Oral mucositis and microbial status in acute lymphoblastic leukemia subjects undergoing high-dose chemotherapy

Aim: To assess oral microbial status in patients with acute lymphoblastic leukemia (ALL) undergoing high-dose chemotherapy and to unravel possible associations between nosocomial pathogens and the establishment of chemotherapy-induced oral mucositis (CIOM). Methods: Oral mucosa, saliva, and peripheral blood samples were collected from 46 ALL subjects one day prior to chemotherapy (D0) and 2 weeks after treatment initiation (D14). Clinical intraoral inspection was performed by a single practitioner, with mucositis classification performed according to the WHO oral toxicity scale. Blood components were quantified by automatic flow cytometry, while oral Staphylococcus aureus and Pseudomonas aeruginosa were detected by Polymerase Chain Reaction with species-specific primers. Associations among bacteria and clinical findings were determined by Fisher’s Exact test, longitudinal bacterial changes by paired Macnemar, and correlations among blood parameters and mucositis status or bacteria via Mann-Whitney. Results: S. aureus displayed higher detection rates at D14 (p < 0.05) and was positively associated with mucositis, adoption of a non-solid diet (all p < 0.001), nausea and fever (all p < 0.05). Conversely, P. aeruginosa did not correlate to CIOM clinical parameters. At the systemic standpoint, lower hemoglobin levels associated with CIOM and fever events (all p < 0.01). Conclusion: The study evidences S. aureus as a potential pathogen in ALL-CIOM, reaffirming microbial control as an important preventive measure during high-dose immunosuppressive therapy. The weight of non-white-blood-cell parameters should be validated as novel CIOM biomarkers in prospective research.