A new approach to laboratory diagnostic of infectious gastroenteritis

Abstract number: 1134_03_73

Olesen B., Hansen D.S., Tybring H., Hansen A., Olsen K.E.P., Bruun B.G.

Objectives:  

In order to optimize use of laboratory facilities and ensure flexibility in relation to current epidemiology, a new approach to laboratory diagnosis of infectious gastroenteritis was applied: choice of examinations for the various pathogens was defined by the demographic, clinical and epidemiological information submitted on the request form.

Methods:  

From April 1-August 31, 2004, hospitals and general practitioners submitted a request form with the following information together with the stool sample(s): 1) acute diarrhoea or persistent diarrhoea (duration > 2 weeks); 2) bloody stools; 3) recent history of foreign travel; 4) > 2 persons with similar symptoms in the surroundings; and 5) nosocomial infection. Based on this information, microbiological analyses were performed according to predefined algorithms. Examination for Salmonella, Campylobacter¸ Yersinia, Shigella, Clostridium difficile and Vibrio spp. were done by culturing. Verotoxin-producing E. coli (VTEC), enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC) and enteroinvasive E. coli (EIEC) were identified by PCR of virulence genes and serotyping. Rota- and adenovirus were detected by antigen tests, norovirus by PCR and parasites by microscopy.

Results:  

In the study period our department examined 2,463 stool samples from 1,242 patients. Preliminary results indicate that 501 patients had acute diarrhoea, 13% of these were infected with Campylobacter, 3% with Salmonella, and 1% each with VTEC, ETEC and rotavirus; 573 patients had persistent diarrhoea, 4% of these were infected with Campylobacter, 1% each with Salmonella and Giardia lamblia; 260 patients had a history of recent foreign travel, 8% of these were infected with Campylobacter, 5% with Salmonella, 4% with Giardia and 3% with ETEC; 77 patients had bloody stools, 16% of these were infected with Campylobacter, 7% with VTEC and 1% with Salmonella. An outbreak of VTEC O157:H7 occurred among visitors to a local petting farm. Sheep and goats on the farm were found to be colonized with O157:H7 with the same distinct PFGE pattern as isolates from the patients.

Conclusions:  

The new approach to microbiological examination of stools according to predefined criteria has a number of advantages: better patient management; collection of microbiological data on defined patient groups, hopefully optimizing use of laboratory facilities; and flexibility regarding adaptation to current epidemiological knowledge.