Renal transplant patients with Nocardia infection at increased risk of graft failure
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A retrospective cohort study published in the Journal of Investigative Medicine showed 0.32% of renal transplant patients had Nocardia infection and that patients with this infection were at an increased risk for graft failure.
In addition, researchers found administration of antithymocyte globulin and presentation of Nocardia infection with brain abscess were associated with an increased risk of graft failure in patients.
“Our investigation confirms that older age, transplantation of deceased donor kidney, and/or therapy with tacrolimus, corticosteroids, and thymoglobulin are associated with increased risk of infection,” Stephanie L. Baer, MD, and colleagues, wrote in the study. “The cohort of patients who were diagnosed with Nocardia infection showed a higher percentage of graft failure at any time and, in addition, had more previous diagnoses of kidney rejection when compared with transplant patients without Nocardia diagnosis.”
Using the United States Renal Data System, researchers examined findings between 2001 and 2011 for 203,233 patients with end-stage renal disease. To determine the risk factors associated with Nocardia infection, researchers used a generalized linear model incorporating person-years at risk and measured the OR for Nocardia infection. They used a Cox proportional hazards analysis to investigate the effect of various demographic, transplant-related or clinical risk factor variables when assessing the time from transplant to graft failure. Researchers used a subcohort to study the association between Nocardia infection and the risk of graft failure within 183 days to account for appropriate follow-up after transplant.
Of the total patients with ESRD, 657 (0.32%) were diagnosed with Nocardia infection, 552 of which were assessed after study exclusions. The most frequent presentations of Nocardia infection were pneumonia (14.13%), followed by brain abscess (7.79%).
Increased risk factors for Nocardia infection were age 65 years and older at initial transplant (OR=2.10), history of transplant failure (OR=1.28), history of transplant rejection (OR=4.83) and receipt of a transplant from a deceased donor (OR=1.23). For immunosuppressant drug therapies using tacrolimus and thymoglobulin, the ORs for infection were 2.45 and 1.89, respectively.
Patients at lower risk for Nocardia infection had received azathioprine (OR=0.73) or sirolimus (OR=0.65), were diagnosed with COPD (OR=0.78), diabetes (OR=0.86) or hepatitis C (OR=0.56), or used tobacco (OR=0.74), according to the study.
“The risk factors found to be associated with a diagnosis of Nocardia infection were expected, such as age, history of transplant failure or rejection, receipt of a deceased donor transplant, or receipt of specific immunosuppressant medications,” Baer told Healio Nephrology. “We hypothesized that due to some of the known side effects of the treatment regimens for Nocardia, there would be associated sequelae of allograft loss, which we did confirm. The incidence of infection of 0.32% was lower than previously reported, most likely due to the strict definition we used to identify the cases.”
According to the researchers, nearly 16% of patients with Nocardia experienced graft failure. Patients with a diagnosis of Nocardia infection showed a higher percentage of graft failure at any time (67.28%) compared with those without Nocardia (42.75%). Further, 60.58% of patients with a history of kidney transplants had Nocardia compared with 27.25% without the infection. Factors significantly associated with graft failure included antithymocyte globulin (HR=2.76), COPD (HR=2.47) and presentation of Nocardia infection with brain abscess (HR=1.85).
“The results from this data set provide evidence that encourages clinicians to suspect Nocardia infection, particularly in the presence of certain risk factors, in the assessment
of pneumonia or brain abscesses in renal transplant patients,” Baer and colleagues wrote. “However, additional studies are required to further evaluate the timing of infection after renal transplant and to identify appropriate prophylaxis regimens to prevent nocardiosis and/or transplant failure after infection.”
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