Association Between Types of Carbapenemase and Clinical Outcomes of Infection Due to Carbapenem Resistance Enterobacterales

Purpose: Compared with non-carbapenemase producing carbapenem-resistant Enterobacterales (non-CP-CRE), carbapenemaseproducing carbapenem-resistant Enterobacterales (CP-CRE) are associated with considerable mortality. However, given that the patients are treated with various therapeutic options, it remains unclear whether differences in types of carbapenemase genes yield different mortality rates. Therefore, this study aims to identify carbapenemase genes and identify whether clinical outcomes differ according to the prevalence of genotype and phenotype of carbapenemase among Enterobacterales clinical isolated. Patients and Methods: A retrospective cohort study was performed to determine whether types of carbapenemase genes have an impact on clinical outcomes. Carbapenem-resistant clinical isolates were collected at a tertiary care university hospital in Songkhla, Thailand, between June 2018 and February 2020. Demographic and microbiological data such as antimicrobial susceptibility, carbapenemase genes, and overall mortality were evaluated. Results: A total of 121 Enterobacterales clinical isolated were evaluated. The blaNDM-1 gene was detected in 44% of the isolates, followed by blaOXA-48 (28%) and blaNDM-1/OXA-48 (28%). NDM-1- or NDM-1/OXA-48- producing isolates were more likely to require meropenem MICs of >= 16 mg/L, while OXA-48-producing isolates were more likely to require meropenem MICs of <16 mg/L. The patients with NDM-1 or NDM-1/OXA-48 had a higher 14 days mortality rate than those with OXA-48 after treating with carbapenem-containing regimens (P-value 0.001) or colistin-containing regimens (P-value < 0.001). Conclusion: Our findings suggest that the mortality for CP-CRE infection in patients with NDM-1 or NDM-1/OXA-48 was higher than the mortality in those with OXA-48, which It seems that the type of carbapenemase gene may affect meropenem MIC levels. Hence, in treatment decisions involving the use of either carbapenem-containing regiment or colistin-containing regiment in patients with CP-CRE infection, especially those in the NDM-1 and NDM-1/OXA-48 groups, the patient symptoms should be closely monitored.

Automated summary

This study aimed to investigate the impact of carbapenemase gene types on clinical outcomes of carbapenem-resistant Enterobacterales (CRE) infection. The results showed that patients infected with NDM-1 or NDM-1/OXA-48 had a higher mortality rate compared to those infected with OXA-48, and the type of carbapenemase gene may affect the minimum inhibitory concentration (MIC) of meropenem. Therefore, close monitoring of patient symptoms is necessary when deciding on treatment options, especially in the NDM-1 and NDM-1/OXA-48 groups, for CRE infection.