Canton R

Diaz-Reganon J

Livermore DM

Morosini MI

on behalf of the PREMIUM Study Group

Rossolini GM

\ua9 The Author 2016. Objectives: To compare the concordance of ceftaroline MIC values by reference broth microdilution (BMD) and Etest (bioM\ue9rieux, France) for MSSA and MRSA isolates obtained from PREMIUM (D372SL00001), a European multicentre study. Methods: Ceftaroline MICs were determined by reference BMD and by Etest for 1242 MSSA and MRSA isolates collected between February and May 2012 from adult patients with community-acquired pneumonia or complicated skin and soft tissue infections; tests were performed across six European laboratories. Selected isolates with ceftaroline resistance in broth (MIC &gt;1 mg/L) were retested in three central laboratories to confirm their behaviour. Results: Overall concordance between BMD and Etest was good, with &gt;97% essential agreement and &gt;95% categorical agreement. Nevertheless, 12 of the 26 MRSA isolates found resistant by BMD scored as susceptible by Etest, with MICs ≤1 mg/L, thus counting as very major errors, whereas only 5 of 380 MRSA isolates found ceftaroline susceptible in BMD were miscategorized as resistant by Etest. Twenty-one of the 26 isolates with MICs of 2 mg/L by BMD were then retested twice by each of three central laboratories: BMD MICs of 2 mg/L were consistently found for 19 of the 21 isolates. Among 147 Etest results for these 21 isolates (original plus six repeats per isolate) 112 were &gt;1 mg/L. Conclusions: BMD and Etest have good overall agreement for ceftaroline against Staphylococcus aureus; nevertheless, reliable Etest-based discrimination of the minority of ceftaroline-resistant (MIC 2 mg/L) MRSA is extremely challenging, requiring careful reading of strips, ideally with duplicate testing

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Etest versus broth microdilution for ceftaroline MIC determination with <em>Staphylococcus aureus</em>: Results from PREMIUM, a European multicentre study

https://eprint.ncl.ac.uk/fulltext.aspx?url=237016/2F54FA5C-28E6-4597-B691-9C574814EA11.pdf&pub_id=237016

Etest versus broth microdilution for ceftaroline MIC determination with <em>Staphylococcus aureus</em>: Results from PREMIUM, a European multicentre study

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