Characterization of carbapenem-resistant clinical Gram-negative isolates from Gaza Strip, Palestine

Antimicrobial resistance is a major global health concern, particularly in low- and middle-income countries 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 and 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. Whole-genome sequencing was used to determine the resistome, multi-locus sequence type, and phylogeny. Broth microdilution was used to study antibiotic susceptibility.

A total of 135 GNB were recovered, comprising 110 Enterobacterales, 22 Pseudomonas aeruginosa, and 3 Acinetobacter baumannii, predominantly from urine samples (65%). Overall, 87% of the 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: 7 NDM-, 2 VIM-, and 3 OXA-23-producing strains, including 1 OXA-23-NDM co-producing A. baumannii. Whole-genome sequencing of eight isolates revealed one VIM-4-producing Escherichia coli, two NDM-1, one NDM-5, and one NDM-19-producing Klebsiella 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 health care, 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.