmanogepix, ibrexafungerp, rezafungin, and olorofim are newer antifungal agents in the pipeline exhibiting remarkable activity against Aspergillus spp.

Summary

The fungus Aspergillus is found ubiquitously around the world and can cause various infections, from harmless saprophytic colonization to severe IA. Understanding the diagnostic criteria to be used in different patient groups and the local epidemiological data and antifungal susceptibility profile is critical for optimal patient management.

Aspergillus Species Causing Invasive Fungal Disease in Queensland, Australia

BACKGROUND

Aspergillus species are important causes of invasive fungal disease, particularly among those with an impaired immune system. Increasing reports have revealed a rising incidence of antifungal drug resistance among Aspergillus spp., particularly among cryptic species. Understanding local antifungal susceptibility patterns is paramount to delivering optimal clinical care.

METHODS

Aspergillus spp. recovered from clinical specimens between 2000 and 2021 from Pathology Queensland were collected. Aspergillus spp. were identified routinely morphologically, and where there was ambiguity or a lack of sporulation, by sequencing of the internal transcribed spacer (ITS) region. All Aspergillus spp. that underwent antifungal susceptibility testing according to the CLSI M38-A3 method and were recorded and included in the study. Amphotericin B, voriconazole, posaconazole, isavuconazole, micafungin, caspofungin, and anidulafungin were tested. Pathology Queensland services all public healthcare facilities in Queensland, Australia.

RESULTS

236 Aspergillus spp. were identified from clinical specimens during the study period. The most frequent species identified were Aspergillus section Fumigati (n = 119), Aspergillus section Flavi (n = 35), Aspergillus terreus (n = 32) and Aspergillus niger (n = 29). Overall, MIC_50/90 values for voriconazole, posaconazole, itraconazole, and isavuconazole were 0.25/1, 0.25/0.5, 0.25/0.5, and 0.5/2 mg/L respectively. Echinocandins demonstrated low MIC values overall with micafungin and anidulafungin both having an MIC_50/90 of 0.015/0.03 mg/L. A total of 15 cryptic species were identified; high triazole MIC values were observed with a voriconazole MIC_50/90 of 2/8 mg/L. From 2017 to 2021 we observed an increase in incidence of isolates with high voriconazole MIC values. There was no difference in voriconazole MIC values between Aspergillus spp. acquired in North Queensland when compared to Southeast Queensland, Australia.

CONCLUSION

Increasing reports of antifungal resistance among Aspergillus spp. is concerning and warrants further investigation both locally and worldwide. Active surveillance of both the emergence of different Aspergillus spp. and changes in antifungal susceptibility patterns over time is crucial to informing clinicians and treatment guidelines.

Genetic Diversity and Azole Resistance Among Natural Aspergillus fumigatus Populations in Yunnan, China

The emergence and spread of azole resistance alleles in clinical and environmental isolates of Aspergillus fumigatus is a global human health concern and endangers the "One Health" approach in our fight against antifungal resistance (AFR) in this pathogen. A major challenge to combat AFR in A. fumigatus is the massive aerial dispersal ability of its asexual spores. Our recent fine-scale survey of greenhouse populations of A. fumigatus near Kunming, Yunnan, China, suggested that the use of azole fungicides for plant protection was likely a major driver of the high-frequency azole-resistant A. fumigatus (ARAF) in greenhouses. Here, we investigated the potential spread of those ARAF and the structure of geographic populations of A. fumigatus by analyzing 452 isolates from 19 geographic locations across Yunnan. We found lower frequencies of ARAF in these outdoor populations than those in greenhouses near Kunming, but there were abundant new alleles and new genotypes, including those associated with azole resistance, consistent with multiple independent origins of ARAF across Yunnan. Interestingly, among the four ecological niches, the sediments of a large lake near Kunming were found to have the highest frequency of ARAF (~ 43%). While most genetic variations were observed within the 19 local populations, statistically significant genetic differentiations were found between many subpopulations within Yunnan. Furthermore, similar to greenhouse populations, these outdoor populations of A. fumigatus in Yunnan were significantly different from those in other parts of the world. Our results call for increased attention to local and regional studies of this fungal pathogen to help develop targeted control strategies against ARAF.

Epidemiology and Antifungal Susceptibility Patterns of Invasive Fungal Infections (IFIs) in India: A Prospective Observational Study

The epidemiology of invasive fungal infections (IFI) is ever evolving. The aim of the present study was to analyze the clinical, microbiological, susceptibility, and outcome data of IFI in Indian patients to identify determinants of infection and 30-day mortality. Proven and probable/putative IFI (defined according to modified European Organization for Research and Treatment of Cancer/Mycoses Study Group and AspICU criteria) from April 2017 to December 2018 were evaluated in a prospective observational study. All recruited patients were antifungal naïve (n = 3300). There were 253 episodes of IFI (7.6%) with 134 (52.9%) proven and 119 (47%) probable/putative infections. There were four major clusters of infection: invasive candidiasis (IC) (n = 53, 20.9%), cryptococcosis (n = 34, 13.4%), invasive aspergillosis (IA) (n = 103, 40.7%), and mucormycosis (n = 62, 24.5%). The significant risk factors were high particulate efficiency air (HEPA) room admission, ICU admission, prolonged exposure to corticosteroids, diabetes mellitus, chronic liver disease (CLD), acquired immunodeficiency syndrome (AIDS), coronary arterial disease (CAD), trauma, and multiorgan involvement (p < 0.5; odds ratio: >1). The all-cause 30-day mortality was 43.4% (n = 110). It varied by fungal group: 52.8% (28/53) in IC, 58.8% (20/34) in cryptococcosis, 39.8% (41/103) in IA, and 33.9% (21/62) in mucormycosis. HEPA room, ICU admission for IC; HEPA rooms, diabetes mellitus for cryptococcosis; hematological malignancies, chronic kidney disease (CKD), sepsis, galactomannan antigen index value ≥1 for IA and nodules; and ground glass opacities on radiology for mucormycosis were significant predictors of death (odds ratio >1). High minimum inhibitory concentration (MIC) values for azoles were observed in C. albicans, C. parapsilosis, C. glabrata, A. fumigatus, A. flavus, R. arrhizus, R. microsporus, and M. circinelloides. For echinocandin, high MIC values were seen in C. tropicalis, C. guillermondii, C. glabrata, and A. fumigatus. This study highlights the shift in epidemiology and also raises concern of high MICs to azoles among our isolates. It warrants regular surveillance, which can provide the local clinically correlated microbiological data to clinicians and which might aid in guiding patient treatment.

Implementation of a clinical decision rule for selecting empiric treatment for invasive aspergillosis in a setting with high triazole resistance

World-wide, emerging triazole resistance increasingly complicates treatment of invasive aspergillosis (IA). In settings with substantial (>10%) prevalence of triazole resistance, empiric combination therapy with both a triazole and liposomal amphotericin B (LAmB) can be considered because of the low yields of susceptibility testing. To avoid toxicity while optimizing outcome, a strategy with monotherapy would be preferable. A newly designed treatment algorithm based on literature and expert consensus provided guidance for empiric monotherapy with either voriconazole or LAmB. Over a four and a half year period, all adult patients in our hospital treated for IA were included and patient data were collected. An independent committee reviewed the attributability of death to IA for each patient. Primary outcomes were 30- and 100-day crude mortality and attributable mortality. In total, 110 patients were treated according to the treatment algorithm. Fifty-six patients (51%) were initially treated with voriconazole and 54 patients (49%) with LAmB. Combined attributable and contributable mortality was 13% within 30 days and 20% within 100 days. Treatment switch to LAmB was made in 24/56 (43%) of patients who were initially treated with voriconazole. Combined contributable and attributable 100-day mortality in this subgroup was 21% and was not increased when compared with patients initially treated with LAmB (P = 0.38). By applying a comprehensive clinical decision algorithm, an antifungal-sparing regime was successfully introduced. Further research is warranted to explore antifungal treatment strategies that account for triazole-resistance.

