P401 Identification and characterization of cryptic species of Aspergillus isolated from clinical samples

Abstract

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PM Background and ObjectiveMolds are emerging as a major cause of life-threatening infections in immunocompromised patients. There is an increasing recognition of the cryptic Aspergillus species, which are organisms that are morphologically indistinguishable yet can be differentiated by molecular methods. These organisms have been known to show a higher minimal inhibitory concentration for the majority of the antifungal agents in vitro. Therefore, correct identification of these cryptic species is very important to administer a proper antifungal agent.In this study, we wish to identify and characterize the cryptic species of Aspergillus from all clinical samples.MethodsPatient routine samples like broncho alveolar lavage, endo-tracheal aspirate, sputum, pus, tissue, and CSF from various wards, OPDs, and ICUs of All India Institute of Medical Sciences, New Delhi which were processed in the Mycology laboratory, department of Microbiology showing growth of Aspergillus species were included in this study. Identification of the isolates was done using phenotypic methods and by Matrix Assisted Laser Desorption Ionization-Time of Flight (MALDI-TOF). For the analysis of cryptic species, the isolates underwent PCR and then sequencing of the ß-tubulin gene was done. Antifungal susceptibility testing was done using micro broth dilution as per the CLSI method.ResultsOf the 92 isolates, using morphological methods, 53 were identified as A. fumigatus, 33 were identified as A. flavus, 3 as A. nidulans, 2 as A. terreus, and 1 as A. niger MALDI-TOF (Vitek MS database) misidentified 2 isolates of A. nidulans and 1 isolate of A, stellatus as A. fumigatus and 1 isolate of A. tubingensis as A. niger. The ß-tubulin sequence analysis for the identification of cryptic species revealed that 2 isolates (2.08%) were cryptic, one was A. stellatus morphologically identified as A. nidulans and another one was A. tubingensis morphologically identified as A. niger.ConclusionCurrently the available data on cryptic Aspergillus species is very limited. Because of its varied susceptibility pattern, it is important to identify the Aspergillus isolates to its species level. There is also a need for expansion of the number of strains for each species in MALDI-TOF MS databases for convenient, faster, and correct identification.