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During M , Hoogenboom-Verdegaal AMM , Engels GB , Peerbooms PGH , Benink RS

24 p in Dutch   1993

Toon Nederlands

English Abstract
This report describes a collaborative study carried out by the Regional Laboratory of Amsterdam and the National Institute of Public Health and Environmental Protection (RIVM), to improve the method for isolating Yersinia spp, from stools of patients with complaints of gastro-enteritis. During a period of one year, the Regional Laboratory of Amsterdam examined 1007 faecal samples for the presence of Yersinia spp, using 6 different methods. Best results were obtained with enrichment in physiological saline with phosphate buffer 0.01 M, pH 7.2 (PBS) during 7 days at 4 degrees C followed by inoculation on and incubation of cefsulodin irgasan novobiocine agar (CIN) during 24 and 48 hours at 37 degrees C. This met gave an isolation percentage of 1.4%. However drawback of this method is the long incubation period. This makes the method unpractical for primary diagnostical use. Therefore improvement of the enrichment was investigated. Tests were carried out at the RIVM, to examine the possibility of increasing the growth rate of Yersinia spp. and decreasing the incubation time by adding glucose and peptone to PBS. Increase of the glucose concentration in PBS+peptone seemed to have little effect on the groth rate of Yersinia. Buffered peptonwater (BPW) was used as an alternative medium. Comparison of BPW with glucose and PBS with glucose showed that BPW was superior. Evaluation took place by examining 1014 faecal samples from patients with complaints of gastroenteritis by the Regional Laboratory of Amsterdam using 4 isolation methods including enrichment in PBS and BPW. Of these methods, enrichment in Rappaport according to Wauters (RVW) and enrichment in PBS gave the best results. The difference with former results using RVW by the Regional Laboratory of Amsterdam is caused by quality improvement due to introduction of a quality assurance system for the media. Apparently the exact composition and preparation of Rappaport-broth according to Wauters is very critical. It is recommended that direct inoculation on CIN should take place and when clinical advantage is expected, enrichment in RVW could take place. When the low isolation frequency and long incubation periods are regarded, it doesn't seem sensible to perform "cold" enrichment methods for routine investigation of faeces for the presence of Yersinia spp.


RIVM - Bilthoven - the Netherlands - www.rivm.nl

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RIVM - Bilthoven - Nederland - www.rivm.nl

( 1993-01-31 )