LAY SUMMARY

Due to resistance of Aspergillus against triazoles, combination therapy with liposomal amphotericin B (LAmB) is applied more often as primary therapy against invasive aspergillosis. This study presents the results of a decision tool which differentiated between triazole or LAmB monotherapy.

Fungicide effects on human fungal pathogens: Cross-resistance to medical drugs and beyond

Fungal infections are underestimated threats that affect over 1 billion people, and Candida spp., Cryptococcus spp., and Aspergillus spp. are the 3 most fatal fungi. The treatment of these infections is performed with a limited arsenal of antifungal drugs, and the class of the azoles is the most used. Although these drugs present low toxicity for the host, there is an emergence of therapeutic failure due to azole resistance. Drug resistance normally develops in patients undergoing azole long-term therapy, when the fungus in contact with the drug can adapt and survive. Conversely, several reports have been showing that resistant isolates are also recovered from patients with no prior history of azole therapy, suggesting that other routes might be driving antifungal resistance. Intriguingly, antifungal resistance also happens in the environment since resistant strains have been isolated from plant materials, soil, decomposing matter, and compost, where important human fungal pathogens live. As the resistant fungi can be isolated from the environment, in places where agrochemicals are extensively used in agriculture and wood industry, the hypothesis that fungicides could be driving and selecting resistance mechanism in nature, before the contact of the fungus with the host, has gained more attention. The effects of fungicide exposure on fungal resistance have been extensively studied in Aspergillus fumigatus and less investigated in other human fungal pathogens. Here, we discuss not only classic and recent studies showing that environmental azole exposure selects cross-resistance to medical azoles in A. fumigatus, but also how this phenomenon affects Candida and Cryptococcus, other 2 important human fungal pathogens found in the environment. We also examine data showing that fungicide exposure can select relevant changes in the morphophysiology and virulence of those pathogens, suggesting that its effect goes beyond the cross-resistance.

Prognostic Scores and Azole-Resistant Aspergillus fumigatus in Invasive Aspergillosis from an Indian Respiratory Medicine ICU (ICU Patients with IA Suspicion)

Objective: To assess the effectiveness of three general prognostic models (APACHE II, SAPS II, and SOFA) with serum galactomannan antigen in a clinically suspected invasive aspergillosis (IA) subpopulation admitted to a respiratory medicine ICU and to identify azole-resistant Aspergillus fumigatus (ARAF) cases. Methodology and Results: A total of 235 clinically suspected IA patients were prospectively enrolled and observed 30-day mortality was 29.7%. The three general models showed poor discrimination assessed by area under receiver operating characteristic (ROC) curves (AUCs, <0.7) and good calibration (p = 0.92, 0.14, and 0.13 for APACHE II, SAPS II, and SOFA, respectively), evaluated using Hosmer–Lemeshow goodness-of-fit tests. However, discrimination was significantly better with galactomannan values (AUC, 0.924). In-vitro antifungal testing revealed higher minimum inhibitory concentration (MIC) for 12/34 isolates (35.3%) whereas azole resistance was noted in 40% of Aspergillus fumigatus isolates (6/15) with two hotspot cyp51A mutations, G54R and P216L. Conclusions: Patients diagnosed with putative and probable IA (71.4% and 34.6%, respectively), had high mortality. The general prognostic model APACHE II seemed fairly accurate for this subpopulation. However, the use of local GM cut-offs calculated for mortality, may help the intensivists in prompt initiation or change of therapy for better outcome of patients. In addition, the high MICs highlight the need of antifungal surveillance to know the local resistance rate which might aid in patient treatment.

Molecular Epidemiology of Azole-Resistant Aspergillus fumigatus in France Shows Patient and Healthcare Links to Environmentally Occurring Genotypes

Resistance of the human pathogenic fungus Aspergillus fumigatus to antifungal agents is on the rise. However, links between patient infections, their potential acquisition from local environmental sources, and links to global diversity remain cryptic. Here, we used genotyping analyses using nine microsatellites in A. fumigatus, in order to study patterns of diversity in France. In this study, we genotyped 225 local A. fumigatus isolates, 112 azole susceptible and 113 azole resistant, collected from the Bourgogne-Franche-Comté region (Eastern France) and sampled from both clinical (n = 34) and environmental (n = 191) sources. Azole-resistant clinical isolates (n = 29) were recovered mainly from cystic fibrosis patients and environmental isolates (n = 84) from market gardens and sawmills. In common with previous studies, the TR₃₄/L98H allele predominated and comprised 80% of resistant isolates. The genotypes obtained for these local TR₃₄/L98H isolates were integrated into a broader analysis including all genotypes for which data are available worldwide. We found that dominant local TR₃₄/L98H genotypes were isolated in different sample types at different dates (different patients and types of environments) with hospital air and patient's isolates linked. Therefore, we are not able to rule out the possibility of some nosocomial transmission. We also found genotypes in these same environments to be highly diverse, emphasizing the highly mixed nature of A. fumigatus populations. Identical clonal genotypes were found to occur both in the French Eastern region and in the rest of the world (notably Australia), while others have not yet been observed and could be specific to our region. Our study demonstrates the need to integrate patient, healthcare, and environmental sampling with global databases in order to contextualize the local-scale epidemiology of antifungal resistant aspergillosis.

Antifungal activity and mechanism of action of 2-chloro-N -phenylacetamide: a new molecule with activity against strains of Aspergillus flavus

Aspergillus genus causes many diseases, and the species Aspergillus flavus is highly virulent. Treatment of aspergillosis involves azole derivatives such as voriconazole and polyenes such as amphotericin B. Due to an increase in fungal resistance, treatments are now less effective; the search for new compounds with promising antifungal activity has gained importance. The aims of this study were to evaluate the effects of the synthetic amide 2-chloro-N-phenylacetamide (A1Cl) against strains of Aspergillus flavus and to elucidate its mechanism of action. Thus, the minimum inhibitory concentration, minimum fungicidal concentration, conidial germination, associations with antifungal agents, cell wall activities, membrane activities and molecular docking were evaluated. A1Cl presented antifungal activity against Aspergillus flavus strains with a minimum inhibitory concentration of between 16 and 256 μg/mL and a minimum fungicidal concentration between 32 and 512 μg/mL. The minimum inhibitory concentration of A1Cl also inhibited conidial germination, but when associated with amphotericin B and voriconazole, it promoted antagonistic effects. Binding to ergosterol on the fungal plasma membrane is the likely mechanism of action, along with possible inhibition of DNA synthesis through the inhibition of thymidylate synthase. It is concluded that the amide 2-chloro-N-phenylacetamide has promising antifungal potential.

Fungal Genomics in Respiratory Medicine: What, How and When?

Respiratory infections caused by fungal pathogens present a growing global health concern and are a major cause of death in immunocompromised patients. Worryingly, coronavirus disease-19 (COVID-19) resulting in acute respiratory distress syndrome has been shown to predispose some patients to airborne fungal co-infections. These include secondary pulmonary aspergillosis and mucormycosis. Aspergillosis is most commonly caused by the fungal pathogen Aspergillus fumigatus and primarily treated using the triazole drug group, however in recent years, this fungus has been rapidly gaining resistance against these antifungals. This is of serious clinical concern as multi-azole resistant forms of aspergillosis have a higher risk of mortality when compared against azole-susceptible infections. With the increasing numbers of COVID-19 and other classes of immunocompromised patients, early diagnosis of fungal infections is critical to ensuring patient survival. However, time-limited diagnosis is difficult to achieve with current culture-based methods. Advances within fungal genomics have enabled molecular diagnostic methods to become a fast, reproducible, and cost-effective alternative for diagnosis of respiratory fungal pathogens and detection of antifungal resistance. Here, we describe what techniques are currently available within molecular diagnostics, how they work and when they have been used.

