Veld PH in 't ,
Hoekstra JA ,
Strijp-Lockefeer NGWM ,
Notermans SHW
54 p
in Dutch
1991
Toon Nederlands
English Abstract Reference materials containing Listeria monocytogenes
were tested in a collaborative study held in june 1989. Fourty laboratories
participated. Each laboratory examinated 25 samples by 2 methods. For each
method 5 of the 25 test samples were negative control samples (negative for
Listeria). One method was standardized and used by all laboratories
(Standard Method), the other was a method chosen by participating laboratory
(OWN method). The median contamination level of the capsules was 9.27.
Based on a lognormal distribution at least 19 out of 20 isolations should be
made. With the Standard Method 97% of the capsules were found positive and
85% of the laboratories made at least 19 isolations. The OWN method gave
significantly less isolations ; 85% of the capsules were found positive and
55% of the laboratories made at least 19 isolations. Four laboratories
(10%) reported false positive isolations with the negative control samples.
Concluded was that the Listeria monocytogenes reference materials are
suitable for testing laboratory performance.
