Experiences from multiplex PCR diagnostics of faeces in hospitalised patients: clinical significance of Enteropathogenic Escherichia coli (EPEC) and culture negative campylobacter

Abstract

Background In hospitalised patients with diarrhoea a positive campylobacter stool Polymerase Chain Reaction (PCR) test with negative culture results as well as Enteropathogenic Escherichia coli (EPEC) positive stool PCRs, challenges the clinician and may lead the unexperienced clinician astray. The aim of the study was to elucidate the clinical significance of positive Campylobacter and/or EPEC test results in hospitalised patients with diarrhoea. Methods We conducted a retrospective case-case study. Case groups with 1) EPEC only and 2) EPEC in combination with any other pathogen in the PCR multiplex array, 3) PCR positive/culture negative Campylobacter, and 4) PCR positive/culture positive Campylobacter were compared. Medical records were reviewed and cases classified according to pre-specified clinical criteria as infectious gastroenteritis or non-infectious causes for diarrhoea. We analyzed the association between laboratory findings (the 4 subgroups) and the pre-specified clinical classification. We further sequenced culture negative campylobacter samples and tested EPEC for bundle forming pilus A (bfpA) gene, distinguishing typical from atypical EPEC. Results A total of 291 patients were included, 169 were PCR positive for Campylobacter and 122 for EPEC. For both pathogens, co-infections were more common in culture negative/PCR positive samples than in culture positive samples. Clinical characteristics differed significantly in and between groups. Campylobacter culture positive patients had very high prevalence of characteristics of acute infectious gastroenteritis, whereas patients with PCR positive test results only often had an alternative explanation for their diarrhoea. Culture positives were almost exclusively C. jejuni/coli , whereas in culture negatives, constituting a third of the total PCR positives, C. concisus was the most frequent species. The vast majority of EPEC only positives had documented non-infectious factors that could explain diarrhoea. The EPEC co-infected group mimicked the culture positive campylobacter group, with most patients fulfilling the infectious gastroenteritis criteria. Conclusions In hospitalised patients, positive PCR results for campylobacter and EPEC should be interpreted in a clinical context after evaluation of non-infectious diarrhoea associated conditions, and cannot be used as a stand-alone diagnostic tool.

Epidemiology of gastrointestinal infections: lessons learned from syndromic testing, Region Zealand, Denmark

“…The QIAstat-Dx® Gastrointestinal Panel detects the eae gene and reports positive samples as EPEC positive. In developed countries, such as Denmark, the clinical importance of EPEC in older children and adults is uncertain [ 23 ]. For this reason, we analyzed EPEC data < 2 years and ≥ 2 years of age.…”

Pathophysiology of enteropathogenic Escherichia coli during a host infection

“…In Norway, for example, EPEC is one of the most common pathogens founded in stools of hospitalised patients with diarrhea. A total of 122 EPEC were isolated from diarrheal stools in a Norway university hospital during 2013–2015 [ 18 ]. In Finland, EPEC caused an outbreak of diarrhea in 237 human patients due to consumption of contaminated salads in 2016 [ 4 ].…”

Risk factors and clinical outcomes associated with multiple as opposed to single pathogens detected on the gastrointestinal disease polymerase chain reaction assay

“…These questions can be particularly difficult to answer among patients with altered immune function which can lead to gut dysbiosis and increase susceptibility to gut pathogen colonization. 5 Despite wide application of the GI PCR, few studies have characterized the prevalence and types of organisms present among multiply-positive patients or have examined the clinical significance of multiple as opposed to single enteric pathogens.…”

“…An alternative hypothesis is that the detection of multiple pathogens usually represents colonization, and that such patients fare similarly to those with just one pathogen present. 1,5,19 By examining outcomes in those with multiple as opposed to single pathogens on GI PCR, we aimed to inform the clinical question of infection versus colonization. The overarching goal of the study was to guide future GI PCR testing decisions and to better interpret results when patients test positive for multiple enteric pathogens.…”