Validation of Rectal Swab Specimens for Sensitive and Specific Carbapenemase Gene Detection in Pediatric Patients.

BACKGROUND

To reduce the spread of carbapenem-resistant gram-negative bacteria, the Centers for Disease Control recommends rectal and perirectal swab surveillance using the Cepheid Xpert® Carba-R Assay. An expressed limitation of the assay is lack of validation data for patients <21 years. To address this limitation, an in-house validation was performed using pediatric stool specimens from patients <21 years.

METHODS

Pediatric validation of the Cepheid Copan Dual Swab Collection Device and Xpert® Carba-R Assay was performed using pooled stool specimens from 17 patients ages <1 to 21 years, spiked with Escherichia coli, Acinetobacter baumannii, Klebsiella pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa harboring β-lactamase mechanisms (Klebsiella pneumoniae carbapenemase, New Delhi metallo-β-lactamase, oxacillinase-48-like carbapenemase, Verona integron-encoded metallo-β-lactamase, and imipenemase). Validation was supported by molecular and culture analysis of 747 pediatric clinical specimens.

RESULTS

Pediatric stool-spiked rectal swabs produced Cepheid Carba-R results with 100% accuracy (SD < 1; CV < 4%) and excellent precision (SD < 1, CV < 4%). Clinical carbapenemase surveillance of >24 000 rectal specimens screened by the Carba-R assay (2018-2024) showed lower carbapenemase-detected percent positivity in patients ages 0 to 20 years (3.0%-4.2%) compared with adults ages 21 to >65 (7.8%-12.7%) (χ2, P < 0.00001). No significant age-group differences were observed in the ability to isolate detected β-lactamase mechanisms from patient specimens.

CONCLUSION

The Cepheid Copan Dual Swab Collection Device with the Xpert® Carba-R Assay is a valid method for rapid (<1 h) screening of carbapenemase-producing organisms (β-lactamase mechanisms: Klebsiella pneumoniae carbapenemase, New Delhi metallo-β-lactamase, oxacillinase-48-like carbapenemase, Verona integron-encoded metallo-β-lactamase, and imipenemase) in pediatric patients.