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Real-time PCR threshold cycle (Ct) cut-offs help to identify agents causing acute childhood diarrhea in Zanzibar


Journal of Clinical Microbiology

Category: Publications

Author: Kristina Elfvinga, Maria Andersson, Mwinyi I. Msellem, Christina Welinder-Olsson, Max Petzold, Anders Bjrkman, Birger Trollfors, Andreas Mrtensson and Magnus Lindha

Published Date: 08 January 2014


Molecular assays might improve identification of causes of acute diarrheal disease, but may lead to more frequent detection of asymptomatic infections.

In the present study real-time PCR targeting 14 pathogens was applied on rectal swabs from 330 children aged 2-59 months in Zanzibar, 165 with acute diarrhea and 165 asymptomatic controls.

At least one pathogen was detected in 94% of patients and 84% of controls, with higher rates in patients for norovirus genogroup II (20% vs. 2.4%, p<0.0001), rotavirus (10% vs. 1.8%, p=0.003) andCryptosporidium (30% vs. 11%, p<0.0001). Detection rates did not differ significantly for enterotoxigenic Escherichia coli (ETEC)-estA (33% vs. 24%), ETEC-eltB (44% vs. 46%), Shigella (35% vs. 33%), and Campylobacter (35% vs. 33%), but for these agents Ct (threshold cycle) values were lower (pathogen loads were higher) in sick children than in controls.

In multivariate analysis, Ct values for norovirus genogroup II, rotavirus, Cryptosporidium, ETEC-estA and Shigella were independently associated with diarrhea. We conclude that this real-time PCR allows convenient detection of essentially all diarrheagenic agents, and provides Ct values that may be critical for interpretation of results for pathogens with similar detection rates in patients and controls.

The results indicate that assessment of pathogen load may improve identification of agents causing gastroenteritis in children.


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