Calixa Therapeutics Inc. today announced the initiation of a Phase 2 clinical trial of CXA-101 in patients with complicated urinary tract infections. CXA-101 is a new broad-spectrum, parenteral cephalosporin antibiotic with excellent in vitro and in vivo activity against Pseudomonas aeruginosa, including drug resistant isolates. Calixa is investigating CXA-101 as a potential treatment for serious bacterial infections in hospitalized patients.