Differences in Antimicrobial Resistance Phenotypes by the Group of CTX-M Extended-Spectrum β-Lactamase
- Author:
Bareum GWON
1
;
Eun Jeong YOON
;
Dokyun KIM
;
Hyukmin LEE
;
Jong Hee SHIN
;
Jeong Hwan SHIN
;
Kyeong Seob SHIN
;
Young Ah KIM
;
Young UH
;
Hyun Soo KIM
;
Young Ree KIM
;
Seok Hoon JEONG
Author Information
- Publication Type:Original Article
- Keywords: CTX-M; Escherichia coli; Extended-spectrum β-lactamase; Klebsiella pneumoniae
- MeSH: Aztreonam; Cefotaxime; Ceftazidime; Cephalosporins; Clavulanic Acid; Diffusion; Escherichia coli; Hospitals, General; Klebsiella pneumoniae; Korea; Mass Screening; Mass Spectrometry; Monobactams; Phenotype; Pneumonia; Polymerase Chain Reaction
- From:Annals of Clinical Microbiology 2019;22(1):1-8
- CountryRepublic of Korea
- Language:English
- Abstract: BACKGROUND: Escherichia coli and Klebsiella pneumoniae clinical isolates producing CTX-M extendedspectrum β-lactamases (ESBLs) were assessed for antimicrobial resistance phenotypes varied by group of enzymes. METHODS: A total of 1,338 blood isolates, including 959 E. coli and 379 K. pneumoniae, were studied. All the strains were collected between January and July 2017 from eight general hospitals in South Korea. The species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antimicrobial susceptibilities were determined by disk diffusion methods and ESBL phenotypes by double-disk synergy tests using disks containing cefotaxime, ceftazidime, cefepime, aztreonam, and clavulanic acid (CA). The genes for β-lactamases were identified by PCR and sequencing. RESULTS: Of total microbes, 31.6% (303/959) E. coli and 24.0% (91/379) K. pneumoniae were resistant to cefotaxime and 28.1% (269/959) E. coli and 20.1% (76/379) K. pneumoniae were CTX-M-type ESBL producers. Among the detected CTX-M ESBLs, 58.0% (156/269) in E. coli and 86.8% (66/76) in K. pneumoniae belonged to group 1, 46.8% (126/269) in E. coli and 14.5% (11/76) in K. pneumoniae were group 9. Ten E. coli and one K. pneumoniae isolates co-produced both groups of CTX-M ESBL. The group 1 CTX-M producers had a higher level of resistance to cefotaxime, ceftazidime, cefepime, and aztreonam and exhibited stronger synergistic activities when combined with CA compared to group 9. CONCLUSION: ESBL phenotypes differ by CTX-M ESBL group and phenotype testing with drugs including 4th generation cephalosporins and monobactams is critical for screening CTX-M-producers with better sensitivity.
