7: Microbiology in Adult Extracorporeal Life Support Patients – A Single Centre UK Study

Background: Infections in extracorporeal life support (ECLS) patients are well described. Multiple factors: invasive lines, prolonged runs of extracorporeal membrane oxygenation (ECMO), increase infection risks. Methods: Microbiology results from day one of ECMO to seven days after decannulation, in all patients on veno-venous (VV) ECMO and veno-arterial (VA) ECMO from January 2018 – April 2024, were recorded. Results: The study included 254 patients: 110 on VV-ECMO (34.5% =female, mean age =46.9yrs, median number of days on ECMO =13); 144 on VA-ECMO (33.3% =female, mean age =48.2yrs, median number of days on ECMO = 6). Positive blood cultures were identified in 42/110 (38.2%) of VV-ECMO patients, and 30/144 (20.8%) of VA-ECMO patients. The most common organisms isolated in both groups were coagulase-negative staphylococci: 25.7% in VV-ECMO and 32.7% in VA-ECMO. Patients with positive blood cultures were 14.9% higher in the VV-ECMO group; p=0.0035; 95% CI (0.0176- 0.2821). Amongst VA ECMO patients, K. pneumoniae was significantly 16.7% higher; p= 0.0087; 95% CI (0.042-0.292). Positive sputum/BAL cultures were identified in 68/110 (61.8%) of VV-ECMO patients, and 46/144 (31.9%) of VA-EMO patients. The most common organism isolated in both groups was P. aeruginosa: 18% in VV-ECMO and 16.7% in VA-ECMO patients. There were 29.9% more positive sputum/BAL cultures in the VV-ECMO group; p <0.01; 95% CI (0.143-0.454). S. maltophilia was 6.5% higher in the VV-ECMO patients; p=0.0048; 95% CI (0.0199-0.1106). Amongst the VA-ECMO group, MSSA was 9% higher; p=0.0156; 95% CI (0.017- 0.164); and H. influenzae was 5.9% higher; p=0.019; 95% CI (0.009-0.107). Limitations: This is a single-centre study, and antibiotic usage data collection is ongoing. Conclusions: There were significantly more positive blood culture and sputum/BAL samples in VV ECMO patients. This could be explained by the longer runs on VV-ECMO; and the differing patient groups.