Aspergillus fumigatus and aspergillosis: From basics to clinics

The airborne fungus Aspergillus fumigatus poses a serious health threat to humans by causing numerous invasive infections and a notable mortality in humans, especially in immunocompromised patients. Mould-active azoles are the frontline therapeutics employed to treat aspergillosis. The global emergence of azole-resistant A. fumigatus isolates in clinic and environment, however, notoriously limits the therapeutic options of mould-active antifungals and potentially can be attributed to a mortality rate reaching up to 100 %. Although specific mutations in CYP 51A are the main cause of azole resistance, there is a new wave of azole-resistant isolates with wild-type CYP 51A genotype challenging the efficacy of the current diagnostic tools. Therefore, applications of whole-genome sequencing are increasingly gaining popularity to overcome such challenges. Prominent echinocandin tolerance, as well as liver and kidney toxicity posed by amphotericin B, necessitate a continuous quest for novel antifungal drugs to combat emerging azole-resistant A. fumigatus isolates. Animal models and the tools used for genetic engineering require further refinement to facilitate a better understanding about the resistance mechanisms, virulence, and immune reactions orchestrated against A. fumigatus. This review paper comprehensively discusses the current clinical challenges caused by A. fumigatus and provides insights on how to address them.

Antimicrobial Use and Resistance in Agriculture and Food Production Systems in Africa: A Systematic Review

In Africa, there is dearth of information on antimicrobial use (AMU) in agriculture and food production systems and its consequential resistance in pathogens that affect animal, human and environmental health. Data published between 1980 and 2021 on the magnitude of AMU and AMR in agriculture and food productions systems in Africa were reviewed. Data from 13-27 countries in Africa indicate that 3558-4279 tonnes of antimicrobials were used in animals from 2015 to 2019. Tetracyclines and polypeptides contributed the largest proportion of antimicrobials used. Cattle and poultry production account for the largest consumption of antimicrobials in Africa. Although limited studies have reported AMR in crops, fish and beekeeping, AMR from a variety of farm animals has been substantially documented in Africa. Some countries in Africa have developed policies/plans to address AMU and AMR in agriculture and food production systems; however, their enforcement is challenged by weak regulations. In conclusion, although there is limited information on the quantities of antimicrobials used in agriculture and food production system, the levels of AMR are high. There is a need to strengthen regulatory authorities with a capacity to monitor AMU in agriculture and food production systems in Africa.

Outpatient parenteral antifungal therapy (OPAT) for invasive fungal infections with intermittent dosing of liposomal amphotericin B

Triazole resistant A. fumigatus has been documented in many parts of the world. In the Netherlands, incidence is now above 10% and results in the need for long-term parenteral therapy with liposomal amphotericin B (LAmB). The long terminal half-life of LAmB suggests that intermittent dosing could be effective, making the application of outpatient antifungal therapy (OPAT) possible. Here, we report our experience with the use of OPAT for Invasive Fungal Infections (IFI). All adult patients treated with LAmB with a 2 or 3 times weekly administration via the outpatient departments in four academic tertiary care centers in the Netherlands and Belgium since January 2010 were included in our analysis. Patient characteristics were collected, as well as information about diagnostics, therapy dose and duration, toxicity, treatment history and outcome of the IFI. In total, 18 patients were included. The most frequently used regimen (67%) was 5 mg/kg 3 times weekly. A partial response to the daily treatment prior to discharge was confirmed by CT-scan in 17 (94%) of patients. A favorable outcome was achieved in 13 (72%) patients. Decrease in renal function occurred in 10 (56%) cases but was reversible in all and was treatment limiting in one patient only. The 100-day mortality and 1-year mortality after initiation of OPAT were 0% and 6%, respectively. In a selected population, and after confirmation of initial response to treatment, our data support the use of OPAT with LAmB for treatment of IFI in an intermittent dosing regimen.

Emergence of Triazole Resistance in Aspergillus spp. in Latin America

Purpose of Review

Azole resistance in Aspergillus spp. is becoming a public health problem worldwide. However, data about this subject is lacking in Latin American countries. This review focuses in the epidemiology and molecular mechanisms of azole resistance in Aspergillus spp. emphasizing in Latin America. Data on Aspergillus fumigatus stands out because it is the most prevalent Aspergillus spp. pathogen.

Recent Findings

Azole resistance in Aspergillus spp. emergence was linked with intensive use of these antifungals both in the clinical setting and in the environment (as pesticides). Reports on azole-resistant A. fumigatus strains are being constantly published in different countries. Molecular mechanisms of resistance mainly involve substitution in the azole target (CYP51A) and/or overexpression of this gene. However, several other non-CYP51A-related mechanisms were described. Moreover, intrinsically resistant cryptic Aspergillus species are starting to be reported as human pathogens.

Summary

After a comprehensive literature review, it is clear that azole resistance in Aspergillus spp. is emerging in Latin America and perhaps it is underestimated. All the main molecular mechanisms of azole resistance were described in patients and/or environmental samples. Moreover, one of the molecular mechanisms was described only in South America. Cryptic intrinsic azole-resistant species are also described.

Trends in Agricultural Triazole Fungicide Use in the United States, 1992-2016 and Possible Implications for Antifungal-Resistant Fungi in Human Disease

BACKGROUND

The fungus Aspergillus fumigatus (A. fumigatus) is the leading cause of invasive mold infections, which cause severe disease and death in immunocompromised people. Use of triazole antifungal medications in recent decades has improved patient survival; however, triazole-resistant infections have become common in parts of Europe and are emerging in the United States. Triazoles are also a class of fungicides used in plant agriculture, and certain triazole-resistant A. fumigatus strains found causing disease in humans have been linked to environmental fungicide use.

OBJECTIVES

We examined U.S. temporal and geographic trends in the use of triazole fungicides using U.S. Geological Survey agricultural pesticide use estimates.

DISCUSSION

Based on our analysis, overall tonnage of triazole fungicide use nationwide was relatively constant during 1992-2005 but increased >4-fold during 2006-2016 to 2.9 million kg in 2016. During 1992-2005, triazole fungicide use occurred mostly in orchards and grapes, wheat, and other crops, but recent increases in use have occurred primarily in wheat, corn, soybeans, and other crops, particularly in Midwest and Southeast states. We conclude that, given the chemical similarities between triazole fungicides and triazole antifungal drugs used in human medicine, increased monitoring for environmental and clinical triazole resistance in A. fumigatus would improve overall understanding of these interactions, as well as help identify strategies to mitigate development and spread of resistance. https://doi.org/10.1289/EHP7484.

