Diagnostic performance of the Xpert Carba-R assay for active surveillance of rectal carbapenemase-producing organisms in intensive care unit patients | Antimicrobial Resistance & Infection Control | Full Text

Diagnostic performance of the Xpert Carba-R assay for active surveillance of rectal carbapenemase-producing organisms in intensive care unit patients | Antimicrobial Resistance & Infection Control | Full Text

Antimicrobial Resistance & Infection Control

Diagnostic performance of the Xpert Carba-R assay for active surveillance of rectal carbapenemase-producing organisms in intensive care unit patients

• Young Jin Ko, 
• Jeeyong Kim, 
• Ha-Nui Kim, 
• Soo-Young Yoon, 
• Chae Seung Lim & 
• Chang Kyu Lee 

Antimicrobial Resistance & Infection Controlvolume 8, Article number: 127 (2019) | Download Citation

Abstract

Background

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.

Methods

A 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.

Results

The 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.

Conclusions

We 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.