Infectious Etiologies and Antimicrobial Management of Acute Chest Syndrome in Adult Sickle Cell Disease Patients: Pathogen Identification Patterns and Clinical Outcomes from a Five-Year Retrospective Study in Eastern Saudi Arabia.

Acute chest syndrome (ACS) is a life-threatening complication of sickle cell disease (SCD) with complex infectious and non-infectious etiologies. Bacterial pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms such as Mycoplasma pneumoniae, play crucial roles in ACS pathogenesis, particularly in immunocompromised SCD patients with functional asplenia. Despite the importance of infectious triggers, regional data on pathogen identification rates and antimicrobial management strategies in ACS remain limited, especially from high-prevalence SCD regions. This study aimed to investigate the infectious etiologies, pathogen identification patterns, and antimicrobial management outcomes of ACS in adult SCD patients in Eastern Saudi Arabia. A five-year retrospective analysis was conducted on patients aged ≥14 years with SCD who were admitted with ACS to Dammam Medical Complex between 2018 and 2022. Comprehensive microbiological evaluation included blood cultures, sputum cultures, and atypical pathogen testing (Mycoplasma pneumoniae, Chlamydia pneumoniae). Data on antimicrobial regimens, pathogen identification rates, vaccination status against encapsulated bacteria, and clinical outcomes were systematically analyzed. Empirical antibiotic strategies and their effectiveness in this immunocompromised population were evaluated. A total of 60 adult SCD patients experiencing 80 episodes of ACS were included. Despite comprehensive microbiological workup, specific infectious pathogens were identified in only 8 (10.0%) episodes, highlighting the complex multifactorial etiology of ACS. Blood cultures yielded pathogens in 5 (6.3%) cases, sputum cultures in 4 (5.0%) cases, and Mycoplasma pneumoniae was identified in 3 (3.8%) episodes. All patients received empirical broad-spectrum antimicrobial therapy, with ceftriaxone and azithromycin combination being the most frequent regimen (76 cases, 95.0%), providing coverage for both typical and atypical bacterial pathogens. Antibiotic escalation was required in 16 (20.0%) episodes. Vaccination rates against Streptococcus pneumoniae were suboptimal at 30 (50.0%), representing a significant risk factor for invasive bacterial infections in this functionally asplenic population. The intensive care unit (ICU) admission rate was 15 (18.8%), and in-hospital mortality was 3 (3.8%), with infectious complications contributing to severe outcomes. In this cohort of SCD patients, ACS demonstrated low rates of specific pathogen identification despite systematic microbiological investigation, supporting the multifactorial infectious and non-infectious etiology of this syndrome. The predominant use of broad-spectrum antimicrobial therapy targeting both typical and atypical bacterial pathogens proved effective in this immunocompromised population. However, suboptimal vaccination rates against encapsulated bacteria represent a critical gap in infection prevention strategies. These findings emphasize the importance of empirical antimicrobial coverage for suspected bacterial pathogens in ACS management and highlight the urgent need for enhanced vaccination programs to prevent infectious complications in functionally asplenic SCD patients.