| Title | Internal transcribed spacer region sequence heterogeneity in Rhizopus microsporus: implications on molecular diagnosis in clinical microbiology laboratories. | | Author(s) | Woo PC, Leung SY, To KK, Chan JF, Ngan AH, Cheng VC, Lau SK, Yuen KY | | Institution | State Key Laboratory of Emerging Infectious Diseases, Research Centre of Infection and Immunology, and Department of Microbiology, Carol Yu Centre for Infection, The University of Hong Kong, Hong Kong. | | Source | J Clin Microbiol 2009 Nov 11. | | Abstract | Although internal transcribed spacer region (ITS) sequence heterogeneity has been reported in a few fungal species, it was very rarely reported in pathogenic fungi, and has never been described in Mucorales, causes of the highly fatal mucormycosis. In a recent outbreak investigation of intestinal mucormycosis due to Rhizopus microsporus in patients with hematological malignancies, PCR of the ITS of four of the 28 R. microsporus strains, P11, P12, D3-1 and D4-1, showed thick bands at about 700 bp. Direct sequencing of the purified bands all showed frequent double peaks along the sequence traces, and occasional triple peaks for P12 D3-1 and D4-1. The thick bands of the four R. microsporus strains were purified and cloned. Sequencing of 10 clones for each strain revealed two different ITS sequences for P11 and three different ITS sequences for P12, D3-1 and D4-1. Variations in ITS sequence among the different rDNA operons in the same strain were only observed in ITS1 and ITS2, but not the 5.8S rDNA region. One copy of P11, P12 and D4-1 respectively and one copy of P11, P12, D3-1 and D4-1 respectively showed identical sequences. This represents the first evidence of ITS sequence heterogeneity in Mucorales. ITS sequence heterogeneity is an obstacle to molecular identification and genotyping of fungi in clinical microbiology laboratories. When thick bands and double peaks are observed during PCR sequencing of a gene target, such a strain should be sent to reference laboratories proficient in molecular technologies for further identification and/or genotyping. | | Language | ENG | | Pub Type(s) | JOURNAL ARTICLE
| | PubMed ID | 19906897 |
|
