Development of EUCAST zone diameter breakpoints and quality control criteria for ceftazidime-avibactam 10-4 µg.
Eur J Clin Microbiol Infect Dis
; 37(6): 1047-1053, 2018 Jun.
Article
in En
| MEDLINE
| ID: mdl-29603034
ABSTRACT
Ceftazidime-avibactam disk studies were performed for disk mass selection and for establishing EUCAST quality control ranges and zone diameter breakpoints. The disk mass study included disk diffusion testing with ceftazidime-avibactam 10-4 and 10-6 µg disks and broth microdilution MIC testing for challenge set of 94 Enterobacteriaceae and 45 Pseudomonas aeruginosa. EUCAST SOP 9.0-based QC and MIC-disk correlations studies were followed for development of ceftazidime-avibactam 10-4 µg ranges for Escherichia coli ATCC 25922, P. aeruginosa ATCC 27583, and Klebsiella pneumoniae ATCC 700603 and for zone diameter breakpoint determination. The ceftazidime-avibactam 10-4 and 10-6 µg disks performed similar in comparison to broth microdilution, with zones ≤ 14 mm for all resistant strains. The 10-4 µg disk was selected and used in QC and breakpoint studies. There was minimal variation of ceftazidime-avibactam 10-4 µg QC study results between disks, media, and sites. The QC ranges were within 7 mm for all strains. The zone diameter breakpoint study demonstrated good correlation of MIC and disk results. The established zone diameter breakpoints resulted in false susceptible rates of 1.6 and 4.0% for Enterobacteriaceae and P. aeruginosa. EUCAST selected the ceftazidime-avibactam 10-4 µg disk and established QC ranges for E. coli 25922 of 24-30 mm, P. aeruginosa ATCC 27853 of 21-27 mm, and K. pneumoniae ATCC 700603 of 18-24 mm. The zone diameter breakpoints that correlated best with the MIC breakpoints of susceptible ≤ 8 mg/L and resistant > 8 mg/L were Enterobacteriaceae (S ≥ 13, R < 13 mm) and P. aeruginosa (S ≥ 17, R < 17 mm).
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Ceftazidime
/
Enterobacteriaceae
/
Disk Diffusion Antimicrobial Tests
/
Azabicyclo Compounds
/
Anti-Bacterial Agents
Limits:
Humans
Language:
En
Journal:
Eur J Clin Microbiol Infect Dis
Journal subject:
DOENCAS TRANSMISSIVEIS
/
MICROBIOLOGIA
Year:
2018
Document type:
Article
Affiliation country:
Estados Unidos