Cross-Species Dissemination of Pandrug-Resistant Acinetobacter baumannii in Humans and Poultry in Egypt: Unveiling Shared Clones, Resistance Mechanisms, and Severe Clinical Outcomes

The emergence and global dissemination of pandrug-resistant (PDR) Acinetobacter baumannii represents a critical public health crisis. This One Health study provides comprehensive surveillance and molecular characterization of carbapenem-resistant, extensively drug-resistant (XDR), and PDR A. baumannii isolates isolated from hospitalized patients and diseased chickens/environment in Egypt. We investigated cross-species clinical and pathological impacts, characterized resistance genes, and analyzed potential transmission links. Of 145 samples, 48 A. baumannii isolates were identified. Resistance profiling revealed an alarming prevalence, with PDR (56.3%) being the dominant phenotype, followed by XDR (43.7%), all exhibiting high multiple antibiotic resistance (MAR) indices (≥0.67). Chickens and humans infected with PDR A. baumannii suffered from increased neutrophilia, anemia, elevated inflammatory markers (CRP and procalcitonin), renal and liver impairment, and upregulation of MMP-9 and IL-8 response genes. Molecular analysis showed that all PDR isolates co-harbored multiple carbapenemase genes, including Class D beta-lactamases (blaOXA-23 (most prevalent), blaOXA-48, blaOXA-58, blaOXA-24) and Class B metallo-beta lactamase (blaVIM, blaIMP, blaNDM). A substantial proportion also carried blaKPC (44.4%) and the carO gene (81.48%). Genotyping using ERIC PCR and Multilocus Sequence Typing (MLST) identified a high diversity (23 ERIC types, DI = 0.986). Significantly, two ERIC types (ET19 and ET20) contained isolates from both human and chicken sources. MLST confirmed this interspecies correlation, with isolates from both hosts clustering into Sequence Types (STs) ST1410 and ST1828. These findings confirm the rapid and alarming spread of highly virulent, multi-carbapenemase-producing PDR A. baumannii strains across the human–animal interface in Egypt. The detection of shared STs between clinical and poultry isolates underscores a potential zoonotic or environmental transmission route, necessitating integrated One Health surveillance and urgent infection control interventions.