Disc methods for detecting AmpC β-lactamase-producing clinical isolates of Escherichia coli and Klebsiella pneumoniae

Brenwald, N P; Jevons, G.; Andrews, J. M.; Ang, Lei; Fraise, A.P.

doi:10.1093/jac/dki278

Cited by 37 publications

(41 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Minimum inhibitory testing assays incorporating these inhibitors have been described (1,5), analogous to the use of beta-lactamase inhibitor combinations for detection of extended-spectrum beta-lactamases. These inhibitors have also been incorporated into disk-based assays, using a variety of combinations of antibiotic substrates and inhibitors (2,5). The use of disk approximation tests by Kirby-Bauer testing to detect inducible AmpC activity has also been described, using one antibiotic as an inducing substrate and a second antibiotic as a reporter substrate (19).…”

mentioning

confidence: 99%

Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli , Klebsiella pneumoniae , and Proteus mirabilis

Tan

et al. 2009

Antimicrob Agents Chemother

152

158

View full text Add to dashboard Cite

There are currently no standardized phenotypic methods for the screening and detection of AmpC enzymes. This study aimed to evaluate different methods to detect AmpC enzymes in Escherichia coli, Klebsiella spp., and Proteus spp., comparing the results from two disk-based methods and an agar dilution method. AmpC activity was determined for 255 clinical isolates by use of a three-dimensional enzyme assay combined with a multiplex PCR assay for plasmid-borne ampC genes. These results were compared against a disk-based inhibitor assay using various combinations of cefpodoxime and cefoxitin as antibiotic substrates and boronic acid or cloxacillin as an AmpC inhibitor. The presence of enzyme induction by disk approximation was evaluated using imipenem, cefoxitin, and amoxicillin-clavulanate as inducing agents against ceftazidime. Finally, an agar dilution assay was performed, using cefoxitin with and without added cloxacillin. AmpC activity was present in 49.8% of test isolates, 93.7% of which were positive for plasmid-borne ampC genes. CIT-like enzymes were predominant in E. coli, and DHA-like enzymes were predominant in Klebsiella spp. The disk-based inhibitor tests performed better than the agar dilution assay, while detection of AmpC by disk induction had a poor sensitivity. The cefoxitin-cloxacillin disk combination provided the best overall performance, with a sensitivity and specificity of 95%. This study confirmed the accuracy of disk-based inhibitor screening for AmpC enzymes, which proved reliable at detecting CIT-and DHA-like plasmid-borne ampC genes. The methods are simple enough for introduction into clinical microbiology laboratories.

show abstract

mentioning

confidence: 99%

Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli , Klebsiella pneumoniae , and Proteus mirabilis

Tan

et al. 2009

Antimicrob Agents Chemother

152

158

View full text Add to dashboard Cite

show abstract

“…One such compound, 3-aminophenyl boronic acid (APB), has recently been used successfully in detecting the production of plasmid-mediated class C ␤-lactamases in Enterobacteriaceae (6,10,12,23). We have subsequently undertaken a study investigating the effects of APB on zone diameters of carbapenem-containing disks in a set of isolates producing KPC-type ␤-lactamases as well as other non-KPC broad-spectrum ␤-lactamases.…”

mentioning

confidence: 99%

Simple Disk-Based Method for Detection of Klebsiella pneumoniae Carbapenemase-Type β-Lactamase by Use of a Boronic Acid Compound

et al. 2008

View full text Add to dashboard Cite

A disk potentiation method using carbapenems as substrates and 3-aminophenyl boronic acid as an inhibitor was evaluated for the detection of Klebsiella pneumoniae carbapenemase (KPC)-type ␤-lactamases. When combined with nonsusceptibility to ertapenem, the method was easy to perform and reliably differentiated isolates producing KPC-type ␤-lactamases from those producing other types of ␤-lactamases.

show abstract

“…There are a few reports of studies designed to detect pAmpC-producing isolates of Klebsiella spp. and E. coli by a method using BA as an inhibitor that closely resembles the phenotypic confirmatory tests for ESBLs (3,5). And Coudron (5) recently described that a BA disk also enhances detection of isolates that harbor both ESBLs and pAmpCs.…”

mentioning

confidence: 99%

Detection of Extended-Spectrum β-Lactamases by Using Boronic Acid as an AmpC β-Lactamase Inhibitor in Clinical Isolates of Klebsiella spp. and Escherichia coli

et al. 2007

View full text Add to dashboard Cite

We evaluated highly sensitive methods using boronic acid (BA) to detect extended-spectrum ␤-lactamase (ESBL) production. A total of 182 clinical isolates of Klebsiella spp. (n ‫؍‬ 118) and Escherichia coli (n ‫؍‬ 64) were analyzed: 62 harbored only ESBLs, 80 harbored both ESBLs and plasmid-mediated AmpC ␤-lactamases (pAmpCs), and 40 harbored only pAmpCs. The CLSI confirmatory test detected all isolates that produce only ESBLs but detected 85% of isolates that produce both enzymes. When a >5-mm increase in the zone diameter of either the cefotaxime (CTX) or the ceftazidime (CAZ) disk in the presence of both clavulanic acid (CA) and BA was considered to be a positive result, the test detected all isolates that harbor ESBLs (؎ pAmpCs) but showed frequent false-positive results (50%) for isolates that produce only pAmpCs. Meanwhile, when a >3-mm increase in the zone diameter of either the CTX/BA or the CAZ/BA disk in the presence of CA was considered to be a positive result, the test also detected all isolates that harbor ESBLs (؎ pAmpCs) and showed less frequent false-positive results (5%) in isolates that produce only pAmpCs. The latter new interpretive guideline has enhanced detection of ESBLs in clinical isolates of Klebsiella spp. and Escherichia coli and allowed detection of an ESBL even when potentially masked by a pAmpC.

show abstract

Disc methods for detecting AmpC β-lactamase-producing clinical isolates of Escherichia coli and Klebsiella pneumoniae

Cited by 37 publications

References 8 publications

Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli , Klebsiella pneumoniae , and Proteus mirabilis

Evaluation of Screening Methods To Detect Plasmid-Mediated AmpC in Escherichia coli , Klebsiella pneumoniae , and Proteus mirabilis

Simple Disk-Based Method for Detection of Klebsiella pneumoniae Carbapenemase-Type β-Lactamase by Use of a Boronic Acid Compound

Detection of Extended-Spectrum β-Lactamases by Using Boronic Acid as an AmpC β-Lactamase Inhibitor in Clinical Isolates of Klebsiella spp. and Escherichia coli

Contact Info

Product

Resources

About