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Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice.

Htoutou Sedlakova M, Hanulik V, Chroma M, Hricova K, Kolar M, Latal T, Schaumann R, Rodloff AC - Med. Sci. Monit. (2011)

Bottom Line: Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality.For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used.The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czech Republic. miroslava.htoutou@seznam.cz

ABSTRACT

Background: Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods.

Material/methods: A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used.

Results: The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively.

Conclusions: The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method.

Show MeSH
Modified DDST for ESBL detection.
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Related In: Results  -  Collection


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f4-medscimonit-17-5-br147: Modified DDST for ESBL detection.

Mentions: For the isolates, the results of the disk diffusion and microdilution methods and the accuracy of the Phoenix automated system were assessed [13,14]. In ESBL-positive strains, the sensitivity of a modified microdilution method with determination of cefoxitin MIC and the ratio of MIC of cefoperazone with the cefoperazone/sulbactam combination (Chart 1), as well as of the ESBL Etest (AB Biodisk) and a modified DDST (Chart 2) were assessed. AmpC strains were tested by a modified AmpC disk test using 3-aminophenylboronic acid (Chart 3) and the modified microdilution method with the determination of cefoxitin MIC and the ratio of MIC of cefotaxime and ceftazidime with the cefotaxime/3-aminophenylboronic acid and ceftazidime/3-aminophenylboronic acid combinations (Chart 1). The criteria of positivity for the individual phenotypic tests are summarized in Table 1.


Phenotypic detection of broad-spectrum beta-lactamases in microbiological practice.

Htoutou Sedlakova M, Hanulik V, Chroma M, Hricova K, Kolar M, Latal T, Schaumann R, Rodloff AC - Med. Sci. Monit. (2011)

Modified DDST for ESBL detection.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3539581&req=5

f4-medscimonit-17-5-br147: Modified DDST for ESBL detection.
Mentions: For the isolates, the results of the disk diffusion and microdilution methods and the accuracy of the Phoenix automated system were assessed [13,14]. In ESBL-positive strains, the sensitivity of a modified microdilution method with determination of cefoxitin MIC and the ratio of MIC of cefoperazone with the cefoperazone/sulbactam combination (Chart 1), as well as of the ESBL Etest (AB Biodisk) and a modified DDST (Chart 2) were assessed. AmpC strains were tested by a modified AmpC disk test using 3-aminophenylboronic acid (Chart 3) and the modified microdilution method with the determination of cefoxitin MIC and the ratio of MIC of cefotaxime and ceftazidime with the cefotaxime/3-aminophenylboronic acid and ceftazidime/3-aminophenylboronic acid combinations (Chart 1). The criteria of positivity for the individual phenotypic tests are summarized in Table 1.

Bottom Line: Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality.For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used.The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology, Faculty of Medicine and Dentistry, Palacky University Olomouc, Czech Republic. miroslava.htoutou@seznam.cz

ABSTRACT

Background: Enterobacteriaceae producing ESBL and AmpC enzymes can be associated with failure of antibiotic therapy and related morbidity and mortality. Their routine detection in microbiology laboratories is still a problem. The aim of this study was to compare the sensitivity of selected phenotypic methods.

Material/methods: A total of 106 strains of the Enterobacteriaceae family were tested, in which molecular biology methods confirmed the presence of genes encoding ESBL or AmpC. In ESBL-positive strains, the sensitivity of the ESBL Etest (AB Biodisk) and a modified double-disk synergy test (DDST) were evaluated. AmpC strains were tested by a modified AmpC disk method using 3-aminophenylboronic acid. For simultaneous detection of ESBL and AmpC, the microdilution method with a modified set of antimicrobial agents was used.

Results: The sensitivity of the ESBL Etest was 95%; the modified DDST yielded 100% sensitivity for ESBL producers and the AmpC test correctly detected 95% of AmpC-positive strains. The sensitivity of the modified microdilution method was 87% and 95% for ESBL and AmpC beta lactamases, respectively.

Conclusions: The detection of ESBL and AmpC beta lactamases should be based on specific phenotypic methods such as the modified DDST, ESBL Etest, AmpC disk test and the modified microdilution method.

Show MeSH