Activity of Tedizolid and Linezolid as Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe and Latin American Countries (2014).

Activity of Tedizolid and Linezolid as Determined by the Reference Broth Microdilution Method against 3,032 Gram-Positive Bacterial Isolates Collected in Asia-Pacific, Eastern Europe and Latin American Countries (2014).

Antimicrob Agents Chemother. 2016 Jun 27;

Authors: Pfaller MA, Flamm RK, Jones RN, Farrell DJ, Mendes RE

Abstract
Tedizolid and linezolid in vitro activities were assessed against 3,032 Gram-positive pathogens collected in Asia-Pacific, Eastern European and Latin American medical centers during 2014. Isolates were tested for susceptibility by the current reference broth microdilution methods. Due to concern over the effect of MIC endpoint criteria on the results of testing the oxazolidinones, tedizolid and linezolid MIC endpoint values were read by two methods: (1) reading the MIC at the first well where the trailing begins without regard for pinpoint trailing as per CLSI M07-A10 and M100-S26 document instructions for reading linezolid (i.e., "80%"; these reads were designated tedizolid 80 and linezolid 80) and (2) at 100% inhibition of growth (designated tedizolid 100 and linezolid 100). All Staphylococcus aureus, Streptococcus pyogenes, S. agalactiae, S. anginosus group and Enterococcus faecalis were inhibited at tedizolid 80/100 MIC values of 0.25/0.5, 0.25/0.25, 0.25/0.5, 0.12/0.25 and 0.5/1 μg/ml, respectively. Generally, MIC50 and MIC90 results for tedizolid 80 and linezolid 80 were one doubling-dilution lower than those read at 100% inhibition. Tedizolid was four- to eight-fold more potent than linezolid against all isolates tested regardless of the MIC end-point criterion used. Despite the difference in potency, ≥ 99.9% of isolates tested in this survey were susceptible to both linezolid and tedizolid using CLSI/EUCAST interpretive criteria. In conclusion, tedizolid demonstrated greater in vitro potency when compared to linezolid against Gram-positive pathogens isolated from patients in medical centers across the Asia-Pacific, Eastern Europe and Latin America.

PMID: 27353270 [PubMed - as supplied by publisher]