Potency of olorofim (F901318) compared to contemporary antifungal agents against clinical Aspergillus fumigatus isolates, and review of azole resistance phenotype and genotype epidemiology in China

Triazole resistance in A. fumigatus is an increasing worldwide problem that causes major challenges in the management of aspergillosis. New antifungal drugs are needed with novel targets, that are effective in triazole-resistant infection. In this study, we retrospectively evaluated potency of the novel drug olorofim compared to contemporary antifungal agents against 111 clinical A. fumigatus isolates collected from Huashan Hospital, Shanghai, China, using EUCAST methodology, and reviewed the literature on triazole resistant A. fumigatus published between 1966 and 2020 in China. Olorofim was active in vitro against all tested A. fumigatus isolates with MIC₉₀ of 0.031mg/L (range 0.008-0.062 mg/L). For 4 triazole-resistant A. fumigatus (TRAF) isolates, the olorofim MIC ranged between 0.016-0.062mg/L. The reported rates of TRAF in China is 2.5% - 5.56% for clinical isolates, and 0-1.4% for environmental isolates.TR₃₄/L98H/S297T/F495I is the predominant resistance mechanism, followed by TR₃₄/L98H. Non TR-mediated TRAF isolates, mostly harboring a cyp51A single point mutation, showed greater genetic diversity than TR-mediated resistant isolates. Resistance due toTR₃₄/L98H and TR₃₄/L98H/S297T/F495I mutations among TRAF isolates might have evolved from separate local isolates in China. Continuous isolation of TRAF in China underscores the need for systematic resistance surveillance as well as the need for novel drug targets such as olorofim.

Molecular Epidemiology of Aspergillus fumigatus in Chronic Pulmonary Aspergillosis Patients

Molecular fungal genotyping techniques developed and employed for epidemiological studies have understandably concentrated on establishing the genetic diversity of Aspergillus fumigatus in invasive aspergillosis due to its severity, the urgency for treatment, and the need to demonstrate possible sources. Some early studies suggested that these strains were phenotypically, if not genotypically, different from others. However, with improved discrimination and evaluations, incorporating environmental as well as clinical isolates from other Aspergillus conditions (e.g., chronic pulmonary aspergillosis and cystic fibrosis), this premise is no longer upheld. Moreover, with the onset of increased global triazole resistance, there has been a concerted effort to incorporate resistance profiling into genotyping studies and the realisation that the wider population of non-immunocompromised aspergillosis patients are at risk. This review summarises the developments in molecular genotyping studies that incorporate resistance profiling with attention to chronic pulmonary aspergillosis and an example of our UK experience.

A comprehensive review on environmental toxicity of azole compounds to fish

BACKGROUND

Azoles are considered as one of the most efficient fungicides for the treatment of humans, animals, and plant fungal pathogens. They are of significant clinical importance as antifungal drugs and are widely used in personal care products, ultraviolet stabilizers, and in aircraft for its anti-corrosive properties. The prevalence of azole compounds in the natural environment and its accumulation in fish raises questions about its impact on aquatic organisms.

OBJECTIVES

The objective of this paper is to review the scientific studies on the effects of azole compounds in fish and to discuss future opportunities for the risk evaluation.

METHODS

A systematic literature search was conducted on Web of Science, PubMed, and ScienceDirect to locate peer-reviewed scientific articles on occurrence, environmental fate, and toxicological impact of azole fungicides on fish.

RESULTS

Studies included in this review provide ample evidence that azole compounds are not only commonly detected in the natural environment but also cause several detrimental effects on fish. Future studies with environmentally relevant concentrations of azole alone or in combination with other commonly occurring contaminants in a multigenerational study could provide a better understanding.

CONCLUSION

Based on current knowledge and studies reporting adverse biological effects of azole on fish, considerable attention is required for better management and effective ecological risk assessment of these emerging contaminants.

Mechanisms of triazole resistance in Aspergillus fumigatus

The ubiquitous fungal pathogen Aspergillus fumigatus is the primary cause of opportunistic mould infections in humans. Aspergilli disseminate via asexual conidia passively travelling through air currents to germinate within a broad range of environs, wherever suitable nutrients are found. Though the average human inhales hundreds of conidia daily, A. fumigatus invasive infections primarily affect the immunocompromised. At-risk individuals can develop often fatal invasive disease for which therapeutic options are limited. Regrettably, the global insurgence of isolates resistant to the triazoles, the frontline antifungal class used in medicine and agriculture to control A. fumigatus, is complicating the treatment of patients. Triazole antifungal resistance in A. fumigatus has become recognized as a global, yet poorly comprehended, problem. Due to a multitude of factors, the magnitude of resistant infections and their contribution to treatment outcomes are likely underestimated. Current studies suggest that human drug-resistant infections can be either environmentally acquired or de novo host selected during patient therapy. While much concerning development of resistance is yet unknown, recent investigations have revealed assorted underlying mechanisms enabling triazole resistance within individual clinical and environmental isolates. This review will provide an overview of triazole resistance as it is currently understood, as well as highlight some of the prominent biological mechanisms associated with clinical and environmental resistance to triazoles in A. fumigatus.

Screening for triazole resistance in clinically significant Aspergillus species; report from Pakistan

Background

Burden of aspergillosis is reported to be significant from developing countries including those in South Asia. The estimated burden in Pakistan is also high on the background of tuberculosis and chronic lung diseases. There is concern for management of aspergillosis with the emergence of azole resistant Aspergillus species in neighbouring countries in Central and South Asia.

Hence the aim of this study was to screen significant Aspergillus species isolates at the Microbiology Section of Aga Khan Clinical Laboratories, Pakistan, for triazole resistance.

Methods

A descriptive cross-sectional study, conducted at the Aga Khan University Laboratories, Karachi, from September 2016–May 2019. One hundred and fourteen, clinically significant Aspergillus isolates [A. fumigatus (38; 33.3%), A. flavus (64; 56.1%), A. niger (9; 7.9%) A. terreus (3; 2.6%)] were included. The clinical spectrum ranged from invasive aspergillosis (IA) (n = 25; 21.9%), chronic pulmonary aspergillosis (CPA) (n = 58; 50.9%), allergic bronchopulmonary aspergillosis (ABPA) (n = 4; 3.5%), severe asthma with fungal sensitization (SAFS) (n = 4; 3.5%), saprophytic tracheobronchial aspergillosis (n = 23; 20.2%). Screening for triazole resistance was performed by antifungal agar screening method. The minimum inhibitory concentration (MIC) of 41 representative isolates were tested and interpreted according to the Clinical and Laboratory Standards Institute broth microdilution method.

Results

All the isolates were triazole-susceptible on agar screening. MICs of three azole antifungals for 41 tested isolates were found to be ≤1 ml/L; all isolates tested were categorized as triazole-susceptible, including 4 isolates from patients previously on triazole therapy for more than 2 weeks. The minimum inhibitory concentration required to inhibit the growth of 90% organisms (MIC₉₀) of itraconazole, voriconazole and posaconazole of the representative Aspergillus isolates was 1 mg/L, 1 mg/L and 0.5 mg/L, respectively.

Conclusion

Triazole resistance could not be detected amongst clinical Aspergillus isolates from the South of Pakistan. However, environmental strains remain to be tested for a holistic assessment of the situation. This study will set precedence for future periodic antifungal resistance surveillance in our region on Aspergillus isolates.

Antifungal Susceptibility Testing: Current Approaches

Although not as ubiquitous as antibacterial susceptibility testing, antifungal susceptibility testing (AFST) is a tool of increasing importance in clinical microbiology laboratories. The goal of AFST is to reliably produce MIC values that may be used to guide patient therapy, inform epidemiological studies, and track rates of antifungal drug resistance. There are three methods that have been standardized by standards development organizations: broth dilution, disk diffusion, and azole agar screening for Aspergillus Other commonly used methods include gradient diffusion and the use of rapid automated instruments. Novel methodologies for susceptibility testing are in development. It is important for laboratories to consider not only the method of testing but also the interpretation (or lack thereof) of in vitro data.

