Background:
Enterococci are the third most common cause of healthcare-associated infections in the United States, affecting 10-12% of all transplant recipients worldwide. Approximately 46% of patients with acute myeloid leukemia (AML) were found to be colonized with Enterococcus [1]. The risk of infection and its complications increases in patients treated with hematopoietic stem cell transplantation (HSCT). Given the high rates of Enterococcus colonization, we aimed to study the impact of Enterococcus infection in AML patients treated with HSCT.
Methods:
We conducted a retrospective analysis using the National Inpatient Sample Database (2018-2021). Adults over the age of 18 who were treated with HSCT for AML and had Enterococcus infections were identified using ICD-10 codes [2]. We performed the analysis using descriptive statistics and multivariate regression, with a p-value of less than 0.05 considered significant.
Results:
Of 40,462 HSCT patients, 1.3% (n=531) were admitted with Enterococcus infection. Among the HSCT recipients, Enterococcus infection was seen in 344 (1.4%) of 23,930 patients with all forms of Leukemia and in 134 (2.4%) of 5,693 patients with AML. There were no significant differences in sociodemographic factors such as age over 60 years, gender, or race between those with and without Enterococcus infection in the AML population (p>0.5). The AML-Enterococcus cohort had longer hospital stays (20.8 vs. 9.5 days, p<0.001) and higher total costs as compared to the AML-non-Enterococcus cohort ($373,619 vs. $147,075, p<0.001). Additionally, the AML-Enterococcus cohort had a higher prevalence of urinary tract infections (28.4% vs. 5.2%, p<0.001), fungal infections (13.4% vs. 8.6%, p<0.05), and acute respiratory failure (26.1% vs. 15.5%, p<0.001). Enterococcus infection was more common among patients with bone marrow dysfunction such as neutropenia (33.6% vs. 20.9%, p<0.001), anemia (79.9% vs. 57.6%, p<0.001), and pancytopenia (61.9% vs. 42.7%, p<0.001). Enterococcus infection also was associated with higher rates of severe sepsis (22.4% vs. 9.4%, p<0.001) and vasopressor usage (6.7% vs. 3%, p<0.05). Crude analysis indicated a higher mortality rate in the AML-Enterococcus cohort compared to the AML-non-Enterococcus cohort (16.1% vs. 8.8%, p<0.05). However, after adjusting for confounders, the mortality risk between the two cohorts was not significantly different (adjusted odds ratio 0.9, 95% CI 0.4-1.7, p>0.05). Similarly, the utilization of palliative care services did not differ between the two cohorts (12.7% vs. 9.8%, p>0.05).
Conclusion:
Enterococcus infection in the AML population who undergo HSCT poses a significant healthcare burden, resulting in longer hospital stays and higher healthcare costs. Patients with bone marrow dysfunction are at increased risk of Enterococcus infection and other opportunistic infections. For AML patients who have previously undergone transplantation and are hospitalized for sepsis, urinary tract infection, or respiratory failure, aggressive treatment with broad-spectrum antibiotics for Enterococcus is necessary. Due to the high crude mortality rate, it is essential to provide multidisciplinary care to reduce hemodynamic compromise and the potential need for vasopressor usage in these patients. It is important to consider Enterococcus as a differential diagnosis for any AML patient with HSCT presenting with a urinary tract infection or respiratory failure. Early recognition and treatment of Enterococcus infection could prevent lengthy hospital stays and reduce costs.
References:
Scheich S, Lindner S, Koenig R, et al.: Clinical impact of colonization with multidrug-resistant organisms on outcome after allogeneic stem cell transplantation in patients with acute myeloid leukemia. Cancer. 2018, 124:286-96. 10.1002/cncr.31045
2021 ICD-10-CM. Accessed: July 14, 2024. https://www.cms.gov/medicare/coding-billing/icd-10-codes/2021-icd-10-cm.
No relevant conflicts of interest to declare.
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