Actinomyces filaments usually occur in 'clumps' whereas nocardia are more
diffuse. Both elicit an acute inflammatory response in 'normal' individuals.
Both  are also positive with Gomori's methenamine silver stain and the
filaments of actinomyces are Gram positive (I don't know about nocardia). 
The filaments are much finer than those of true fungi.

Alan Brownhill
Birmingham Children's Hospital
UK

> -----Original Message-----
> From:	p=NHS NATIONAL
> INT;a=NHS;c=GB;dda:RFC-822=spoelstr(a)numbat.murdoch.edu.au; 
> Sent:	22 January 2001 01:55
> To:	p=NHS NATIONAL
> INT;a=NHS;c=GB;dda:RFC-822=histonet(a)pathology.swmed.edu;
> Subject:	PAS/norcadia
> 
> Dear histoneters, we are having trouble distinguishing Norcadia and
> Actinomyces on a paraffin section. The texts I've consulted don't list
> norcadia giving a pas positive reaction. The organism we have has pas
> positive mycelium within a sulpur-granulated pustule. 
> 
> Thanks in advance 
> 
> Gerard Spoelstra
> School of Biomedical Science
> Murdoch University
> Western Australia
>  
>