A One Health Scoping Review of Antimicrobial Resistance in Cambodia: Evidence Mapping and Insights into Klebsiella pneumoniae

Antimicrobial resistance (AMR) is a growing global public health threat that disproportionately affects low- and middle-income countries (LMICs), including Cambodia. The distribution of AMR across interconnected human, animal, food, and environmental sectors highlights the importance of using a One Health approach to better understand and address this issue. In Cambodia, AMR is increasingly reported among key pathogens, including K. pneumoniae. In particular, the emergence of colistin and carbapenem resistance in this organism is of major clinical concern, as it compromises the effectiveness of critical antimicrobial agents used for the treatment of severe multidrug-resistant (MDR) infections, leading to increased morbidity, mortality, and healthcare costs. This scoping review aims to systematically map and summarize available One Health evidence on AMR in Cambodia across human, animal, food, and environmental sectors. By integrating evidence from these interconnected sectors, the review identifies major AMR patterns, potential transmission pathways and associated risk factors, as well as priority pathogens to inform future research priorities and policy development. Following the PRISMA-ScR guidelines, we searched PubMed/MEDLINE, Europe PMC, Google Scholar, Google Search, and grey literature sources. Of the 611 records identified, 455 unique records were screened, resulting in 94 studies included in the final analysis. Data were summarized narratively by categorizing evidence across human, animal, food, and environmental sectors. K. pneumoniae was included as a pre-specified pathogen of interest, because of its clinical relevance and AMR relevance in the Cambodian context. AMR burden in Cambodia is high, particularly among Gram-negative bacteria such as K. pneumoniae. The included studies reported substantial AMR, with estimates varying considerably according to population, setting, specimen type, study period, and laboratory definitions. High rates of extended-spectrum β-lactamase (ESBL) production and reported colistin and carbapenem resistance were observed in both hospital and community settings. K. pneumoniae is a key pathogen in healthcare-associated infections and neonatal sepsis, with frequent reports of multidrug-resistant (MDR) and carbapenem-resistant (CRKP) strains. Evidence linking human, animal, food, and environmental sectors was limited. As the data on shared resistance determinants and genetically similar isolates were cross-sectional in nature; they only suggest potential pathways and cannot prove directional transmission. Major drivers of AMR and associated factors include inappropriate antimicrobial use, agricultural practices, limited diagnostic capacity, inadequate infection prevention and control, and environmental contamination. Significant gaps remain in genomic surveillance and cross-sectoral research on AMR in Cambodia. Addressing these gaps will require strengthening One Health efforts and integrated cross-sectoral surveillance. K. pneumoniae may serve as a One Health sentinel pathogen for healthcare-related AMR surveillance, particularly ESBL and CRKP strains. However, this potential needs to be evaluated through pathogen-neutral, longitudinal, and cross-sectoral surveillance. Strengthening laboratory capacity, improving antimicrobial stewardship, and developing integrated surveillance systems are critical to mitigating AMR in the country.