the potency of tedizolid, linezolid, and vancomycin against extensively drug-resistant <i>staphylococcus aureus</i> clinical isolates

Background: staphylococcus aureus is considered a normal flora by colonization in the nose and skin of humans, yet it is a major cause of nosocomial infections and a life-threatening pathogen. among antibiotics, oxazolidinones and glycopeptides have activity against gram-positive pathogens.objectives: the present study aimed to determine the frequency and comparison of the minimum inhibitory concentration of tedizolid, linezolid, and vancomycin against extensively drug-resistant (xdr) s. aureus strains isolated from hospitalized patients. methods: this descriptive-analytical study was performed on 58 s. aureus isolates collected from 164 hospitalized patients over the course of one year. the kerby-bauer test was used to identify xdr isolates. broth microdilution test was used according to clsi m100-s25 (2015) criteria to determine the minimum inhibitory concentration (mic) of vancomycin, linezolid, and tedizolid. results: the frequency of xdr s. aureus clinical isolates was 28 (48.3%). determining mic showed that all xdr s. aureus isolates tested were susceptible to tedizolid (mic, ≤ 2 µg/ml), while 92/8% (mic, ≤ 4 µg/ml) and 60.70% (mic, ≤ 2 µg/ml) of xdr isolates were categorized as susceptible to linezolid and vancomycin, respectively. the concentration of tedizolid that inhibited 90% of isolates (mic90) was 2 µg/ml, 2-fold lower than linezolid (mic90 = 4 µg/ml) and 64-fold lower than vancomycin (mic90 = 128 µg/ml). there was a significant di erence between the frequency of xdr isolates from the aspirate, trachea, and wound infections, so 22% of vancomycin-resistant isolates and all strains resistant to linezolid were isolated from hospitalized patients in the infectious ward (p = 0.04).conclusions: we conclude that tedizolid has a beneficial e ect on xdr isolates of s. aureus and possesses more potent in vitro activity than the rest agents.