First reported case of Aspergillus granulosus infection in a cardiac transplant patient

Aspergillus granulosus femoral osteomyelitis in a cardiac transplant patient: first reported case and literature review

Aspergillus osteomyelitis is a rare complication of extrapulmonary invasive aspergillosis, which usually presents as spondylodiscitis. The clinical picture is usually paucisymptomatic and of long evolution, which leads to diagnostic difficulties, especially in immunosuppressed patients presenting a delayed systemic host response. We report a case of femoral osteomyelitis caused by Aspergillus granulosus in a heart transplant recipient successfully treated with a combined surgical and antifungal approach. A 65-year-old heart transplant male presented with left knee pain lasting 3 months. X-ray and magnetic resonance imaging identified a lesion with aggressive characteristics at the distal third of the left femur, due to which the patient underwent excisional surgery. Aspergillus granulosus was cultured from the removed material and antifungal treatment with oral isavuconazole was started. Chest imaging excluded pulmonary aspergillosis, while the positron emission tomography/computed tomography (PET/CT) identified a remnant of a prosthetic vascular graft sewn to the proximal third of the right axillary artery, through which a catheter-based micro-axial left ventricular assist device was implanted previously as bridge to transplant therapy. The patient presented a rapid clinical improvement with complete functional recovery following the surgical treatment and the antifungal therapy and finally underwent surgical removal of the residual vascular graft. This is the first reported episode of long bone osteomyelitis due to A. granulosus that occurred in a heart transplant recipient without pulmonary infection and was successfully treated with isavuconazole. The PET/CT was useful in supporting the diagnostic process and follow-up. Cryptic fungal species can cause invasive infections, particularly in immunocompromised patients. Molecular methods are crucial in fungal identification.

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.

Invasive Aspergillosis Due to Aspergillus Section Usti: A Multicenter Retrospective Study

BACKGROUND

Aspergillus spp. of section Usti (A. ustus) represent a rare cause of invasive aspergillosis (IA). This multicenter study describes the epidemiology and outcome of A. ustus infections.

METHODS

Patients with A. ustus isolated from any clinical specimen were retrospectively identified in 22 hospitals from 8 countries. When available, isolates were sent for species identification (BenA/CaM sequencing) and antifungal susceptibility testing. Additional cases were identified by review of the literature. Cases were classified as proven/probable IA or no infection, according to standard international criteria.

RESULTS

Clinical report forms were obtained for 90 patients, of whom 27 had proven/probable IA. An additional 45 cases were identified from literature review for a total of 72 cases of proven/probable IA. Hematopoietic cell and solid-organ transplant recipients accounted for 47% and 33% cases, respectively. Only 8% patients were neutropenic at time of diagnosis. Ongoing antimold prophylaxis was present in 47% of cases. Pulmonary IA represented 67% of cases. Primary or secondary extrapulmonary sites of infection were observed in 46% of cases, with skin being affected in 28% of cases. Multiple antifungal drugs were used (consecutively or in combination) in 67% of cases. The 24-week mortality rate was 58%. A. calidoustus was the most frequent causal agent. Minimal inhibitory concentrations encompassing 90% isolates (MIC90) were 1, 8, >16, and 4 µg/mL for amphotericin B, voriconazole, posaconazole, and isavuconazole, respectively.

CONCLUSIONS

Aspergillus ustus IA mainly occurred in nonneutropenic transplant patients and was frequently associated with extrapulmonary sites of infection. Mortality rate was high and optimal antifungal therapy remains to be defined.

