P257 Amplified fragment length polymorphism fingerprinting supports the absence of correlation of genotype with clinical phenotype or source of the isolate in Aspergillus flavus infections

Abstract

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PMObjectives Aspergillus flavus accounts for ∼ 10% of bronchopulmonary aspergillosis and is the second leading etiological agent of invasive aspergillosis worldwide. It is the commonest cause of fungal rhinosinusitis and ocular mycoses in tropical countries including India. We report amplified fragment length polymorphism genotyping of a set of clinical and environmental isolates to unravel the genetic diversity of A. flavus in India and to further determine correlation between isolate genotype and the source/clinical phenotype of the Aspergillus infection.MethodsTwo sets of morphologically identified isolates of A. flavus from clinical (n = 71) and environmental sources (n = 22) were included in the study using a stratified random sampling method. Clinical strains were isolated from lower respiratory tract specimens (n = 22), sinus and sino-nasal biopsies (n = 25), corneal samples (n = 12), and others (n = 12). Environmental strains were isolated from different niches like air, soil, and infected crop samples. Aspergillus fumigatus F145 was used as an out-group. DNA was extracted from the fungal broth culture following the method of Lee et al. AFLP was done as per an earlier described method using HpyCH41V and Mse1 (New England BioLabs) for restriction digestion followed by selective amplification of restriction-digested products with 1 mm HpyCH4 IV primer with one selective residue (5-Flu-GTA-GACTGCGTACCCGTC-3’), 1 mm MseI primer with four selective residues (5-GATGAGTCCTGACTAATGAA). Fingerprint data was analyzed in BioNumerics software version 7.6 (Applied Maths, Belgium). The phylogenetic tree was constructed using Pearson's Correlation coefficient. An AFLP genotype was assigned to a cluster using an arbitrary cut-off value of ≥90% fingerprint similarity. The distribution of genotypes among different categories was analyzed by Fisher's exact test or Pearson's χ 2 goodness of fit test with Yates correction factor as appropriate and two-tailed P-values of <.05 were considered statistically significant.ResultsThe analyses revealed a total of 16 AFLP genotypes with 5 major clusters (≥ 5 isolates) reflecting the extent of genetic diversity in A. flavus. Genotype VIII encompassed predominantly clinical isolates (P <.01) and genotype XI with majority of isolates from environmental sources (P <.0001). The strains which were isolated from invasive and non-invasive forms or from different sites (pulmonary, sinus, and ocular) did not diverge into separate or unique clusters. Although the genotypes had an asymmetric distribution in different clinical presentations as revealed by the χ2 goodness of fit test, none of the genotypes was exclusively responsible for causing a particular infection. Isolates from the north zone of India shared genotypes with those from the southern region of the country. Three isolates formed a separate genotype XVI and diverged from the A. flavus cluster by 42% fingerprint similarity. Partial β-tubulin and calmodulin gene sequencing-based phylogeny reconstruction placed those three isolates in A. tamarii clade of the A. flavus species complex.Conclusions: This study suggests that every genotype of A. flavus has the potential of causing an allergic, non-invasive or invasive infection. Further, A. flavus sensu stricto was predominantly (97%) isolated from clinical specimens revealing the majority of infections/colonization are caused by this species compared to other members in the Flavi complex.