In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species

David J. Farrell (1) , Marion Robbins (1) , William Rhys-Williams (2) , William G. Love (2)

1 Quotient Bioresearch Ltd.
2 Sussex Innovation Centre

The antibacterial activity of XF-73, a dicationic porphyrin drug, was investigated against a range of Gram-positive and Gram-negative bacteria with known antibiotic resistance profiles, including resistance to cell wall synthesis, protein synthesis, and DNA and RNA synthesis inhibitors as well as cell membrane-active antibiotics. Antibiotic-sensitive strains for each of the bacterial species tested were also included for comparison purposes. XF-73 was active [minimum inhibitory concentration (MIC) 0.25-4mg/L] against all of the Gram-positive bacteria tested, irrespective of the antibiotic resistance profile of the isolates, suggesting that the mechanism of action of XF-73 is unique compared with all other antibiotic classes tested. Gram-negative activity was lower (MIC 1mg/L to >64mg/L). Minimum bactericidal concentration data confirmed that the activity of XF-73 was bactericidal. Time-kill kinetics against healthcare-associated and community-associated meticillin-resistant isolates demonstrated that XF-73 was rapidly bactericidal, with >5 log kill obtained after 15min at 2× MIC, the earliest time point sampled. The post antibiotic effect (PAE) for XF-73 under conditions where the PAE for vancomycin was <0.4h was found to be >5.4h. XF-73 represents a novel broad-spectrum Gram-positive antibacterial drug with potentially beneficial characteristics for the treatment and prevention of Gram-positive bacterial infections.

Mots clés: XF-73; Antibacterial; Gram-positive; PAE; Time-kill

David J. Farrell, Marion Robbins, William Rhys-Williams, William G. Love. In vitro activity of XF-73, a novel antibacterial agent, against antibiotic-sensitive and -resistant Gram-positive and Gram-negative bacterial species. International Journal of Antimicrobial Agents, 2010, 35 (6), pp.531. ⟨10.1016/j.ijantimicag.2010.02.008⟩. ⟨hal-00585823⟩