Molecular identification and amphotericin B susceptibility testing of clinical isolates of Aspergillus from 11 hospitals in Korea.
BACKGROUND
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.


METHODS
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.


RESULTS
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%).


CONCLUSIONS
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.
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Min Seok
MS
Heo
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea. shinjh@chonnam.ac.kr.
Jong Hee
JH
Shin
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Min Ji
MJ
Choi
Department of Laboratory Medicine, The Catholic University of Korea College of Medicine, Seoul, Korea.
Yeon Joon
YJ
Park
Department of Laboratory Medicine, Chonbuk National University Medical School and Chonbuk National University Hospital Branch of National Culture Collection for Pathogens, Jeonju, Korea.
Hye Soo
HS
Lee
Department of Laboratory Medicine, College of Medicine, Chungnam National University, Gwangju, Korea.
Sun Hoe
SH
Koo
Department of Laboratory Medicine, Kyungpook National University School of Medicine, Daegu, Korea.
Won Gil
WG
Lee
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Soo Hyun
SH
Kim
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Myung Geun
MG
Shin
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Soon Pal
SP
Suh
Department of Laboratory Medicine, Chonnam National University Medical School, Gwangju, Korea.
Dong Wook
DW
Ryang
D000666:Amphotericin B / Q000494:pharmacology*; D000935:Antifungal Agents / Q000494:pharmacology*; D001230:Aspergillus / Q000187:drug effects* / Q000302:isolation & purification; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006761:Hospitals; D006801:Humans; D008826:Microbial Sensitivity Tests; D009181:Mycoses / Q000175:diagnosis / Q000382:microbiology; D056910:Republic of Korea; D017422:Sequence Analysis, DNA; D014404:Tubulin / Q000235:genetics
D000935:Antifungal Agents; D004271:DNA, Fungal; D014404:Tubulin; D000666:Amphotericin B
Amphotericin B; Aspergillus; CLSI; Etest; Identification