Communicating Microbiology Results. It’s Not Just What You Say, But How You Say It

Background Gaps in microbiology communication can lead to suboptimal antibiotic prescribing. In May 2016, our laboratory modified reporting of respiratory cultures growing commensal flora only to specify “no methicillin-resistant Staphylococcus aureus/MRSA or Pseudomonas aeruginosa” (PA). The purpose of this study was to compare MRSA and PA antibiotic therapy utilization before and after the change. Methods IRB approved, quasi-experiment at four hospitals with an antimicrobial stewardship program. Dates: August 1, 2015–January 31, 2016 and August 1, 2016–January 31, 2017. Included: ≥18 years, commensal flora only respiratory culture, empiric MRSA and PA antibiotic for treatment of lower respiratory infection. Excluded: non-respiratory infection. Primary outcome: MRSA or PA therapy de-escalated. Secondary outcomes: time to culture result, MRSA and PA antibiotic days of therapy, length of stay. Safety outcomes: acute kidney injury (AKI), C. difficile (CDI), subsequent multi-drug-resistant organism (MDRO), in-hospital all-cause mortality. Results Two hundred and ten patients included, 105 per group. Median age 64 and 61 years, male sex 52% and 56% in pre- and post-group, respectively. Empiric antibiotics, pre vs. post: vancomycin 94% vs. 95%; cefepime 66% vs. 36%; piperacillin–tazobactam 10% vs. 46%. MRSA or PA antibiotics de-escalated: 39% pre and 73% post (P < 0.001). See Table 1 for variables associated with antibiotic de-escalation. Days of therapy: 7 vs. 5 days (P < 0.001). AKI 31% vs. 14% (P = 0.003). Eight subsequent MDRO in pre and one in post (P = 0.035). No differences: time to culture result, length of stay, mortality, CDI. Conclusion Improved microbiology communication to assist prescriber interpretation of commensal respiratory flora was associated with a reduction in the proportion of patients that received antibiotics targeting MRSA and PA. Table 1. Antibiotic de-escalation No antibiotic de-escalation Unadjusted 
OR [CI] Adjusted 
OR [CI] No MRSA, no PA comment 77 (65%) 28 (30%) 5.0 [2.5–10.0] 5.7 [2.9–11.0] Charlson Comorbidity Index < 3 42 (36%) 60 (65%) 3.4 [1.9–6.0] 3.0 [1.6–5.7] APACHE II ≤15 45 (39%) 56 (61%) 2.5 [1.4–4.4] 2.7 [1.4–5.3] Long-term care 14 (12%) 9 (10%) 0.8 [0.3–2.0] 0.4 [0.1–1.0] ≥2 SIRS criteria 52 (44%) 53 (58%) 1.7 [1.0–3.0] – Previous antibiotics 57 (48%) 40 (44%) 0.8 [0.5–1.4] – Hospitalization >48 hours 51 (43%) 39 (42%) 1.0 [0.6–1.7] – Disclosures S. Davis, Merck: Received grant through college that I’m faculty for, Grant recipient; Allergan: Speaker’s Bureau, Consulting fee; Allergan: Consultant and Scientific Advisor, Consulting fee; Medicines Company: Consultant and Scientific Advisor, Consulting fee; Zavante: Consultant and Scientific Advisor, Consulting fee.