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The Journal of the Japanese Society for Clinical Microbiology |
Biblioraphy Information
| ArticleTitle |
The prevalence of acquired ampC genes in Escherichia coli suspected to produce AmpC β-lactamase based on phenotypic testing and their microbiological profile |
| Language |
J |
| AuthorList |
Chiyo Shintani1,2), Aki Sakurai3,4), Manami Hamagishi1,2), Kenjiro Matsui1,2), Akiko Sei4), Masahiro Suzuki4), Yohei Doi3,4) |
| Affiliation |
1) Department of Clinical Laboratory, Fujita Health University Hospital
2) Division of Infection Control, Department of Quality and Safety in Healthcare, Fujita Health University Hospital
3) Department of Infectious Diseases, Fujita Health University School of Medicine
4) Department of Microbiology, Fujita Health University School of Medicine |
| Publication |
J.J.C.M.: 34 (3), 184-189, 2024 |
| Received |
January 25, 2024 |
| Accepted |
April 15, 2024 |
| Abstract |
This study aimed to investigate the prevalence of acquired ampC genes in Escherichia coli isolates which were suspected to produce AmpC β-lactamase based on susceptibility testing and AmpC/ESBL differentiation disk results. Of 4211 E. coli strains isolated from clinical samples in a single facility during the study period, 45 isolates demonstrating cefmetazole (CMZ) MIC ≥ 32 μg/mL or inferred to produce AmpC as a possible resistance mechanism by VITEK2 advanced expert system (AES), and showing a positive test result for AmpC by the AmpC/ESBL differentiation disk were included. Phenotypic confirmatory testing of AmpC using boronic acid, susceptibility testing, and detection of acquired ampC genes by PCR were conducted. As a result, 30 study isolates (67%, 30/45) harbored acquired ampC genes belonging to the CIT family (70%, 21/30) and DHA family (30%, 9/30). The non-susceptibility rates to CMZ and third-generation cephalosporins were significantly higher in isolates with acquired ampC genes than in those without. DHA-producing isolates were often inferred to produce ESBL by AES. Of 15 isolates without acquired ampC genes, 6 (40%, 6/15) were presumed to overproduce chromosomal AmpC. In conclusion, the prevalence of acquired ampC genes was high in E. coli isolates in which AmpC production was suspected based on the susceptibility testing and AmpC/ESBL differentiation disk results. |
| Keywords |
AmpC, Escherichia coli |
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