In vitro activity of ceftazidime/avibactam against Gram-negative strains in Colombia 2014-2018

Ceftazidime/avibactam (CAZ/AVI) has shown in vitro activity against multidrug-resistant (MDR) Gram-negative bacteria, especially Enterobacterales and carbapenem-resistant Pseudomonas aeruginosa. However, in vitro activity of CAZ/AVI against Gram-negative bacteria in Colombian hospitals is still unknown. The study aimed to analyse the in vitro antimicrobial activity of CAZ/AVI against Gram-negative bacteria collected from hospitals in Colombia using the Antimicrobial Testing Leadership and Surveillance (ATLAS) database.

Enterobacterales and P. aeruginosa samples were obtained from four hospitals in Colombia between 2014 and 2018. Samples of blood, abdominal fluid, urine, soft tissues, and respiratory tract were collected from adult and paediatric patients. The 2020 Clinical and Laboratory Standards Institute (CLSI) breakpoints were used for the interpretation of susceptibility. Meropenem-non-susceptible Enterobacterales and P. aeruginosa isolates were screened for extended-spectrum β-lactamase (ESBL) production. Isolates that were positive for ESBL activity were examined by PCR for detecting genotypic resistance.

A total of 2005 Enterobacterales were isolated; 29.28% were not susceptible to levofloxacin, 29.14% to aztreonam, and 25.19% to cefepime. The CAZ/AVI was the antibiotic with the best susceptibility against carbapenem-resistant Enterobacterales (CRE) (94.64%), non-metallo-β-lactamase(MBL)-producing Enterobacterales (98.06%), and MDR Enterobacterales (98.36%). For carbapenem-resistant P. aeruginosa, in vitro activity of CAZ/AVI was 59.26%, and 50% for non-MBL-producing P. aeruginosa.

CAZ/AVI shows excellent in vitro activity against MDR Enterobacterales and CRE. For MDR P. aeruginosa and carbapenem-resistant P. aeruginosa, in vitro activity of CAZ/AVI was lower compared to the activity against Enterobacterales, but CAZ/AVI was the antibiotic with the best activity.