Impact of rectal screening for fluoroquinolone and third-generation cephalosporin-resistant Enterobacterales in hematological wards: a pre-post intervention study

Background Rising FQR-E challenges prophylaxis efficacy in neutropenic patients, especially in FQR-E high-prevalence settings. Correlation between colonizing microorganisms and bloodstream isolates is well known. Methods We performed a pre-post intervention study at AOU of Modena (pre-intervention period [Phase1] September 2021 - February 2023, post-intervention period [Phase2] March 2023 - August 2024) assessing the effect of the introduction of FQR-E and 3GCR-E screening in high-risk neutropenic adults. Results of screening guided both prophylaxis discontinuation and Empirical antibiotic therapy (EAT) regimen. Primary outcome was antibiotic consumption in days of therapy (DOTs) and defined daily dose (DDD/100 PD). Secondary outcomes included adherence to protocols on screening, prophylaxis, and EAT, along with 30- and 90-day overall and infection-related mortality, intensive care unit admission, C. difficile infection, hospital stays >30 days, chemotherapy delays due to infection, and acquisition of new MDR colonization. Results A total of 201 patients, 85 in Phase1 and 116 in Phase2 period were enrolled. Median age was 59 years, 55.2% were male, 40.3% had an AML, 62.7% underwent HSCT, with no statistical differences in baseline characteristics between groups. We collected data from 413 total episodes of neutropenia with a median duration of 15 days (IQR 9-25), and a total of 275 FN events. Overall, microbiologically documented infections (MDI) accounted for 34.6% of FN, 33.0% in Phase1, 35.5% in Phase2 (p.0194). Inside the CDI, pulmonary involvement was the most frequent (38.5%), followed by abdominal implication (30.8%) Among 116 Phase2 patients, 51.7% tested positive for FQR-E, of them, 30.2% had initial screening negative then positive, with a median time of positivization of 35 days (IQR 9-112) and 26.7% with a initial screening positive; 36.6% tested positive for 3GCR-E where 12.9% had initial screening negative then positive with a median time of positivization of 68 day (IQR 21-133), while 26.7% had initial screening positive. In Phase2 we found a reduced quinolone use (27.16 vs. 18.74 DDD/100 PD, p=0.004) without a significant increase in carbapenem use (7.90 vs. 8.98/100PD, p=0.150), All patients (100%) in Phase2 underwent rectal screening, adherence to EAT protocols reached 95.6% while adherence to prophylaxis discontinuation was 69.9%. Finally, no difference in secondary outcomes between two groups were observed: 30-day mortality accounted for 9.4% in Phase1 and 1.7% in Phase 2 (p=0.263) while ICU admission were 7.1% in Phase1 and 6.9% in Phase2 (p=0.964). We also found a 100% of concordance between colonizing microorganism and those found in blood culture for 8 bloodstream infection in colonized Phase2 patients, all except one undergoing effective EAT according to internal protocol. Conclusions With our intervention, we obtained a reduction in the use of quinolones without a significant increase in carbapenems use in a setting with high-prevalence for FQR-E and 3GCR-E. Adherence to screening protocol and EAT was optimal, while reinforcement is needed to improve prophylaxis discontinuation. A lack of statistically significant between secondary outcomes shows a non-negative clinic impact of our intervention.