Activity of ceftolozane-tazobactam and comparators when tested against Gram-negative isolates collected from paediatric patients in the USA and Europe between 2012 and 2016 as part of a global surveillance programme.

Ceftolozane-tazobactam is a combination of an antipseudomonal cephalosporin and a β-lactamase inhibitor. Ceftolozane-tazobactam was approved by the US Food and Drug Administration in 2014 and by the European Medicines Agency in 2015 for use in adults to treat complicated urinary tract infections, acute pyelonephritis, and complicated intra-abdominal infections with metronidazole. Studies for paediatric indications are planned. The Programme to Assess Ceftolozane-Tazobactam Susceptibility monitors the resistance of ceftolozane-tazobactam to Gram-negative isolates worldwide. In total, 6240 Gram-negative isolates were collected between 2012 and 2016 from paediatric patients (<18 years old) in 31 US hospitals (4207 isolates) and 48 European hospitals (2033 isolates), and tested for susceptibility (S) to ceftolozane-tazobactam by broth microdilution. Other antibiotics tested included amikacin, colistin and meropenem. The most common infection type in hospitalized paediatric patients was pneumonia (n=2018), followed by urinary tract infection (n=1569) and bloodstream infection (n=1236). In total, 4316 Enterobacteriaceae and 1765 non-enterics were isolated. The most common species were Escherichia coli (n=1919), Pseudomonas aeruginosa (n=1236) and Klebsiella pneumoniae (n=709). In all regions, the three most active antimicrobials against paediatric Enterobacteriaceae isolates were amikacin (99.0%S), meropenem (98.9%S) and ceftolozane-tazobactam (94.6%S). For all P. aeruginosa, colistin (98.9%S) and ceftolozane-tazobactam (97.4%S) were the most active. In conclusion, for all Enterobacteriaceae, ceftolozane-tazobactam was the most potent cephalosporin tested, with only meropenem and colistin having higher susceptibility rates. For P. aeruginosa, ceftolozane-tazobactam was the most potent β-lactam and had a similar susceptibility rate to colistin.