Characterization of Carbapenem-Resistant Clinical Gram-Negative Isolates From Gaza Strip, Palestine

• High prevalence of multidrug-resistant Gram-negative bacteria in two Gaza hospitals prior to the 2023 war. • Nearly half of isolates were resistant to meropenem, with 9% confirmed as carbapenemase producers. • Carbapenemase-producing isolates, mainly NDM-type, remained susceptible only to colistin among locally available antibiotics. • Major discrepancies were observed in bacterial identification and resistance detection using routine phenotypic methods. • Ongoing war-related collapse of health, water, and sanitation systems is likely to accelerate antimicrobial resistance spread. Antimicrobial resistance is a major global health concern, particularly in low- and middle-income and conflict-affected settings. This study characterized carbapenem-resistant Gram-negative bacteria (GNB) isolated from clinical samples collected in two Gaza hospitals prior to the 2023 war. Between December 2021 to April 2022, GNB from infections were collected at Al Nasser and Al Shifa hospitals. Disc diffusion, synergy, and modified Hodge tests were performed locally. Carbapenemases were confirmed using CarbaNP and NG-Test CARBA 5 assays. WGS was used to determine resistome, MLST and phylogeny. Broth microdilution was used to study antibiotic susceptibility. A total of 135 GNB were recovered, comprising 110 Enterobacterales, 22 Pseudomonas aeruginosa , and three Acinetobacter baumannii , predominantly from urine samples (65%). Overall, 87% of isolates were multidrug-resistant. Meropenem resistance was detected in 100% of A. baumannii isolates, 55% of P. aeruginosa , and 47% of Enterobacterales. Carbapenemase production was confirmed in only 12 isolates: seven NDM-, two VIM-, and three OXA-23–producing strains, including one OXA-23-NDM co-producing A. baumannii . WGS of eight isolates revealed one VIM-4–producing E. coli , two NDM-1, one NDM-5, and one NDM-19–producing K. pneumoniae , and three OXA-23- (including one OXA-23/NDM-1) producing A. baumannii . Prior to the onset of the war, Gaza hospitals already faced a significant burden of multidrug-resistant and carbapenemase-producing GNB, compounded by limited treatment options and diagnostic challenges. The continued disruption of healthcare, water, and sanitation systems is likely to accelerate the spread of antimicrobial resistance, underscoring the urgent need for enhanced surveillance and robust antimicrobial stewardship in conflict-affected areas.