New species in Aspergillus section Usti and an overview of Aspergillus section Cavernicolarum

Aspergillus sections Usti and Cavernicolarum are accommodated in the subgenus Nidulantes. In the present study, a polyphasic approach using morphology and multi-gene phylogeny was applied to investigate the taxonomy of these two sections. Based on the phylogenetic analysis, Aspergillus section Usti includes 25 species, which can be assigned to four series: Calidousti, Deflecti, Monodiorum and Usti. Aspergillus sigarelli is newly described in this section and this species was isolated from a cigarette from PR China and belongs to series Calidousti. It is clearly distinct from other members in this series based on ITS, BenA, CaM and RPB2 sequences. Aspergillus section Usti members like A. calidoustus and A. granulosus are important opportunistic pathogens, it is speculative that more pathogenetic species will be found by using polyphasic taxonomy approaches. Aspergillus section Cavernicolarum includes five species, the growth rates on agar media and size and ornamentation of conidia are important characters for differentiating species in section Cavernicolarum.

Clinical Relevance and Characteristics of Aspergillus calidoustus and Other Aspergillus Species of Section Usti

The Aspergilli of section Usti (group ustus) are represented by over 20 species, of which Aspergillus calidoustus is the most relevant human pathogen. Invasive aspergillosis (IA) caused by these fungi is rare but could represent an emerging issue among the expanding population of patients with long-term immunosuppression receiving antifungal prophylaxis. Clinicians should be aware of this unusual type of IA, which often exhibits distinct clinical features, such as an insidious and prolonged course and a high occurrence of extra-pulmonary manifestations, such as skin/soft tissue or brain lesions. Moreover, these Aspergillus spp. pose a therapeutic challenge because of their decreased susceptibility to azole drugs. In this review, we outline the microbiological and clinical characteristics of IA due to Aspergillus spp. of section Usti and discuss the therapeutic options.

Aspergillus baeticus sp. nov. and Aspergillus thesauricus sp. nov., two species in section Usti from Spanish caves

Two novel species of Aspergillus that are clearly distinct from all known species in section Usti were revealed during a study of microfungal communities in Spanish caves. The novel species identified in this study and additional species of Aspergillus section Usti are associated with places and substrates related to human activities in caves. Novel species are described using data from four loci (ITS, benA, caM and rpb2), morphology and basic chemical and physiological analyses. Members of the species Aspergillus thesauricus sp. nov. were isolated from various substrates, including decaying organic matter, cave air and cave sediment of the Cueva del Tesoro Cave (the Treasure cave); the species is represented by twelve isolates and is most closely related to the recently described Aspergillus germanicus. Members of the species Aspergillus baeticus sp. nov. were isolated from cave sediment in the Gruta de las Maravillas Cave (the Grotto of the Marvels); the species is represented by two isolates. An additional isolate was found in the Cueva del Tesoro Cave and in the Demänovská Peace Cave (Slovakia), suggesting a potentially wide distribution of this micro-organism. The species is related to Aspergillus ustus and Aspergillus pseudoustus. Both species were unable to grow at 37 °C, and a weakly positive, light greenish yellow Ehrlich reaction was observed in A. thesauricus. Unique morphological features alone are sufficient to distinguish both species from related taxa.

