Table 1.
Target organisms: primary diagnostic methods
| Methods | Reference | |
|---|---|---|
| Bacteria | ||
| Salmonella spp.* | Direct plating – xylose lysine deoxycholate (XLD) agar. Enrichment culture – mannitol selenite broth and subculture onto XLD agar | National standard operating procedure B30 |
| Shigella spp.* | Direct plating – XLD agar | National standard operating procedure B30 |
| Campylobacter spp.* | Direct plating – modified cefeoperazone, charcoal deoxycholate (CCD) agar | National standard operating procedure B30 |
| Escherichia coli O157* | Direct plating on cefixime tellurite sorbitol MacConkey (CT-SMAC) agar. Enrichment in modified tryptone soya broth with novobiocin | National standard operating procedure B30 |
| Clostridium difficile | C.DIFF CHEK-60 and TOX A/B QUIK CHEK (TechLab, USA) | National standard operating procedure B10 |
| Yersinia enterocolitica* | Direct plating – cefsulodin irgasin novobiocin (CIN) selective agar | National standard operating procedure B30 |
| Vibrio spp.* | Direct plating – thiosulphate citrate bile salt sucrose (TCBS) agar and alkaline peptone water (APW) enrichment | National standard operating procedure B30 |
| Aeromonas spp. | Direct plating – Aeromonas selective agar | National standard operating procedure B30 |
| Clostridium perfringens* | Direct plating – neomycin fastidious anaerobe agar | National standard operating procedure B30 |
| Protozoa | ||
| Cryptosporidium spp. | Stain using auramine-phenol and examined using an incident-light fluorescent microscope for characteristic oocysts | National standard operating procedure B31 |
| Ova, cysts and parasites* | Direct and concentration microscopy | National standard operating procedure B31 |
| Viruses | ||
| Adenovirus | ProSpecT Adenovirus EZ Microplate assay (Oxoid Ltd, UK) | |
| Rotavirus | ProSpecT Adenovirus EZ Microplate assay (Oxoid Ltd, UK) | |
| Norovirus | Primary test: internally controlled, one-step, real-time RT–PCR assay for norovirus detection and genogrouping | Rolfe et al. [33] |
| Confirmatory test: RIDA®GENE Norovirus V real-time RT–PCR (R-Biopharm Rhône Ltd, UK) | ||
All positive isolates were sent to the relevant reference laboratory and confirmed.
Notes: (1) All patients screened for Salmonella spp., Shigella spp., Campylobacter spp. and Escherichia coli O157, except convalescent cases of previous isolates, and contacts of positive cases. (2) If clinically indicated, patients who fulfilled any of the following criteria were screened for Clostridium difficile: antibiotic-associated diarrhoea, diarrhoea in hospitalized patients aged ⩾2 years; pseudomembranous colitis; and diarrhoea in patients aged >65 years, children with Hirschsprung's Disease. (3) If clinically indicated, patients who fulfilled any of the following criteria were screened for Yersinia enterocolitica: acute diarrhoea, mesenteric lymphadenitis, terminal ileitis, pseudo-appendicitis, septicaemia, metastatic infections, immunological sequelae (e.g. reactive arthritis). (4) If the clinical information indicated a history of foreign travel then specimens were tested for Vibrio spp. (5) If the clinical information indicated a history of contact with untreated water then specimens were tested for Aeromonas spp. (6) Investigation of suspected food poisoning caused by Clostridium perfringens was performed if clinical information was relevant, after consultation with medical microbiologist. (7) If clinically indicated, patients who fulfilled any of the following criteria were screened for Cryptosporidium: symptomatic patients from the community, emergency hospital admissions; paediatric wards; immunocompromised patients. (8) If clinically indicated, patients who fulfilled any of the following criteria were screened for ova, cysts and parasites: liquid stools from the community, emergency hospital admissions; paediatric wards; a history of foreign travel; persistent diarrhoea; eosinophilia; malabsorption or AIDS. (9) Specimens from children aged ⩽6 years with a history of diarrhoea and vomiting were examined for rotavirus and adenovirus serotypes 40, 41. (10) Norovirus was only investigated in association with outbreaks in the community and healthcare setting.