Dear Carol,
I'm not in Australia but the requirements will very likely depend on the status of yr product / process, eg RTE ?.
For example, here is one Australian scenario for meat, I daresay this may be as tough (no pun intended) as it gets (but see below) -
Regulatory guidelines for the control of Listeria.pdf 72.84KB
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(there is also a detailed [generic] set of [Australian] environmental testing procedures for Listeria elsewhere on this forum)
Logically the testing will be risk associated with the product / process / consumer / history, eg the species previously mentioned for starters but practically one heck of a lot of work is potentially envisageable.
No comparative data AFAIK but I suspect that for food processing, USA is probably the World's No1 environmental test requirer (perhaps due historical events / laudable awareness of responsibility to consumer / microbiological safety know-how).
I'm only guessing but, with the exception of previous validated disaster events, in most locations, I would predict only the basics, eg plate count / indicators, (+/-) listeria are legal contenders. Typical sampling routines for pathogens like Salmonella tend to be statistically questionable when negative results are examined.
Interesting to see some geographical input ??
Rgds / Charles.C