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.
