Detection of ESBL among AmpC producing enterobacteriaceae using inhibitor-based method

Area of Science:

• Microbiology
• Clinical Diagnostics
• Antimicrobial Resistance

Background:

• Multiple beta-lactamases in bacteria limit treatment options and present diagnostic challenges.
• Boronic acid (BA) is an AmpC enzyme inhibitor investigated for detecting co-expression of AmpC and ESBLs.

Purpose of the Study:

• To evaluate the efficacy of different phenotypic methods for detecting ESBL and AmpC production.
• To assess the utility of boronic acid in identifying co-producing bacterial isolates.

Main Methods:

• Screened 259 Enterobacteriaceae isolates for ESBL and AmpC production using CLSI double-disk diffusion, cefepime-clavulanic acid, and boronic disk potentiation methods.
• AmpC detection involved cefoxitin alone and with boronic acid, confirmed by three-dimensional disk methods.
• Antibiotic susceptibility testing was performed on all isolates.

Main Results:

• 20.46% of isolates were co-producers of ESBL and AmpC; 26.45% produced ESBL only, and 5.40% produced AmpC only.
• The boronic acid disk potentiation method accurately identified all 53 co-producing isolates.
• The study compared various phenotypic methods for detecting these enzyme types.

Conclusions:

• The boronic acid disk test, following CLSI guidelines, is a simple, highly efficient method for detecting isolates with both AmpC and ESBL co-production.
• This method aids in accurate identification, potentially guiding antimicrobial therapy choices.