Diagnosis of enteric pathogens in children with gastroenteritis

The aim of this study was to determine the isolation trends of common and e merging pathogens in children over a 12-month period. The study group inclu ded 412 children under 6 years with diarrhoea who were either hospitalised, or seen in the outpatients department of The Sydney Children's Hospital. P athogens were detected in 137 (33%) samples, with rotavirus most common (40 %), followed by adenovirus (26%), astrovirus (12%), Campylobacter jejuni (1 2%), Salmonella spp. (10%) and Giardia lamblia (< 1%). Giardia-specific ant igen (GSA) was detected in 11 of 382 (3%) using an enzyme immunoassay (EIA) , and this included four samples in which cysts of G. lamblia were detected by microscopy. Using electron microscopy (EM), viruses were detected in 29 of 120 (24%) samples from hospitalised children and 53 of 171 (31%) outpat ients (P = 0.23). Amongst this subset, Norwalk-like viruses (NLVs) were det ected by RT-PCR in 10 samples including six of 14 with small round viruses, one of seven with small viral-like particles (SVLPs), and three of 126 EM- negative samples. Lactoferrin, detected by EIA, was 59% more likely to be p ositive in samples infected with salmonella/ campylobacter than in samples in which bacterial pathogens were not isolated. As an indicator for infecti on with these bacterial agents, the assay showed a sensitivity and specific ity of 95 and 40.3%, respectively. A routine microbiological analysis of st ools from children of this age group should include a screen for foodborne bacterial agents and rotavirus. Tests for adenovirus, astrovirus and NLVs s hould be secondary. The cost-effectiveness of including the EIAs for lactof errin and G. lamblia in the routine testing protocol needs to be evaluated.