Zerbaxa is a new antibiotic approved for the treatment of complicated urinary tract infections, and in combination with metronidazole, complicated intra-abdominal infections. Zerbaxa contains a cephalosporin, ceftolozane, and a β-lactamase inhibitor, tazobactam. Ceftolozane exhibits significant activity against Gram-negative bacilli; tazobactam extends this spectrum to include β-lactamase producing bacteria and some anaerobic species.

Ceftolozane has a similar chemical structure to ceftazidime. However, a side chain modification provides enhanced antipseudomonal activity. Pseudomonas aeruginosa is responsible for 10% of nosocomial infections. The growing incidence of multi-drug resistance in this species is associated with significant morbidity and mortality. Zerbaxa is able to evade many of the resistance mechanisms of P. aeruginosa including efflux pumps, reduced uptake through porin channels, and modification of penicillin-binding proteins. It is not, however, stable to carbapenemases or metallo-β-lactamases.

The most common adverse effects reported are nausea, diarrhoea, headache, and pyrexia. Zerbaxa does not exhibit significant activity against Clostridium difficile and the risk of C. difficile-associated diarrhoea is assumed to be the same as other β-lactam antibiotics. Excretion is predominantly renal, therefore dose reduction is recommended in patients with impaired renal function.


  1. Morales E, Cots F, Sala M, Comas M, Belvis F, Riu M, et al. Hospital costs of nosocomial multi-drug resistant Pseudomonas aeruginosa acquisition. BMC Health Services Research, 2012.
  2. Streeter K, Katouli M. Pseudomonas aeruginosa: a review of their pathogenesis and prevalence in clinical settings and the environment. Infect Epidemiol Med. 2016; 2(1): 25-32.
  3. Zerbaxa (ceftolozane/tazobactam) Australian approved product information. Newmarket: Merck Sharp and Dohme Pty Ltd. Approved November 2015.

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