Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/19/2008
Publication Date: 1/19/2008
Citation: Kano, R., Perrone, G., Peterson, S.W., Baddley, J.W., Marr, K.A., Alexander, B., Andes, D., Kontoyiannis, D., Pappas, P.G., Balajee, S.A. 2008. Comparative sequence analyses of multiple loci reveal rare Aspergillus species in transplant recipients (transnet study). Meeting Abstract.
Technical Abstract: Invasive aspergillosis (IA) is the leading cause of mortality in blood and marrow transplant recipients. Although A. fumigatus accounts for the majority of IA, non-fumigatus species are emerging as an uncommon, yet devastating cause of IA. The Transplant Associated Infection Surveillance Network (TRANSNET) is a nationwide surveillance network of 25 transplant centers created to monitor trends in the prevalence of invasive fungal infections (IFI) in transplant recipients. We recently conducted a detailed molecular analysis to evaluate species distribution of non-fumigatus aspergilli in the TRANSNET population. As a part of this large ongoing study, we report the recovery of several previously unrecognized aspergilli; the identities of these novel species have been confirmed using comparative sequence analyses and phylogenies of multiple loci. A total of 30 aspergilli - 4 section Versicolores, 6 section Usti, 19 section Nigri and one section Nidulantes were subjected to detailed sequence analyses using the ITS regions and 2 protein coding loci - calmodulin (calM) and beta tubulin (benA). Additionally, a total of at least 10 isolates per section of previously described isolates were included for phylogenetic analyses. Nucleotide sequences were edited using the SequencherTM program and maximum likelihood phylogenies were constructed. Antifungal susceptibilities of the isolates to the antifungal drugs amphotericin B (AMB), itraconazole (ITZ), voriconazole (VRZ) and posaconazole (POSA) were performed using CLSI M38A broth microdilution method. Two isolates of A. sydowii, 1 isolate each of A. protuberus and 1 A. tabacinus were identified in the section Versicolores. All the 6 section Usti isolates were identified as A. calidoustus (Aspergillus calidoustus sp. novo). Within the section Nigri, 9 isolates were A. niger and 10 isolates were A. tubingensis. One A. nidulans isolate was re-identified as a Emericella quadrilineata. All section Versicolores and Nigri isolates had a similar antifungal susceptibility profile. A. calidoustus had high MIC to all antifungals tested. This is the first report of A. protuberus, A. tabacinus and A. tubingenesis recovered from clinical samples. A. calidoustus is a newly described species within the section Usti that has high in vitro MICs to antifungals, and the clinical relevance of this species needs to be further evaluated. Results of this very large screening study reveal that these previously unrecognized aspergilli were rare causes of IA in transplant population.