Comparison of the Clinical Outcomes of Patients With Positive Xpert Carba-R Tests for Carbapenemase-Producing Enterobacterales According to Culture Positivity

Background: We aimed to compare the clinical outcomes of patients with positive Xpert Carba-R assay results for carbapenemase-producing Enterobacterales (CPE) according to CPE culture positivity.

Methods: We retrospectively collected data for patients with positive CPE (positive Xpert Carba-R or culture) who underwent both tests from August 2018 to March 2021 in a 2700-bed tertiary referral hospital in Seoul, South Korea. We compared the clinical outcomes of patients positive for Xpert Carba-R according to whether they were positive (XPCP) or negative (XPCN) for CPE culture.

Results: Of 322 patients with CPE who underwent both Xpert Carba-R and culture, 313 (97%) were positive for Xpert Carba-R for CPE. Of these, 87 (28%) were XPCN, and 226 (72%) were XPCP. XPCN patients were less likely to have a history of previous antibiotic use (75.9% vs 90.3%; P = .001) and to have Klebsiella pneumoniae carbapenemase (21.8% vs 48.9%; P < .001). None of the XPCN patients developed infection from colonization within 6 months, whereas 13.4% (29/216) of the XPCP patients did (P < .001). XPCN patients had lower transmission rates than XPCP patients (3.0% [9/305] vs 6.3% [37/592]; P = .03). There was no significant difference in CPE clearance from positive culture results between XPCN and XPCP patients (40.0% [8/20] vs 26.7% [55/206]; P = .21).

Conclusions: Our study suggests that XPCN patients had lower rates of both infection and transmission than XPCP patients. The Xpert Carba-R assay is clinically useful not only for rapid identification of CPE but also for predicting risks of infection and transmission when performed along with culture.