Abstract
BackgroundThere are growing concerns regarding the spread of carbapenemase-producing organisms (CPOs) among patients in long-term care facilities (LTCFs) and hospitals in South Korea. We have established a screening protocol for the detection of CPOs in high-risk patients upon admission to intensive care units (ICUs). The diagnostic performance of the Xpert Carba-R assay was compared to that of rectal culture for CPO detection in high-risk patients upon ICU admission.MethodsA total of 408 consecutive rectal swabs were obtained from December 2016 to December 2017. CPO screening was performed using the Xpert Carba-R assay (Cepheid, Sunnyvale, CA, USA). When a carbapenemase gene was detected, additional rectal swabs were incubated overnight and inoculated on chromID CARBA medium (bioMérieux, Marcy l’Etoile, France). Bacterial carbapenemase genes, including blaKPC, blaNDM, blaVIM, blaIMP-1, and blaOXA-48, were confirmed by conventional PCR. The diagnostic performance of the Carba-R assay was ascertained based on the culture results.ResultsThe prevalence of CPO carriage was 7.4% according to the Carba-R assay and 3.7% according to rectal culture. The median Ct values of IMP-1 and KPC were significantly different (35.2 vs. 26.6, P = 0.0143). The overall sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the Carba-R assay were 100.0% (95% confidence interval [CI], 78.2–100.0), 96.7% (94.4–98.2), 53.6% (40.4–66.4) and 100.0% (99.0–100.0), respectively.ConclusionsWe demonstrated the prevalence of CPO carriage in high-risk patients upon ICU admission and evaluated the diagnostic performance of the Carba-R assay. The combined use of the Xpert Carba-R assay and culture produces rapid and reliable results for the active surveillance of rectal CPO in ICU patients.
Highlights
There are growing concerns regarding the spread of carbapenemase-producing organisms (CPOs) among patients in long-term care facilities (LTCFs) and hospitals in South Korea
Evaluation of the limit of detection (LoD) for the Carba-R assay and carbapenem-resistant Enterobacteriaceae (CRE) culture The highest threshold cycle (Ct) values measured for the five carbapenemase-producing Enterobacteriaceae (CPE) isolates were 36.5, 37.7, 32.2, 36.9 and 37.0 for the detection of blaKPC, blaNDM, blaVIM, blaIMP-1 and blaOXA-48, respectively, corresponding to 225, 22.5, 2,250, 225 and 225 Colony forming unit (CFU)/swab
Prevalence of rectal CPO carriage A total of 408 rectal swabs were analyzed during the study period
Summary
There are growing concerns regarding the spread of carbapenemase-producing organisms (CPOs) among patients in long-term care facilities (LTCFs) and hospitals in South Korea. We have established a screening protocol for the detection of CPOs in high-risk patients upon admission to intensive care units (ICUs). The diagnostic performance of the Xpert Carba-R assay was compared to that of rectal culture for CPO detection in high-risk patients upon ICU admission. In South Korea, high rates of carbapenem resistance among glucose nonfermenting gram-negative bacilli (CR-NF) and the increased prevalence of CRE have become serious problems in hospitalized patients [5, 6]. We have established a screening protocol for detecting CPOs in high-risk patients upon admission to intensive care units (ICUs) using real-time PCR and rectal culture (Fig. 1).
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