Martin Stryjewski, MD, Co-Investigator and Physician in Infectious Diseases, Department of Medicine, Centro de Estudios Medicos e Investigaciones Clinicas (CEMIC), Buenos Aires, Argentina, presented the findings on behalf of the Assessment of Telavancin in Skin and Skin Structure Infections (ATLAS) Study Group.

S. aureus is a known and common cause of cSSSIs, and over the last few years, community-associated MRSA has become epidemic in many regions of the world, Dr. Stryjewski said. Therefore, new antibacterial agents are needed for treatment of patients with serious MRSA infections.

The ATLAS trials were designed to investigate the use of a novel rapidly bactericidal lipoglycopeptide -- telavancin -- that is known to act via inhibition of bacterial cell wall synthesis and disruption of the bacterial cell membrane integrity.

"The ATLAS studies comprise the largest prospective, double-blind, cSSSI clinical trial programme to date, and the MRSA cohort was the largest enrolled in a registrational programme," Dr. Stryjewski noted.

Telavancin has been associated with low minimum inhibitory concentrations (MICs) against Gram-positive bacteria, including MRSA, and with favourable outcomes in phase 2 trials with patients with cSSSIs.

The ATLAS database, which contained data on 1,867 patients with cSSSIs randomisation to telavancin (n = 928) or vancomycin (n = 939), provided baseline data on a total of 719 patients (38.5%) with MRSA or methicillin-susceptible S. aureus (MSSA). Data were also available on 1,148 patients with MSSA.

Dr. Stryjewski thus posed their question: "Are the patients infected with MRSA different from other patients?"

Baseline data for patients with MRSA and MSSA showed that MRSA was more commonly associated with a younger age (44.6 and 51.4 years) and Black racial origin (Caucasian, 75% and 79%; Hispanic/ Latino, 19% and 22%; Black, 21% and 10%).

When a similar comparison was made across the cSSSI types, the researchers found that MRSA was associated with major abscesses (59% and 32%), with MSSA more specifically associated with deep/ extensive cellulitis (21% and 48%).

When analysed according to infection site, MRSA and MSSA both paralleled the cSSSI locations, and were more often associated with the lower extremities (42% and 56%), as compared to head/ neck (8% and 6%), front torso (15% and 13%), back torso (15% and 9%), and upper extremities (20% and 16%).

Dr. Stryjewski indicated that for the full population of these patients with cSSSIs who were microbiologically evaluable (n = 870), the PVL positive versus negative distribution of their S. aureus isolates was 64% versus 36%. Again, when divided according to MRSA versus MSSA, the PVL-positive isolates were seen to be more common among patients with MRSA infections than patients with MSSA infections (85% versus 31%).

He concluded that this baseline study revealed that MRSA appears to be more common in patients with cSSSIs who are younger than 65 years of age, of Black origin, with major abscess, and with PVL-positive status.

This research was supported by Theravance Inc., USA.


[Presentation title: Baseline Characteristics of Patients, With or Without MRSA, in Two Phase 3 Studies Comparing Telavancin With Vancomycin for the Treatment of Complicated Skin and Skin Structure Infections. Abstract O143]

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