Comparison of methods to analyse susceptibility of German MDR/XDR Pseudomonas aeruginosa to ceftazidime/avibactam

Schaumburg F, Bletz S, Mellmann A, Becker K, Idelevich EA

Forschungsartikel (Zeitschrift) | Peer reviewed

Zusammenfassung

Ceftazidime/avibactam (CZA) is a new β-lactam/β-lactamase inhibitor combination with promising properties as avibactam can inhibit a broad range of β-lactamases (e.g. blaKPC, blaOXA-48). The objectives of this study were: (i) to assess CZA susceptibility rates; (ii) to compare gradient and disk diffusion tests with broth microdilution (BMD) for CZA susceptibility testing; and (iii) to study the clonal structure and antimicrobial resistance genes in multi-drug-resistant (MDR) and extensively drug-resistant (XDR) Pseudomonas aeruginosa. Isolates (n=192) from routine diagnostics (Germany, 2013-2018) were tested by BMD reference method, gradient diffusion test (Etest, bioMérieux and MIC Test Strip, Liofilchem) and disk diffusion test (MAST and Oxoid). All isolates were whole-genome sequenced to screen for metallo-β-lactamases and to assess the clonal structure using core-genome multi-locus sequence typing. In total, 64.1% of isolates (n=123) were susceptible to CZA (minimum inhibitory concentration required to inhibit the growth of 50% of organisms 8 mg/L, minimum inhibitory concentration required to inhibit the growth of 90% of organisms >256 mg/L, range 0.5->256 mg/L). Susceptibility rates were higher in MDR (85.0%) than in XDR (49.1%) P. aeruginosa. Among commercial susceptibility testing methods, Etest showed highest accuracy in comparison to BMD (essential agreement 94.8%, categorical agreement 94.3%). CZA-resistant isolates (n=69) mainly belonged to ST235 (n=29, blaIMP-positive). In conclusion, CZA is a promising treatment option for infections caused by MDR P. aeruginosa. CZA-resistant P. aeruginosa mainly belong to the pandemic ST235 high-risk clone. Etest can be considered as an alternative to BMD.

Details zur Publikation

Jahrgang / Bandnr. / Volume54
Ausgabe / Heftnr. / Issue2
Seitenbereich255-260
StatusVeröffentlicht
Veröffentlichungsjahr2019 (07.05.2019)
Sprache, in der die Publikation verfasst istEnglisch
DOI10.1016/j.ijantimicag.2019.05.001
StichwörterAntimicrobial susceptibility testing; Ceftazidime/avibactam; Pseudomonas aeruginosa; Resistance; Whole-genome sequencing

Autor*innen der Universität Münster

Becker, Karsten
Institut für Medizinische Mikrobiologie
Bletz, Stefan
Institut für Hygiene
Idelevich, Evgeny
Institut für Medizinische Mikrobiologie
Mellmann, Alexander
Institut für Hygiene
Schaumburg, Frieder
Institut für Medizinische Mikrobiologie