Antibiotic Susceptibility Testing (Agar Disk Diffusion and Agar Dilution) of Clinical Isolates of Enterococcus faecalis and E. faecium: Comparison of Mueller-Hinton, Iso-Sensitest, and Wilkins-Chalgren Agar Media

Chemotherapy ◽  
1998 ◽  
Vol 44 (4) ◽  
pp. 217-229 ◽  
Author(s):  
Walter H. Traub ◽  
Udo Geipel ◽  
Birgit Leonhard
Keyword(s):  
Enterococcus Faecalis ◽  
Antibiotic Susceptibility ◽  
Susceptibility Testing ◽  
Clinical Isolates ◽  
Disk Diffusion ◽  
Antibiotic Susceptibility Testing ◽  
Mueller Hinton ◽  
Agar Dilution ◽  
Agar Media

scholarly journals Mutations in the fks1 Gene in Candida albicans, C. tropicalis, and C. krusei Correlate with Elevated Caspofungin MICs Uncovered in AM3 Medium Using the Method of the European Committee on Antibiotic Susceptibility Testing

2008 ◽  
Vol 52 (9) ◽  
pp. 3092-3098 ◽  
Author(s):  
Marie Desnos-Ollivier ◽  
Stéphane Bretagne ◽  
Dorothée Raoux ◽  
Damien Hoinard ◽  
Françoise Dromer ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Antibiotic Susceptibility ◽  
Susceptibility Testing ◽  
Antifungal Susceptibility ◽  
Clinical Isolates ◽  
Antibiotic Susceptibility Testing ◽  
Wild Type ◽  
European Committee ◽  
Rpmi Medium

ABSTRACT Mutations in two specific regions of the Fks1 subunit of 1,3-β-d-glucan synthase are known to confer decreased caspofungin susceptibility on Candida spp. Clinical isolates of Candida spp. (404 Candida albicans, 62 C. tropicalis, and 21 C. krusei isolates) sent to the French National Reference Center were prospectively screened for susceptibility to caspofungin in vitro by the broth microdilution reference method of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing (AFST-EUCAST). Twenty-eight isolates (25 C. albicans, 2 C. tropicalis, and 1 C. krusei isolate) for which the caspofungin MIC was above the MIC that inhibited 90% of the isolates of the corresponding species (MIC90) were subjected to molecular analysis in order to identify mutations in the fks1 gene. Substitutions in the deduced protein sequence of Fks1 were found for 8 isolates, and 20 isolates had the wild-type sequence. Among the six C. albicans isolates harboring mutations, six patterns were observed involving amino acid changes at positions 641, 645, 649, and 1358. For C. tropicalis, one isolate showed an L644W mutation, and for one C. krusei isolate, two mutations, L658W and L701M, were found. Two media, RPMI medium and AM3, were tested for their abilities to distinguish between isolates with wild-type Fks1 and those with mutant Fks1. In RPMI medium, caspofungin MICs ranged from 0.25 to 2 μg/ml for wild-type isolates and from 1 to 8 μg/ml for mutant isolates. A sharper difference was observed in AM3: all wild-type isolates were inhibited by 0.25 μg/ml of caspofungin, while caspofungin MICs for all mutant isolates were ≥0.5 μg/ml. These data demonstrate that clinical isolates of C. albicans, C. tropicalis, and C. krusei with decreased susceptibility to caspofungin in vitro have diverse mutations in the fks1 gene and that AM3 is potentially a better medium than RPMI for distinguishing between mutant and wild-type isolates using the AFST-EUCAST method.

scholarly journals Current and Emerging Methods of Antibiotic Susceptibility Testing

Diagnostics ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 49 ◽  
Author(s):  
Zeeshan A. Khan ◽  
Mohd F. Siddiqui ◽  
Seungkyung Park
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Infection ◽  
Economic Burden ◽  
Antibiotic Susceptibility ◽  
Historical Perspective ◽  
Susceptibility Testing ◽  
Empirical Therapy ◽  
Pivotal Role ◽  
Disk Diffusion ◽  
Antibiotic Susceptibility Testing

Antibiotic susceptibility testing (AST) specifies effective antibiotic dosage and formulates a profile of empirical therapy for the proper management of an individual patient’s health against deadly infections. Therefore, rapid diagnostic plays a pivotal role in the treatment of bacterial infection. In this article, the authors review the socio-economic burden and emergence of antibiotic resistance. An overview of the phenotypic, genotypic, and emerging techniques for AST has been provided and discussed, highlighting the advantages and limitations of each. The historical perspective on conventional methods that have paved the way for modern AST like disk diffusion, Epsilometer test (Etest), and microdilution, is presented. Several emerging methods, such as microfluidic-based optical and electrochemical AST have been critically evaluated. Finally, the challenges related with AST and its outlook in the future are presented.

scholarly journals Antimicrobial Susceptibilities of Commonly Encountered Bacterial Isolates to Fosfomycin Determined by Agar Dilution and Disk Diffusion Methods

2011 ◽  
Vol 55 (9) ◽  
pp. 4295-4301 ◽  
Author(s):  
Ching-Lan Lu ◽  
Chia-Ying Liu ◽  
Yu-Tsung Huang ◽  
Chun-Hsing Liao ◽  
Lee-Jene Teng ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Enterococcus Faecalis ◽  
Susceptibility Testing ◽  
Inhibition Zone ◽  
Common Species ◽  
Disk Diffusion ◽  
Content Type ◽  
Zone Diameter ◽  
Agar Dilution

ABSTRACTWe studied the antimicrobial activity of fosfomycin against 960 strains of commonly encountered bacteria associated with urinary tract infection using standard agar dilution and disk diffusion methods. Species studied included 3 common species ofEnterobacteriaceae,Pseudomonas aeruginosa,Acinetobacter baumannii, andStenotrophomonas maltophilia; methicillin-susceptible and -resistantStaphylococcus aureus; and vancomycin-susceptible and resistantEnterococcus faecalisandE. faecium. MICs and inhibition zone diameters were interpreted in accordance with both the currently recommended Clinical and Laboratory Standards Institute (CLSI) criteria for urinary tract isolates ofEscherichia coliandEnterococcus faecalisand the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria forEnterobacteriaceae. Tentative zone diameter interpretive criteria were developed for species not currently published by CLSI or EUCAST.Escherichia coliwas uniformly susceptible to fosfomycin, as were most strains ofKlebsiella pneumoniaeandEnterobacter cloacae. A. baumanniiwas resistant to fosfomycin, while the prevalence of resistance inP. aeruginosaandS. maltophiliawas greatly affected by the choice of MIC breakpoint. New tentative zone diameter criteria forK. pneumoniae,E. cloacae,S. aureus, andE. faeciumwere able to be set, providing some interim laboratory guidance for disk diffusion until further breakpoint evaluations are undertaken by CLSI and EUCAST.

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