Susceptibility testing challenges with ceftaroline, MRSA and a 1 mg/L breakpoint

The Journal of Antimicrobial Chemotherapy
David M LivermoreNeil Woodford

Abstract

A 1 mg/L susceptibility breakpoint for ceftaroline and staphylococci is universally agreed; EUCAST counts MIC >1 mg/L as resistant whereas CLSI and FDA count 2 mg/L as intermediate and >2 mg/L as resistant. We investigated whether routine diagnostic tests reliably distinguish MICs of 1 versus 2 mg/L. Thirty-five UK laboratories collected Staphylococcus aureus isolates and performed tests with 5 μg (as EUCAST) or 30 μg (as CLSI) discs and either confluent growth on Mueller-Hinton agar (as EUCAST and CLSI) or semi-confluent growth on Iso-Sensitest agar (as BSAC). They also ran Etests for MRSA. Reference MICs were determined centrally by CLSI and BSAC agar dilution. We obtained paired local disc and central MIC results for 1607 S. aureus (33% MRSA). EUCAST's zone breakpoint recognized 56% of isolates found resistant in MIC tests, but the positive predictive value (PPV) for resistance was 11.0%; corresponding proportions by CLSI testing were 28.0% and 13.4%. The BSAC disc method detected 25% of resistant isolates, with a PPV of 18.2%. Essential agreement, ±1 dilution, of local Etests and central agar MICs was >95%, but only 20% of the isolates found non-susceptible by agar dilution were found non-susceptible by Etest and vice versa...Continue Reading

References

Jan 1, 1991·The Journal of Antimicrobial Chemotherapy·R A Cox
Jul 15, 2006·The Journal of Antimicrobial Chemotherapy·J M Andrews, UNKNOWN BASC Working Party on Susceptibility Testing
Jun 6, 2007·The Journal of Antimicrobial Chemotherapy·Shazad MushtaqDavid M Livermore
Jan 26, 2010·The Journal of Antimicrobial Chemotherapy·Hélène MoisanFrançois Malouin
Mar 9, 2012·The Journal of Antimicrobial Chemotherapy·Rodrigo E MendesKlaudia Kosowska-Shick
Jul 17, 2012·Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy·Jennifer C LinJoshua Fierer
Oct 26, 2012·The Journal of Antimicrobial Chemotherapy·R A HoweUNKNOWN BSAC Working Party on Susceptibility Testing
Mar 6, 2013·Antimicrobial Agents and Chemotherapy·Alasdair P MacGowanKaren E Bowker
Oct 18, 2013·Clinical Microbiology and Infection : the Official Publication of the European Society of Clinical Microbiology and Infectious Diseases·E MatuschekG Kahlmeter
Apr 20, 2014·European Journal of Clinical Microbiology & Infectious Diseases : Official Publication of the European Society of Clinical Microbiology·L M KoethJ E Ambler
Nov 25, 2014·Diabetes/metabolism Research and Reviews·B A LipskyE J C Goldstein
Jul 5, 2015·The Journal of Antimicrobial Chemotherapy·David M LivermoreNeil Woodford

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