Comparative Evaluation of Disc Diffusion and E-test with Broth Micro-dilution in Susceptibility testing of Amphotericin B, Voriconazole and Caspofungin against Clinical Aspergillus isolates
Background: Clinical importance of Aspergillus has increased over the past few decades because of rise in immunosuppressive drugs and immune-modulating diseases. Antifungal susceptibility of Aspergillus is rarely performed by clinical laboratories because of lack of easier method. This study ha...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
JCDR Research and Publications Private Limited
2015-01-01
|
| Series: | Journal of Clinical and Diagnostic Research |
| Subjects: | |
| Online Access: | https://jcdr.net/articles/PDF/5395/10467_CE(Ra)_F(Sh)_PF1(PAK)_PFA(AK)_PF2(PAG).pdf |
| Summary: | Background: Clinical importance of Aspergillus has
increased over the past few decades because of rise in
immunosuppressive drugs and immune-modulating diseases.
Antifungal susceptibility of Aspergillus is rarely performed by
clinical laboratories because of lack of easier method. This
study has investigated and compared susceptibility pattern of
Aspergillus isolates by disc diffusion, E-test and broth microdilution for amphotericin B, voriconazole and caspofungin.
Materials and Methods: Disk diffusion (DD) method of
antifungal susceptibility (AFS) was evaluated for three different
classes of antifungals: amphotericin B (AMB), voriconazole
(VCZ) and caspofungin (CAS). Forty four clinical isolates of
Aspergillus were selected; these included 34 A.fumigatus,
8 A.flavus and 2 A. terreus. AFS by DD and E-test was done
on non-supplemented Mueller Hinton Agar (MHA) and was
compared to Clinical Laboratory Standard Institute(CLSI) broth
micro-dilution (BMD) method of AFS.
Results: Disk diffusion method for amphotericin B showed
87.5% agreement while E-test showed 93.8% agreement
with broth micro-dilution. The agreement with broth microdilution was similar for both disk diffusion and E-test in case
of voriconazole (93.8%) and caspofungin (100%). 31.8% and
9.1% Aspergillus isolates were found to have amphotericin
B and voriconazole MIC values above epidemiological cut
off value (ECV) respectively. All isolates were within ECV for
caspofungin.
Conclusion: CLSI method of DD promises to be easier,
reproducible and cost effective method of susceptibility testing,
but this method must be interpreted with caution in case of
amphotericin B susceptibility testing. E-test correlates better
than DD with BMD. |
|---|---|
| ISSN: | 2249-782X 0973-709X |