Comparative analysis of respiratory infection and clinical outcomes in Saudi hematology: malignant versus non-malignant cohorts

Background Respiratory infections are a primary cause of mortality in malignancy, yet the temporal dynamics and pathogen profile of the respiratory tract (RT) in these patients remain poorly defined. This 13-year study characterizes the culture isolate spectrum, seasonality, and survival impacts of RT infections in malignant versus non-malignant populations. Methods We conducted a 13-year retrospective observational study (2007–2020) at King Abdulaziz University Hospital, Jeddah, Saudi Arabia, enrolling 104 hematological patients with confirmed respiratory infections — 77 with malignant hematological disorders and 27 with non-malignant hematological disorders. Respiratory specimens were processed by conventional culture. Microbial prevalence was compared at the patient level using Fisher’s exact test with Benjamini-Hochberg FDR correction. Survival analysis was performed using Kaplan-Meier estimation with log-rank testing, stratified by infection type and pathogenicity classification. Spearman rank correlation matrices were computed to explore microbial co-occurrence patterns. Results Malignant patients demonstrated significantly higher case-fatality rate and markedly shorter overall survival. Mixed bacterial growth was the strongest discriminator between groups (p<0.001). Opportunistic pathogens were enriched in malignant patients while strict pathogens predominated in non-malignant individuals. Spearman correlation analysis revealed diffuse co-occurrence patterns in malignant patients — consistent with immunosuppression-driven ecological instability — contrasting with tightly structured-associated clustering in non-malignant patients. Infection peaks occurred in spring and summer for malignant patients versus winter for non-malignant patients. Conclusion Malignancy fundamentally shifts the RT environment toward ecological instability and opportunistic overgrowth. These findings underscore the necessity for microbial distribution and seasonally tailored prophylactic strategies to manage infections in immunocompromised hematological populations effectively.