2153. Clinical Impact of Addition of Oropharynx MRSA PCR to Anterior Nares MRSA PCR for Patients Admitted with Pneumonia

BACKGROUND: Anterior nares (AN) MRSA PCR can help identify MRSA colonization as a risk factor for MRSA pneumonia and can be especially useful, given high NPV, in making treatment decisions when lower respiratory tract (LRT) cultures are lacking. Oropharynx (OP) MRSA carriage without AN colonization can occur suggesting the potential benefit of duel site screening, but doubles resource utilization. We evaluated concordance between the AN and OP sites and whether the addition of OP MRSA PCR testing provides clinical benefit. METHODS: MRSA PCR was performed using Xpert SA Nasal Complete (Cepheid; FDA-cleared and modified). Results were retrieved from January 2017 to July 2018 for adult in-patients who received both AN and OP testing within the same calendar day. Medical charts were reviewed for a clinical course, respiratory culture results, and effect of discordant PCR results. RESULTS: AN and OP MRSA PCRs were performed on 1,419 adult inpatients, concordance was 96.5% (n = 1370, see Table). In 38 of 49 discordant cases, PCR was used to evaluate the etiology of pneumonia. Of those, 22 (58%) had LRT culture results available within 48 h to direct therapy. We further evaluated the value of OP PCR by focusing on AN-/OP+ (n = 22) discordant results, of which 16 were used to evaluate pneumonia. LRT culture results were available in 7 (44%) of these cases. Three had isolation of MRSA; however, the remaining 4 were culture-negative but still received vancomycin for an average of 5 days. Of the 9 that were AN−, OP+, and without culture results, only 4 had clinical signs and symptoms consistent with MRSA pneumonia. OP MRSA PCR is $303. CONCLUSION: OP and AN MRSA PCR screening are highly concordant in patients with pneumonia. 355 AN/OP PCRs (4/1419), at > $100,000 in additional healthcare costs, were needed to detect one potentially missed MRSA pneumonia compared with AN PCR only approach. Our results suggest addition of OP MRSA PCR: (1) has limited clinical utility for pneumonia evaluation as it is unlikely to be discordant with AN testing, which will not significantly alter the very high NPV and when discordant (AN-/OP+) has a <50% PPV, (2) is unlikely to be cost-effective, and (3) has unintended consequences such as overuse of MRSA therapy. Additionally, there is an opportunity to improve PCR ordering to include only those situations in which LRT cultures are lacking. [Image: see text] DISCLOSURES: Alexander Lepak, MD, Paratek Pharmaceuticals: Research Grant; Tetraphase Pharmaceuticals: Research Grant.