Rectal swabs can be used for diagnosis of viral gastroenteritis with a multiple real-time PCR assay

Background: Viral agents, especially norovirus, are the most common cause of nosocomial spread of epidemic gastroenteritis (GE). Rapid and reliable detection of these agents could reduce the risk of outbreaks.

Objective: To evaluate the diagnostic performance of rectal swab samples compared to standard stool samples for detection of agents causing viral GE by PCR.

Study design: Complete pairs of rectal swab and stool samples, obtained simultaneously from patients with symptoms of acute onset GE, were analysed with a multiple real-time PCR targeting six different gastroenteritis agents (astro-, adeno-, rota-, sapo- and norovirus GI and II). Cycle threshold (Ct) values were registered for positive samples. A positive PCR result in either sample for any virus was considered gold standard.

Results: 69 sample pairs were included of which 29 were negative in both sample types and 38 were positive in both sample types. One pair was positive in the stool sample only and another pair was positive in the rectal swab sample only. Sensitivity for both sample types was 97.5% (39/40).

Conclusion: Rectal swab samples are as reliable as stool samples for PCR-based diagnosis of viral gastroenteritis in patients with a short duration of symptoms and may be used as a complement to stool samples, especially when immediate sampling is desirable.