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

The Molecular Identification and Antifungal Susceptibility of Clinical Isolates of Aspergillus Section Flavi from Three French Hospitals

(1) Background: Aspergillus flavus is a cosmopolitan mold with medical, veterinary, and agronomic concerns. Its morphological similarity to other cryptic species of the Flavi section requires molecular identification techniques that are not routinely performed. For clinical isolates of Aspergillus section Flavi, we present the molecular identification, susceptibility to six antifungal agents, and clinical context of source patients. (2) Methods: One hundred forty fungal clinical isolates were included in the study. These isolates, recovered over a 15-year period (2001-2015), were identified based on their morphological characteristics as belonging to section Flavi. After the subculture, sequencing of a part of the β-tubulin and calmodulin genes was performed, and resistance to azole antifungals was screened on agar plates containing itraconazole and voriconazole. Minimum inhibitory concentrations were determined for 120 isolates by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) broth microdilution method. (3) Results: Partial β-tubulin and calmodulin sequences analysis showed that 138/140 isolates were A. flavus sensu stricto, 1 isolate was A. parasiticus/sojae, and 1 was A. nomiae. Many of the isolates came from samples collected in the context of respiratory tract colonization. Among probable or proven aspergillosis, respiratory infections were the most frequent, followed by ENT infections. Antifungal susceptibility testing was available for isolates (n = 120, all A. flavus ss) from one hospital. The MIC range (geometric mean MIC) in mg/L was 0.5-8 (0.77), 0.5-8 (1.03), 0.125-2 (0.25), 0.03-2 (0.22), 0.25-8 (1.91), and 0.03-0.125 (0.061) for voriconazole, isavuconazole, itraconazole, posaconazole, amphotericin B, and caspofungin, respectively. Two (1.67%) isolates showed resistance to isavuconazole according to current EUCAST breakpoints with MICs at 8 mg/L for isavuconazole and voriconazole. One of these two isolates was also resistant to itraconazole with MIC at 2 mg/L. (4) Conclusions: The present characterization of a large collection of Aspergillus belonging to the Flavi section confirmed that A. flavus ss is the predominant species. It is mainly implicated in respiratory and ENT infections. The emergence of resistance highlights the need to perform susceptibility tests on section Flavi isolates.

Potential benefit of combination antifungal therapy in Aspergillus endocarditis

Aspergillus endocarditis (AE) is a rare condition with a mortality rate greater than 60%. While it is generally accepted that both antifungal therapy and surgery are necessary for survival, the optimal antifungal regimen is unclear. A 62-year-old man was diagnosed with AE of a prosthetic aortic valve, complicated by cerebral emboli. He underwent debridement of the aortic valve abscess and valve replacement, and was managed with a combination of liposomal amphotericin B and voriconazole for 7 weeks followed by long-term suppressive azole therapy. He remained well at follow-up 18 months later. Data from a review of case reports published between 1950 and 2010 revealed greater survival rates in patients managed with two or more antifungals as opposed to single agent therapy. We provide an updated literature review with similar findings, suggesting that dual agent antifungal therapy should be considered in patients with AE.

Native valve dual pathogen endocarditis caused by Burkholderia cepacia and Aspergillus flavus - a case report

Introduction

Infective endocarditis (IE) is an important clinical condition with significant morbidity and mortality among the affected population. A single etiological agent is identifiable in more than 90 % of the cases, however, polymicrobial endocarditis (PE) is a rare find, with a poor clinical outcome. Here we report a case of native valve dual pathogen endocarditis caused by Burkholderia cepacia and Aspergillus flavus in an immunocompetent individual. It is among unique occurrences of simultaneous bacterial and fungal etiology in IE.

Case presentation

A 30-year-old male was admitted to a cardiology institute with complaints of low grade intermittent fever and progressive shortness of breath for last two months. He was a known case of rheumatic heart disease and had suffered an episode of IE three years ago. On the basis of clinical presentation and the results of radiological investigations, a diagnosis of infective endocarditis was made. Paired blood samples for culture and sensitivity, sampled before the commencement of antimicrobial therapy, yielded growth of Burkholderia cepacia which was highly drug resistant. Sensitivity results-directed therapy consisting of tablet Trimethoprim–Sulfamethoxazole, two double-strength tablets 12 hourly, and Meropenem, 1 g IV every 8 h, was commenced. Despite mild relief of fever intensity, overall clinical condition did not improve and double valve replacement therapy was carried out. Excised valves were sent for microbiological analysis. Burkholderia cepacia was grown on tissue culture with a similar antibiogram to that previously reported from the blood culture of this patient. Direct microscopy of section of valvular tissue with 10 % KOH revealed abundant fungal hyphae. Patient serum galactomannan antigen assay was also positive. Histopathological examination of vegetations also revealed hyphae typical of species of the genus Aspergillus. The patient was successfully treated with meropenem, trimethoprim–sulfamethoxazole and voriconazole.

Conclusion

The hallmark of successful treatment in this case was exact identification of pathogens, antibiogram-directed therapy and good liaison between laboratory experts and treating clinicians.