Xpert carba R assay for carbapenem resistant gram-negative bacterial blood culture isolates: An experience at a tertiary care hospital

• Author Details:   
• Prasanna N Bhat ^*
• Kavitha Prabhu
• Anup Kumar Shetty
• Ganesh Nayak S

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Background: Carbapenem resistant blood stream infections are a serious threat to provision of effective and affordable healthcare to the patients. It is important to determine the mechanism of the resistance, so that the appropriate treatment can be provided to the patient. The study aims to evaluate the blood stream infections caused by the carbapenem resistant Gram-negative bacteria which were tested by Xpert Carba R assay.

Materials and Methods: Isolates of Gram-negative bacteria from blood culture of the patients, which had been tested by the Xpert Carba R assay, were included in the study after ethical clearance from the institute ethics committee. The clinical details and the laboratory parameters of the patients were collected from the electronic case records. Statistical analysis was done using SPSS version 23.

Results: Forty-nine isolates were included in the study. The assay was negative for 14.3% (7/49) patients. The common genes detected were blaNDM, 67.3% (33/49) and blaOXA-48, 36.7% (18/49). These genes co-occurred in 20.4% (10/49) patients. The crude mortality rate was the least due to the pathogens with the blaNDM, whilst it was highest for the pathogens with blaNDM + blaOXA-48, though not statistically significant.

Conclusions: The Xpert Carba R assay is useful for the carbapenemase gene detection among the Enterobacterales. The blaNDM gene is the commonest gene detected in the study, blaNDM + blaOXA-48 co-occurrence is common. The Xpert Carba R assay should be used cautiously for the carbapenem resistant Acinetobacter infections, which has higher crude mortality in the study.