Microbiological diagnosis of severe diarrhea in kidney transplant recipients by use of multiplex PCR assays

Abstract

Diarrhea is a frequent complication after kidney transplantation, ascribed to adverse effects of the immunosuppressive therapy in case of negative microbiological examination of the stools. The aim of this study was to improve the microbiological diagnosis by implementing molecular tests. Fifty-four severe diarrhea events that occurred in 49 adult kidney transplant recipients from September 2010 to November 2011 were investigated. One or several enteric pathogens were detected in 13 (23%) stool samples using classical microbiological methods versus 39 (72%) for the seven commercially available multiplex PCR assays used retrospectively (P = 0.006). Interestingly, molecular diagnosis identified 15 multiple infections compared to none using classical techniques. The primary pathogens detected were enteropathogenic Escherichia coli (EPEC) (n = 15; 38%), Campylobacter spp. (n = 15; 38%), and Norovirus (n = 14; 36%). Specificities for Campylobacter and Norovirus infection diagnosis were 75 and 100%, respectively, by comparison to reference methods. Based on molecular findings, a cyclosporine-mycophenolate mofetil combination was identified as a risk factor for developing Norovirus-induced diarrhea. Norovirus infections were also responsible for higher weight loss than all the other causes of diarrhea. In samples from asymptomatic immunocompromised and immunocompetent patients, EPEC but not Norovirus and Campylobacter infections were detected at a frequency similar to that observed in symptomatic kidney transplant recipients. In conclusion, molecular tools significantly improved the detection of single and multiple enteric infections by comparison to classical techniques and could quickly become the key element in the management of severe acute diarrhea in transplant recipients.

Fig 1

Monthly distribution of samples collected during the 15-month study and seasonal pattern of circulation of enteric pathogens detected by molecular tools from September 2010 to November 2011. Bacterial, parasitic, and viral etiologies are shown. The black line indicates the number of samples collected each month.

Fig 2

Comparison of enteric pathogens detection in adult kidney transplant recipients by classical microbiological techniques and the multiplex PCR assays.

Fig 3

Microbiological findings obtained from the molecular analyses of the three control groups. (A) Transplant patients (n = 30) sampled 6 months after resolution of severe diarrhea. (B) Renal transplant recipients (n = 30) with no history of diarrhea. (C) Immunocompetent patients without diarrheal symptoms (n = 30).