The negative cofactor 2 complex is a key regulator of drug resistance in Aspergillus fumigatus

The frequency of antifungal resistance, particularly to the azole class of ergosterol biosynthetic inhibitors, is a growing global health problem. Survival rates for those infected with resistant isolates are exceptionally low. Beyond modification of the drug target, our understanding of the molecular basis of azole resistance in the fungal pathogen Aspergillus fumigatus is limited. We reasoned that clinically relevant antifungal resistance could derive from transcriptional rewiring, promoting drug resistance without concomitant reductions in pathogenicity. Here we report a genome-wide annotation of transcriptional regulators in A. fumigatus and construction of a library of 484 transcription factor null mutants. We identify 12 regulators that have a demonstrable role in itraconazole susceptibility and show that loss of the negative cofactor 2 complex leads to resistance, not only to the azoles but also the salvage therapeutics amphotericin B and terbinafine without significantly affecting pathogenicity.

Resistance to primary treatments of invasive aspergillosis is growing. Here, the authors generate a knockout library for 484 transcription factors in Aspergillus fumigatus, and show that loss of the NCT complex leads to cross-resistance to all primary and some salvage therapeutics without affecting pathogenicity.

Prospective multicenter surveillance of clinically isolated Aspergillus species revealed azole-resistant Aspergillus fumigatus isolates with TR34/L98H mutation in the Kyoto and Shiga regions of Japan

The prevalence of azole-resistant Aspergillus fumigatus (ARAF) in Japan is unclear. We aimed to investigate the epidemiology of clinically isolated Aspergillus species and the frequency of azole resistance in Aspergillus species, particularly Aspergillus fumigatus, in the Kyoto and Shiga regions of Japan. Strains of clinically isolated Aspergillus species were prospectively collected from nine acute care hospitals. Species identification was performed by DNA sequence analysis, and all strains were subjected to antifungal susceptibility testing. Sequencing of the Aspergillus cyp51A gene and promoter region and genotyping by short tandem repeats were performed for ARAF isolates. A total of 149 strains were collected, and 130 strains were included for the subsequent analysis after the exclusion of duplicate isolates. The most commonly isolated species was Aspergillus fumigatus, accounting for 43.1% (56 isolates) overall, and seven (12.7%) of 55 strains of A. fumigatus were azole-resistant. Azole-resistance of other Aspergillus species were also found that two (22.2%) of nine strains of A. tubingensis and two (28.6%) of seven strains of A. flavus were azole-resistant. DNA sequence analysis of the ARAF strains revealed that two carried the cyp51A TR34/L98H mutation, one carried G448S, one carried M220I, and three had no relevant mutations (wild type). Genotyping and phylogenetic analyses showed that the TR34/L98H strains were clustered with the strains from the Netherlands and France. These data suggest the emergence of ARAF with TR34/L98H in Japan, and continuous surveillance will be important to identify trends in resistance.

Azole-resistant Aspergillus fumigatus: A global phenomenon originating in the environment?

Aspergillus fumigatus is the predominant etiological agent of invasive aspergillosis (IA), a difficult-to-manage fungal disease associated with a high case fatality rate. Azole antifungals, particularly voriconazole, have significantly improved the survival rate of patients with IA. However, the clinical advances made possible through the use of medical azoles could be threatened by the emergence of azole-resistant strains which has been reported in an ever-increasing number of countries over the last 10 years. The major resistance mechanism, that combines point mutation(s) in the coding sequence of cyp51A gene and an insertion of a tandem repeat in the promoter region of this gene which leads to its overexpression (TR₃₄/L98H and TR₄₆/Y121F/T289A), is presumed to be of environmental origin. However, the emergence of clinical and environmental azole-resistant strains without the cyp51A gene mutation suggests that other mechanisms could also be responsible for azole resistance (for example, overexpression of efflux pumps). The development of resistance may be linked to either long-term use of azole antifungals in patients with chronic aspergillosis (patient-acquired route) or selection pressure of the fungicides in the environment (environmental route). The fungicide-driven route could be responsible for resistance in azole-naive patients with IA. This literature review aims to summarize recent findings, focusing on the current situation of azole-resistance in A. fumigatus, and provides better understanding of the importance of the environmental route in resistance acquisition.

The Emergence of Rare Clinical Aspergillus Species in Qatar: Molecular Characterization and Antifungal Susceptibility Profiles

Aspergillus are ubiquitous mold species that infect immunocompetent and immunocompromised patients. The symptoms are diverse and range from allergic reactions, bronchopulmonary infection, and bronchitis, to invasive aspergillosis. The aim of this study was to characterize 70 Aspergillus isolates recovered from clinical specimens of patients with various clinical conditions presented at Hamad general hospital in Doha, Qatar, by using molecular methods and to determine their in vitro antifungal susceptibility patterns using the Clinical and Laboratory Standards Institute (CLSI) M38-A2 reference method. Fourteen Aspergillus species were identified by sequencing β-tubulin and calmodulin genes, including 10 rare and cryptic species not commonly recovered from human clinical specimens. Aspergillus welwitschiae is reported in this study for the first time in patients with fungal rhinosinusitis (n = 6) and one patient with a lower respiratory infection. Moreover, Aspergillus pseudonomius is reported in a patient with fungal rhinosinusitis which is considered as the first report ever from clinical specimens. In addition, Aspergillus sublatus is reported for the first time in a patient with cystic fibrosis. In general, our Aspergillus strains exhibited low MIC values for most of the antifungal drugs tested. One strain of Aspergillus fumigatus showed high MECs for echinocandins and low MICs for the rest of the drugs tested. Another strain of A. fumigatus exhibited high MIC for itraconazole and categorized as non-wild type. These findings require further analysis of their molecular basis of resistance. In conclusion, reliable identification of Aspergillus species is achieved by using molecular sequencing, especially for the emerging rare and cryptic species. They are mostly indistinguishable by conventional methods and might exhibit variable antifungal susceptibility profiles. Moreover, investigation of the antifungal susceptibility patterns is necessary for improved antifungal therapy against aspergillosis.

Emerging Fungal Infections: New Patients, New Patterns, and New Pathogens

The landscape of clinical mycology is constantly changing. New therapies for malignant and autoimmune diseases have led to new risk factors for unusual mycoses. Invasive candidiasis is increasingly caused by non-albicans Candida spp., including C. auris, a multidrug-resistant yeast with the potential for nosocomial transmission that has rapidly spread globally. The use of mould-active antifungal prophylaxis in patients with cancer or transplantation has decreased the incidence of invasive fungal disease, but shifted the balance of mould disease in these patients to those from non-fumigatus Aspergillus species, Mucorales, and Scedosporium/Lomentospora spp. The agricultural application of triazole pesticides has driven an emergence of azole-resistant A. fumigatus in environmental and clinical isolates. The widespread use of topical antifungals with corticosteroids in India has resulted in Trichophyton mentagrophytes causing recalcitrant dermatophytosis. New dimorphic fungal pathogens have emerged, including Emergomyces, which cause disseminated mycoses globally, primarily in HIV infected patients, and Blastomyceshelicus and B. percursus, causes of atypical blastomycosis in western parts of North America and in Africa, respectively. In North America, regions of geographic risk for coccidioidomycosis, histoplasmosis, and blastomycosis have expanded, possibly related to climate change. In Brazil, zoonotic sporotrichosis caused by Sporothrix brasiliensis has emerged as an important disease of felines and people.

