Comparison of galactomannan lateral flow assay and enzyme immunoassay to identify Aspergillus spp. in bronchoalveolar lavage fluid.

Aspergillus species can colonize and infect immunocompetent and immunocompromised hosts. Conventional fungal identification depends on microscopic analysis and microorganism medium growth. Other diagnostic methods, non-growth dependent, to invasive fungal infections, are the biomarkers that detect circulating polysaccharides, for example, 1-3-ß-d-Glucan and galactomannan. Both are polysaccharides present on the external layer of fungi cell wall and can be detected in clinical samples during the growth of the fungus in the patient. This study aimed to compare the galactomannan detection of Lateral Flow Assay and Enzyme Immunoassay methods in Bronchoalveolar Lavage Fluid. The galactomannan antigen in Bronchoalveolar Lavage Fluid was measured using Enzyme Immunoassay according to the manufacturer's instructions (PLATELIA ASPERGILLUS™ BioRad) and, using a Lateral Flow Assay according to the manufacturer's instructions (Galactomannan LFA IMMY©). The 71 samples were Bronchoalveolar Lavage Fluid of patients hospitalized at Unicamp Clinical Hospital between 2019 and 2021; of these samples 12/71 (16.9 %) resulted in positive Galactomannan-Lateral Flow Assay. In contrast, Galactomannan-Enzyme Immunoassay resulted as positive in 9/71 (12.6 %) samples, a difference that showed not significant statistically (p-value = 0.36) Comparing both assays' results identified 8 divergences between them, about 11 % of the total sample. The Sensitivity (73.3 %), Specificity (92.35 %), Positive Predictive Value (62.85 %) and Negative Predictive Value (95.15 %) of Lateral Flow Assay were calculated using the Galactomannan Enzyme Immunoassay as standard. The Lateral Flow Assay demonstrated good results when compared with the Enzyme Immunoassay.

Insights into Aspergillus fumigatus Colonization in Cystic Fibrosis and Cross-Transmission between Patients and Hospital Environments.

BACKGROUND: Approximately 60% of individuals with cystic fibrosis (CF) are affected by Aspergillus fumigatus infection. This condition is correlated with a decline in lung function and is identified as an independent risk factor contributing to hospital admissions among CF patients. This study investigates the dynamic interplay of A. fumigatus within the context of CF patients, tracing its evolution over time, with a specific emphasis on colonization dynamics. METHODS: An analysis was conducted on 83 sequential A. fumigatus isolates derived from sputum samples of six patients receiving care at a renowned CF hospital in Brazil. Employing microsatellite genotyping techniques, alongside an investigation into cyp51A gene mutations, this research sheds light on the genetic variations, colonization, and resistance of A. fumigatus within the CF respiratory environment. RESULTS: Our research findings indicate that CF patients can harbor A. fumigatus strains from the same clonal complexes for prolonged periods. Additionally, we identified that clinical isolates have the potential to spread among patients in the same healthcare facility, evidencing hospital contamination. Two patients who underwent long-term Itraconazole treatment did not show phenotypic resistance. However, one of these patients exhibited mutations in the cyp51A gene, indicating the need to monitor resistance to azoles in these patients colonized for long periods by A. fumigatus. We also observed co-colonization or co-infection involving multiple genotypes in all patients over time. CONCLUSION: This comprehensive examination offers valuable insights into the pathogenesis of A. fumigatus infections in CF patients, potentially shaping future therapeutic strategies and management approaches. This enhanced understanding contributes to our knowledge of A. fumigatus impact on disease progression in individuals with cystic fibrosis. Additionally, the study provides evidence of cross-contamination among patients undergoing treatment at the same hospital.

Uncovering a Novel cyp51A Mutation and Antifungal Resistance in Aspergillus fumigatus through Culture Collection Screening.

BACKGROUND: Aspergillus fumigatus is an important concern for immunocompromised individuals, often resulting in severe infections. With the emergence of resistance to azoles, which has been the therapeutic choice for Aspergillus infections, monitoring the resistance of these microorganisms becomes important, including the search for mutations in the cyp51A gene, which is the gene responsible for the mechanism of action of azoles. We conducted a retrospective analysis covering 478 A. fumigatus isolates. METHODS: This comprehensive dataset comprised 415 clinical isolates and 63 isolates from hospital environmental sources. For clinical isolates, they were evaluated in two different periods, from 1998 to 2004 and 2014 to 2021; for environmental strains, one strain was isolated in 1998, and 62 isolates were evaluated in 2015. Our primary objectives were to assess the epidemiological antifungal susceptibility profile; trace the evolution of resistance to azoles, Amphotericin B (AMB), and echinocandins; and monitor cyp51A mutations in resistant strains. We utilized the broth microdilution assay for susceptibility testing, coupled with cyp51A gene sequencing and microsatellite genotyping to evaluate genetic variability among resistant strains. RESULTS: Our findings reveal a progressive increase in Minimum Inhibitory Concentrations (MICs) for azoles and AMB over time. Notably, a discernible trend in cyp51A gene mutations emerged in clinical isolates starting in 2014. Moreover, our study marks a significant discovery as we detected, for the first time, an A. fumigatus isolate carrying the recently identified TR46/F495I mutation within a sample obtained from a hospital environment. The observed cyp51A mutations underscore the ongoing necessity for surveillance, particularly as MICs for various antifungal classes continue to rise. CONCLUSIONS: By conducting resistance surveillance within our institution's culture collection, we successfully identified a novel TR46/F495I mutation in an isolate retrieved from the hospital environment which had been preserved since 1998. Moreover, clinical isolates were found to exhibit TR34/L98H/S297T/F495I mutations. In addition, we observed an increase in MIC patterns for Amphotericin B and azoles, signaling a change in the resistance pattern, emphasizing the urgent need for the development of new antifungal drugs. Our study highlights the importance of continued monitoring and research in understanding the evolving challenges in managing A. fumigatus infections.

