Analysis of Telavancin In Vitro Activity Tested Against a USA Collection of Staphylococcus aureus Clinical Isolates Causing Hospital-Acquired Pneumonia (2013–2014)

Abstract

Background: Telavancin is approved in the USA and Europe (methicillin-resistant [MRSA] only) for the treatment of hospital-acquired (HABP) and ventilator-associated bacterial pneumonia (VABP) caused by S. aureus when alternative treatments are not suitable. This study provides a current in vitro activity analysis for telavancin and comparators against S. aureus causing HABP in USA hospitals during 2013 – 2014. Methods: 1,353 S. aureus collected from 29 USA sites located in the nine USA Census regions were included. Susceptibility testing was performed based on CLSI guidelines (M07-A10 and M100-S25). MIC interpretation was guided by FDA (2014), CLSI (2015) and/or EUCAST (2015) criteria. MRSA resistant to three or more drug classes were defined as multidrugresistant (MDR). Results: Telavancin had MIC50, MIC90 and MIC100 of 0.03, 0.06 and 0.06 mg/mL, respectively, against methicillin-susceptible, MRSA, non-MDR and MDR subsets. All isolates were inhibited by telavancin at the susceptible breakpoint (i.e. ≤0.12 mg/mL). Telavancin MIC values were at least 16-fold lower than vancomycin (MIC50/90, 1/1 μg/mL) and linezolid (MIC50/90, 1/1 μg/mL) MIC results against MRSA isolates (all 100.0% susceptible to vancomycin and linezolid). Telavancin, vancomycin (MIC50/90, 1/1 μg/mL) and linezolid (MIC50/90, 1/1 μg/mL) showed activity against the MDR subset, while other agents had limited coverage. S. aureus with vancomycin MIC=2 μg/mL had telavancin MIC50 (0.06 μg/mL) twofold higher than those with vancomycin MIC at ≤1 μg/mL. However, telavancin had MIC100 results of 0.06 μg/mL, regardless of subset. Conclusions: Telavancin had potent in vitro activity against S. aureus causing HABP, including less susceptible and MDR subsets, inhibiting all S. aureus at ≤0.06 μg/mL. These results confirm the potent in vitro activity of telavancin against S. aureus causing HABP in USA hospitals. CONCLUSIONS • Telavancin had potent in vitro activity against S. aureus causing HABP among hospitalized patients in USA institutions, including isolates less susceptible to vancomycin and MDR subsets. • All S. aureus were inhibited by telavancin at ≤0.06 μg/mL and telavancin was consistently more potent than comparator agents. These in vitro results support the use of telavancin for the treatment of HABP caused by S. aureus in USA hospitals.