Ann Lab Med.  2015 Nov;35(6):602-610. 10.3343/alm.2015.35.6.602.

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

• Heo MS
• Shin JH
• Choi MJ
• Park YJ
• Lee HS
• Koo SH
• Lee WG
• Kim SH
• Shin MG
• Suh SP
• Ryang DW

• KMID: 2363263
• DOI: http://doi.org/10.3343/alm.2015.35.6.602

Abstract

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 beta-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 beta-tubulin sequencing accounted for 25.7% (35/136) of the isolates. Of all 136 isolates, 36 (26.5%) had AMB MICs of > or =2 microg/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 < or =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.

Keyword

Aspergillus; Amphotericin B; Identification; Etest; CLSI

MeSH Terms

Amphotericin B/*pharmacology
Antifungal Agents/*pharmacology
Aspergillus/*drug effects/isolation & purification
DNA, Fungal/chemistry/genetics/metabolism
Hospitals
Humans
Microbial Sensitivity Tests
Mycoses/diagnosis/microbiology
Republic of Korea
Sequence Analysis, DNA
Tubulin/genetics
Amphotericin B
Antifungal Agents
DNA, Fungal
Tubulin

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