Abstract
Antimicrobial resistance (AMR) is a major global health threat worldwide, including in Fiji, where treatment options for carbapenem-resistant organisms (CROs) are severely limited. The World Health Organization (WHO) has identified carbapenemase-producing Acinetobacter baumannii (A. baumannii), Pseudomonas aeruginosa (P. aeruginosa), and Enterobacterales as CROs, due to their ability to inactivate carbapenems—a class of last-resort antimicrobials.
This study aimed to evaluate five novel antimicrobials—sulbactam-durlobactam, minocycline, cefiderocol, ceftazidime-avibactam, and aztreonam—against clinical CRO isolates from three Fijian hospitals. Minimum inhibitory concentration (MIC) testing, which determines the lowest concentration of an antibiotic needed to stop visible bacterial growth, was used to assess susceptibility of CROs. Synergy testing was also conducted to evaluate the combined effect of ceftazidime-avibactam and aztreonam for P. aeruginosa and Enterobacterales.
Cefiderocol showed broad efficacy across most isolates, making it a promising treatment option. Synergy testing demonstrated that combining ceftazidime-avibactam and aztreonam enhanced antimicrobial activity, rendering many previously resistant Enterobacterales isolates susceptible to the drug pairing. Interestingly, aztreonam alone was more effective against P. aeruginosa. However, resistance to cefiderocol was observed in some A. baumannii and Enterobacterales strains, underscoring the complexity of AMR.
Addressing AMR in Fiji is not only urgent for local health outcomes but also relevant for New Zealand, due to close travel ties and the potential for cross-border transmission. By expanding access to effective antimicrobials and implementing resistance surveillance, this research supports both local and regional AMR preparedness. Collaborative strategies between nations are vital for building resilient healthcare systems in the Pacific.