Comparison of galactomannan lateral flow assay and enzyme immunoassay to identify Aspergillus spp. in bronchoalveolar lavage fluid

Abstract Aspergillus species can colonize and infect immunocompetent and immunocompromised hosts. Conventional fungal identification depends on microscopic analysis and microorganism medium growth. Other diagnostic methods, non-growth dependent, to invasive fungal infections, are the biomarkers that detect circulating polysaccharides, for example, 1-3-β-d-Glucan and galactomannan. Both are polysaccharides present on the external layer of fungi cell wall and can be detected in clinical samples during the growth of the fungus in the patient. This study aimed to compare the galactomannan detection of Lateral Flow Assay and Enzyme Immunoassay methods in Bronchoalveolar Lavage Fluid. The galactomannan antigen in Bronchoalveolar Lavage Fluid was measured using Enzyme Immunoassay according to the manufacturer's instructions (PLATELIA ASPERGILLUS™ BioRad) and, using a Lateral Flow Assay according to the manufacturer's instructions (Galactomannan LFA IMMY©). The 71 samples were Bronchoalveolar Lavage Fluid of patients hospitalized at Unicamp Clinical Hospital between 2019 and 2021; of these samples 12/71 (16.9 %) resulted in positive Galactomannan-Lateral Flow Assay. In contrast, Galactomannan-Enzyme Immunoassay resulted as positive in 9/71 (12.6 %) samples, a difference that showed not significant statistically (p-value = 0.36) Comparing both assays' results identified 8 divergences between them, about 11 % of the total sample. The Sensitivity (73.3 %), Specificity (92.35 %), Positive Predictive Value (62.85 %) and Negative Predictive Value (95.15 %) of Lateral Flow Assay were calculated using the Galactomannan Enzyme Immunoassay as standard. The Lateral Flow Assay demonstrated good results when compared with the Enzyme Immunoassay.

Selection of Aspergillus fumigatus isolates carrying the G448S substitution in CYP51A gene after long-term treatment with voriconazole in an immunocompromised patient.

We present a case of a 55-year-old man with a heart transplant who acquired Invasive Aspergillosis by Aspergillus fumigatus with the focus in the kidney. During about two years of antifungal treatment, most of the time with voriconazole, it was possible to obtain nine isolates of A. fumigatus, with the same genotypic characteristics, but with an increase in MIC for several azoles. The two last isolates presented high MICs for Voriconazole (>8 µg/mL>). Sequencing of the CYP51A gene showed G448S amino acid substitution in the same two isolates. In long-term treatments with antifungals, it would be important to regularly evaluate the susceptibility of isolated strains, as resistance to azoles has been increasingly described around the world.

Development and validation of LAMP primer sets for rapid identification of Aspergillus fumigatus carrying the cyp51A TR46 azole resistance gene.

Infections due to triazole-resistant Aspergillus fumigatus are increasingly reported worldwide and are associated with treatment failure and mortality. The principal class of azole-resistant isolates is characterized by tandem repeats of 34 bp or 46 bp within the promoter region of the cyp51A gene. Loop-mediated isothermal amplification (LAMP) is a widely used nucleic acid amplification system that is fast and specific. Here we describe a LAMP assay method to detect the 46 bp tandem repeat insertion in the cyp51A gene promoter region based on novel LAMP primer sets. It also differentiated strains with TR46 tandem repeats from those with TR34 tandem repeats. These results showed this TR46-LAMP method is specific, rapid, and provides crucial insights to develop novel antifungal therapeutic strategies against severe fungal infections due to A. fumigatus with TR46 tandem repeats.

Aspergillus fumigatus Clinical Isolates Carrying CYP51A with TR34/L98H/S297T/F495I Substitutions Detected after Four-Year Retrospective Azole Resistance Screening in Brazil.

Azole antifungal resistance in Aspergillus fumigatus is a worldwide concern. As in most public hospitals in Brazil, antifungal susceptibility tests are not routinely performed for filamentous fungi at our institution. A 4-year retrospective azole antifungal resistance screening revealed two azole-resistant A. fumigatus clinical isolates carrying the CYP51A TR34 (34-bp tandem repeat)/L98H (change of L to H at position 98)/S297T/F495I resistance mechanism mutations, obtained from two unrelated patients. Broth microdilution antifungal susceptibility testing showed high MICs for itraconazole, posaconazole, and miconazole. Short tandem repeat (STR) typing analysis presented high levels of similarity between these two isolates and clinical isolates with the same mutations reported from the Netherlands, Denmark, and China, as well as environmental isolates from Taiwan. Our findings might indicate that active searching for resistant A. fumigatus is necessary. They also represent a concern considering that our hospital provides tertiary care assistance to immunocompromised patients who may be exposed to resistant environmental isolates. We also serve patients who receive prophylactic antifungal therapy or treatment for invasive fungal infections for years. In these two situations, isolates resistant to the antifungal in use may be selected within the patients themselves. We do not know the potential of this azole-resistant A. fumigatus strain to spread throughout our country. In this scenario, the impact on the epidemiology and use of antifungal drugs will significantly alter patient care, as in other parts of the world. In summary, this finding is an important contribution to alert hospital laboratories conducting routine microbiological testing to perform azole resistance surveillance and antifungal susceptibility tests of A. fumigatus isolates causing infection or colonization in patients at high risk for systemic aspergillosis.