Boni Catherine^{1, 2}, Yapi Adompo Jaurès Cedric^{3, 2,}, Méité Syndou^{3, 2}, Yapi Ivanne Alexia², Gnegouri Rachelle¹, Bahan Gninissemet Armel², Koffi Stephane², Kacou-N’douba Adèle², Kouassi-M’bengue Alphonsine²

Background: Cancer patients receiving chemotherapy are highly vulnerable to environmental infections due to treatment-induced immunosuppression, yet bacterial contamination and antibiotic resistance patterns in African oncology facilities remain uncharacterized. We conducted a comprehensive environmental surveillance of a West African chemotherapy unit to identify infection risks threatening these vulnerable patients. Methods: We collected 39 environmental samples (36 surfaces, 3 air) from high-touch sites across the chemotherapy unit at Centre National de Radiothérapie et d'Oncologie Médicale Alassane Ouattara (August-October 2024). Bacterial isolates underwent identification using conventional methods and API systems, with antimicrobial susceptibility testing by Kirby-Bauer disk diffusion under EUCAST 2023 guidelines. Extended-spectrum β-lactamase (ESBL) production was confirmed by double-disk synergy testing. Results: Surface contamination occurred in 63.9% of samples; air remained sterile. Twenty-nine isolates recovered: Bacillus spp. (34.5%), coagulase-negative staphylococci (27.6%), Pseudomonas aeruginosa (20.7%), Enterobacteriaceae (17.2%). Water sources harbored Pseudomonas and ESBL-producers. Resistance was substantial: 40% Enterobacteriaceae produced ESBLs with fluoroquinolone co-resistance, 14.3% coagulase-negative staphylococci exhibited methicillin/aminoglycoside resistance, all P. aeruginosa (6/6) showed intermediate colistin susceptibility. Bacillus demonstrated aminopenicillin resistance but carbapenem susceptibility. No carbapenemase-producers detected. Conclusions: This chemotherapy unit surveillance reveals concerning environmental contamination with resistant opportunistic pathogens. Bacillus predominance and water-associated Pseudomonas/ESBL-Enterobacteriaceae colonization highlight unique tropical ecology patterns. Enhanced cleaning protocols, water system management, and antimicrobial stewardship adapted to local resistance are urgently needed. These baseline data inform infection prevention programs protecting vulnerable African cancer patients.

Antimicrobial resistance, Environmental surveillance, Healthcare-associated infections, Sub-Saharan Africa, Côte d’Ivoire