A simple and low cost tetra-primer ARMS-PCR method for detection triazole-resistant Aspergillus fumigatus

The mutation at codon L98 accompanied by a tandem repeat of 34 base pairs (TR₃₄/L98H) in the 5´upstream region of cyp51A is the principal mechanism of triazole resistance of Aspergillus fumigatus. We aimed to evaluate a simple and low-cost tetra-primer amplification refractory mutation system (ARMS)-PCR technique for detection of TR₃₄/L98H mutations in the cyp51A gene of azole-resistant A. fumigatus. The tetra-primer ARMS-PCR assay optimized by four primers in one reaction consists of external primers for detection of tandem repeats in the promoter region and internal primers for detection of a point mutation in codon 98 (L98H) in the cyp51A gene of azole-resistant A. fumigatus. The specificity of TR₃₄/L98H mutation detection was assessed by testing 36 clinical and environmental A. fumigatus strains. The tetra-primer ARMS-PCR assay from A. fumigatus, containing wild-type sequence (T allele) and L98H mutation at cyp51A (A allele), yielded two DNA fragments of 908 bp and 740 bp and two of 942 bp and 212 bp, respectively. None of the A. fumigatus isolates without the TR₃₄/L98H mutation yielded false-positive results. The ARMS-PCR assay was 100% concordant with DNA sequencing results. Prevalence and screening of the TR₃₄/L98H mutation in the cyp51A gene in A. fumigatus isolates may now be determined by a fast, low-cost, and simple method in resource-poor settings.

Fungicide-driven alterations in azole-resistant Aspergillus fumigatus are related to vegetable crops in Colombia, South America

Aspergillus fumigatus resistant to azole as first-line therapy has been reported in azole-naïve patients. This worldwide resistance phenomenon has been linked to fungicide-driven alterations in the cyp51A gene and its promoter region (such as TR₃₄/L98H and TR₄₆/Y121F/T289A). Azole-resistant A. fumigatus related to the use of triazole fungicides in flower fields was recently reported In Colombia. The purpose of this study was to investigate the presence of azole-resistant A. fumigatus in soil samples from vegetable crops such as carrots, potatoes, maize, strawberries, and pea, and from prepared farming land surrounding the city of Bogotá. Species identification was based on sequencing of the β-tubulin and calmodulin genes. All A. fumigatus strains were screened for azole resistance on agar supplemented with itraconazole or voriconazole. Among the 60 soil samples, 34 (56.6%) were positive for A. fumigatus and 15 samples exhibited strains (n = 18) that grew on agar supplemented with itraconazole or voriconazole. Triazole-resistant strains were isolated from soil samples associated with carrot, potato, maize, and pea crops. Sequencing of the cyp51A gene and its promoter region indicated polymorphism, mainly with the presence of TR₄₆/Y121F/T289A (n = 8), TR₃₄/L98H, and TR₅₃. Eight resistant isolates exhibited cyp51A wild type without alterations in the promoter region. Our study showed evidence of dissemination of azole-resistant A. fumigatus, with high genetic diversity, in vegetable crops in Colombia. These data underline the need to determine the prevalence of azole resistance in A. fumigatus in clinical and environmental settings for other regions of Colombia as well as Latin America.

Resistance mechanism and proteins in Aspergillus species against antifungal agents

Aspergillus

species contain pathogenic and opportunistic fungal pathogens which have the potential to cause mycosis (invasive aspergillosis) in humans. The existing antifungal drugs have limitation largely due to the development of drug-resistant isolates. To gain insight into the mechanism of action and antifungal drug resistance in Aspergillus species including biofilm formation, we have reviewed protein data of Aspergillus species during interaction with antifungals drugs (polynes, azoles and echinocandin) and phytochemicals (artemisinin, coumarin and quercetin). Our analyses provided a list of Aspergillus proteins (72 proteins) that were abundant during interaction with different antifungal agents. On the other hand, there are 26 proteins, expression level of which is affected by more than two antifungal agents, suggesting the more general response to the stress induced by the antifungal agents. Our analysis showed enzymes from cell wall remodelling, oxidative stress response and energy metabolism are the responsible factors for providing resistance against antifungal drugs in Aspergillus species and could be explored further in clinical isolates. Also, these findings have clinical importance since the effect of drug targeting different proteins can be potentiated by combination therapy. We have also discussed the opportunities ahead to study the functional role of proteins from environmental and clinical isolates of Aspergillus during its interaction with the antifungal drugs.

Abbreviations

IPA: invasive pulmonary aspergillosis; IA: invasive aspergillosis; AmB: Amphotericin B; CAS: Caspofungin; VRC: Voriconazole; ITC: Itraconazole; POS: Posaconazole; ART: Artemisinin; QRT: Quercetin; CMR: Coumarin; MIC: minimal inhibitory concentration

Inducible Cell Fusion Permits Use of Competitive Fitness Profiling in the Human Pathogenic Fungus Aspergillus fumigatus

Antifungal agents directed against novel therapeutic targets are required for treating invasive, chronic, and allergic Aspergillus infections. Competitive fitness profiling technologies have been used in a number of bacterial and yeast systems to identify druggable targets; however, the development of similar systems in filamentous fungi is complicated by the fact that they undergo cell fusion and heterokaryosis. Here, we demonstrate that cell fusion in Aspergillus fumigatus under standard culture conditions is not predominately constitutive, as with most ascomycetes, but can be induced by a range of extracellular stressors. Using this knowledge, we have developed a barcode-free genetic profiling system that permits high-throughput parallel determination of strain fitness in a collection of diploid A. fumigatus mutants. We show that heterozygous cyp51A and arf2 null mutants have reduced fitness in the presence of itraconazole and brefeldin A, respectively, and a heterozygous atp17 null mutant is resistant to brefeldin A.

Triazole resistance surveillance in Aspergillus fumigatus

Triazole resistance is an increasing concern in the opportunistic mold Aspergillus fumigatus. Resistance can develop through exposure to azole compounds during azole therapy or in the environment. Resistance mutations are commonly found in the Cyp51A-gene, although other known and unknown resistance mechanisms may be present. Surveillance studies show triazole resistance in six continents, although the presence of resistance remains unknown in many countries. In most countries, resistance mutations associated with the environment dominate, but it remains unclear if these resistance traits predominately migrate or arise locally. Patients with triazole-resistant aspergillus disease may fail to antifungal therapy, but only a limited number of cohort studies have been performed that show conflicting results. Treatment failure might be due to diagnostic delay or due to the limited number of alternative treatment options. The ISHAM/ECMM Aspergillus Resistance Surveillance working group was set up to facilitate surveillance studies and stimulate international collaborations. Important aims are to determine the resistance epidemiology in countries where this information is currently lacking, to gain more insight in the clinical implications of triazole resistance through a registry and to unify nomenclature through consensus definitions.

Determination of azole fungal residues in soils and detection of Aspergillus fumigatus-resistant strains in market gardens of Eastern France

Medical azole antifungals are major compounds used to prevent and to treat invasive aspergillosis (IA). Azole fungicides, called DMI (14-alpha demethylase inhibitors), are also widely used for crop protection and have been reported to be linked to azole-resistant A. fumigatus (aR-Af) development in the environment. The aim of this study was to determine whether or not market gardens that spray DMIs in Eastern France are also affected by the presence of aR-Af. Forty aR-Afs were detected in soils in only two of the four market gardens using DMIs, with 23% (7/30) and 10% (3/30) of soils containing aR-Af. A total of 87.5% of these isolates had the TR34/L98H mutation and 22.5% the TR46/Y121F/T289A mutation on the cyp51A gene. Analyses of residual azole concentrations in soils showed the presence of difenoconazole for up to 2 years after spraying, but only in soils of market gardens where aR-Af was detected. It is very important to identify professional activities that could lead to aR-Af development and to develop preventive measures for at-risk patients living near professional activities using DMIs. We have to better understand why, in some cases, the use of DMI is not linked to aR-Af. Measures should be taken to avoid the use of DMI conferring cross-resistance to preserve the efficiency of human therapeutics.

