Molecular Identification and Amphotericin B Susceptibility Testing of Clinical Isolates of Aspergillus From 11 Hospitals in Korea

• Published in: Annals of laboratory medicine Vol. 35; no. 6; pp. 602 - 610
• Main Authors: Heo, Min Seok, Shin, Jong Hee, Choi, Min Ji, Park, Yeon-Joon, Lee, Hye Soo, Koo, Sun Hoe, Lee, Won Gil, Kim, Soo Hyun, Shin, Myung-Geun, Suh, Soon-Pal, Ryang, Dong-Wook
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society for Laboratory Medicine 01.11.2015; 대한진단검사의학회
• Subjects: Amphotericin B - pharmacology; Antifungal Agents - pharmacology; Aspergillus - drug effects; Aspergillus - isolation & purification; DNA, Fungal - chemistry; DNA, Fungal - genetics; DNA, Fungal - metabolism; Hospitals; Humans; Microbial Sensitivity Tests; Mycoses - diagnosis; Mycoses - microbiology; Original; Republic of Korea; Sequence Analysis, DNA; Tubulin - genetics; 병리학; CLSI; Aspergillus; Identification; Amphotericin B; Etest
• ISSN: 2234-3806; 2234-3814; 2234-3814
• DOI: 10.3343/alm.2015.35.6.602

We investigated the species distribution and amphotericin B (AMB) susceptibility of Korean clinical Aspergillus isolates by using two Etests and the CLSI broth microdilution method. A total of 136 Aspergillus isolates obtained from 11 university hospitals were identified by sequencing the internal transcribed spacer (ITS) and β-tubulin genomic regions. Minimal inhibitory concentrations (MICs) of AMB were determined in Etests using Mueller-Hinton agar (Etest-MH) and RPMI agar (Etest-RPG), and categorical agreement with the CLSI method was assessed by using epidemiological cutoff values. ITS sequencing identified the following six Aspergillus species complexes: Aspergillus fumigatus (42.6% of the isolates), A. niger (23.5%), A. flavus (17.6%), A. terreus (11.0%), A. versicolor (4.4%), and A. ustus (0.7%). Cryptic species identifiable by β-tubulin sequencing accounted for 25.7% (35/136) of the isolates. Of all 136 isolates, 36 (26.5%) had AMB MICs of ≥2 μg/mL by the CLSI method. The categorical agreement of Etest-RPG with the CLSI method was 98% for the A. fumigatus, A. niger, and A. versicolor complexes, 87% for the A. terreus complex, and 37.5% for the A. flavus complex. That of Etest-MH was ≤75% for the A. niger, A. flavus, A. terreus, and A. versicolor complexes but was higher for the A. fumigatus complex (98.3%). Aspergillus species other than A. fumigatus constitute about 60% of clinical Aspergillus isolates, and reduced AMB susceptibility is common among clinical isolates of Aspergillus in Korea. Molecular identification and AMB susceptibility testing by Etest-RPG may be useful for characterizing Aspergillus isolates of clinical relevance.