This 3 arm study will compare the efficacy and safety of beta-lactam with that of 'standard care' in patients with complicated skin and skin structure infections requiring hospitalization. Patients will be randomized to receive 1)beta-lactam 750mg iv q8h 2)beta-lactam 1500mg iv q8h or 3)'standard care' [PRP (nafcillin or flucloxacillin) or vancomycin, plus aztreonam or ciprofloxacin]. The anticipated time on study treatment is <3 months and the target sample size is 100-500 individuals.

Inclusion Criteria:

• adult patients, >=18 years of age;
• skin or skin structure infection requiring hospitalization;
• clinical diagnosis of a skin or skin structure infection caused by bacteria known or suspected to be susceptible to the randomized study treatment;
• material from site of infection is clinically purulent or seropurulent.

Exclusion Criteria:

• presenting with sustained shock (SBP<90mm Hg for > 2 hours, despite adequate fluid resuscitation);
• known or suspected concomitant bacterial infection requiring antibiotic treatment;
• skin infection or chronic non-healing ulcer of > 2 weeks duration;
• patients in whom surgery is the primary treatment.