Surveillance for Azole-Resistant Aspergillus fumigatus in a Centralized Diagnostic Mycology Service, London, United Kingdom, 1998-2017

Background/Objectives: Aspergillus fumigatus is the leading cause of invasive aspergillosis. Treatment is hindered by the emergence of resistance to triazole antimycotic agents. Here, we present the prevalence of triazole resistance among clinical isolates at a major centralized medical mycology laboratory in London, United Kingdom, in the period 1998-2017. Methods: A large number (n = 1469) of clinical A. fumigatus isolates from unselected clinical specimens were identified and their susceptibility against three triazoles, amphotericin B and three echinocandin agents was carried out. All isolates were identified phenotypically and antifungal susceptibility testing was carried out by using a standard broth microdilution method. Results: Retrospective surveillance (1998-2011) shows 5/1151 (0.43%) isolates were resistant to at least one of the clinically used triazole antifungal agents. Prospective surveillance (2015-2017) shows 7/356 (2.2%) isolates were resistant to at least one triazole antifungals demonstrating an increase in incidence of triazole-resistant A. fumigatus in our laboratory. Among five isolates collected from 2015 to 2017 and available for molecular testing, three harbored TR34/L98H alteration in the cyp51A gene that are associated with the acquisition of resistance in the non-patient environment. Conclusion: These data show that historically low prevalence of azole resistance may be increasing, warranting further surveillance of susceptible patients.

High prevalence of triazole resistance in clinical Aspergillus fumigatus isolates in a specialist cardiothoracic centre

OBJECTIVES

To evaluate the prevalence of triazole-resistant Aspergillus fumigatus and common molecular cyp51A polymorphisms amongst clinical isolates in a specialised cardiothoracic centre in London, UK.

METHODS

All A. fumigatus isolates were prospectively analysed from April 2014 to March 2016. Isolates were screened with a four-well VIPcheck™ plate to assess triazole susceptibility. Resistance was confirmed with a standard microbroth dilution method according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Triazole-resistant A. fumigatus isolates were subjected to a mixed-format real time polymerase chain reaction (RT-PCR) assay (AsperGenius^®) to detect common cyp51A alterations.

RESULTS

We identified 167 clinical A. fumigatus isolates from 135 patients. Resistance to at least one azole antifungal drug was confirmed in 22/167 (13.2%) of isolates from 18/135 (13.3%) patients, including 12/74 (16.2%) patients with cystic fibrosis (CF). The highest detection rate of azole-resistant A. fumigatus was among the 11- to 20-y age group. All triazole-resistant isolates (n = 22) were resistant to itraconazole, 18 showed cross-resistance to posaconazole and 10 displayed reduced susceptibility to voriconazole. No pan-azole-resistant A. fumigatus was identified. TR₃₄/L98H was identified in 6/22 (27.3%) of azole-resistant isolates and detectable in 5/12 (42%) patients with CF.

CONCLUSIONS

In our specialist cardiothoracic centre, the prevalence of triazole-resistant A. fumigatus is alarmingly high (13.2%). The majority of azole-resistant isolates were from patients with CF. We found a higher prevalence of the environmentally driven mutation TR₃₄/L98H in our A. fumigatus isolates than in published UK data from other specialist respiratory centres, which may reflect differing patient populations managed at these institutions.

Emergence of Azole-Resistant Aspergillus fumigatus from Immunocompromised Hosts in India

This prospective study shows that the rate of azole-resistant Aspergillus fumigatus (ARAF) in an immunocompromised Indian patient population with invasive aspergillosis (IA) is low, 6/706 (0.8%). This low rate supports the continued use of voriconazole as the first line of treatment. However, the ARAF isolates from India in this study exhibited three kinds of unreported cyp51A mutations, of which two were at hot spots, G54R and P216L, while one was at codon Y431C.

Insight into the Significance of Aspergillus fumigatus cyp51A Polymorphisms

Triazole antifungal compounds are the first treatment choice for invasive aspergillosis. However, in the last decade the rate of azole resistance among Aspergillus fumigatus strains has increased notoriously. The main resistance mechanisms are well defined and mostly related to point mutations of the azole target, 14-α sterol demethylase (cyp51A), with or without tandem repeat integrations in the cyp51A promoter. Furthermore, different combinations of five Cyp51A mutations (F46Y, M172V, N248T, D255E, and E427K) have been reported worldwide in about 10% of all A. fumigatus isolates tested. The azole susceptibility profile of these strains shows elevated azole MICs, although on the basis of the azole susceptibility breakpoints, these strains are not considered azole resistant. The purpose of the study was to determine whether these cyp51A polymorphisms (single nucleotide polymorphisms [SNPs]) are responsible for the azole susceptibility profile and whether they are reflected in a poorer azole treatment response in vivo that could compromise patient treatment and outcome. A mutant with a cyp51A deletion was generated and became fully susceptible to all azoles tested. Also, three cyp51A gene constructions with different combinations of SNPs were generated and reintroduced into an azole-susceptible wild-type (WT) strain (the ΔakuB^KU80 strain). The alternative model host Galleria mellonella was used to compare the virulence and voriconazole response of G. mellonella larvae infected with A. fumigatus strains with WT cyp51A or cyp51A with SNPs. All strains were pathogenic in G. mellonella larvae, although they did not respond similarly to voriconazole therapeutic doses. Finally, the full genomes of these strains were sequenced and analyzed in comparison with those of A. fumigatus WT strains, revealing that they belong to different strain clusters or lineages.

Elevated MIC Values of Imidazole Drugs against Aspergillus fumigatus Isolates with TR34/L98H/S297T/F495I Mutation

The use of azole fungicides in agriculture is believed to be one of the main reasons for the emergence of azole resistance in Aspergillus fumigatus Though widely used in agriculture, imidazole fungicides have not been linked to resistance in A. fumigatus This study showed that elevated MIC values of imidazole drugs were observed against A. fumigatus isolates with TR₃₄/L98H/S297T/F495I mutation, but not among isolates with TR₃₄/L98H mutation. Short-tandem-repeat (STR) typing analysis of 580 A. fumigatus isolates from 20 countries suggested that the majority of TR₃₄/L98H/S297T/F495I strains from China were genetically different from the predominant major clade comprising most of the azole-resistant strains and the strains with the same mutation from the Netherlands and Denmark. Alignments of sterol 14α-demethylase sequences suggested that F495I in A. fumigatus was orthologous to F506I in Penicillium digitatum and F489L in Pyrenophora teres, which have been reported to be associated with imidazole resistance. In vitro antifungal susceptibility testing of different recombinants with cyp51A mutations further confirmed the association of the F495I mutation with imidazole resistance. In conclusion, this study suggested that environmental use of imidazole fungicides might confer selection pressure for the emergence of azole resistance in A. fumigatus.

Azole-Resistance in Aspergillus terreus and Related Species: An Emerging Problem or a Rare Phenomenon?

Objectives: Invasive mold infections associated with Aspergillus species are a significant cause of mortality in immunocompromised patients. The most frequently occurring aetiological pathogens are members of the Aspergillus section Fumigati followed by members of the section Terrei. The frequency of Aspergillus terreus and related (cryptic) species in clinical specimens, as well as the percentage of azole-resistant strains remains to be studied.

Methods: A global set (n = 498) of A. terreus and phenotypically related isolates was molecularly identified (beta-tubulin), tested for antifungal susceptibility against posaconazole, voriconazole, and itraconazole, and resistant phenotypes were correlated with point mutations in the cyp51A gene.

