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.

Norovirus

“…Norovirus was detected in stool samples during 13 of 54 (36%) severe diarrhea events in 49 kidney transplant recipients, with receipt of cyclosporine together with mycophenylate being a risk factor (62). It was associated with a mean weight loss of 3.0 kg, which was significantly greater than the weight loss associated with other causes of diarrhea.…”

Multicenter Evaluation of the BD Max Enteric Bacterial Panel PCR Assay for Rapid Detection of Salmonella spp., Shigella spp., Campylobacter spp. (C. jejuni and C. coli), and Shiga Toxin 1 and 2 Genes

“…by the ProGastro SSCS PCR and negative by culture were not confirmed by an alternate PCR method (9). Buss et al noted 5/24 (21%) samples false positive for Campylobacter by FilmArray that were not confirmed by alternate PCR, and Coste reported confirming 9/15 (60%) false-positive results by using an alternate PCR and EIA methods (23,29). False-positive results could also be due to crossreactivity of primers and probes with other targets.…”

“…Not only are these assays more sensitive than routine culture and EIA methods, they are also more likely to detect coinfections, as evidenced in this evaluation and others (6,10,21). However, multiplex assays that report bacterial, viral, and parasitic targets simultaneously may generate results that were not requested by clinicians and create complexities in reporting as well as in interpretation (17,29,30). For example, detection of Clostridium difficile in colonized individuals who actually harbor an agent of acute bacterial enteritis may lead to overtreatment for this pathogen.…”

Chronic Diarrhea Secondary to Human Sapovirus in a Renal Transplant Recipient

“…Although less frequently observed causes of diarrhea in solid organ transplantation than bacterial causes, both sapovirus and norovirus should be considered in patients who develop chronic diarrhea following transplantation. Of the up to 45% of post-kidney transplant recipients who report chronic diarrhea, norovirus has been found to be the cause of 17-26% of these cases [8,9]. Chronic infection with sapovirus has only been reported in one retrospective cohort study, though the presentation and effects are very similar to those of norovirus [9].…”

“…Colonoscopy is often nondiagnostic in these patients, thus norovirus/sapovirus screening should be performed prior to endoscopic evaluation in patients with chronic diarrhea, after bacterial and parasitic infections have been ruled out [9]. Recently, screening methods for norovirus using PCR have been developed, and diagnostic PCR techniques have shown to be superior to previous culture methods to screen for bacteria, parasites, and also viruses including norovirus [8,12]. These PCR studies, however, are not readily available.…”