Analysis of Clinical Gram-Negative Carbapenem Resistant Acinetobacter baumannii and Klebsiella pneumoniae Isolates from Wounds of Patients at a Hospital Reveals Complex Resistome and the First Report of blaSPM and blaSME Genes in Trinidad, West Indies.

Antimicrobial resistance poses a critical global threat, with carbapenem-resistant pathogens representing a significant challenge to healthcare systems. This study aimed to characterize carbapenem-resistant pathogens isolated from wound infections in patients from a major hospital in Trinidad using a combination of traditional microbiological and molecular techniques. A total of 25 Gram-negative bacterial isolates were analyzed phenotypically for antimicrobial resistance and genetically profiled for resistance mechanisms using polymerase chain reaction and whole genome sequencing. Analysis of the data revealed most of the isolates were Acinetobacter baumannii (A. baumannii) (56%; n = 14) and Klebsiella pneumoniae (K. pneumoniae) (28%; n = 7), but a small number of Enterobacter (12%; n = 3), and Pseudomonas (4%; n = 1) were also identified. While the isolates were determined to be carbapenem resistant, 32% (n = 8) also exhibited extended spectrum beta-lactamases characteristics. Key resistance determinants identified from whole genome sequencing included blaOXA-23 (n = 2), blaOXA-90 (n = 2), and blaOXA-72 (n = 1) in A. baumannii and blaNDM-5 (n = 1) in K. pneumoniae. The co-occurrence of carbapenemase and extended spectrum beta-lactamase genes, such as blaCTXM-124 in A. baumannii and blaTEM-1B and blaCMY-4 in K. pneumoniae, emphasized the complexity of resistance mechanisms that limits therapeutic options. Notably, this is the first study to report on the occurrence of blaSPM and blaSME in A. baumannii in Trinidad. By contributing critical insights into the molecular epidemiology of antimicrobial resistance in the setting of the Caribbean, this study offers a foundation for region-specific interventions to mitigate the clinical and economic impact of resistant infections. It will also help improve antimicrobial stewardship, and control efforts, and therefore supports the need for investment in diagnostic stewardship.