Results: The majority of isolates was identified as A. terreus (86.8%), followed by A. citrinoterreus (8.4%), A. hortai (2.6%), A. alabamensis (1.6%), A. neoafricanus (0.2%), and A. floccosus (0.2%). One isolate failed to match a known Aspergillus sp., but was found most closely related to A. alabamensis. According to EUCAST clinical breakpoints azole resistance was detected in 5.4% of all tested isolates, 6.2% of A. terreus sensu stricto (s.s.) were posaconazole-resistant. Posaconazole resistance differed geographically and ranged from 0% in the Czech Republic, Greece, and Turkey to 13.7% in Germany. In contrast, azole resistance among cryptic species was rare 2 out of 66 isolates and was observed only in one A. citrinoterreus and one A. alabamensis isolate. The most affected amino acid position of the Cyp51A gene correlating with the posaconazole resistant phenotype was M217, which was found in the variation M217T and M217V.

Conclusions:Aspergillus terreus was most prevalent, followed by A. citrinoterreus. Posaconazole was the most potent drug against A. terreus, but 5.4% of A. terreus sensu stricto showed resistance against this azole. In Austria, Germany, and the United Kingdom posaconazole-resistance in all A. terreus isolates was higher than 10%, resistance against voriconazole was rare and absent for itraconazole.

In vitro combination of voriconazole with micafungin against azole-resistant clinical isolates of Aspergillus fumigatus from different geographical regions

In vitro interaction of voriconazole with micafungin was evaluated against 33 clinical Aspergillus fumigatus isolates, including azole-resistant (n=31) and -susceptible (n=2) isolates. Interaction was synergistic for only 1 resistant isolate carrying the TR₃₄/L98H mutation. No antagonistic effects were observed for 96.8% of azole-resistant isolates.

Investigation of Multiple Resistance Mechanisms in Voriconazole-Resistant Aspergillus flavus Clinical Isolates from a Chest Hospital Surveillance in Delhi, India

Invasive and allergic infections by Aspergillus flavus are more common in tropical and subtropical countries. The emergence of voriconazole (VRC) resistance in A. flavus impacts the management of aspergillosis, as azoles are used as the first-line and empirical therapy. We screened 120 molecularly confirmed A. flavus isolates obtained from respiratory and sinonasal specimens in a chest hospital in Delhi, India, for azole resistance using the CLSI broth microdilution (CLSI-BMD) method. Overall, 2.5% (n = 3/120) of A. flavus isolates had VRC MICs above epidemiological cutoff values (>1 μg/ml). The whole-genome sequence analysis of three non-wild-type (WT) A. flavus isolates with high VRC MICs showed polymorphisms in azole target genes (cyp51A, cyp51B, and cyp51C). Further, four novel substitutions (S196F, A324P, N423D, and V465M) encoded in the cyp51C gene were found in a single non-WT isolate which also exhibited overexpression of cyp51 (cyp51A, -B, and -C) genes and transporter genes, namely, MDR1, MDR2, atrF, and mfs1 The homology model of the non-WT isolate suggests that substitutions S196F and N423D exhibited major structural and functional effects on cyp51C drug binding. The substrate (drug) may not be able to bind to binding pocket due to changes in the pocket size or closing down or narrowing of cavities in drug entry channels. Notably, the remaining two VRC-resistant A. flavus isolates, including the one which had a pan-azole resistance phenotype (itraconazole and posaconazole), did not show upregulation of any of the analyzed target genes. These results suggest that multiple target genes and mechanisms could simultaneously contribute to azole resistance in A. flavus.

Prevalence of azole-resistant Aspergillus fumigatus in the environment of Thailand

Occurrence of azole-resistant Aspergillus fumigatus (ARAF) in the environment is an emerging problem worldwide, likely impacting on patient treatment. Several resistance mutations are thought to have initially arisen through triazole-based fungicide use in agriculture and subsequently being propagated in a similar manner. Here we investigated the prevalence of ARAF in the environment of Thailand and characterized their susceptibility profiles toward clinically used azole compounds along with underlying resistance mutations. Three hundred and eight soil samples were collected and analyzed, out of which 3.25% (n = 10) were positive for ARAF. All isolates obtained were resistant to itraconazole (MIC ≥ 8 μg/ml), two showed additional increased MIC values toward posaconazole (MIC = 0.5 μg/ml), and one other toward voriconazole (MIC = 2 μg/ml). Sequencing of the respective cyp51A genes revealed that eight of the isolates carried the TR34/L98H allele and those two with elevated MIC values to posaconazole the G54R substitution. Although a clear correlation between the use of triazole-based fungicides and isolation of ARAF strains from agricultural lands could not be established for Thailand, but this study clearly demonstrates the spread of globally observed ARAF strains to the environment of South East Asia.

Recent advances on topical antimicrobials for skin and soft tissue infections and their safety concerns

Antimicrobial resistance of disease-related microorganisms is considered a worldwide prevalent and serious issue which increases the failure of treatment outcomes and leads to high mortality. Considering that the increased resistance to systemic antimicrobial therapy often needs of the use of more toxic agents, topical antimicrobial therapy emerges as an attractive route for the treatment of infectious diseases. The topical antimicrobial therapy is based on the absorption of high drug doses in a readily accessible skin surface, resulting in a reduction of microbial proliferation at infected skin sites. Topical antimicrobials retain the following features: (a) they are able to escape the enzymatic degradation and rapid clearance in the gastrointestinal tract or the first-pass metabolism during oral administration; (b) alleviate the physical discomfort related to intravenous injection; (c) reduce possible adverse effects and drug interactions of systemic administrations; (d) increase patient compliance and convenience; and (e) reduce the treatment costs. Novel antimicrobials for topical application have been widely exploited to control the emergence of drug-resistant microorganisms. This review provides a description of antimicrobial resistance, common microorganisms causing skin and soft tissue infections, topical delivery route of antimicrobials, safety concerns of topical antimicrobials, recent advances, challenges and future prospective in topical antimicrobial development.

Triazole phenotypes and genotypic characterization of clinical Aspergillus fumigatus isolates in China

This study investigated the triazole phenotype and genotypic of clinical Aspergillus fumigatus isolates from China. We determined the triazole susceptibility profiles of 159 A. fumigatus isolates collected between 2011 and 2015 from four different areas in China tested against 10 antifungal drugs using the Clinical Laboratory Standard Institute M38-A2 method. For the seven itraconazole-resistant A. fumigatus isolates identified in the study, the cyp51A gene, including its promoter region, was sequenced and the mutation patterns were characterized. The resistant isolates were genotyped by microsatellite typing to determine the genetic relatedness to isolates from China and other countries. The frequency of itraconazole resistance in A. fumigatus isolates in our study was 4.4% (7/159). Six of the seven triazole-resistant isolates were recovered from the east and southeast of China, and one from was recovered from the west of China. No resistant isolates were found in the north. Three triazole-resistant isolates exhibited the TR₃₄/L98H mutation, two carried the TR₃₄/L98H/S297T/F495I mutation and one harbored a G54V mutation in the cyp51A gene. Analysis of the microsatellite markers from seven non-wild-type isolates indicated the presence of five unique genotypes, which clustered into two major genetic groups. The cyp51A gene mutations TR₃₄/L98H and TR₃₄/L98H/S297T were the most frequently found mutations, and the G54V mutation was reported for the first time in China. The geographic origin of the triazole-resistant isolates appeared to concentrate in eastern and south-eastern areas, which suggests that routine antifungal susceptibility testing in these areas should be performed for all clinically relevant A. fumigatus isolates to guide antifungal therapy and for epidemiological purposes.