New taxa in Aspergillus section Usti

Based on phylogenetic analysis of sequence data, Aspergillus section Usti includes 21 species, inclucing two teleomorphic species Aspergillus heterothallicus (= Emericella heterothallica) and Fennellia monodii. Aspergillus germanicus sp. nov. was isolated from indoor air in Germany. This species has identical ITS sequences with A. insuetusCBS 119.27, but is clearly distinct from that species based on β-tubulin and calmodulin sequence data. This species is unable to grow at 37 °C, similarly to A. keveii and A. insuetus. Aspergillus carlsbadensis sp. nov. was isolated from the Carlsbad Caverns National Park in New Mexico. This taxon is related to, but distinct from a clade including A. calidoustus, A. pseudodeflectus, A. insuetus and A. keveii on all trees. This species is also unable to grow at 37 °C, and acid production was not observed on CREA. Aspergillus californicus sp. nov. is proposed for an isolate from chamise chaparral (Adenostoma fasciculatum) in California. It is related to a clade including A. subsessilis and A. kassunensis on all trees. This species grew well at 37 °C, and acid production was not observed on CREA. The strain CBS 504.65 from soil in Turkey showed to be clearly distinct from the A. deflectus ex-type strain, indicating that this isolate represents a distinct species in this section. We propose the name A. turkensis sp. nov. for this taxon. This species grew, although rather restrictedly at 37 °C, and acid production was not observed on CREA. Isolates from stored maize, South Africa, as a culture contaminant of Bipolaris sorokiniana from indoor air in Finland proved to be related to, but different from A. ustus and A. puniceus. The taxon is proposed as the new species A. pseudoustus. Although supported only by low bootstrap values, F. monodii was found to belong to section Usti based on phylogenetic analysis of either loci BLAST searches to the GenBank database also resulted in closest hits from section Usti. This species obviously does not belong to the Fennellia genus, instead it is a member of the Emericella genus. However, in accordance with the guidelines of the Amsterdam Declaration on fungal nomenclature (Hawksworth et al. 2011), and based on phylogenetic and physiological evidence, we propose the new combination Aspergillus monodii comb. nov. for this taxon. Species assigned to section Usti can be assigned to three chemical groups based on the extrolites. Aspergillus ustus, A. granulosus and A. puniceus produced ustic acid, while A. ustus and A. puniceus also produced austocystins and versicolorins. In the second chemical group, A. pseudodeflectus produced drimans in common with the other species in this group, and also several unique unknown compounds. Aspergillus calidoustus isolates produced drimans and ophiobolins in common with A. insuetus and A. keveii, but also produced austins. Aspergillus insuetus isolates also produced pergillin while A. keveii isolates produced nidulol. In the third chemical group, E. heterothallica has been reported to produce emethallicins, 5'-hydroxyaveranthin, emeheterone, emesterones, 5'-hydroxyaveranthin.

Aspergillus species identification in the clinical setting

Multiple recent studies have demonstrated the limited utility of morphological methods used singly for species identification of clinically relevant aspergilli. It is being increasingly recognised that comparative sequence based methods used in conjunction with traditional phenotype based methods can offer better resolution of species within this genus. Recognising the growing role of molecular methods in species recognition, the recently convened international working group meeting entitled "Aspergillus Systematics in the Genomic Era" has proposed several recommendations that will be useful in such endeavors. Specific recommendations of this working group include the use of the ITS regions for inter section level identification and the beta-tubulin locus for identification of individual species within the various Aspergillus sections.

Cerebral aspergillosis caused by Aspergillus granulosus

Disseminated disease by Aspergillus granulosus has been reported only once previously in a cardiac transplant recipient. We report a fatal central nervous system infection in a lung transplant recipient. Key features of this species in the section Usti include growth at 37 degrees C and large, randomly spaced aggregates of variably shaped Hülle cells.

Polyphasic taxonomy of Aspergillus section Usti

Aspergillus ustus is a very common species in foods, soil and indoor environments. Based on chemical, molecular and morphological data, A. insuetus is separated from A. ustus and revived. A. insuetus differs from A. ustus in producing drimans and ophiobolin G and H and not producing ustic acid and austocystins. The molecular, physiological and morphological data also indicated that another species, A. keveiisp. nov. is closely related but distinct from A. insuetus. Aspergillus section Usti sensu stricto includes 8 species: A. ustus, A. puniceus, A. granulosus, A. pseudodeflectus, A. calidoustus, A. insuetus and A. keveii together with Emericella heterothallica.

Special considerations for the clinical microbiology laboratory in the diagnosis of infections in the cancer patient

The clinical microbiology laboratory faces enormous challenges in diagnosing infections that cause morbidity and mortality in cancer patients. Such laboratories face several issues that surpass those faced by laboratories that perform more routine work. Issues such as sources of clinical specimens, need for correlation and interaction between laboratory and clinical services, blood cultures, susceptibility testing, and the role of new molecular diagnostic techniques are considered in this article.